thThe 10 International Symposium
on Water Environment Systems---with Perspective of Global Safety(December 8thth– 9 ,2022)

Department of Civil and Environmental Engineering
Graduate School of Engineering
Tohoku University

Sponsors
GP-RSS Program
International Joint Graduate Program in Resilienceand Safety Studies of Tohoku University
http://gp-rss.tohoku.ac.jp/

SyDE Program
WISE Program for Sustainability in the Dynamic
Earth of Tohoku University
https://syde.tohoku.ac.jp/

Tohoku University
Department of Civil and Environmental Engineering,
Graduate School of Engineering, Tohoku University
http://www.eng.tohoku.ac.jp/

Organizers
Dr. So KAZAMA
Dr. Yu-You LI
Dr. Daisuke SANO
Dr. Keiko Udo
Dr. Daisuke KOMORI
Dr. Kengo KUBOTA
Dr. Rajapaksha Mudiyansekage Janaka Bamunawala
Dr. Yusuke Hiraga(Professor, Tohoku Univ)(Professor, Tohoku Univ)(Professor, Tohoku Univ)(Professor, Tohoku Univ)(Associate Professor, Tohoku Univ)(Associate Professor, Tohoku Univ)(Associate Professor, Tohoku Univ)(Research Associate, Tohoku Univ)

Secretariats
Dr. Yu QIN
Dr.Tao YAMAMOTO
DC Student, Zibin LUO
DC Student, Juntong HA
DC Student, Shitong ZHOU(Assistant Professor, Tohoku Univ)(Research Fellow, Tohoku Univ)(Tohoku Univ)(Tohoku Univ)(Tohoku Univ)

th
The 10 International Symposium on Water Environment Systems---with Perspective of Global Safety

PARTICIPANTS
01

Agro-Environmental Protection Institute, China
Haixin GUO
Bingkun CHEN

02

Fukushima University, Japan
Yoshiyuki YOKOO
Sora MARUTA
Yuki KUSAKABE
Sheikh Hefzul BARI

03

University of Moratuwa, Sri Lanka
Luminda GUNAWARDHANA

07

Associate Professor
Senior Lecturer

Tohoku Institute of Technology, Japan
Keisuke ONO

08

Associate Professor

Shandong University, China
Qigui NIU

06

Associate Professor

King Mongkut's University of Technology Thonburi, Thailand
Chaiwat EKKAWATPANIT

05

Professor
Student
Student
Student

National Research Centre, Egypt
Samir I. GADOW

04

Professor
Student

Lecturer

Malang State University, Indonesia
Eli Hendrik SANJAYA

Lecurer

09

Xi'an University of Architecture and Technology, China

10

Shanghai University, China

11

China Agricultural University, China

Xuanyu ZHAI
Xiaohuan YANG
Ruixin WU
Yanyan LI
Jiahao ZHANG

12
13

Student
Student
Student
Student
Student

Suzhou University of Science and Technology, China
Yixiao LIU
Yuqin FAN

Student
Student

Nanjing Tech University, China
Xiang LI
Yang YANG
Chen-Shun LU

Student
Student
Student

th
The 10 International Symposium on Water Environment Systems---with Perspective of Global Safety

Tao YAMAMOTO
Postdoc Researcher
Kampachiro URASAKI
Student
Yanxiao WEI
Student
Wenzhao ZHAO
Student
Ziang HE
Student
Shitong ZHOU
Student
Weiyi WANG
Student
Juntong HA
Student
Abeygunasekara HASHANI
Student
Amalia Naﬁsah Rahmani IRAWAN
Student
Sartsin PHAKDIMEKStudent
Shoichi KUROSAWA
Student
Ayaka OKAMOTO
Student
Kumudu Madhawa KURUGAMA
Student
Atsuya IKEMOTO
Student
Andre FORTES
Student
Mohammad Naser SEDIQI
Student
Muthiah SADIDAH
Student

PARTICIPANTS
PARTICIPANTS

14 Tohoku university, Japan

Schedule(GMT+9)
8 Dec (THUR)
10:00~12:00
9 Dec (FRI)
09:00~09:05
09:05~09:10
Session 1
09:10~09:22
09:22~09:34

09:34~09:46

09:46~09:58
09:58~10:10
10:10~10:22

10:22~10:34

10:34~10:46
10:46~10:58

10:58~11:10

11:10~11:22

11:22~11:34
11:34~11:46

11:46~11:58
11:58~12:10

12:10~13:00

Fieldwork
Opening remarks
Group photo
Oral session I
Development of a HCR-BrISH for detection of environmental microorganisms.
--Kampachiro URASAKI, Tohoku Univsity.
Removal of four RNA viruses from swine wastewater by AnMBR the interplay between adsorption,
rejection and virus type.
--Xuanyu ZHAI, Xi'an University of Architecture and Technology.
Highlighting the key role of temperature and chemical environment in pathogen inactivation ofanaerobic digestion of pig manure.
--Jiahao ZHANG, China Agricultural University.
Eﬀective and Selective Removal of Phosphate from Water by Functional Carbon.
--Bingkun CHEN, Agro-Environmental Protection Institute.
Anammox Microorganisms Diversity in Sediment of Reservoir Located in Indonesia.
--Eli Hendrik Sanjaya, Malang State University, Indonesia.
Refractory dissolved organic matter as carbon source for advanced nitrogen removal from maturelandﬁll leachate: A review and prospective application.
--Ruixin WU, Shanghai University.
Achieving Stable Mainstream Partial Nitritation-Anammox Process by SuccessfulRegulation ofNitrite-Oxidizing Bacteria.
--Yanxiao WEI, Tohoku University.
Experimental study on two-stage PN/HAP-A process for treating garbage methane fermentation liquid.
--Wenzhao ZHAO, Tohoku University.
Emerging onsite electron donors for advanced nitrogen removal from anammox eﬄuent of leachatetreatment: A review and future applications.
--Yanyan LI, Shanghai University.
Preparation of a spherical biochar colloidal probe and its application in deciphering the mechanismof biochar mitigating membrane fouling.
--Xiaohuan YANG, Xi'an University of Architecture and Technology.
High solid of co-digestion performance of lipid waste and food waste by a thermophilic Hollow Fiberanaerobic membrane bioreactor.
--Ziang HE, Tohoku University
Eﬀects of oleate loads on methanogenesis under mesophilic and thermophilic conditions.
--Xiang LI, Nanjing Tech University.
Combining Steam Injection with Hydrodynamic Cavitation for Sludge Pretreatment to Improve SludgeSolubility and Digestion Performance.
--Shitong ZHOU, Tohoku University.
Inﬂuence of nitrate as electron acceptor on Nap anaerobic biodegradation.
--Qigui NIU, Shandong University.
Current options in the treatment of agricultural drainage wastewater.
--Samir I.GADOW, National Research Centre, Egypt.

Lunch breakSchedule(GMT+9)
13:00~14:30 Poster session
Poster exhibition (Room A)
An overview of sewage treatment for human heath safety in the Song Dynasty.
--Yixiao LIU, Suzhou University of Science and Technology.
Performance comparison of Anammox process with EDTA chelation of Fe(III) and Fe(III) salts addition.
--Yang YANG, Nanjing Tech University.
Successful demonstration of a pilot-scale internal circulation reactor integrated with partial nitritationanammox for the treatment of real membrane-manufacturing wastewater.
--Yuqin FAN, Suzhou University of Science and Technology.
Impacts of diﬀerent Biochar/Ni types on the anaerobic digestion of high salinity wastewater.
--Chen-Shun LU, Nanjing Tech University.
Eﬀect of aeration intensity on a compact bioﬁlm reactor for rural domestic sewage treatment in China:
pollutant removal performance and hydrodynamic behavior.
--Weiyi WANG, Tohoku University.
Eﬀect of up-ﬂow anaerobic sludge blanket reactor treating methanolic wastewater by adding complexaccelerant.
--Juntong HA, Tohoku University.

Poster exhibition (Room B)
Predictive numerical modeling of landslide susceptibility:A case study for Uma Oya catchment,
Sri Lanka.
--Abeygunasekara HASHANI, Tohoku University.
Validation of awatershed storage eﬀects for the analysis of climate change.
--Sora MARUTA, Fukushima University.
Assessment of the chemical compositional characteristics as mass movements in granite zone.
--Yuki KUSAKABE, Fukushima University.
Population Movement caused by Flood Damage at City Level.
--Ayaka OKAMOTO, Tohoku University.
Innovative ensemble approach of spatial prediction of ﬂood using bivariate index of entropyand support vector machine models.
--Kumudu Madhawa KURUGAMA, Tohoku University.

Poster exhibition (Room C)
Understanding drought risk in the coastal region of Bangladesh using gridded meteorological data.
--Sheikh Hefzul BARI, Fukushima University.
Use of Irrigation reservoirs to reduce inundation depth by ﬂooding.
--Atsuya IKEMOTO, Tohoku University.
Preliminary Analysis of Flood Events and Human-ﬂood Interactions in Cascade Dams Area in CitarumWatershed, Indonesia.
--Muthiah SADIDAH, Tohoku University.
Evaluation on high-altitude snow observation for snowmelt ﬂood forecasting.
--Shoichi KUROSAWA, Tohoku University.
Satellite and UAV derived vegetative roughness in Nanakita river: case of Typhoon Hagibis.
--Andre FORTES, Tohoku University.

Schedule(GMT+9)
Session 2 Oral session II
14:30~14:55

Climate risk and vulnerability assessment (CRVA) framework for the built environment:
A case study in SEZAD industrial zoneYixiao LIU, Suzhou University of Science and Technology--Luminda GUNAWARDHANA, University of Moratuwa.

14:55~15:20

Climate Change Adaptation using Managed Aquifer Recharge.
--Chaiwat EKKAWATPANIT, University of Technology Thonburi.

15:20~15:45

Minecraft as a tool for disaster education: A case study of ﬂood inundation in Fukushima, Japan.
--Keisuke ONO, Tohoku Institute of Technology.

15:45~16:00

Spatio-temporal projection of the change in sustainability of Kabul River Basin under SSP scenarios.
`--Mohammad Naser SEDIQI, Tohoku University.

16:00~16:15

Identifying Landslides Using SAR, Optical Imagery and Spatial indices in Google Earth Engine.
--Sartsin PHAKDIMEK, Tohoku University.

16:15~16:30

Coﬀee break

16:15~16:45

Decadal variations of drought indicators in Indonesia from 1981 - 2020.
--Amalia Naﬁsah Rahmani IRAWAN, Tohoku University.

16:45~17:00

Study of Adaptation Measures for Flood Damage Mitigation by Adopting Eﬀect of Climate Change.
--Tao YAMAMOTO, Tohoku University.

17:00~17:25

A data-based modeling approach of rainfall-runoﬀ processes: its development history and a blueprint
for the future.
--Yoshiyuki YOKOO, Fukushima University.

17:25~17:35

Closing Remarks

The 10th International Symposium on Water Environment Systems----- with Perspective of Global Safety(Dec. 8th ~ 9th , 2022)

GP-RSS & SyDe
Tohoku University

Development of an HCR-BrISH for environmental microorganisms○ Kampachiro URASAKI1*, Yu-You LI 1 & Kengo KUBOTA2
1

Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University,
Miyagi 980-8579, Japan.
2
Department of Frontier Sciences for Advanced Environment, Graduate School of Environmental Studies, Tohoku
University, Miyagi 980-8579, Japan.
*
E-mail: kampachiro.urasaki.p1@dc.tohoku.ac.jp

Abstract
Electron microscopy enables to detect the microbial cells with high spatial resolution. In situ hybridization thatcan label the microbial with specific element has been developed (e.g., Gold-ISH). But there is no report that canlabel microbial cells phylogenetically with other element. In this study, we attempted to develop a novel brominelabelling method, “HCR-BrISH (hybridization chain reaction-bromine in situ hybridization)” to detect microbial
cells phylogenetically by electron microscopy. An HCR-BrISH protocol was optimized based on HCR-FISH
protocol. In HCR-BrISH protocol, some thymidines in amplifier probes were replaced to bromodeoxyuridines. As
a result, Bromine signal was not obtained in EDX spectrograph although labelling amplifier probes tomicrobial cells was confirmed.
Keywords: HCR-ISH; Bromodeoxyuridine (BrdU); Scanning electron microscopy; Energy Dispersive Xray Spectroscopy
1 Introduction
FISH (fluorescence in situ hybridization) is widely used invarious fields because it can detect microorganisms at singlecell resolution without cell cultivation and DNA/RNA
extraction. In recent years, detection using X-ray-based
techniques, e.g., SEM (scanning electron microscopy), arebecoming mainstream due to their high spatial resolution. For
X-rays detection, labeling the microbial cells with heavy
elements is necessary. In this study, bromine is selected aslabelling element of the microbial cell. We proposed the
TSA-BrISH (tyramide signal amplification-bromine in situ
hybridization) in the previous report; however, in TSABrISH, bromine labeled to the microbial cell was not able tobe detected by SEM-EDX [1]. In this report, we propose“HCR-BrISH (hybridization chain reaction-BrISH).” An
HCR-BrISH protocol uses an HCR-FISH protocol [2] andBrdU (bromodeoxyuridine). HCR is an extension reaction of
two amplifier probes. BrdU is a nucleoside analogue of dT(thymidine). In this report, we attempted to label microbial
cells with a high density of bromine by performing HCRBrISH using amplifier probes in which dT was replaced by
BrdU.

probe-H1 were labeled with Cyanine 5 and Alexa Fluor 488,
respectively, in order to observe the microbial cells by
epifluorescence microscopy. Initiator probe and amplifierprobes were purchased from TSUKUBA OLIGO SERVICE
CO., LTD and Japan Bio Services Co.,LTD, respectively.

2 Materials and methods
2.1 Sample preparation
The strain used in this study was Comamonas testosteroni.
The strain was cultivated in LB medium at 37˚C withagitation. During exponentially growth phase, the cell was
fixed in a 4% paraformaldehyde solution in phosphatebuffered saline (PBS; 150 mM NaCl, 20 mM PO43- [pH7.4])
for 12 h at 4oC, and stored in ethanol/PBS solution at -20˚C.
2.2 HCR-BrISH
The scheme of HCR-BrISH is shown in Figure 1. The
protocol was in accordance with “quick HCR-FISH” method[2] except the amplifier probes. The probe information wasshown in Table 1. Two sets of amplifier probes wereprepared. In set A, nine dTs were replaced to BrdU. In set C,
30 dTs were replaced to BrdU. Initiator probe and amplifier

3 Results and discussion
Figure 2 shows the fluorescence images of C.testosteroni
detected by epifluorescence microscopy. Cyanine 5
fluorescence signal (middle panel) indicates the initiator
probe successfully hybridized with ribosomal RNA. Alexa
Fluor 488 fluorescence signals (under panel) indicate themicrobial cells were labeled with amplifier probes. The
fluorescence signal of set C was tended to be weaker than thatof set A. It is speculated that higher replace number of BrdU
inhibited amplification efficiency.
Figure 3 shows the secondary elecbtron images and EDX
spectrograph of C.testosteroni obtained by SEM analysis.
EDX spectrograph showed no bromine peak from the target
cells whichever the amplifier probe used, set A or set C.

1

The 10th International Symposium on Water Environment Systems----- with Perspective of Global Safety(Dec. 8th ~ 9th , 2022)

4 Conclusions
We attempted to develop “HCR-BrISH”, a novel highsensitive bromine labelling method. The labelling of
amplifier probe to the microbial cells was confirmed;
however, labeled bromine density was insufficient to be
detected by SEM-EDX.

Reference[1] Kampachiro Urasaki, et al., Development of a BrISH forenvironmental microorganisms, The 9th International
Symposium on Water Environment Systems - with
Perspective of Global Safety, 2021/11/25-26, Online, Poster.
[2] Takashi Yamaguchi, et al., (2015). Rapid and sensitive
identification of marine bacteria by an improved in situ DNA
hybridization chain reaction (quickHCR-FISH). Systematicand applied microbiology, 38(6), 400-405.

2

GP-RSS & SyDe
Tohoku University

The 10th International Symposium on Water Environment Systems----- with Perspective of Global Safety (Dec. 8th ~ 9th , 2022)

GP-RSS & SyDe
Tohoku University

Removal of four RNA viruses from swine wastewater by AnMBR theinterplay between adsorption, rejection and virus type
○ Xuanyu Zhai1, Baolei Wu2, Jinfan Zhang1 & Rong Chen 1,3*
Key Lab of Environment Engineering, Shanxi Province, Xi’an University of Architecture and Technology, No.
13 Yanta Road, Xi’an 710055, PR China
2
Vanke School of Public Health, Tsinghua University, Beijing 100008, PR China
3International S＆T Cooperation Center for Urban Alternative Water Resources Development, Key Laboratory ofNorthwest Water Resource, Environment and Ecology, MOE, Xi’an University of Architecture and Technology,
No. 13 Yanta Road, Xi’an 710055, PR China*
E-mail: chenrong@xauat.edu.cn
Abstract
Anaerobic membrane bioreactor (AnMBR) is widely used in swine wastewater, but there were few studies on theremoval of RNA viruses from swine wastewater by AnMBR. In this study, the interplay between adsorption,
rejection and virus type of porcine hepatitis E virus (HEV), porcine kobuvirus (PKoV), porcine epidemic
diarrhoea virus (PEDV), and transmissible gastroenteritis coronavirus (TGEV) was systematically investigated in
AnMBR. Results revealed that the viruses concentration on the solid phase (73%~95%) was higher than in theliquid phase, indicating that most of the viruses were attached to the solids in the mixed liquor. In addition,
membrane rejection experiments showed that membrane pore foulants (22%~76%) played a major role in therejection of viruses by the membrane.
Keywords: Anaerobic membrane bioreactor (AnMBR); High concentration organic wastewater; Virus removal;
Virus adsorption; Membrane fouling.
1

1 Introduction
Swine wastewater harbor a large amount of infectious
viruses, in terms of the species and magnitude, among which
RNA viruses was paid more attention for its higher mutation
rates, cross-species transmission risk, and huge economic
losses. Swine wastewater is characterized by high solids
content and poor hydrolysis efficiency, while AnMBR
enables the separation of sludge retention time (SRT) andhydrolysis retention time (HRT), enhancing further
degradation of less biodegradable organic matter. Meanwhile,
membrane in AnMBR can act as an important barrier against
viruses.
In this study, the removal of HEV, PKoV, PEDV andTGEV from swine wastewater was investigated by AnMBR.
The virus adsorption of the mixed liquor in the bioreactor was
analyzed and the partitioning of viruses in the solid-liquid
phase of the mixed liquor was studied. In addition, the virus
rejection of fouled membrane was investigated.

2 Materials and methods
2.1 AnMBR and operation condition

Fig.1. Schematic of anaerobic membrane bioreactor
A built-in submerged AnMBR with a working volume of
2.5 L was used in this study to treat swine wastewater (Fig.1).
Polyvinylidene fluoride (PVDF) membrane was employedwith an average pore size of 0.22 𝜇m, HRT of 4 d. The mixed
liquor suspended solids (MLSS) was maintained steady at
72.10±1.93 g/L.
2.2 Samples
The influent and effluent were enriched by membrane andmixed liquor was separated into solid and liquid phases by
centrifugation at 10,000g for 1 h. Determination of sample
virus concentration by qPCR.
2.3Membrane contribution
Swine wastewater was filtered through the intact fouled
membrane, and the log removal value (LRV) obtained
represented the combined removal contribution of the cakelayer, organic foulants, inorganic foulants, irrecoverable
foulants and the pristine membrane. Subsequently, themembrane was rinsed with pressure water to remove the cakelayer and then the swine wastewater was filtered through themembrane. The LRV obtained represented the combined
removal contribution of organic foulants, inorganic foulants,
irrecoverable foulants and the pristine membrane. The
membrane was immersed in 0.1% NaClO solution for 24 h toremove organic fouling and then the sewage influent was
filtered through the membrane. The LRV obtained
represented the combined removal contribution of inorganic
foulants, irrecoverable foulants and the pristine membrane.
The fouled membrane immersed in a 10 g/L citric acidsolution for 4 h and then the swine wastewater was filteredthrough the membrane. The LRV obtained represented the
combined removal contribution of irrecoverable foulants andthe pristine membrane. Finally, the pristine membrane wasused to filter the swine wastewater and the LRV obtained
represented the combined removal contribution of thepristine membrane.

3 Results and discussion

3

The 10th International Symposium on Water Environment Systems

GP-RSS & SyDe----- with Perspective of Global Safety (Dec. 8th ~ 9th , 2022)

Virus Concentration（Log10 c/L）

(c)

Virus Concentration（Log10 c/L）

(b)

9

INF
EFF

HEV
8
7
6
5
4
3

1

9

3
5
7
time（day）

(d)
INF
EFF

PEEV
8
7
6
5
4
3

1

9

3
5
7
time（day）

9

INF
EFF

PKoV

8
7
6
5
4
3

1

9
Virus Concentration（Log10 c/L）

Virus Concentration（Log10 c/L）

(a)

3
5
7
time（day）

9

9

INF
EFF

TGEV

8
7
6
5
4
3

1

3

5
7
time（day）

9

Fig. 2. Virus concentrations for (a)HEV, (b)PKoV,(c)PEDV, and (d)TGEV in the AnMBR influent andeffluent.
3.2 biomass adsorption
The distribution of HEV, PKoV, PEDV and TGEV in thesolid and liquid phases of the mixed liquor were shown in
Fig.3. As shown in Fig.3a, most of the viruses were attachedto suspended particles (73-95%). Specifically, of these four
viruses, the sludge had the highest adsorption efficiency for
PKoV (95%) and the lowest for TGEV (73%). The
differential virus allocation rate between liquid and solid
phases in this study was probably due to the specific virus
type and surface characteristics. Indeed, Chaudhry[1] had
reported that MS2, phiX174, and fr with similar surface
electrical properties showed divergent biomass binding
preference.
The averaged concentrations of HEV, PKoV, PEDV andTGEV in the solid phases were 1.16, 2.08, 1.30 and 0.26 LRV,
respectively (Fig.3b). During the study period, the TMP
increased from 12.0 to 35.1 kPa and the virus concentrationin the mixed liquor was relatively constant, so the TMP was
not related to the virus adsorbed by the biomass.
liquid

8%

5%

solid

Virus Concentration(%)

27%

92%

95%

90%
73%

HEV

PKoV

(b)

5

10%

PEDV

TGEV

Virus Concentration（Log10 copies/L）

(a)

4

HEV
PKOV
PEDV
TGEV

3.3 Virus rejection by each membrane fouling component
The pristine membrane rejection removal values for HEV,
PKoV, PEDV and TGEV were 0.19, 0.40, 0.46, 0.66,
respectively, which might be related to the size of the virus(Fig.4a). HEV is an RNA virus of approximately 27-34 nm
in diameter, however the PVDF membrane employed in thisstudy had a nominal pore size of 0.22 𝜇m, which wasapproximately 10 times larger than the diameter of HEV.
Therefore, smaller diameter viruses were less effectively
retained by the pristine membrane and size sieving effect was
the main virus rejection mechanism of the pristine membrane.
Virus rejection by fouled membranes could be divided into
the five components acting on the viruses rejection: cakelayer, organic foulants, inorganic foulants, irrecoverable
foulants and pristine membrane, respectively (Fig.4).
Specifically, inorganic, organic and irreversible foulants
accounted for 1.53% of the total membrane resistance, they
contributed 71.27%, 75.57%, 22.18% and 49.49% of the total
membrane rejection rate for HEV, PKoV, PEDV and TGEV,
respectively. The pristine membrane accounted for 0.22% of
the total membrane resistance and retained 19-42% of thevirus. The cake layer made up 98.25% of the total membrane
resistance, but retained only 5-30% viruses. Therefore,
viruses were primarily retained by the pore foulants, followedby the pristine membrane, and finally the cake layer. The
pore foulants were the main contributor to viruses rejection
by the fouled membrane, and the membrane resistance waslow, so the rejection contribution per unit membrane
resistance was significant.
（a）

（b）

3.0
LRVm
LRVir
LRV-inorg
LRV-org
LRVc

2.5
2.0

98.25%LRV

3.1 Virus removal performance
During the investigation period of the AnMBR, HEV,
PKoV, PEDV and TEGV in the influent were 107.38±0.08,
108.14±0.32, 107.79±018 and 106.2±0.02 copies/L, respectively, whilethe virus concentrations in the effluent decreased gradually
over time. The averaged overall LRVs for HEV, PKoV,PEDV and TGEV were 1.62 ± 0.17, 3.05 ± 0.6, 2.41 ± 0.35
and 1.34 ± 0.31 logs, respectively (Fig.2). Of these four
viruses, the bioreactor had the highest removal efficiency for
PKoV and was the least removal efficiency for TGEV.

Tohoku University

0.31%

1.5

0.86%
1.0

0.36%
0.22%

0.5

Rc
Rp-inorg

0.0
HEV

PKoV

PEDV

Rp-org
Rir

Rm

TGEV

Fig.4. (a) The contribution of each membrane foulingcomponent to virus rejection (b) The filtration resistanceof each membrane fouling component.

4 Conclusions
The removal of viruses AnMBR was mainly achieved by
the biological attachment and membrane rejection. Viruses
accumulate heavily in the mixed liquor and wereconcentrated in the biomass (over 90%). The pore foulants
and the pristine membrane were the main drivers ofmembrane rejection. In addition, the biomass attachment
capacity and the pristine membrane rejection were related to
the virus type.

3

2

Reference
1[1] Chaudhry R. M., Holloway R. W., Cath T. Y., et al.
Impact of virus surface characteristics on removal
mechanisms within membrane bioreactors, Water Research,(2015) 144-152

0
12

17.2

21.8
TMP (kPa)

29.3

35.1

Fig. 3. Virus allocation rate in liquid and solid phases;(b) Virus concentrations in sludge particles at varying
TMPs.

4

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDe
Tohoku University

Highlighting the key role of temperature and chemical environment inpathogen inactivation of anaerobic digestion of pig manure○ Jia-Hao ZHANG1, Min LIN1, Wei QIAO1* & Renjie DONG1
1

College of Engineering, Biomass Engineering Center, China Agricultural University, Beijing 100083,
China.
*E-mail: qiaowei@cau.edu.cn; wayqiao@sina.cn
Abstract
Cost-effective hygienization of animal manure through anaerobic digestion was a long-standing challenge. Twostage AD process introducing 55 and 70 ℃ biological hydrolysis following a 37 ℃ reactor was thus studied andcompared to a parallelly operated mesophilic reactor at the same total HRT (30 days). The numbers of E. coli andfecal coliforms in the effluent of both the two-stage AD systems were much low and comparable. The inactivation
rate kh of E. coli in the 70, 55, and 37 ℃ reactors was 19.768, 0.936, and 0.032 h-1, respectively, which indicatedthe importance of temperature. At 37 ℃, acetate below 255 mg/L had no hygienization effects on E. coli, butammonium bicarbonate of 2800 mg/L could completely inactivate E. coli in 24h. The chemical environment-derived
impacts on pathogen inactivation were unexpected and need further studies.
Keywords: anaerobic digestion, pathogen inactivation, kinetics, temperature, chemical effects𝐶𝑁
log ( ) = −𝑘ℎ 𝑡
𝐶0

1 Introduction
Anaerobic digestion (AD) is a widely used technology totreat manure for pollution control, energy recycling, andpathogen inactivation. However, mesophilic AD cannot
effectively eliminate pathogens and the thermophilic process
required too much energy even though it had better
hygienization performance [1]. Two-stage AD that
introduces high temperatures for pathogen inactivation andthe subsequent mesophilic methane formation for process
stability control and saving energy input is therefore morepractical. During the AD process, the chemical environment
had significant changes, i.e. high acetate concentration in thefirst stage and the formation of NH4HCO3 in the second stage
methane reactor. So far, if the chemical environment cancontribute to pathogen inactivation and thus reduce thetemperature level was still unclear.
Therefore, this study aimed to improve the sanitization of
two-stage AD by introducing longer thermal treatment andverifying the temperature and chemical functionalparameters of pathogen inactivation.

(1)

2.4 Inhibition by chemicals
E. coli (ATCC 25922) type strain was selected for the
inhibition test. According to the actual concentration in MAD,
255 mg/L acetate and 1600 mg/L NH4HCO3 were added to
the LB broth separately, and the pH was adjusted to 7.4. Thenthe tubes were inoculated with E. coli pure culture andincubated at 37±1 ℃ for 24 h. Serial concentrations (0~0.25
mol/L) of NH4CO3, NH4Cl, and NaHCO3 were selected to
explore their inhibitory effect.

3 Results and discussion
3.1 Performance of pathogens inactivation
In Figure 1, the fecal coliforms and E. coli in MAD effluent
remained at 103-104 CFU or MPN/ml, while two-stage AD
systems reduced the fecal coliforms and E. coli that were
below the limit of China and the European Commission.
Although a small number of fecal coliforms was still present
in the 55°C reactor, they became undetectable in thesubsequent mesophilic reactor. A study reported that the
number of fecal coliforms and enterococci in sludge
remained high after 60 minutes of pasteurization at 80℃ [2].
The recovery of coliform bacteria and Enterococcus spp.
during the process of storage and farm utilization after the
MAD with 60 minutes of pasteurization at 70℃ was reported
by Bagge and De. These results are inconsistent with thisstudy, possibly because the longer thermal treatment time andother chemical factors have a positive effect on inactivating
pathogens, which makes hygienization performance better.
3.2 Kinetic models for E. coli inactivation
The inactivation of E. coli in AD conformed to the firstorder kinetic model shown in Figure 2. The constants kh
obtained for 70, 55, and 37 ℃ mono-reactor were 19.768,
0.936, and 0.032 h-1, respectively. It was reported the kh of E.
coli in the anaerobic storage of sludge was only 0.007 h-1 at
15 ℃ [3]. The constants kh of E. coli in the 25 ℃ storage andAD (37 ℃ and 52.5 ℃) of dairy manure were 0.004, 0.024,
and 0.075 h-1 [4]. The kh of MAD in the previous study is thesame as the result of this study, but notably, the kh of the hightemperature reactor is much lower than this study, perhaps

2 Materials and methods
2.1 Two-stage AD systems
TMAD system: 55 ℃ (5 d) + 37 ℃ (25 d)
HMAD system: 70 ℃ (5 d) + 37 ℃ (25 d)
MAD system: 37 ℃ (30 d)
All reactors were CSTR with a working volume of 4 L anda stirring speed of 100 rpm, and were fed once a day.
2.2 Pathogenic bacteria enumeration methods
Raw pig manure and AD effluent were sampled during thestable period for bacteria enumeration. The enumeration of E.
coli was conducted according to GB 4789.38-2012 using
VBR Agar-MUG. Fecal coliforms were enumerated using
the procedures described in GB 4789.39-2013.
2.3 Inactivation kinetics
During a feed period (24h), effluent from 37 ℃ monoreactor, 55 ℃, and 70 ℃ reactors were sampled at irregularintervals for E. coli detection. The First-order model [1] wasused to fit the E. coli inactivation, where CN and C0 were theconcentration of E. coli at a certain time and the beginning,respectively, and kh was the inactivation rate constant.

5

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
because the concentrations of ammonia or VFAs in ourreactor are higher and the heat may exacerbate theinactivation of pathogens by these chemicals [1].

GP-RSS & SyDe
Tohoku University

could not inhibit E. coli. But the inactivation effect wassignificant when adding the same moles NH4HCO3, whichindicated that the inactivation of E. coli was mainly related
to free ammonia and confirmed the previous study [1]. Park
demonstrated that the addition of Na2CO3 could enhance theinactivation of E. coli O157:H7 and Salmonella
Typhimurium DT104 during the storage of cattle manure.
There are few studies on the pathogens' inactivation ofalkalinity, and its mechanism needs to be further explored.

Figure 1 Reduction of fecal coliforms and E. coli

Figure 4 Inhibition of NH4+ / NH3 on E. coli

4 Conclusions
The hyperthermophilic temperature was not necessarily
adopted since the thermophilic already has acceptablehygienization performance. In a well-stable mesophilic
process, acetate was not a factor for the pathogens’
inactivation. In contrast, the NH4HCO3 that formed in theanaerobic degradation of organic matter was found to besignificantly effective to eliminate E. Coli. Taking theadvantage of the naturally formed chemical environment toinactivate pathogens would save the energy input and hightemperature would not be mandatory. Further studies arerecommended to investigate the mechanism behind it.

Figure 2 Inactivation of E. coli in a 24h feed cycle
3.3 Effects of chemicals on pathogen inactivation
The number of E. coli decreased at a slow rate in MAD and
it was necessary to investigate the effect of chemicals in the
MAD reactor. This study selected two intermediate productsin the AD environment: acetate and NH4HCO3, and exploredtheir inhibition on E. coli. The results showed (Figure 3) that
255 mg/L(pH7.4) acetate could not suppress the growth of E.
coli at 37 ℃. A study reported that the reductions of E. coli
and fecal coliforms did not increase with raisingconcentrations of VFAs to 2500 mg/L(pH7.5) [5]. Free VFAs
are more toxic than ionic VFAs because free VFAs can freely
permeate the cell membrane, then make the cytoplasm
acidified by ionizing to kill bacteria. However, few studies
on free VFAs are currently available.

Reference[1] Jiang Y, et al. Inactivation of pathogens in anaerobic
digestion systems for converting biowastes to bioenergy: A
review. Renew. Sust. Energ. Rev. (2020) 120:109654.
[2] Bonjoch X, et al. Resistance of Fecal Coliforms andEnterococci Populations in Sludge and Biosolids to Different
Hygienisation Treatments. Microb Ecol (2009) 57:478–83.
[3] Horan NJ, et al. Die-off of enteric bacterial pathogens
during mesophilic anaerobic digestion. Water Res. (2004)
38:1113–20.
[4] Pandey PK, et al. Escherichia coli persistence kinetics
in dairy manure at moderate, mesophilic, and thermophilictemperatures under aerobic and anaerobic environments.
Bioprocess Biosyst. Eng. (2015) 38:457–67.
[5] Arias DE, et al. Biogas production, waste stabilization
efficiency, and hygienization potential of a mesophilicanaerobic plug flow reactor processing swine manure andcorn stover. J. Environ. Manage. (2021) 284:112027.

Figure 3 Effect of chemicals on the growth of E. coli.
3.4 Inhibition effects of NH4+/NH3 on pathogen
The dose of 1600 mg/L for NH4+-N could effectively
inactivate E. coli. Results showed (Figure 4) that NH4Cl

6The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDe
Tohoku University

Effective and Selective Removal of Phosphate from Water
by Functional Carbon○ Bingkun Chen,1 Haixin Guo1*
1

Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China*

E-mail: haixin_g@126.com

Abstract
The waste plastic sheeting-derived functional carbon adsorbent doped with Ca metal was synthesized throughpyrolysis carbonization mixture of plastic sheeting and Ca(OH)2 with mechanochemical pretreatment.
Characterization results (e.g. SEM-EDS, FTIR, XPS) showed that Ca was successfully loaded on waste plastic
sheeting-derived functional carbon adsorbent. The phosphorus removal performance of Ca-PE was studied bybatch adsorption experiments, and the mechanism of phosphate adsorption was studied by SEM-EDS, FTIR, XPS
and XRD. The adsorption behavior of phosphates on the functional carbon prepared from waste plastic sheeting
was investigated by batch adsorption experiment and the mechanism was studied by XPS and XRD. The
adsorption isotherms of phosphate on this functional carbon were well described by the Langmuir model withhigh determination coefficients (R2>0.96) and the maximum adsorption capacity was 263.6 mg/g. The
quasi-second-order kinetic model could fitted well with the adsorption data. This study provides an experimental
basis for the effective and selective removal of phosphate from water by functional carbon and also provides abasis for the application of reducing the calcination temperature of carbon materials prepared by polyethylene.
Keywords: Functional Carbon; Phosphate adsorption; Polyethylene; Calcium hydroxide.
1 Introduction

2 Materials and methods

Phosphorus is an indispensable nutrient element in thegrowth process of aquatic plants existing in various forms
depending on the pH values of water, such as PO 43−,HPO42−
and H2PO4−. With the growth in human activity such as
household, agricultural and industrial, the phosphate
contamination of water has become a great concern [1].
Because the increasing phosphate concentration in
wastewater may cause eutrophication, leading to water
hypoxia, death of aquatic plants and animals, and damage towater quality[2]. Current treatment processes for phosphateremoval from wastewater include Chemical precipitation[3],biological[4] and adsorption[5]. Compared with othertechnology, the adsorption method has received much more
attention, because it is convenient, economical, highly
selective, less potential for secondary pollution. Especially,functional carbon which could be synthesized from waste
solid materials (e.g. agricultural solid waste, sewage sludge)
has been the most widely used adsorbent in water
treatment[6].
Waste plastic sheeting, one kind of agricultural solid
waste, has been widely used in the agriculturalindustry. Waste plastic sheeting exhibits high stability andcauses environmental pollution. In this work, Ca- modified
functional carbon materials were obtained from waste
plastic sheeting by pyrolysis carbonization mixture ofplastic sheeting and Ca(OH)2. The functional carbon
performance of this adsorbent was determined by theadsorption capacity performance of the phosphate fromwater. The phosphorus absorption effect of prepared carbon
material in water was studied by batch adsorption
experiment. The morphology of the synthesized Camodified functional carbon materials was studied by various
characterization methods, and its adsorption mechanism wasstudied.

All the chemicals and materials were purchased from the
Merck and Aldrich Chemical Reagent Co, Ltd (China). The
prepared adsorbent compounds were characterized by
SEM-EDS, FTIR (KBr), XPS and XRD spectra. The batch
adsorption experimental of phosphate on the preparedfunctional carbon was studied with 200rpm shaken.

3 Results and discussion
In order to explore the structural characteristics of Ca-PE
adsorbent, scanning electron microscopy (SEM) were
performed on the samples to observe the microstructure
information of the surface of the adsorbent material. As
shown in Figure 1(a,b), the surface of Ca-PE-500 is
relatively rough, while the surface of Ca-PE-800 is
relatively smooth. It is stated that Ca(OH)2 particles canbetter adhere to the surface of polyethylene at 500 °C, while
the difference in pore structure in the material is attributed
to the decomposition of Ca(OH)2, and the calcination
temperature of 800 °C may make Ca(OH)2 completely
thermally decomposed, thereby making the surface
smoother. Figure 1(c) is the product of polyethylene
calcination alone, we found that the product is an oily
substance, indicating that polyethylene calcination alone at
this temperature can not prepare carbon materials, andcalcination after incorporation of Ca(OH)2 can form carbon
materials as shown in Figure 1(d), which has a good ability
to adsorb phosphate in water.

7

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

(a)

(b)

(c)

(d)

adsorbents, XRD analysis was performed on Ca-PE-500 and
Ca-PE-800. The data was analyzed and processed using
Jade 6.0 and the results are shown in Figure 2. We can findthat there is almost no difference between the diffraction
peaks of the XRD patterns of the two materials, indicatingthat temperature treatment cannot change the compositionof the materials. The main characteristic peaks of Ca-PE are
from the Ca(OH)2 (PDF#04-0733) and CaO (PDF#28-0775)
phases. It can be further proved that Ca(OH)2 is successfully
loaded on polyethylene, and the appearance of CaO
diffraction peak may be due to the reaction of Ca(OH)2
components with H2O to form CaO during the calcinedmaterial.

Fig. 1. SEM images of (a) Ca-PE-500, (b) Ca-PE-800 and(c) carbon materials cannot be prepared by PE alone
and (d) carbon materials made by mixing calcium
The associated adsorption isotherms and kinetic
parameters are shown in Table 1. The adsorption isothermsof phosphate on this functional carbon were well describedby the Langmuir model with high determination coefficients(R2> 0.96) and the maximum adsorption capacity was 263.6
mg/g. This indicates that the effective adsorption surface of
Ca-PE in the process of phosphate adsorption is amonolayer homogeneous adsorption surface. The
quasi-secondary kinetic model R2 of both adsorbents isgreater than the quasi-first-order kinetic model R2, and thequasi-second-order kinetic model assumes that thephosphorus removal process of the adsorbent is controlled
by chemical rates (chemisorption). The chemical adsorption
process is mainly the chemical reaction of the metal cations
contained in the adsorbent with the phosphate anion in thesolution to form an insoluble precipitate or crystallization,that is, Ca2+ combines with PO43- to form hydroxyapatite(HAP) precipitation. This indicates that chemisorption plays
a dominant role in the phosphate adsorption process.
Table 1 Physical properties of biochar samples.
Langmuir model
Adsorbents

kL

qmax

(L/mg)(mg/g)

Ca-PE-500

0.0124

263.6

Ca-PE-800

0.0125260.3

pseudo-first-order model
k1

qe

(h-1)

(mg/L)

0.966

20.1

0.483

0.958

19.9

0.483

R2

GP-RSS & SyDe
Tohoku University

The combination of Ca(OH)2 and polyethylene calcination
can successfully attach Ca to carbon materials, have highadsorption capacity for phosphate in water, and significantly
reduce the calcination temperature of polyethylene
carbonization to generate carbon materials. The adsorption
isotherms of phosphate on this functional carbon were welldescribed by the Langmuir model with high determination
coefficients (R2>0.96) and the maximum adsorption
capacity was 263.6 mg/g. The quasi-second-order kinetic
model could fitted well with the adsorption data.
Ca-PE
removes the phosphate aqueous solution by chemical
precipitation and electrostatic interaction with phosphate toform calcium phosphate. The maximum adsorption capacity
was 263.6 mg/g. The characterization of SEM, XRD andother properties showed that the successful loading of
Ca(OH)2 made carbon materials on polyethylene, andgreatly reduced the calcination temperature of carbon
materials prepared by polyethylene and reduced energy
consumption. This study provides an experimental basis forthe effective and selective removal of phosphate from waterby functional carbon and also provides a basis for theapplication of reducing the calcination temperature ofcarbon materials prepared by polyethylene.

pseudo-second-order modelk2

qe(g/mg·h)(mg/L)

0.937

0.005

231.2

0.998

0.933

0.008

240.8

0.998

R2

4 Conclusions

Reference

R2[1] Tarayre, C.; De Clercq, L.; Charlier, R.;et al. New
perspectives for the design of sustainable bioprocesses forphosphorus recovery from waste. Bioresour. Technol. 2016,
206, 264–274.
[2] Yi, M.; Chen, Y. Enhanced phosphate adsorption on
Ca-Mg-loaded biochar derived from tobacco stems. Water
Sci. Technol. 2018, 78, 2427–2436.
[3] Tang C C, Liu M, Chen H M, et al. Research pr
ogress of adsorption and phosphorus removal technolog
y[J]. Technology of Water Treatment,2014, 40(9):1-7, 12(in Chinese).
[4] Feng J M. Research on phosphorus removal
performance and mechanism of the red soil substrate fillingsin constructed wetlands [D]. Shanghai: Shang hai Jiao Tong
University, 2014 (in Chinese).
[5] Cai R. Capture and reuse of phosphorus in entropaic
water by iron-impregnated biochar [D]. Chang sha: Hunan
Normal University, 2017 (in Chinese).
[6] Mitrogiannis, D.; Psychoyou, M.; Baziotis, I.; et al.
Removal of phosphate from aqueous solutions byadsorption onto Ca(OH)2 treated natural clinoptilolite.
Chem. Eng. J. 2017, 320, 510–522.

Fig. 2. XRD spectra of Ca-PE-500 and Ca-PE-800
materials
In order to investigate the effect of calcination
temperature on the phase composition of functional carbon

8The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDe
Tohoku University

Anammox Microorganisms Diversity in Sediment of Reservoir Locatedin Indonesia○ Eli Hendrik Sanjaya1*, Sitoresmi Prabaningtyas3, Suharti1, Hong Chen4, Yan Guo5 Mohd Fadhil
Md Din6 & Annisa Elchamida3
1

Department Chemistry, Malang State University, Indonesia.
Biotechnology Program, Department of Applied Sciences, Malang State University, Indonesia.
3 Department of Biology, Malang State University, Indonesia.
4
Key Laboratory of Water-Sediment Sciences and Water Disaster Prevention of Hunan Province, School of
Hydraulic Engineering, Changsha University of Science & Technology, Changsha 410004, China .
5
Department of Environmental Engineering, School of Energy and Environmental Engineering, Universityof Science and Technology Beijing, Beijing 100083, PR China.
6
Centre for Environmental Sustainability and Water Security (IPASA), School of Civil Engineering, Facultyof Engineering, Universiti Teknologi Malaysia, 81310 Skudai Johor, Malaysia.
*E-mail: eli.hendrik.fmipa@um.ac.id.
2

Abstract
Recently, anaerobic ammonium oxidation (anammox) process is common in treating ammonia richwastewater. However, it is still very limited in developing country. In both laboratory scale research and its
application in industry. Indonesia has a large waters area, which is very potential to be source of anammox
microorganism. However, studies on the topic of anammox are still lacking. Therefore, as a preliminary study for
anammox microorganisms isolation, this research investigated the diversity of anammox microorganism in thesediment of reserveoir. The New generation sequencing (NGS) was used for analyzing the microbial diversity.
The results show that the diversity of microorganisms in the sediments of the Selorejo and Karangkates reservoirs
has similarities at the level of medium diversity. At these two locations, several phyla, including the phylum
Firmiculus, Acidobacteria, Proteobacteria, Planctomycetes, Actinobacteria, and Bacteroidetes was found. The
phylum Proteobacteria has the most significant number of members, with four classes: Alphaproteobacteria,
Betaproteobacteria, Deltaproteobacteria, and Gammaproteobacteria. Therefore, in both reservoir has a highpotential to be a source of anammox microorganisms.

Keywords: Anammox, microbial diversity, reservoir
Thus, in this study, biodiversity and its potential as asource of anammox microbes in sedimentary waters of
Karangkates (KRT) and Selorejo (SLRJ) were carried out
based on NGS analysis of the 16S rRNA gene.

1 Introduction
The presence of anammox is found in various aquatic
environments and widely distributed in marine
environments [1] in estuaries [2][3] wetlands [4], lacustrine
ecosystems [5][6], rivers [7] [8], in surface and subsystemfreshwater [3][9] and subsurface natural wetlands andartificial wastewater treatment plant systems [10]. Researchon the application of anammox microbes in wastewater
treatment in several developed countries has been relatively
developed. However, research on anammox microbes inIndonesia is still minimal. There is no Indonesianindigenous anammox microbe. Thus, as an initial study, it isnecessary to analyze the diversity and potential of nitrite
and ammonia-degrading bacteria (anammox) in thesediments/reservoirs of Karangkates and Selorejo.
Currently, the method of microbial biodiversity analysis
that has high accuracy is the analysis of the 16S rRNA geneusing Next Generation Sequencing (NGS). The habitat ofanammox bacteria is found in aquatic environments such as
rivers, reservoirs, rice fields, to groundwater. In East Java,
Indonesia has several dams, two of which are Karangkates
and Selorejo Dams.

2 Materials and methods
Bacterial Biodiversity Testing with NGS (Next Generation
Sequencing)Parameters observed were the diversity, abundance, anddistribution of bacteria based on 16S rRNA analysis using
Next Generation Sequencing (NGS). The index was
calculated by the Shann-Wiener index (diversity of bacterial
communities), Shimpson index (species dominance),
Buzas-Gibson index (diversity and evenness), andBerger-Parker index (Species Abundance Distribution).

3 Results and discussion
Based on the results of the analysis of the 16S rRNA gene,it showed that the abundance of bacteria in both locations
was relatively high and tended to have an overall similarity
as indicated by the total number of OTUs (Operational
Taxonomy Units) of 9643 (in SLRJ) and 9645 (in KRT).
The Shanon-Wiener index of bacteria in SLRJ was 1247
and KRT 1322, indicating moderate diversity (1-3 moderate

9The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
categories). The data shows that the bacterial community
tends to show an uneven distribution of species abundance(Species Abundance Distribution). In the case of a linear
distribution, the fraction of the total individual sample
contributed by the most abundant species, known as theBerger-Parker index, synthetically describes the SAD of the
disturbed community.
There are similarities in discovering bacteria in the
Selorejo and Karangkates reservoirs, including the phylum
Firmiculus, Acidobacteria, Proteobacteria, Planctomycetes,
Actinobacteria, and Bacteroidetes. Phylum Proteobacteria
has
the
most
members,withfourclasses:
Alphaproteobacteria,
Betaproteobacteria,
Deltaproteobacteria, and Gammaproteobacteria.
The comparation of microbial diversity in Karangkater and
Selorejo Reservoir is shown in Table 1.
Table 1 Anammox Species Diversity in SLRJ and KRT

GP-RSS & SyDe
Tohoku University

Desulfulrivibrio

Desulfulrivibrio

alkaliphilus 1%

alkaliphilus 1%

Haliangium ochraceum

Haliangium ochraceum

1%

1%.

Enterobacteriaceae 1%

Enterobacterales 1%

Rhodanobacteraceae

Rhodanobacteraceae

1%

1%.

Xanthomonadaceae 1%
PlanctLimnoglobus roseus

Limnoglobus roseus

omycet2%, Tuwongella1%

esimmobilis 1%,

SLRJ

KRT

Aquisphaera

Aquisphaera

FirmicB thuringiensis 2%,

Bacillus thuringiensis

giovannonii 2%,

giovannonii 1%

ulus

Bacillus cereus 0,9%2%,

Planctomycetes

Paenibacillus 1%

Bacillus cereus 1%,

bacterium ETA_A1 1%

Clostridium 1%

Bacillus asanii 1%

Paeniclostridium

Paenibacillus 1%

sordellii 0.9 %clostridiales 3%

Acidob

Luteitalea pratensis

Luteitalea pratensis

acteria

3%,

4%,

Candidatus solibacter

Candidatus solibacter

usilatus 5%

usilatus 5%

Candidatus koribacter

Candidatus koribacterversatilis 7%,

versatilis 7%,

Terriglobus 1%,

Terriglobus 2%,

Acidisarcina

Acidisarcina

polymorpha 1%

polymorpha 1%.

ProteoRhodospirillaceae 1%,

Rhodospirillales 1%

bacteri

Xanthobacteraceae

Methylocystis 0,9%,

a

0,9%,

Bradyryzhobium 0,9%,

Methyloceanibacter

Hyphomicrobium 1%,

0,9%, Methylocystis

Rhodoplanes sp.

1%, Bradyryzhobium

Z2-YC6860 5%

1%, Hyphomicrobium

Varlovorax sp. PMC12

nitrativorans 1%,

2%,

Rhodoplanes sp.

Cupriavidus 1%,

4 Conclusions

Reference[1] Schmid, M. C., et al., Anaerobic ammonium-oxidizing
bacteria in marine environments: Widespread occurrence
but low diversity, Environ. Microbiol., 9, (2007) 1476–
1484.
[2] Trimmer, M., J. C. Nicholls, and B. Deflandre,
Anaerobic ammonium oxidation measured in sediments
along the Thames Estuary, United Kingdom, Appl. Environ.
Microbiol., 69, (2003) 6447–6454.
[3] Wang, S., G. B. Zhu, Y. Z. Peng, M. S. M. Jetten, and C.
Yin, Anammox bacterial abundance, activity, andcontribution in riparian sediments of the Pear River Estuary,
Environ. Sci. Technol., 46, (2012) 8834–8842.

Z2-YC6860 6%
Burkholderiaceae 2%

The diversity of microorganisms in the sediments of the
Selorejo and Karangkates reservoirs has similarities, as
indicated by the total number of OTUs (Operational
Taxonomy Units) of 9643 and 9645, respectively. At these
two locations, several phyla, including the phylum
Firmiculus, Acidobacteria, Proteobacteria, Planctomycetes,
Actinobacteria,
andBacteroidetes.
ThephylumProteobacteria has the most significant number of members.
Thus, these two locations can be a source for isolating
anammox microbes.

[4] Zhu, G. B., S. Wang, Y. Wang, C. Wang, N.

Burkholderia 1%

Risgaard-Petersen, and M. S. M. Jetten, Anaerobic

10

The 10th International Symposium on Water Environment Systems----- with Perspective of Global Safetythth(Dec. 8 ~ 9 , 2022)

GP-RSS & SyDe
Tohoku University

Refractory dissolved organic matter as carbon source for advanced
nitrogen removal from mature landfill leachate: A review andprospective application
Ruixin Wu1,*, Yu-You Li2, Jianyong Liu1

School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai
200444, China.
2
Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku
University, 6-6-06 Aza, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan.
*
E-mail: elisawuu@163.com

1

Abstract

Partial nitrification-anammox is a promising process for treating mature landfill leachate, butthere are still 11% nitrate to be removed. Denitrification or partial denitrification can be used toremove the nitrate in the presence of carbon source to achieve advanced nitrogen removal. However,there is a lack of biodegradable organic matter which can be used as denitrifying carbon source inmature landfill leachate. Fortunately, refractory dissolved organic matter (rDOM) was exploited to
be used as a potential denitrifying carbon source in recent years. The performances, mechanisms ofusing rDOM as denitrification carbon source are summarized in this review. Furthermore, in orderto improve the rDOM utilization efficiency, several methods to improve the biodegradability ofrDOM are summarized, which include extended hydraulic retention time, sludge retention time,bioaugmentation and advanced oxidation processes. A novel integrated anammox-based process is
proposed for mature landfill leachate treatment, in which ozonated nanofiltration concentrate isrecirculated with many benefits.
Keywords: Mature landfill leachate; Anammox; Refractory dissolved organic matter (rDOM);
Carbon source; Ozonation
1 Introduction
Mature landfill leachate contains high concentration ofammonia and low concentration of biodegradable organiccarbon, which makes the conventional nitrification anddenitrification processes difficult to carry out in leachate
treatment to achieve nitrogen removal. As is known to all,although mature leachate contains high concentration oforganic matter, the dissolved organic matter (DOM) in
mature landfill leachate is mainly composed of refractory
dissolved organic matter (rDOM), with a relatively low
biochemical oxygen demand (BOD)/chemical oxygen
demand (COD) ratio (less than 0.1). If simultaneous
anammox and (partial) denitrification (SAD) process with
rDOM as carbon source is feasible in mature leachate
treatment, it can not only achieve advanced nitrogen
removal, but also save the cost of aeration and additional
carbon source.
However, due to the low utilization rate of rDOM, it isdifficult to achieve advanced nitrogen removal only throughusing rDOM as carbon source in mature leachate. Therefore,
some measures are needed to improve the utilization ofrDOM as carbon source for denitrification. Measures suchas extending HRT, prolonging sludge retention time (SRT) ,introducing rDOM degrading bacterial communityand using
advanced oxidation processes (AOPs) were used to increase
the rDOM utilization rate. These measures can changerDOM into easily degradable organic matter, which can beused as carbon source for denitrification to remove thenitrate produced by PNA and then achieve advanced
nitrogen removal. AOPs are generally used to remove all

11

the rDOM in the conventional landfill leachate treatment
process . In fact, rDOM can also be converted into easily
degradable organic matter by AOPs to provide carbon
source for denitrification. However, it is not clear how torealize it in leachate treatment process.
In this review, the shortage of readily biodegradableorganic matter and the mechanisms of utilizing rDOM as
the carbon source are summarized and discussed from theperspective advanced nitrogen removal from mature landfill
leachate. Based on the literature summary, an integrated
process of treating mature landfill leachate with rDOM as
the carbon source is proposed, in which ozonatednanofiltration concentrate is recirculated.

2. The deficiency of carbon
denitrification in mature leachatesourcefor

The DOM in mature landfill leachate is mainly composedof volatile fatty acids and the rDOM, such as humic
substances accounting for most of DOM in leachate (up to60%). As a result, the relatively low BOD/COD ratio leads
to the few carbon sources available for denitrification, as
shown in Table 1.
The mature landfill leachate contains only a small amountof readily degradable organic matter, which decreased with
the increase of landfill age.
The rDOM is difficult to remove by conventional
biological processes, which means microorganisms canhardly use it as carbon source for denitrification. However,if the rDOM can be explored and utilized, the amount ofcarbon source in mature landfill leachate can satisfy theneed of advanced nitrogen removal treatment.

The 10th International Symposium on Water Environment Systems----- with Perspective of Global Safetythth(Dec. 8 ~ 9 , 2022)

3. Feasibility of rDOM as carbon source foradvanced nitrogen removal
Previous studies showed that rDOM was partiallydegraded to biodegradable organics by specific heterotrophs(e.g., Chloroflexi and Chlorobi) in the anammox-based
system, which could serve as the electron donor for
denitrification to achieve advanced nitrogen removal.
RDOM in SAD is a potential carbon source that can beutilized by denitrifying bacteria.
Mechanism of rDOM in anammox-based treatment of
mature landfill leachate was shown in Fig. 1.
EPS adsorption-biodegradation was the key mechanism forthe removal of rDOM. The anammox bacteria can be
stimulated to produce more EPS by the addition of fulvic
acid in the process of treating mature landfill leachate. EPS
provide more extracellular enzymes and nutrients for
microorganisms, and EPS contribute to the formation of
biofilms, which can protect the anammox activity, enabling
it to achieve stable nitrogen removal efficiency even in thepresence of organic matter.
Table 2 summarized the bacterial communities that candegrade rDOM in the SNAD process. As can be seen from
Table 2, when anammox process was used to treat
wastewater containing high concentrations of ammonia
nitrogen and rDOM, anammox bacteria can coexist withbacteria which can degrade rDOM (Wang et al., 2019).
Adequate adaption time is the key to enrich the rDOM
degrading bacterial community.

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remaining organic matter in the ozonated NFC can be
introduced into AD to further recover the bioenergy.
Firstly, NFC is an urgent secondary pollutant in thetreatment of mature landfill leachate. Controlling theozonation process to maximize biodegradability of rDOM
can not only reduce the cost of ozonation, but also realize
recycling of the ozonated NFC into the SAD reactor as
carbon source for denitrification, thus reducing the cost ofcarbon source.
Secondly, the optimum pH for treating NFC withozonation process is between 8 and 9 because the hydroxide
ion could induce the ozone molecules to produce hydroxyl
radicals in the water. The pH of SAD effluent is usually
above 8, so ozone process is suitable to improve its
biodegradability. However, if Fenton method is used, thepH (optimal pH is 2-4) needs to be adjusted firstly. In theacidic environment, large amounts of H2O2 and Fe2+ to
produce moderate hydroxyl radicals, which makes Fenton
expensive and produces large amounts of iron mud resulting
in secondary pollution. Therefore, it can be seen that the
proposed process is economically and environmentallyfriendly and technically feasible.

4. Enhancing degradation of rDOM to provide
carbon source for SAD

In order to promote the degradation of rDOM, somemethods such as increasing HRT and SRT in SAD, thebioaugmentation technology in SAD, and advanced
oxidation technology were adopted.
Longer HRT allowed bacteria to have sufficient time toabsorb rDOM in the mature landfill leachate and thenassociate enzymes to decompose them into small organic
molecules.
The longer SRT, which could be realized in the biofilm or
MBR systems, could promote the enrichment of distinct
microbial communities degrading rDOM.
To enhance the release of carbon source from rDOM
biodegradation, activated sludge contained enrichedrDOM-degrading bacteria could be introduced into SAD
systems to enhance the release of carbon source from rDOM
biodegradation.
AOPs, such as Fenton, photocatalytic, ozonation andelectrochemical technology, could generate highly activehydroxyl radical (OH·) for the degradation of rDOM andincreasing biodegradability of organic compounds. Ozone
oxidation process can effectively improve thebiodegradability of different wastewater, as shown in Table
3 (Chen et al., 2019).

5. Enhancing degradation of rDOM to provide
carbon source for SAD

Based on the above proposed idea, an innovative
anammox-based process is proposed to achieve advanced
nitrogen removal of mature landfill leachate.
Ozonation can improve the biodegradability of the NFC
and recycling ozonated NFC into SAD to can provide
carbon source for (partial) denitrification. On the premise ofsatisfying the carbon source required by SAD, the12Fig. 1. An innovative integrated process for advanced
nitrogen removal using rDOM as carbon source inmature leachate treatment.

6. Conclusion

Through sludge adsorption-degradation, rDOM in mature
landfill leachate could be biodegraded by bacteria such as
Chloroflexi as denitrifying carbon source, which promoted
advanced nitrogen removal in anammox-based process. In
order to improve the biodegradability of rDOM and reducethe carbon source addition cost, some measures such as
extended HRT, SRT, bioaugmentation and AOPs can betaken. An innovative integrated process based on SAD wasproposed, which could simultaneously remove ammonia
nitrogen and rDOM from mature landfill leachate. In thisprocess, recycling ozonated NFC could not only avoid
secondary pollution, but also provide carbon source for(partial) denitrification and achieve advanced nitrogen
removal.

Reference[1] Chen, W., Zhang, A., Jiang, G., Li, Q., 2019. Transformation anddegradation mechanism of landfill leachates in a combined process of
SAARB and ozonation. Waste Manag 85, 283-294.
[2] Wang, Y.M., Lin, Z.Y., He, L., Huang, W., Zhou, J., He, Q., 2019.
Simultaneous partial nitrification, anammox and denitrification (SNAD)
process for nitrogen and refractory organic compounds removal frommature landfill leachate: Performance and metagenome-based microbial
ecology. Bioresource Technology 294, 11.

The 10th International Symposium on Water Environment Systems

GP-RSS & SyDe

(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

Tohoku University

Achieving Stable Mainstream Partial Nitritation-Anammox Process
by Successful Regulation of Nitrite-Oxidizing Bacteria
1○ Wei Yanxiao1*, Xia Weize1, Ye Min1 & Yu-You Li1,2

Department of Environmental Engineering, Environmental University, Miyagi 980-8579, Japan.
2
Department of Water Environment, Engineering University, Miyagi 980-8579, Japan.
*
E-mail: wei.yanxiao.q5@dc.tohoku.ac.jp

Abstract
The long-term stable operation is still a challenge for partial nitritation and anammox (PN/A) process in thetreatment of low-strength ammonium wastewater. The nitrite oxidizing bacteria (NOB) growth can destroy thestability of part of the PNA system. This study explores solutions to the NOB growth problem using a laboratoryscale reactor. The results showed that NOB reduced the nitrogen removal efficiency from up to around 85% to 32.5%
in mainstream condition. NOB inhibition strategies such as intermittent aeration and FA inhibition were applicatedbut did not successfully in controlling NOB growth. The final enhanced Anammox activity brought the removal
rate up to 76.3 again. Based on the analysis on the physicochemical properties of the granules, the size decreased toaround 280μm in mainstream. The dissolution granules of may be the reason for the weakened anammox activity,
which favored NOB growth. These results provide an alternative NOB inhibition method to maintain a healthy
PN/A process in mainstream.
Keywords: Anammox; Nitrite oxidizing bacteria; Partial nitritation; Hydroxyapatite; Mainstream.
1 Introduction
The partial nitritation/anammox (PN/A) process is
considered to have the potential to update the currently
widely used traditional nitrification and denitrification
processes due to its advantages such as energy saving andreduction of greenhouse gas emissions. Although PN/A
process has been successfully applied to high strengthammonium wastewater in sidestream, the application of
PN/A process to treat low-concentration ammonium
wastewater such as mainstream municipal wastewaterremains a big challenge. For example, uncontrolled nitrite
oxidizing bacteria (NOB) growth can significantly reduce
nitrogen removal efficiency. NOB competes with ammonia
oxidizing bacteria (AOB) and anammox in substrateutilization and thus can interfere with the PN/A system. The
widely reported inhibition strategies such as using freeammonia (FA), free nitrous acid and dissolved oxygen (DO)control do not always work. The long-term stable operationof the mainstream PN/A process still needs further research.
To achieve long-term stable nitrogen removal efficiency inthe mainstream PN/A process, this study used a laboratoryscale air-lift reactor. The variation of nitrogen removal
efficiency and factors affecting the balance between partial
nitritation, and anaerobic ammonia oxidation system wereassessed by analyzing physicochemical properties to findways to rebuild and maintain a healthy nitrogen removal
system. The spatial distribution and microbial community
structure of different functional bacteria are analyzing to
finally elucidate the competitive relationship between NOB
and the PN/A system.

2 Materials and methods
2.1 Reactor Setup

The experimental apparatus includes the main body of thebioreactor, the water influent system, and the aeration system,
which is shown in Fig. 1.

13

Fig. 1. Schematic diagram of the experimental setup

2.2 Operation Phases

The PN/A reactor was inoculated with the sludge from theeffluent of another PN/A reactor treating mainstream. The
PN/A reactor was continuously fed with synthetic
wastewater. Additional trace elements were added asprevious study reported [1]. The PN/A reactor wascontinuously operated for 325 days. And the entire procedurecan be divided for 8 phases (Table 1).
Table 1 Operation Phases.
Ninf

NLR

(mg/L)(kg/m3/d)

12

100

0.2

3-113

6

100

0.4

3

114-153

3

50

0.4

4

154-199

3

50

0.4

5

200-215

24

500

0.5

6

216-291

24

500

0.5

7

292-310

24

500

0.4

8

311-325

3

50

0.4

PhasesDay(d)

HRT(h)

1

1-2

2

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
2.3 Analytical methods

NH4+-N, NO2--N, NO3--N, P- and Ca2+ concentrations were
measured by capillary electrophoresis (Agilent 7100, Agilent
Technologies, USA). DO concentration was measured by
DO meter (DM-31P). Other tests were analyzed according to
APHA standard methods [3]. Sludge samples were collected
at the end of each phase for Fluorescence in situ hybridization,
16S rRNA gene sequencing and qPCR test.

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finally was controlled. Returning to the mainstream again,
the NRE reached a maximum of 76.3% with the average ratioof 0.22.
From the above data it can be seen that the enhanced activityof Anammox fully utilizes nitrite and ultimately eliminates
NOB from the system.

3 Results and discussion
The nitrogen removal performance of PN/A during the 8phases is illustrated in Fig. 2. After successful start-up inphase 1, HAP granules with excellent sedimentation
performance were cultivated in phase 2. The nitrogen
removal efficiency (NRE) up to around 85% was obtained.
When the HRT was shortened to 3h and the influent ammonia
nitrogen concentration was reduced to 50 mg/L, NOB started
its activity. NRE finally reduced to 62.4% in phase 3.

Fig. 3. HAP granule size
As shown in Fig. 3, Hydroxyapatite (HAP) granule size wastested. It can be found that the proportion of large particles isreduced under mainstream conditions, and then recovered insidestream. The maximum mean size was 452μm in phase 1
and decreased to around 280μm in phase 4. Compared withother studies, the mean size of around 338μm granule wasobtained [1]. The granule size is proportional to pH and isalso related to the microbial activity. HAP granules provide
shelter for anammox growth while improving sludge settlingproperties. The smaller particle size indicates disintegrationof the particles, which may be responsible for the decreased
activity of Anammox and the NOB dominance.
Regarding the microbiological data, it is still being tested.

Those results will be helpful to analyze the growth of
NOB and changes in its competition with anammox.

4 Conclusions(1) The PNA reactor was successfully started, and up to 83%
total nitrogen removal efficiency was achieved at HRT 6h
and relatively large HAP granules (mean size 452μm) wereobtained.
(2) Strategies such as intermittent aeration and FA inhibition
were not successful in controlling NOB growth. At low
nitrogen loads, decreased anammox activity was responsible
for NOB dominance. But it was successfully reversed the
direction of the nitrogen oxidation by enhancing Anammox.
(3) HAP granules are difficult to maintain stable undermainstream conditions.
Fig. 2. Operation performance
To control the NOB activity, intermittent aeration wasapplicated in phase 4. But it did not limit the continued
growth of NOB with NRE decreased to 32.5%. According to
the nitrogen balance, NOB competed better than anammox innitrite utilization in phase 4. Around 35 mg/L FA wasprovided in phase 5. The FA concentration was set to achieve
inhibition on NOB with less side effects on anammox [2].
However, NOB activity was only slightly suppressed. The
NO3- to ΔNH4+ ratio decreased from 0.58 to 0.50. The reason
for that may be that anammox activity has been compromised
to utilize normal levels of nitrite, which has been confirmedby activity tests (data are not shown here). To enhance theanammox activity, 0.5 g/L MLVSS Anammox was
additionally added for twice. The NOB existed in the system

14

Reference[1] Chen, R., Ji, J., ... & Li, Y. Y. (2019). Successful
operation performance and syntrophic micro-granule inpartial nitritation and anammox reactor treating low-strengthammonia wastewater. Water research, 155, 288-299.
[2] Chen, Y., Feng, G., Guo, G., Luo, Z., Rong, C., Wang,
T., ... & Li, Y. Y. (2022). Nitrogen removal by aHydroxyapatite-enhanced Micro-granule type One-stage
partial Nitritation/anammox process following anaerobic
membrane bioreactor treating municipal wastewater.
Bioresource Technology, 348, 126740.
[3] APHA, 2005. Standard Methods for the Examination of
Water and Wastewater. APHA-AWWA-WEF, Washington,
DC, USA.

The 10th International Symposium on Water Environment Systems

GP-RSS & SyDe
Tohoku University(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

Experimental study on two-stage PN/HAP-A process for treating
garbage methane fermentation liquid○ Wenzhao Zhao1*, Ying Song1 , Yi Xue2 & Yu-You Li1,2
1

Department of Civil and Environmental Engineering, Tohoku University, Gr aduate School ofEngineering, Miyagi 980-8579, Japan2
Department of Frontier Science for Advanced Environment, Graduate School of Environmental Studies,
Tohoku University, Miyagi 980-8579, Japan*
E-mail: zhao.wenzhao.q5@dc.tohoku.ac.jp

Abstract
A two-stage partial nitritation/hydroxyapatite-Anammox) (PN/HAP-A) system was set up to verify the applicationof the system on garbage methane fermentation liquid. The PN reactor had good ability to convert ammonium tonitrite. Moreover, HAP-anammox reactor, the critical core of the system, had a good nitrogen removal performance.
This study focuses on the efficiency and stability of the system in dealing with high-strength garbage fermentation
liquid. Through 200-days operation, the stable removal performance of system was obtained. The system nitrogenloading rate (NLR) increased from of 1.0 g-N·(L·d)-1 to 2.9 g-N·(L·d)-1, the nitrogen removal efficiency maintained
at 85.6%. The study achieved an enhancement on nitrogen loading rate when treating methane fermentation liquid
by Partial nitritation/HAP-Anammox process, which the results can also be promoted to pilot and full-scale on thehigh-strength ammonium wastewater treatment.
Keywords: Anammox; methane fermentation; HAP; AOB.
1 Introduction

Table 1 Operation Conditions

High-strength ammonium sewage is widespread in
wastewater treatment process, especially as a by-product inthe drainage after anaerobic treatment, such as garbage
fermentation liquid. Based on this problem, anaerobic
ammonium oxidation (Anammox) process is a suitable way
to be applied which can significantly reduce the energy
consumption and operating cost, and at the same time achieve
efficient total nitrogen removal, which is an environmentallyfriendly sewage treatment process[1]. The new denitrification
process is a feasible solution to face the challenges in lowcarbon society, sustainable development and circular
economy which these trends have become more important in
the development of human society.
Considering the stability in operation, using two-stage
PN/HAP-A (Partial Nitritation/HAP-Anammox) system maybe the better solution in the engineering for actual wastewater
treatment. The process will separate AOB and Anammox into
two reactors and operate individually, which can easily
control and enrich corresponding functional microorganisms.
In addition, cultivated HAP-anammox granular sludge areusing in the study. The granular sludge retention capacity
would also be a key factor which can avoid the functional
microorganism washing out.
In this study, the treatment of fermentation liquid frombiogas production center by two-stage anammox processusing HAP-anammox granule sludge at 25°C was evaluatedby long-term continuous experiments, which the results canprovide a reference for practical applications.

Phase

I

II

III

IV

V

pH

8.13

8.22

8.21

8.29

8.31

1446

1495

1783

1761

1810

553

609

664

694

653

8320

8040

8240

8140

8040

P (mg·L-1)

16.2

35.6

19.8

24.2

44.9

-1

Ca (mg·L )

34.2

66.1

58.1

58.3

90.4

Fe (mg·L-1)

7.5

7.6

7.4

7.4

6.5

-1

31.0

36.4

33.7

35.8

50.4

NH4+-N (mg·L-1)-1

COD (mg·L )Alkalinity(mg-CaCO3·L-1)

Mg (mg·L )As demonstrated in Fig.1, the PN reactor (working volumeof 10 L) and EGSB reactor (working volume of 5 L) wereapplied for PN and Anammox, respectively. Both reactors
were controlled at 25 ℃. The throughput varied from 12 L·
d-1 to 24 L·d-1 using raw fermentation liquid.

2 Materials and methods
2.1 Reactor configuration and operation
The substrate using in the experiment was periodicallycollected from a garbage biogas power generation center
located in Nagaoka City, Niigata Prefecture, Japan. The main
composition of the substrate is showed in Table 1.

15

Fig. 1 Schematic diagram of the System

The 10th International Symposium on Water Environment Systems

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2.2 Analysis of liquid samples
Liquid samples of influent and effluent were filtered with a
0.45 μm filter. Ammonium, nitrite and nitrate were analyzed
by capillary electrophoresis (Agilent 7100). IC/TOC wasdetermined using a total organic carbon analyzer (Shimadzu,
TOC-L, Japan). Alkalinity, mixed liquor volatile suspended
solids (MLVSS) and mixed liquor suspended solids (MLSS)
were analyzed according to APHA standard methods.

3 Results and discussion
The performance of the two-stage system is shown in Fig.2
and Fig.3 for PN reactor and Anammox reactor, respectively.
The influent contained 1500 to 1800 mg·L-1 ammonium
during the operation and the system had an average TN
removal efficiency of 85.6%.

limitation of aeration ability and oxygen transfer rate. Whenenter the Phase III, a well-controlled ratio at 1.2 can make theeffluent of PN reactor suitable for Anammox unit. The
alkalinity consumed in the reactor has a proportional linear
relationship with the ammonium in the influent water, which
the value can be defined between 4.5-5 (Table.2).
Table 2 Average operation results of system
Phase

I

II

III

IV

V

NRE

75.9

78.4

84.1

83.2

85.6

NO2--N/NH4+-N

0.96

0.90

1.15

1.19

1.21

ΔIC/ΔNH4+-N

1.58

1.46

1.17

1.42

1.55

ΔAlkalinity/ΔNH4+-N

6.86

5.86

5.24

4.67

4.78

ΔCOD (mg·L-1)

103

120

174

166

156

ΔCa (mg·L-1)

6.1

26.1

23.7

41.5

38.6

ΔP (mg·L-1)

7.4

20.1

6.4

16.8

17.8

ΔCa/ΔP

0.82

1.3

1.45

2.47

2.17

The NLR in EGSB reactor increased to the 8.2 g-N·(L·d)-1
in the phase V and the reactor still showed a good
performance on TN removal at 82.4%, while also had a 57%
removal of phosphorus. The effluent showed that the nitrateis the main factor influencing the TN removal efficiency. The
HAP granular sludge distributions in HAP-A reactor isshowed in Fig.4.

Fig. 2 Operation performance of PN reactor
The garbage fermentation liquid was fed into the PN unit
without dilution with ammonium concentration of 1466±51
mg·L-1 in the phase I. The NLR increased from 2 to 4
gN·(L·d)-1 in the operation. The NO2--N/NH4+-N ratio is notcontrolled well during the early phases because of theFig. 4 HAP granular sludge in HAP-A reactor

4 Conclusions(1) The efficiency and stability of the two-stage PN/HAP-A
process was evaluated and confirmed for the treatment of thegarbage fermentation liquid. The NLR of PN/HAP-A system
is 2.9 g-N·(L·d)-1 while the NRE is 85.6%. The NLR of thePN and HAP-Anammox reactor can maintain at 4 g-N·(L·d)-1
and 8.2 g-N·(L·d)-1, respectively.
(2) The conversion rate of ammonium should be maintainat 55% in PN reactor, while the ratio of alkalinity toammonium is between 4.5-5 to demonstrate sufficientalkalinity in the PN reactor.

Reference

Fig. 3 Operation performance of HAP-Anammox reactor

16[1] Valenzuela-Heredia D, Panatt C, Belmonte M et al,2022.
Performance of a two-stage partial nitritation-anammox
system treating the supernatant of a sludge anaerobic digester
pretreated by a thermal hydrolysis process. Chemical
Engineering Journal, 429, 131301.

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

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Emerging onsite electron donors for advanced nitrogen removal fromanammox effluent of leachate treatment: A review and futureapplications○ Yanyan Li1*, Yanxu Liu1, Jinghuan Luo1, Yu-You Li2, Jianyong Liu1
1

School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai
200444, China.
2Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku
University, 6-6-06 Aza, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan.
*
E-mail: li.yanyan.s5@dc.tohoku.ac.jp.

Abstract
Partial nitrification-anammox process is promising in leachate treatment, but the 11% residue nitrate limits thetotal nitrogen removal efficiency. Denitrification or partial denitrification and anammox are both practical polishingprocesses of anammox effluent, requiring extra electron donors. Fortunately, there are organic matter, sulfide andmethane in leachate or produced by leachate treatment, which can serve as onsite electron donors. In this review,the mechanisms and processes using these three kinds of electron donors for residue nitrate reduction in anammox
effluent of leachate are systematically summarized and discussed. It can be concluded that, biodegradable organic
matter is an effective electron donor, sulfide is a promising electron donor, methane is a potential electron donor.
Two possible applications in future based on anammox treatment of fresh and mature leachate using sulfide andmethane as onsite electron donors are proposed. Through sulfide reutilization, energy-saving with about 14% of
aeration reduction can be achieved.
Keywords: Leachate; Anammox; Advanced nitrogen removal; Electron donors; Sulfide; Methane.
1 Introduction

2 Biodegradable organic matter is an effective

Municipal solid waste leachate contains a high ammonium
nitrogen concentration, which usually can be up to 2000 mg
N/L or higher. Partial nitrification (PN)-anammox process
can remove nitrogen efficiently with less aeration amount,carbon source demand, and waste sludge production(reducing by 63%, 100%, 90%, respectively) compared withthe traditional nitrification and denitrification process, which
has become a research hotspot for decades. In 2009, theapplication of the full-scale anammox process in leachate
treatment was reported for the first time. So far, theengineering application of anammox process has beenrealized in wastewaters with high ammonium nitrogen.
Theoretically, the maximum nitrogen removal efficiency of
anammox process is 89%, while 11% of the total nitrogen(TN) is converted into nitrate. As for nitrogen removal fromleachate using anammox process, the residue nitrateconcentration will be as high as 200 mg N/L, which is still
too high for discharge directly. The residue nitrate needs tobe removed by biological methods such as complete
denitrification or partial denitrification (PD, providing nitrite
for anammox), during which electron donor is required.
There are a few kinds of mass in leachate that can serve aselectron donors for residue nitrate reduction.
In this review paper, the mechanisms and processes using
three emerging onsite electron donors (organic matter,
sulfide, and methane) for residue nitrate reduction in
anammox effluent are systematically summarized anddiscussed. Some research prospects are put forward.
Specifically, two possible applications in future based onanammox of fresh and mature leachate treatment areproposed to achieve the purpose of advanced nitrogen
removal, energy recovery, full utilization of electron donors
and reduction of energy consumption.

electron donor

17

Fresh leachate contains a high concentration of organic
matter, and the proportion of biodegradable organic matter ishigh. Biodegradable organic matter can be used as anelectron donor for complete denitrification or PD throughdifferent kinds of processes, such as returning the anammox
effluent to the AD reactor or using leachate as an electron
donor directly.
Mature leachate contains a certain concentration of organic
matter, and the proportion of biodegradable organic matter isvery low. Recent studies have shown that ROM such as
humus can be biodegraded by anammox process and can beused for denitrification.
As a novel and effective biological nitrogen removal
process, anammox process is proved to be effective for the
degradation of ROM. Recent studies have shown that ROM
in leachate can be used as an electron donor to achieveadvanced nitrogen removal and the removal efficiency of
ROM and TN removal efficiency were 67.7% and 94.9%,
respectively. The removal mechanism of ROM is that it isfirst adsorbed by anammox sludge, and then mineralized or
biodegraded into small molecule biodegradable organic
matter for utilization by denitrifying bacteria.

3 Sulfide is a promising electron donor
Landfill leachate contains a certain amount of sulfate,ranging from 8 to 7750 mg/L. Sulfate is reduced to H2S byheterotrophic reduction, and the solubility of H2S in water ishigh, so it dissociates into sulfide in water. Under the neutral
condition of AD, sulfide in anaerobic effluent mainly exists
in the form of HS-. Some autotrophic denitrifying bacteria
can use sulfide as an electron donor and nitrate as an electron

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
acceptor to achieve simultaneous removal of nitrogen andsulfide. Sulfide can be completely oxidized to SO42− and canbe partially oxidized to S0. The N/S molar ratio will affect theformation of the final product during sulfide-oxidizing
autotrophic denitrification (SOAD). In recent years, sulfate
with strong oxidation capacity can be used as an electron
acceptor of anammox has attracted attention. Compared withthe conventional NirAnammox process, PN is not required in
the Sulfammox process. Therefore, the reduction of energy
consumption and the minimum production of sludge can beachieved. New Sulfammox process can provide great
potential for energy saving, environmental protection andefficient removal of ammonium and sulfate in wastewater.
Because the growth environment of AnAOB and Sulfammox
bacteria is similar, and the optimal pH is 7–8.5, thecoexistence of Sulfammox and NirAnammox is possible[1].

4 Methane is a potential electron donor
The biogas produced by AD cannot be fully recovered
because some of the biogas will be dissolved in the water,
and the solubility is affected by some factors. Under different
partial pressure of methane, the amount of dissolved methane
in anaerobic wastewater is 10–25 mg/L. Methane can beoxidized aerobically or anaerobically in two different
microbial processes, both of which can be combined with
denitrification. A batch experiment showed that the activitiesof methane aerobic oxidation, denitrification, nitrification
and anammox could exist at the same time. AMOB weresuccessfully enriched by AOB biomass from the PN reactor,
and dissolved methane was oxidized to methanol. PNANAMMOX process has been proved to be feasible inmembrane-aerated biofilm reactor, which can successfully
regulate the layer distribution and symbiosis of AOB andAnAOB. Therefore, the integration of AME-D and PNANAMMOX may be feasible. By supplying oxygen in thehollow fibre membrane of MBfR, anaerobic wastewatercontaining ammonium and dissolved methane exists in bulk
liquid. It then forms layered biofilm on the membrane surface
with aerobic layer, microaerobic layer, and anaerobic layerfrom the inside to the outside.

5 Possible applications of advanced nitrogen
removal using anammox based processes
SOAD, PN and ANAMMOX processes are proposed for
fresh leachate treatment to use different S species repeatedly
to minimize the electron donors waste (Fig. 1). On the one
hand, the use of sufficient sulfide as an electron donor can
not only realize advanced nitrogen removal, but also avoid
the oxidization of sulfide back to sulfate. The energy
consumption of sulfide oxidization during the PN stage canbe reduced or avoided through as an electron donor of nitrate
in anammox effluent during SOAD between AD and PNANAMMOX. On the other hand, sulfate can become thesubstrate for anammox and is converted to elemental sulfur,
reducing the demand for nitrite, that is, reducing the amountof aeration and saving energy. Fresh leachate is firstly
introduced into AnMBR for AD. The effluent of PNANAMMOX containing nitrate is recycled to SOAD reactor,
residue nitrate from anammox can be removed by using
sufficient sulfide as an electron donor to achieve advanced
nitrogen removal. Finally, nanofiltration (NF) is used in thetreatment of PN-ANAMMOX effluent to ensure that theleachate discharge meets the requirements of the standard.

18

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Fig. 1. A possible application in future for advanced
nitrogen removal from anammox effluent of freshleachate treatment.
Mature leachate contains low concentrations of organic
matter and sulfate but a higher concentration of ammonium
nitrogen. The biodegradable part of organic matter isconverted into methane during AD, including dissolved
methane. Using dissolved methane as an electron donor can
not only avoid greenhouse gas emissions, but also realize
advanced nitrogen removal. Therefore, the integrated process
of methane oxidation coupled with PD is most suitable formature leachate treatment, achieving cost-saving and full
utilization of electrons. MBfR should be selected to avoid
dissolved methane being blown into the atmosphere. On the
one hand, the oxygen in the membrane lumen can oxidize
ammonium nitrogen to nitrite as the substrate for anammox.
On the other hand, it can oxidize the methane to organic
matter. An integrated process is proposed for mature leachate
treatment (Fig. 2).

Fig. 2. A possible application in future for advanced
nitrogen removal from anammox effluent of matureleachate treatment.

6 Conclusions
Organic matter, sulfide, and methane can be used as onsite
electron donors for residue nitrate reduction in anammox
effluent of leachate treatment. Biodegradable organic matter
is an effective electron donor, sulfide is a promising electron
donor, methane is a potential electron donor. For freshleachate, sulfide-oxidizing autotrophic denitrification, partial
nitrification and anammox are suggested as novel optimized
processes to achieve energy saving with about 14% of
aeration reduced and sulfide reutilization. For matureleachate, membrane biofilm reactor for simultaneous partial
nitrification, anammox, methane oxidation coupled withpartial denitrification is a potential alternative.

Reference[1] L. Wu, Y. Peng, et al., Low temperature advanced
nitrogen and sulfate removal from landfill leachate by nitriteanammox and sulfate-anammox. Environ. Pollut., 259 (2020),
Article 113763

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

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Preparation of a spherical biochar colloidal probe and its application in
deciphering the mechanism of biochar mitigating membrane fouling○ Xiaohuan YANG1, Silian XIA1, Litu Hao1 & Rong Chen1,2*
Key Lab of Environmental Engineering, Shaanxi Province, Xi’an University of Architecture andTechnology, No.13 Yanta Road, Xi’an, 710055, PR China.
2International S&T Cooperation Center for Urban Alternative Water Resources Development, Key
Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi’an University ofArchitecture and Technology, No.13 Yanta Road, Xi’an, 710055, PR China .
*E-mail: 1090633365@qq.com.
1

Abstract
To better unravel biochar’s interface behavior and mitigation mechanism on membrane fouling, spherical biochar
colloidal probes were prepared by adhering microspheres to the free end of the cantilever and used to quantitatively
determine adhesion force in a foulant-biochar-membrane system. The study investigated the differences inphysicochemical properties of biochars and their mitigation effect on membrane fouling. Results indicated that
dosing biochars can strengthen the electrostatic repulsion between BSA and membrane, mitigating BSA adhesion
or deposition on the membrane surface. Additionally, the regular biochar (SBC and HC) exhibited better mitigation
on membrane fouling than irregular biochar due to better physicochemical properties, adsorption capacity, and moreporous fouling layer structure composed of microparticles, which caused a higher BSA rejection and loading factor
over the membrane. Importantly, the stronger adhesion force of SBC-PVDF (0.90 mN/m) than BSA-PVDF (0.50mN/m) alleviated membrane fouling in the initial stage of the filtration, and the adhesion force of SBC-BSA(0.049mN/m) alleviated membrane fouling in the later stage, resulting in higher water flux. The interaction force
between aged SBC and BSA was comparable to that between BSA and BSA (0.14 mN/m) and stronger than thatbetween original SBC and BSA (0.051 mN/m), implying further mitigating membrane fouling.
Keywords: biochar; membrane fouling; hydrothermal carbonization, colloidal probes, interfacial forces.
1 Introduction
In recent years, membrane-based technologies are widelyused in wastewater treatment, whereas membrane foulinghinders the practice application. It is reported that carbonbased materials show great promise in membrane foulingcontrol. As common additives, powder activated carbon(PAC) and granular activated carbon (GAC) have been
applied to retard membrane fouling. However, compared toactivated biochar, biochar was produced by a simple and lowcost pyrolysis process without activation. The feasibility ofbiochar in mitigating membrane fouling has been proven inmembrane bioreactors, so it is a good alternative to GAC and
PAC for membrane fouling control [1].
There are not many studies involved in biochar’s influence
on membrane fouling. Limited by the diversity andcomplexity of the fouling process, the potential mechanismsof biochar were mainly summarized by changes in reactants
and products. Therefore, measuring microscopic interfacial
forces in a mixed biochar-foulant-membrane system is ofgreat significance to explore the mechanism of biochar on
membrane fouling.
In this study, a spherical biochar probe was prepared andutilized to quantitatively determine the adhesion forces ofbiochar–membrane, and biochar–foulant, which will provide
a theoretical method to improve membrane fouling control ofbiochar.

2 Materials and methods
2.1 Preparation of biochar colloidal probes

19

Spherical biochar (SBC) was prepared by a two-stage
process: hydrothermal carbonization (230°C, 5 h) andpyrolysis (500°C, 2 h). Spherical biochar colloidal probes
were prepared by adhering biochar microspheres to the free
end of the probe’s cantilever (Fig.1) and then were used toquantitatively determine adhesion force in a foulant-biocharmembrane system.

Fig. 1. (a) The SEM image of biochar microspheres, (b)the image of biochar microspheres under the microscope,and (c) the image of the probe adhered with a biochar
microsphere under the AFM scope.

2.2 Membrane filtration experiments
Bovine serum albumin (BSA) filtration experiments withthe addition of conventional biochar (CBC), hydrochar (HC),and SBC were constructed. Corncob was a feedstock forbiochar preparation. For CBC, dried fragments of corncob
were directly pyrolyzed in a non-circulated air atmospherefor 2.0 h at 500°C. HC was prepared by hydrothermal
carbonization with a reaction temperature of 230°C for 5 h.
The membrane filtration system was performed using adead-end setup consisting of a feed solution system, a deadend membrane cell, a draw solution system, and an online

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDe
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balance monitoring system. The membrane flux J and BSA
rejection (R) were calculated by the following equations:
J =V / (A•t)(1)
R=(Cf -Cp) /Cf ×100%(2)
Where, V is the change of permeate volume (L), A is theeffective membrane sample area (m2), and t is the samplingtime (h). Cf and Cp are the concentrations of BSA (mg/L) in
the feed and permeate, respectively.

3 Results and discussion

Fig. 2. (a)The normalized water flux curves of individual
foulant BSA and biochar, and BSA with biochar additionand (b) BSA rejection vary with time over the filtration
experiments.
In Fig.2(a), the normalized water flux curves of individual
foulant BSA and biochar demonstrated that protein-like
substances were representative of the organic matter
triggering membrane fouling and biochar did not cause
excessive membrane fouling. The permeate flux of BSA withbiochar indicated that biochar contributed to mitigating BSA
membrane fouling. In addition, it was obvious that the SBC
exerted a remarkable mitigating effect on BSA fouling,followed by HC and CBC, namely, the regular sphericalbiochar was better than irregular biochar in alleviating
membrane fouling. In Fig.2(b). BSA rejection of all filtration
tests was less than 10%. In a single BSA microfiltration
system, BSA rejection was mainly attributed to theadsorption and deposition of BSA in or on the membrane. In
the BSA-biochar system, BSA rejection of BSA-HC- and
BSA-SBC- fouled membrane were higher than that of BSAfouled membrane. This may be due to the BSA adsorption bybiochar.
A spherical biochar colloidal probe was successfully
prepared and applied to uncover biochar’s influence on
membrane fouling. In Fig.3, the stronger adhesion force of
SBC-PVDF (0.90 mN/m) than BSA-PVDF (0.50 mN/m)
alleviated membrane fouling in the initial stage of the20

Fig. 3. (a) Representative adhesion force-distance curvesof membrane–foulant and foulant–foulant, and thefrequency distributions of the (b) membrane–foulant,and (c) foulant–foulant.
and the adhesion force of SBC-BSA (0.049 mN/m) alleviatedmembrane fouling in the later stage, resulting in higher water
flux. The interaction force between aged SBC and BSA wascomparable to that between BSA and BSA (0.14 mN/m) andstronger than that between original SBC and BSA (0.049mN/m), implying further mitigating membrane fouling.

4 Conclusions(1) Due to higher adsorption ability and more porous foulinglayer formation, SBC and HC exhibited better mitigation
effects on membrane fouling than CBC, causing higher BSA
rejection and loading factor over the membrane.
(2) At the micro-interface, the adhesion force data indicatedthat the existence of spherical biochar can alleviate
membrane fouling in the initial stage and later stage of thefiltration process. Aged SBC possessed further mitigation on
membrane fouling.

Reference[1] Z. Lei, Y. Ma, J. Wang, X.C. Wang, Q. Li, R. Chen,
Biochar addition supports high digestion performance andlow membrane fouling rate in an anaerobic membranebioreactor under low temperatures, Bioresour. Technol. 330(2021) 124966.

The 10th International Symposium on Water Environment Systems

GP-RSS & SyDe

(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

Tohoku University

High solid of co-digestion performance of lipid waste and food waste bya thermophilic Hollow Fiber anaerobic membrane bioreactor○ Ziang HE1, Yuanyuan REN2, Chen WANG2, Yu-You LI1,2*
Department of Frontier Science for Advanced Environment, Graduate School of Environmental Sciences, Tohoku
University, Sendai 980-8579, Japan.
2
Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University, Sendai
980-8579, Japan;*E-mail: he.zi.ang.p8@dc.tohoku.ac.jp.

Abstract
The co-digestion performance of thermophilic (55℃) HF-AnMBR in treating lipid waste and food waste for 280
days was investigated. The OLR were increased from 7.34 to 18.37 g-COD/L/d by increasing the lipids content
from 10%, 30%, 50% and 70% on dry based. The COD conversion efficiency for methane was 80.14%, 91.13%,
92.07% and 83.87%, and the sludge yield was 0.015, 0.016, 0.016, 0.011 g VSS/g COD at OLRs of 7.34, 10.69,
14.78 and 18.37 g-COD/L/d, respectively. The COD, protein and carbohydrate concentrations in permeate wasstable, with an average of 3674.21, 1753.77 and 148.77 mg/L, respectively. During lipids hydrolysis, the main long
chain fatty acid (LCFA) were C16 and C18 in lipid content of 10%. When the lipid content increasing, the proportionof C18 is stable, but the proportion of C16 is decreasing from 34% to 17%. It indicates that β-oxidation from C18
to C16 is rate-limiting step. The ultra long chain fatty acids like C20 and C24 are also increasing in high lipid
content. The long-term stable performance of the AnMBR indicated that the co-digestion of lipid waste and foodwaste was effectively decomposed.

Keywords: Anaerobic membrane bioreactor; lipid waste, food waste, biogas production, LCFAs.
1 Introduction
Around 1.6 billion tonnes of food prepared for humanconsumption is wasted according to the report of the Foodand Agriculture Organization (FAO), and the carbon
footprint of food waste is approximately 3.3 billion tonnes of
the CO2 equivalent of greenhouse gas into the atmosphereper year. The past methods of disposing of food waste, suchas landfilling, incineration and composting, generate large
quantities of greenhouse gases, which is not a desirable
scenario, and more than 70% of economic entities in theworld have committed to achieving carbon net-zeroemissions by the middle of the century. A suitablecountermeasure for disposing of food waste is urgently
needed. Moreover, between 8.3% and 21% of the content offood waste is lipids which produce greater amounts of biogas
than protein and carbohydrate during methane fermentation.
That is, a huge amount of bioenergy is contained in foodwaste, and the efficient use of lipid rich food waste inmethane fermentation has yet to be fully explored.
Anaerobic membrane bioreactor (AnMBR) technology
could be defined as an anaerobic digestion treatment withmembrane separation. The unique function of the AnMBR isretaining solids in the reactor and discharging permeate via
membrane filtration. Due to this unique function, total
biomass retention, excellent effluent quality, low sludge
yield and energy recovery can be achieved. However, thesustainable flux of membrane filtration is hard to maintain,
especially for high concentration substrates like food waste,
which has total solids content (TS) of around 14% to 25. In
addition, membrane fouling is inevitable and directly affects
the operating efficiency of the AnMBR. Therefore, despite
the huge methane production potential of the digestion oflipids, significant challenges remain to the engineering

21

applications for the digestion of high concentration lipids richfood waste. Hence, the first purpose of this study is todemonstrate the potential of the methane fermentation of richlipid food waste by the AnMBR. The second purpose is toinvestigate the effect of food waste with different lipid ratios
during methane fermentation at 55℃.

2 Materials and methods
Table 1 operation condition
Item

Unit

Start upPhase I

TS-Lipids/TS-FW

%

10

10

30

50

70

HRT

day

30

15

15

15

15

SRT

day

30

30

30

30

30

4.1

4.1

4.2

4.9

4.5

pH

Phase II Phase III Phase IV

TS

g/L

105.1

105.1

120.5

140.2

160.2

VS

g/L

98.1

98.1

116.4

133.1

150.1

VS/TS

%

96.7

96.7

96.5

94.9

95.9

T-COD

g/L

110.1

110.1

160.4

221.7

275.56

S-COD

g/L

46.76

46.76

49.55

48.49

47.49

T-Carbohydrate

g/L

49.4

49.4

50.3

59.3

58.3

S-Carbohydrate

g/L

8.65

8.65

8.41

8.63

8.77

T-Protein

g/L

27.8

27.8

26.3

30.2

31

S-Protein

g/L

7.03

7.03

7.14

7.23

7.13

Lipids

g/L

10.51

10.51

30.5

49

70.1

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

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The long-term continuous experiment was operated in 4
phases. In phase I, the TS of the substrate was 10% and the
HRT was 30d. After a successful start-up, the HRT of phaseII, phase III and phase IV was shortened to 15d and TS of
the food waste was 10%. Then the OLR of rest phases wasincreased by rising the lipid content from 10%, 30%, 50%
to 70%. Figure 2 presents the operation performance of theexperiment considering three typical operational factors:
gas production rate, methane composition and sludge
concentration. These were stable in all phases, indicatingthat this reactor was operated successfully for 280d, even at
a COD loading rate up to 18.37g-COD/L/d. With the risinglipid content, the biogas production rate increased
dramatically, with biogas production rates of 3.55±0.15,
5.5±0.25, 7.56±0.31, 8.56±0.34 L/L/d, for corresponding
methane fraction of 58.6, 62.1, 63.0, 63.1%, respectively,
and corresponding OLRs of 7.34, 10.69, 14.78 and 18.37gCOD/L/d from phase I to phase IV. Considering theseresults, the increase in biogas production is the most active
point in the long-term performance since the methane
production potential of lipids is theoretically much higher
than that of protein and carbohydrates. The results
demonstrate that the co-digestion of lipids with artificial
food waste at a rate of 10%, 30%, 50% and 70% lipid
content in the TS of the substrate results in a 54.9-141.1%
increase in the biogas production rate.
With the increasing of lipid content, the composition of
accumulated-long chain fatty acid in sludge was changed.
In lipid content of 10%, the main LCFA is C16 and C18.
When the lipid content increasing, the proportion of C18 isstable, but the proportion of C16 is decreasing from 34% to17%. It indicates that β-oxidation from C18 to C16 is ratelimiting step.
The sludge yield in each phases was evaluated. Due tothe high methane production potential for lipid, the sludge
yield was very low. It was 0.015, 0.016, 0.016, 0.011 g
VSS/g COD at OLRs of 7.34, 10.69, 14.78 and 18.37 gCOD/L/d, respectively. So for the reason of high methane
production and low sludge yield, it indicates that the lipid
was suitable for anaerobic digestion.

3 Results and discussion

4 Conclusions
In this study, we applied the HF-AnMBR to digest theartificial lipid-rich food waste with different contents of lipid.
(1) Operating the HF-AnMBR treating lipid-rich foodwaste with around 10%-70% of lipid resulted in stablelong-term performance.
(2) The main LCFAs were C16 and C18 in lipid content of
10%. When the lipid content increasing, the proportionof C18 is stable, but the proportion of C16 is decreasingfrom 34% to 17%. It indicates that β-oxidation from
C18 to C16 is rate-limiting step.

Reference[1] Li, Y.Y., Sasaki, H., Yamashita, K., Saki, K., Kamigochi,
I., 2002. High-rate methane fermentation of lipid-rich foodwastes by a high-solids co-digestion process. Water Sci.
Technol.45, 143–150. https://doi.org/10.2166/wst.2002.0420

22

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDe
Tohoku University

Effects of oleate loads on methanogenisis under mesophilic andthermophilic conditions
Xiang Li1,Yijuan Yan1,Yong Hu1*
1

School of Environmental Science and Engineering, Nanjing Tech University, Nanjing 211816, PR China*
E-mail: huyong333@163.com

Abstract
This study investigated the influence of oleate loads (mM-oleate/g-VS) on methanogenesis under mesophilic andthermophilic conditions. Generally, mesophilic anaerobic system is more stable than thermophilic system, which
embodied in higher initial microbes’ abundance and higher oleate tolerance. Furthermore, oleate not only presents
its negative effects on methanogenesis, it also presents its potential to produce methane. This paper provides
noticeable and avoidable oleate loads under different experimental conditions as a guidance for future anaerobic
bioreactor of lipidic waste biodegradation.
Keywords: oleate loads; acetoclastic methanogenesis; hydrogenotrophic methanogenesis; temperature.
1 Introduction
The amount of lipidic waste such as fat, oil and grease(FOG) increases yearly due to population growth andcatering industry development. As a critical step inbiodegradation of FOG, long chain fatty acids (LCFAs) havelong pathway of β-oxidation which become the rate-limiting
step in AD process (He and Yan 2016). LCFAs can adsorb to
the cell membrane of anaerobic microorganisms, andgenerate block layers to obstruct cell membrane and prevent
microbes from obtaining essential nutrients for their vital
movement (Kurade et al. 2019). Meanwhile, theaccumulation of LCFAs can poison anaerobic microbes anddestroy their homeostasis, leading to damages such astransformation and death to microbes (Elsamadony et al.
2021). Therefore, LCFAs have been widely recognized as
inhibitors of AD system.
Previous study has shown that different sludge volatilesolid contents mediate hydrolytic conversion efficiency ofanaerobic sludge, but they will be apt to poisoned on accountof LCFAs accumulation (Mahmoud et al. 2004). LCFA loads(mM-LCFA/g-VS) is utilized to further manifest therelationship between LCFAs concentration and sludge
volatile solid contents. From these above discussions, there
are few systematical researches focusing on the influence of
LCFA loads on methanogenic activity under different
experimental conditions.
As a typical unsaturated LCFA, oleate (C18:1) has
continuously attracted much attention for their abundance inwastewater (Alves et al. 2009). In this paper, we utilize oleate
as a representative inhibitor in anaerobic serum vial bottles.
Firstly, we analyze the initial microbial community
composition of mesophilic and thermophilic sludge by 16S
rRNA identification to further verify subsequent conclusions.
Then we carried out another batch experiment to explore theinfluence of oleate loads on methanogenic activity underacetoclastic or hydrogenotrophic pathways by utilizing initialmesophilic and thermophilic sludge.

2 Materials and methods
2.1. 16S rRNA analysis
The microbial community of initial mesophilic andthermophilic sludge was analyzed by 16S rRNA cloning andsequencing. The detailed operation procedure about genomic

23

sampling and analysis was carried out according to previous
thesis (Jing et al. 2013).
2.2. Seed sludge and substrate
Sufficient seed sludge derived from a continuous-stirredtank reactor (CSTR). It was cultivated under mesophilic andthermophilic conditions in the incubator for three days
respectively to recover methanogenesis activity. 2000 mgCOD/L sodium acetate was configured to cultivate acetateutilizing methane producing archaea (MPA).
2.3 Experiment designFirstly, seed sludge, phosphate buffer, substrate, sodium
oleate and distilled water were added in each anaerobic serum
vial bottles. Subsequently, we compressed the bottle with abutyl stopper and sealed it with an aluminum crimp caps. The
headspace was swilled by N2 when utilizing acetate as
substrate. On the other hand, H2/CO2 (80:20, v/v) was used
to fill the headspace when cultivating hydrogen-utilizing
MPA. Finally, 250 mg/L Na2S·9H2O was injected into allbottles. The liquid volume containing anaerobic sludge,
phosphate buffer, substrate, and sodium oleate wasmaintained at 50 mL. Subsequently, these bottles were
statically cultivated at mesophilic (35℃) and thermophilic(55℃) conditions respectively in a shaker (MMS-220,
EYELA) for heating and shaking. Each experiment was
performed in three parallel vial bottles. Table. 1. lists thedetailed experimental condition of diverse oleateconcentration and volatile solid contents respectively. Gas
production was measured three times a day until total COD
almost converts into theoretical biogas yield.
Table. 1. Detailed experimental conditions
Number

VS
(g/L)

MA1
MA3
MA5
MA7
MA9
MH1
MH2
MH3
MH4
MH5
MH6
MH7
MH8
MH9
MH10

2
4
6
8
10
2
2
4
4
6
6
8
8
10
10

Oleateconcentration
(mM)
0
0
0
0
0
0
1.5
0
1.5
0
1.5
0
1.5
0
1.5

2.4. Analytical methods

Number

VS
(g/L)

MA2
MA4
MA6
MA8
MA10
TH1
TH2
TH3
TH4
TH5
TH6
TH7
TH8
TH9
TH10

2
4
6
8
10
2
2
4
4
6
6
8
8
10
10

Oleateconcentration
(mM)
0.5
0.5
0.5
0.5
0.5
0
1.5
0
1.5
0
1.5
0
1.5
0
1.5

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
Sludge volatile solid contents were detected according
to standard methods (American Public Health Association,2012). Biogas production was measured by glass syringe.
The pH value was measured by a handheld pH meter(LAQUAtwin, Horiba Ltd., Albany, NY). The compositionof biogas was determined by a gas chromatography(Shimadzu GC 2014) equipped with a flame ionization
detector and a StabiliwaxR-DA capillary column (Resteck,
Bellefonte, PA, USA).

GP-RSS & SyDe
Tohoku University

potential (1010 mL CH4/g VS) theoretically (Kim et al. 2004,
Raposo et al. 2012). Therefore, in the future FOG
biodegradation anaerobic reactor, we should not only take theadverse effect of oleate loads on anaerobic sludge into
consideration so that we can maintain the stability of AD
reactor as much as possible, but also consider their biogas
production potential.

4 Conclusions
3 Results and discussion
In general, Fig. 1. presents that the abundance of
microbes’ species in mesophilic serum bottles surpass that inthermophilic bottles, especially acetate-utilizing andhydrogen-utilizing archaea for methane production.
Therefore, though thermophilic condition promotes substratehydrolyzation process and has higher theoretically potential
to produce methane, anaerobic mesophilic reactors used forlipidic waste degradation are more stable and reliable thanthermophilic ones because they possess larger microbe’s
quantity and more abundant microbe’s species (Labatut et al.
2014).

.
Fig. 1. Microorganism composition (a) archaea genus composition inmesophilic and thermophilic sludge (b) bacteria phylum composition inmesophilic and thermophilic sludge

9080

SMA (%)(b) 100

SMA (%)(a) 100

80

70

60

60

40

20

50

0
2

4

6

8

10

12

14

16

2

oleate load (mM-oleate/g-VS)

4

6

8

10

12

14

16

oleate load (mM-oleate/g-VS)(c) 100

SMA (%)

90
80
70
60
50
40
2

4

6

8

10

12

14

16

oleate load (mM-oleate/g-VS)

Fig. 2. The relationship between oleate loads and SMA percentage (a)acetoclastic SMA in mesophilic sludge (b) hydrogenotrophic SMA in
mesophilic sludge (c) hydrogenotrophic SMA in thermophilic sludge.

Fig. 2. presents the relationship between oleate loads
and AD results, the IC50 of Fig. 2. (b) is 6.68 mM-oleate/gVS. However, in Fig. 2. (a) and (c), the optimal oleate load
is both 5 mM-oleate/g-VS. This indicates that moderateoleate load not only detriments slightly to anaerobic microbes,
but also owns bioavailable potential, which accords with theconclusion that LCFAs have high methane production

24

Generally, 16S rRNA analysis manifests the abundanceof initial archaea and other bacteria decrease as temperaturerises which shows an unstable omen to thermophilic AD
system for lipidic waste treatment. On the other hand, oleateloads (mM-oleate/g-VS) is a critical index in anaerobic
bioreactor because 6.68 mM-oleate/g-VS will result in 50%
decrease of methane production in hydrogenotrophic
mesophilic sludge. Meanwhile, this paper provides a
guidance of noticeable and avoidable oleate loads for futureanaerobic lipidic waste digestion bioreactor.

Reference
1. American Public Health Association (APHA), American Water
Works Association, Water Environment Federation, 2012. Standard
Methods for the Examination of Water and Wastewater, 22nd Edition,
Standard Methods.
2. Alves, M.M., Pereira, M.A., Sousa, D.Z., Cavaleiro, A.J., Picavet, M.,
Smidt, H. and Stams, A.J. (2009) Waste lipids to energy: how to optimize
methane production from long-chain fatty acids (LCFA). Microb
Biotechnol
2(5),538-550.http://doi.org/10.1111/j.17517915.2009.00100.x
3. Elsamadony, M., Mostafa, A., Fujii, M., Tawfik, A. and Pant, D.
(2021) Advances towards understanding long chain fatty acids-induced
inhibition and overcoming strategies for efficient anaerobic digestion
process.
Water
Res
190,
116732.http://doi.org/10.1016/j.watres.2020.116732
4. He, X. and Yan, T. (2016) Impact of microbial activities and hydraulicretention time on the production and profile of long chain fatty acids ingrease interceptors: a laboratory study. Environmental Science: Water
Research&
Technology
2(3),474482.http://doi.org/10.1039/c6ew00013d
5. Jing, Z., Hu, Y., Niu, Q., Liu, Y., Li, Y.Y. and Wang, X.C. (2013)
UASB performance and electron competition between methaneproducing archaea and sulfate-reducing bacteria in treating sulfate-richwastewater containing ethanol and acetate. Bioresour Technol 137, 349357.http://doi.org/10.1016/j.biortech.2013.03.137
6. Kim, S.H., Han, S.K. and Shin, H.S. (2004) Kinetics of LCFA
inhibition on acetoclastic methanogenesis, propionate degradation andbeta-oxidation. J Environ Sci Health A Tox Hazard Subst Environ Eng
39(4), 1025-1037.http://doi.org/10.1081/ese-120028411
7. Kurade, M.B., Saha, S., Salama, E.S., Patil, S.M., Govindwar, S.P.
and Jeon, B.H. (2019) Acetoclastic methanogenesis led by
Methanosarcina in anaerobic co-digestion of fats, oil and grease forenhanced production of methane. Bioresour Technol 272, 351359.http://doi.org/10.1016/j.biortech.2018.10.047
8. Labatut, R.A., Angenent, L.T. and Scott, N.R. (2014) Conventional
mesophilic vs. thermophilic anaerobic digestion: A trade-off between
performanceandstability?
Water
Research
53,
249258.http://doi.org/10.1016/j.watres.2014.01.035
9. Mahmoud, N., Zeeman, G., Gijzen, H. and Lettinga, G. (2004)
Anaerobic stabilisation and conversion of biopolymers in primary sludge- effect of temperature and sludge retention time. Water Research 38(4),983-991.http://doi.org/10.1016/j.watres.2003.10.016
10. Raposo, F., De la Rubia, M.A., Fernández-Cegrí, V. and Borja, R.
(2012) Anaerobic digestion of solid organic substrates in batch mode:
An overview relating to methane yields and experimental procedures.
Renewable and Sustainable Energy Reviews 16(1), 861877.http://doi.org/10.1016/j.rser.2011.09.008

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

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Combining Steam Injection with Hydrodynamic Cavitation for Sludge
Pretreatment to Improve Sludge Solubility and Digestion Performance○ Shitong ZHOU1*, Guangze GUO1, Yemei LI2,3, Yu-You LI1,2
1

Department of Frontier Science for Advanced Environment, Graduate School of Environment Studies,
Tohoku University,6-6-06 Aoba, Aramaki-Aza, Sendai, Miyagi 980-8579, Japan.
2
Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku
University,6-6-06 Aoba, Aramaki-Aza, Sendai, Miyagi 980-8579, Japan.
3
Material Cycles Division, National Institute for Environmental Studies, Tsukuba 305-8506, Japan*E-mail: zhou.shitong.q2@dc.tohoku.ac.jp.

Abstract
Two novel pretreatment methods (VT-SI and IHSI) that integrated steam injection into hydrodynamic cavitation(HC) in different ways were applied to improve sludge solubility as well as digestion performance. The raw
sludge and pretreated sludge were digested in a thermophilic anaerobic membrane bioreactor (ThAnMBR)
respectively. The analysis for sludge properties revealed a significant enhancement in sludge solubility after
VT-SI and IHST pretreatment, with the ratio of soluble COD to total COD increased by around 91.3% and 84.6%
respectively. Besides, sludge digestion performance was also improved, with the biogas production rate (L/L/d)increasing by 6.9% and 5.8%, and the organics to methane conversion efficiency (L-CH4/g-VS) rising from 0.289
to 0.372 and 0.338 L-CH4/g-VSfed. And the energy balance analysis found that in ThAnMBR scenario, either the
raw sludge or pretreated sludge, the energy recovery could not satisfy the energy consumption. But in case of
traditional AD reactor, regardless the energy used for sludge recycle and permeate extracting, the VT-SI could
realize higher net energy production than that of raw sludge, presenting a promising application prospect in future.
Keywords: Sludge Pretreatment; Hydrodynamic Cavitation; Sludge Solubility; Biogas Production; Energy
Recovery
1 Introduction
Anaerobic digestion (AD) has commonly been applied
as a low-cost and energy-producing technology for sludge
treatment in wastewater treatment plants (WWTPs), since it
can remove organic pollutants and simultaneously produce
biogas. However, the complex sludge structure including
extracellular polymeric substances (EPS) matrix, cell wall,etc., greatly strains the full utilization of organics in thesludge, resulting in low biodegradability degree, slowhydrolysis rate, and limited biogas production efficiency.
Sludge pretreatment has been proposed to disrupt sludge
structure and release more biodegradable organics. There
have been various pretreatment methods developed andmany of them have been verified effective, but the mostcommonly applied ones, such as thermal hydrolysis, alkali
addition, and ultrasonic treatment, require either highenergy cost, new treatment facility construction or a large
amount of chemical dosage. It is necessary and importantfor WWTPs to look for more electricity-saving andcost-effective methods for sludge pretreatment to pursue
energy self-sufficiency and carbon neutrality.
Hydrodynamic cavitation (HC) has aroused more andmore interests recently, as it presents multiple merits like
low operation cost, convenient application, effective organic
removal and so on. The effect of HC is attributed to instantand dramatic change of pressure in the fluid, which lead tothe formation, growth and expansion and further explosionof cavities. Commonly applied HC instruments like venturi
tube or orifice plate all have simple configurations and arevery easy to operate, showing high applicability in WWTPs,
since sludge pretreatment can be realized by changing thepipeline design. Apart from HC, what else can we do to25

enhance the pretreatment effect and increase the energy
efficiency in the WWTPs? In fact, the recovery of the waste
heat generated has always been a neglected but very
promising source, and there is a large amount of steam
generated in WWTPs. This part of the steam, if utilized, will
not only improve the HC performance but also increase theefficiency of energy utilization in wastewater treatment
plants, as the high-temperature steam not only heats thesludge but also promotes cavitation.
Therefore, this study is to investigate the effect of the
combination of steam injection and HC on sludge
biodegradability and methane conversion performance in athermophilic AnMBR system with two different
pretreatment methods. The energy balance under different
scenarios was also estimated.

2 Materials and methods
2.1 Substrate and Pretreatment methods
The substrate was concentrated excess sludge collectedfrom S WWTPs in Sendai. Two pretreatment methods wereapplied before sludge digestion., both of which combined
the steam injection and HC, but presented different steam
utilization ways. One was a venturi tube-type with steam
injection (VT-SI) and another was a steam inflowing type
(IH-SI). The schematic diagram of these two methods isshown in fig.1-a, 1-b. The VT-SI was based on the venturi
tube with an injection inlet designed in the throat so that thesteam could be injected at a high speed to promote thecavitation. In the IH-SI, the sludge passed through a nozzle
which was surrounded by the steam transporting pipe. The
sludge, as well as the steam, were mixed in the sequent area
where the cavitation occurred. In this process, the sludge

The 10th International Symposium on Water Environment Systems

GP-RSS & SyDe

(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
was heated from 30 ℃ to 50 ℃ due to the injection of large
amount of high-temperature steam.
2.2 Experimental Device and Operation Conditions
A thermophilic anaerobic membrane bioreactor (shownin fig.1-c) was applied for sludge digestion to investigate
the methane production performance. The raw excess
sludge as well as two pre-treated sludge were fed as thesubstrate, respectively. The TS concentration of the bulk
sludge in the system was kept at around 30 g/L bycontrolling the daily sludge discharge volume.

Tohoku University

production rate as well as biogas yield efficiency were
calculated in each stage based on the biogas production andcomponent data. The calculated results showed the biogas
production rate were 0.954, 1.02, and 1.01 L/L/d in thestage of unpretreated sludge, VT-SI, and IHSI, respectively,
and the biogas yield efficiency were 0.289, 0.372, and 0.338
L-CH4/g-VSfed, accordingly, implying a 6.9% and 5.8%
increase in biogas production rate and a 28.7% and 17.0%
enhancement in methane yield efficiency. The materialbalance based on COD was also conducted, and it was
found the ratio of COD converting to methane has increased
from 42.0% to 46.2% and 46.0% after VT-SI and IHSI
treatment. It can be seen that the improvement effect on
methane production seemed not as effective as that on
sludge solubility, which might be attributed to the masking
effect of thermophilic digestion, namely the relatively highbiodegradation degree and methane conversion efficiency ofthermophilic digestion itself.
Table 1 The biogas production performance of each sludge

Fig. 1. The schematic diagram of the pretreatment methods andexperimental device. a. VT-SI; b. IHSI; c. ThAnMBR

Substrate/Pretreatment method

3 Results and discussion
3.1 Significant Sludge Solubility Improvement
Different analyses were conducted to investigate theeffect of pre-treatment on sludge properties. It showed that
TS and SS concentrations decreased after VT-SI and IHSI
pretreatment. The result of the particle size distribution alsopresented a smaller mean particle size compared with theunpretreated sludge. This implied the great crushing solid
removal effect of these two methods. More importantly,
there were significant soluble organics raised, in terms ofproteins(PN), polysaccharides（PS）, and COD. Taking theratio of soluble organics to total organics as the indicator
representing sludge solubility, it was found that the sludge
solubility increased by about 91% and 85%, respectively
after VT-SI and IHSI treatment. Besides, it was noted thedramatic increase of soluble protein content, was nearly fourtimes compared to the unpretreated one. This was because
the sludge was rich in protein but most of which wasprotected inside the EPS or cellular structure, and the HC
helped destroy such structure and release morebiodegradable organics.

BiogasComposition

Unit

Raw WAS

VT-SI

IHSI

CH4

%

63.1

65.0

63.3

CO2

%

34.3

33.6

34.4

H2S

ppm

500

527

588

(L/L-reactor/d)

0.954

1.02

1.01

L-CH4/g-VSfed

0.289

0.372

0.338

Biogas production rate
Methane Yield Efficiency

3.3 Energy Analysis
The energy balance analysis was also conducted toestimate the economic benefits when introducing these two
pretreatment methods. The energy recovery mainly camefrom biogas production, heat energy recovered by AnMBR
and pretreatment, while the energy consumption including
pretreatment, heating, biogas sparging, feeding, sludge
cycle, mixing, permeate extracting and heat loss. The
calculated results showed that in every stage, the energy
recovery could not satisfy the energy demand to operate thethermophilic AnMBR, since the sludge recycle andpermeate extracting take a great deal of energy. It seemedthat the energy consumed on pumps has long been
underestimated. However, in a case of a regular sludge
digestion reactor, such as CSTR, when the energy
consumed on sludge cycle and permeate extracting wereomitted, the net energy production could be realized in raw
sludge and VT-SI scenario, with the net energy production
were 1.501 and 2.018 kJ/g-VS, respectively. This indicatedthat VT-SI possess advantages over IHSI due to the lessenergy consumption on pretreatment but similar biogas
improvement effect, and there was still a promising
application prospect of such an integrated pretreatment
method.

4 Conclusions⚫
⚫
⚫
Fig. 2. Soluble substances concentration in sludge before and after
pretreatment

3.2 Enhanced Biogas Production Performance
All three kinds of sludge had been fed as the substrate ina ThAnMBR system to evaluate the methane conversion
efficiency under thermophilic condition. The biogas

26

VT-SI and IHSI greatly improved the sludge solubility,with the soluble COD in sludge nearly doubled.
VT-SI and IHSI also enhanced the sludge digestion
performance, as the VS to methane conversion
efficiency increased by 28.7% and 17.0, respectively.
In a traditional digestor scenario, the VT-SI could
realize high net energy production than raw sludge.

Reference[1] Guo, G., Li, Y., Zhou, S., Chen, Y., Qin, Y., & Li, Y. Y. (2022).
Enhanced degradation and biogas production of waste activated sludge
by a high-solid anaerobic membrane bioreactor together with in pipe
thermal pretreatment process. Bioresource Technology, 346, 126583.

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDe
Tohoku University

Influence of nitrate as electron acceptor on Nap anaerobic biodegradation○ Qigui Niu1,2,3*, Yilin Yao1 & Jingyi Li1
1

School of Environmental Science and Engineering, Shandong University, 72#Jimo Binhai Road,
Qingdao, Shandong Province, 266237, China.
2 China–America CRC for Environment & Health, Shandong University, 72#Jimo Binhai Road, Qingdao,
Shandong Province, 266237, China.
3
Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, Shandong
University，Qingdao, Shandong 266237, China.
*E-mail: niuqg@sdu.edu.cn.

Abstract
Simultaneous methanogenesis, denitrification, and Nap anaerobic biodegradation in the up-flow anaerobic sludge
blanket reactor (UASB). This study focuses on the promotion of adding nitrate as electron acceptor on naphthene(Nap) biodegradation. After 106 d domestication period, the biological removal of Nap reached 5.38 mg/(L·d). With
the nitrate addition as electron acceptor, the biological removal of Nap increased 2.3 times. Interesting, with thenitrate addition, the absorption by sludge of Nap also increased with the ratio of Nap absorption by sludge/ Napbiodegradation increased from 0.55 to 1.36. The concentration of extracellular polymeric substances (EPS) changed
with the nitrate addition. And EPS became less hydrophobicity to absorb more Nap. This research confirms that
adding nitrate is a promising strategy for the biodegradation of refractory organic compounds.
Keywords: Nap anaerobic biodegradation; Methanogenesis; Electron acceptor; Extracellular polymeric
substances.
1 Introduction
PAHs are lipophilic and mutagenic that have attracted
worldwide attention owing to their ubiquity, abundance,
persistence, and toxicity. Aerobic PAHs degradation has
been well studied and the associated mechanism of
biotransformation was clearly. However, PAHs do notextensively present in oxic environments, but have markedly
increased longevity in anoxic environments, such as
petroleum-polluted soil, deep subsurface oil reservoirs,
underground water, and saturated sediments.
Anaerobic digestion (AD) possesses a perfect electron
utilization system including electron production, electrontransport and electron consumption, for which organic
compounds provide electrons as electron donor and theseelectrons are subsequently used for producing methane. The
syntrophic association between the electroactive bacteria andmethanogens can maintain the stable performance of AD.
Electroactive bacteria decompose organic compounds, suchas PAHs then generate and transfer electrons to methanogens
directly or indirectly. However, seldom of research focus on
adding electron acceptor to promote the microbial behavior.
In this study, the AD electron utilizes the system in the upflow anaerobic sludge blanket (UASB) reactor (7.5 L work
volume) was specifically constructed, and then Nap wasadded as another electron donor, while NO3- wasincorporated as another electron acceptor to explore thepromotion on Nap anaerobic digestion, which can provide areference for subsequent practical studies.

2 Materials and methods
2.1 Reactor Setup and Operation
UASB reactor was used with work volume of 7.5 L. The
operating conditions of the reactor were shown in Table 1.
The whole 250 d experiment was divided into four stages

27

based on varied electron donor and acceptor concentrations.
During stage I (phase I, II and III), cyclodextrin was used ascarbon source and electron donor to build AD system. Thenin stage II (phase IV, V, VI and VII), Nap was added asanother electron donor. Next in stage III (VIII, IX and X),
KNO3 was added as another electron acceptor. Finally instage IV (phase XI, XII, XIII, XIV and XV), COD was
reduced by half. Gas production and methane production
were recorded. The effluent samples from the reactor werecollected every two days to determine chemical oxygen
demand (COD), Nap, ORP, pH, NO3- and NO2-. And sludge
samples were collected to determine Nap in sludge every twodays. At the end of every phase, sludge samples werecollected to extract EPS according to our previous study.1

Table 1 Operation conditions

2.2 Sampling and analytical methods
COD, pH, ORP, NO3-, NO2-, TS and VS were analyzed
according to standard methods. And the composition of
methane was detected by absorbing CO2 at standard
atmospheric pressure. Nap was measured by HighPerformance Liquid Chromatography (HPLC) as describedin our previous study.2

3 Results and discussion
This part is Results and discussion. The reactor performanceis shown in Figure 1 during 270 d in a continuous UASBThe 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
reactor. It was divided into four major stages including 15
phases. The pH and ORP were stable during the operation. In
stage II, the Nap influent concentration was increased fromthe value of 10 mg/L to 60 mg/L, the production of methaneraised from 957.82±169.5 mgCOD/(L*d) to 1333.54±176.62
mgCOD/(L*d). Meanwhile, the Nap removal rate increased
from 2.45±0.21 mg/(L*d) to 5.38±0.54 mg/(L*d). In stage III,
when the NO3- was added as the electron acceptor, the Napremoval rate increased from 5.38±0.54 m/(L*d) to 6.50±2.64
mg/(L*d) and NO3- removal efficiency reached 97.26%.
Stage II Stage IIII

OLR (mgCOD/(L*d))NO3--Nin

OLR

Stage IV
90

Napin

60
2000
30
0

0

9

pHin

pH

pHout

NO3--Nin / Napin(mg/(L*d))Stage I
4000

6

0
ORP

ORP (mv)

-100
-200
-300
-400
12000

Yield (mL/d)

Biomethane
Biogas6000

0

CODin (mg/L)

6000

CODin

CODout

4000
2000
0
TVFA

TVFA COD (mg/L)

1000

GP-RSS & SyDe
Tohoku University

It could be inferred that NO3- as the electron acceptor could
promote the biodegradation of Nap. Some electrons mightflow to denitrifying bacteria, which promoted the utilizationof electrons. Then, HRT was changed from 2d to 1d, and theremoval concentration of Nap increased significantly from6.50±2.64 mg/(L*d) to 14.04±2.27 mg/(L·d), which
explained the potential of removing Nap. During stage IV,
CODin changed from 3000 mg/L to 1500 mg/L, with the
CODin/NO3- ratio declined to 3:1. As a result, more electrons
might flow to denitrifying bacteria, causing methane
production decreased from 901.57±79.03 mg COD/(L·d) to735.37±238.80 mg COD/(L·d). Meanwhile, the Nap removal
rate to decrease from 11.37±2.38 mg/(L·d) to 7.46±2.78
mg/(L·d), while the removal rate of nitrate remained above
95%. It is quite important to point out that the Nap in effluent
is maintained at a very low level. Almost all the Nap was
removed in an airtight reactor, since 40%-50% of Nap were
removed by biodegradation and the rest were absorbed by thesludge. With the NO3- addition as the electron acceptor, theratio of Nap biodegradation / Nap absorption by sludge
decreased from 1.36 in stage II (phase V) to 0.55 in stage III(phase X) (Figure S2). EPS plays a key role in the Nap
adsorption and it will be further analyzed in this work.
It is well known that EPS could effectively protect microbes
against the harm of toxic substances by absorbing organic
compounds. During stage II (Figure 2), with Nap increasing,PN decreased from 5.89± 0.52 mg/gTS to 4.68 ± 0.24
mg/gTS and the ratio of PS/PN increased from 0.34 to 0.55.
With the NO3- addition, PS/PN further increased to the valueof 0.76 indicating that the hydrophobicity of EPS decreased,
which is consistent with the increased adsorption capacity ofNap (Figure 1h).

500

4 Conclusions

040

Nap(mg/L)

NapoutSimultaneous methanogenesis, denitrification, and Nap
anaerobic biodegradation in the UASB reactor. Adding
electron acceptor could promote the biodegradation of Nap.
Efficient synergistic Nap biodegradation and methane
production was realized by regulating the ratio of
CODin/NO3-. Nap biodegradation reached the highest 14.04
mg/(L*d) at CODin/ NO3-=6:1, which was three times than
without nitrate. With nitrate addition as electron acceptor,
EPS became less hydrophobicity, which resulted more Nap
was absorbed by sludge.

Napin

20

0
0.6

Naps (mg/gTS)

Naps

0.3

0.0
10

NO3--NoutNO2--NoutN (mg/L)

8

Reference

6
2
0

0

30

60

90

120

180

210

240

(1) Li, J.; Yao, Y.; Shi, Y.; Tang, J.; Gadow, S. I.; Liu, R.; Niu,

270

Time(d)Q. [Bmim]FeCl4 mediated inhibition and toxicity during

Fig. 1. Reactor performance

anaerobic digestion: Dose-response kinetics, biochar-dependent
detoxification and microbial resistance. Water Res. 2022, 210,
117969.
(2) Song, L.; Song, Y.; Li, D.; Liu, R.; Niu, Q. The auto
fluorescence characteristics, specific activity, and microbialcommunity structure in batch tests of mono-chicken manuredigestion. Waste Manag 2019, 83, 57-67.

Fig. 2. Proteins (PN), polysaccharides (PS) in EPS andthe ratio of PN/PS

28

The 10th International Symposium on Water Environment Systems

GP-RSS & SyDe

(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

Tohoku University

Current options in the treatment of agricultural drainage wastewater○ Gadow I. Samir 1*, Saber M. 1 & Zaghloul A. 1
1

National Research Centre, Cairo, Egyp.

At the time being, water is a restrictedindispensable

sustainable

waters at Belbeis and El-Rahawy, as well as

development worldwide. In Egypt, water

assessing the efficiency of four remediation

resourcesthetechniques, i.e., DHS, wetland, micro-algae andchallenges for achieving the highest possible

the combined action of certain biological,

water use efficiency are not that easy. Decision-

chemical and mineral remediate amendments.

makers in Egypt adopted several strategies to

The overall results showed that surface water

securedistribution

was more polluted with different pollutants

including the reuse of low-quality water

during the rainy season compared dry season,

particularly agricultural drainage water that is

especially TCOD which was detected in thealready used in farming on a large scale. Most ofwide range concentration of 553.4 to 924.3mg

the agricultural drainage water in Egypt is apt to

L-1 and 544.3 to 821.5mg L-1at Belbeis and El

many types of pollutants coming from varied

Rahawy drains during dry and rainy seasons,sources. Those pollutants are contentiously

respectively. Our results confirmed that there

disposed of in agricultural drains and could be

was a variation in pollutant levels with seasons.

destroying the soil ecosystem when used in

TCOD, SCOD, BOD5, EC, pH and potential

farming. In Egypt, climate change is expected

toxic elements levels in all water samples

especially in the summer season, these warming

generally exceeded Egyptian water quality

conditions had some adverse impacts on theguidelines for the protection of agriculturalagro-environmental ecosystem. This, however,water uses. The obtained results confirmed thatwhen linked to the low quality of irrigation

El-Rahawi and Belbeis water samples exhibitedwater, would need urgent and fast actions. Thishighresearch covered the biological and chemicalcompared to river Nile water. River Nile water

are

water

resourceforcharacteristics of two agricultural drainage

fairly inadequate

allocation

and

and

29

intensities

withpathogenic

bacteria

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDe
Tohoku University

samples were free from either Salmonella or

1x106, 1x102, 30x106, 20x106, 1x106 and 7x106

Shigella,ofand 50x106, 2x106, 1x104, 79x107, 6x106,

Campylobacter sp. E. coli and E. coli O157

88x106 and 75x106 respectively at the Bridge(3x102, 30 and 1, respectively). El-Rahawi waterand Mosque sites at Belbeis agriculture drain.

samples (after Hadar site) had the highest

However, the counts of bacteria, fungi,

density of E. coli (5x104) and Salmonella sp.

Azotobacter sp., Clostridium sp., Pseudomonas(4x103), while Belbeis (at El-Kantara site) had asp., phosphate dissolving bacteria and cellulose

lower density of Salmonella (10) and Shigella sp.

decomposers were within the range of 57x106,(20) and the highest density of Campylobacter2x104, 1x102, 45x106, 7x106, 1x106 and 2x106

sp.

with

(6x104).

thelowestThe

studiednumbers

indigenous

microorganisms included total bacteria, total
fungi,

Azotobactersp.,

Clostridium

sp.,

Pseudomonas sp., phosphate-dissolving bacteria
and cellulose decomposers. Results revealed
that the counts of bacteria, fungi, Azotobactersp.,

Clostridium

sp.,

Pseudomonassp.,

phosphate dissolving bacteria and cellulose
decomposers were 93x106, 1x106, 1x103, 6x106,
27x106, 1x106, 2x106 and 18x106, 2x106, 1x104,
7x106, 25x106, 25x106, 2x106 respectively at Elhod and El-hadar sites at El-Rahawi agriculture
drain. Whereas, the counts of bacteria, fungi,
Azotobacter sp., Clostridium sp., Pseudomonassp., phosphate dissolving bacteria and cellulose
decomposers were within the range of 62x106,30

respectively in River Nile water.

The 10th International Symposium on Water Environment Systems----- with Perspective of Global Safety(Dec. 8th ~ 9th , 2022)

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Climate risk and vulnerability assessment (CRVA) framework for thebuilt environment: A case study in SEZAD industrial zone
○ Luminda GUNAWARDHANA1* & Mahad BAAWAIN2
1

Department of Civil Engineering, University Moratuwa, Katubedda, Sri Lanka.
2Ministry of Labor, Muscat, Sultanate of Oman.
*
E-mail: lumindang@uom.lk

Abstract
According to the Intergovernmental Panel on Climate Change (IPCC), potential variability in future climate willplace greater pressure on economic, environmental, and social assets. Subsequent damages to the built environment
can be substantially reduced by assessing the climate change impacts on vulnerable sectors in the early stages of the
project planning and implementing appropriate adaptation measures. The objective of this climate risk vulnerability
assessment (CRVA) is to examine climate change threats to the Special Economic Zone Authority at Duqm
(SEZAD) area in Oman to determine to what extent the infrastructure and natural environment are vulnerable toclimate change and to recommend measures that will improve the climate resilience. The SEZAD area is expected
to develop as a industrial economic center based on a seaport, ship repair yard, and dry-dock complex. Surface airtemperature, rainfall, wind speed, and sea level rise were considered for the CRVA analysis. Meteorological records
at Masirah observational station during the 2004-2019 period were used to define the baseline climate. Future
projections from five general circulation models (GCMs) and two representative concentration pathways (RCP 4.5:
stabilization scenario and RCP 8.5: business-as-usual) were downscaled using stochastic models to the local scale.
These projections were incorporated in risk assessment in two future periods: 2040-2059 and 2060-2079. Results
show that the severity of the extreme temperature and rainfall effects will continue to rise in the future. A 12.5% ofannual occurrence probability of a heat wave in the baseline period is likely to reach 41.5% in the 2060-2079 period
according to the RCP 8.5 scenario. The estimated 1% annual exceedance probability (AEP) of 1-day rainfall in thebaseline period (return level = 288.5 mm/day) will likely increase to a 2.7% AEP level during the 2040-2059 period
as projected by the RCP 8.5 scenario. Extreme droughts are likely possible even though such events have notoccurred during the baseline period. A significant change in the days with strong winds (1-hr gust more than 15m/s) was projected in all future periods compared to observations in the baseline period. Results also showed thatthese strong winds will not likely be strengthened up to destructive levels on the Saffir-Simpson Hurricane Scale.
Total inundation land along a 90 km coastal line ranges from about 6 km2 to 50 km2 corresponding to 0.5 m to 5.0
m sea level rise, respectively. The impacts of hazards were assessed in terms of economic, environmental, social,
and public safety, and the resulting climate risk was calculated under 5 categories ranging from negligible risk to
extreme risk. Several adaptation measures were then outlined to cope with the potential damages.
Keywords: GCM; RCP; Duqm; Saffir-Simpson Hurricane Scale; Multi-Model Ensembles.
1 Introduction
In recent decades, governments in the Middle East region
invest extensively in the built environment focusing on theeconomic development of the nations. Most of these designs
are based on the stationarity assumption, which considers thesame probability characteristics of hydro-meteorologicalevents that occurred in the past to be continued to the future.
However, the intensity and the frequency of the extreme
events are likely to increase under climate change resulting
in exacerbating infrastructure damages, disrupting criticalsystems, and increasing operational and maintenance costs[1].
The Climate Risk vulnerability assessment (CRVA) is used
to quantify climate risks that may occur during the design
period of the project and propose the best cause of action to
mitigate or very least reduce the subsequent damages.
Vulnerability to climate change is defined as the degree towhich a system is susceptible to, or unable to cope with,adverse effects of climate change including climate
variability and extremes. Risk of the climate change can beassessed by considering both the consequence of an event

31

occurring and the likelihood that the same event occurs. The
likelihood is used as a general description of probability or
frequency, that is, how likely it is that a hazardous event will
occur. A consequence is the outcome or impact of an event.
A risk assessment process such as the ‘risk matrix’ is a
structured way of identifying impacts, adaptive responses,
and vulnerability to climate change [2].
SEZAD area in Oman is expected to develop as a worldscale industrial economic center based on a seaport, ship
repair yard and dry-dock complex, to international standards.
The purpose of this CRVA is to understand the climate andassess climate change threats to the SEZAD area, todetermine to what extent the infrastructure and naturalenvironment is vulnerable to climate change, and torecommend measures that will improve the climate resilience.

2 Study area
The entire SEZAD development area is about 123,000 ha.
Predominant land use area is allocated for industrial andresidential zones. In addition, about 2,400 ha has been
designated to develop as tourism projects. The designatedThe 10th International Symposium on Water Environment Systems----- with Perspective of Global Safety(Dec. 8th ~ 9th , 2022)

area is featured five main rivers (locally known as wadis) thatchannel the water from the hilly area toward the sea (Fig. 1).
Among these, Wadi Jurf flows directly in the middle of theplanned industrial area. Wadi Saay flows from the south to
the Arabian Sea through the area of the new port expansion.
In order to lower the flood risk downstream, large artificial
channel areas; Jurf and Saay dams were designed on the
upstream sides of the catchments. When designing thechannels, it was expected that two dams are able to reduce a
1000-year peak discharge to a 100-year peak discharge by
routing floodwater through the reservoirs.
Surface air temperature, rainfall, wind speed, and sea level
rise were considered for the CRVA analysis. Meteorologicalrecords at Masirah observational station during the 20042019 period were used to define the baseline climate. The
climate in Duqm is characterized by arid to hyper-arid.
According to the available data in Masirah from 2004 to 2019,
temperature varies from 47.2 ˚C maximum to 11.7 ˚Cminimum with an average of 26.7 ˚C. Annual total rainfall
averaged over the same period in Masirah is about 57 mm. In
general, the total rainfall amount and intensity are higher inJune. For example, tropical storm Ashobaa brought 213
mm/day of rainfall intensity to Masirah in June 2015.

GP-RSS & SyDE
Tohoku University

parameters, identify how they will change due to global
climate change, assess how these climate hazards may affectthe project design or impact the project assets, and thendetermine how to adapt the project specifications. ThisCRVA implements this approach to the extent possible.

3.1 Rainfall indices
When the changes in extreme rainfall are considered,previous research found that the contribution from extreme
rainfall to the annual total rainfall has steadily increased in
two major cities: Muscat and Salalah in the Sultanate of
Oman during the 1990-2009 period [3]. Therefore, thefollowing set of rainfall indices that explore the potentialchanges of extreme rainfall in the future was considered.
1. 100-year 1-day and 5-day maximum rainfall in thebaseline and future periods,
2. annual exceedance probability of the baseline 100-year
return level of the maximum 1-day and 5-day rainfall (%),
3. annual exceedance probability of a day with daily rainfall
exceeding 25 mm (%),
4. annual exceedance probability of a day with daily rainfall
exceeding 50 mm (%),
5. annual exceedance probability of a 5-days event withtotal rainfall exceeding 50 mm,
6. annual exceedance probability of a 5-days event withtotal rainfall exceeding 100 mm, and7. the number of droughts in the baseline and future periods.
Although rainfall is a major indicator of the availability ofwater, the temperature is also an important factor that can
influence the availability of water as it controls the rates of
evapotranspiration. Under climate change, large increases inpotential evapotranspiration (PET) in a warmer climate may
cause an increase in widespread drying. Therefore, theStandardized Precipitation Evapotranspiration Index (12month SPEI) was used for assessing the temporal variation ofdroughts. The Hargreaves method was used for estimating
PET. Data requirements include daily maximum andminimum temperatures. SPEI scale used for categorizing theseverity of the drought is as follows.
• Extreme droughts: SPEI ≤ −2,• Severe droughts: −2 < SPEI ≤ −1.5, and• Moderate droughts: −1.5 < SPEI ≤ −1.

3.2 Maximum temperature indicesFig. 1. SEZAD area with Jurf and Saay watersheds

3 Methodology
When determining how climate change may influence a
project, the standard approach is to determine current climate

32

In Duqm area, the following indices were used to estimate
potential variations of maximum temperature in future
periods relative to the baseline period.
1. Monthly averaged daily maximum temperature of thewarmest month,
2. maximum daily temperature estimated for different
percentiles starting from 90th to 99.9th,
3. average number of days per year with daily maximum
temperature above 40˚C,
4. number of heat waves, and5. yearly probability of occurrence of heat waves, at least
one time, at least two times, at least three times, and morethan three times.
According to the Task Team on the Definition of Extreme
Weather and Climate Events commissioned by the World
Meteorological Organization, a heat wave is defined as aperiod of marked unusual hot weather (maximum, minimum,

The 10th International Symposium on Water Environment Systems----- with Perspective of Global Safety(Dec. 8th ~ 9th , 2022)

and daily average temperature) over a region persisting atleast three consecutive days during the warm period of theyear based on local (station-based) climatological conditions,with thermal conditions recorded above-given thresholds.
Accordingly, a heat wave in Duqm area was defined as an
event, which satisfied the following three conditions.
1. During a period of five consecutive days, the maximum
daily temperature reached at least the 98th percentile ofmaximum temperature in the baseline period (38.8 ˚C) in atleast three days,
2. during these five days, the mean maximum daily
temperature was at least 38.8 ˚C, and3. during which, the maximum daily temperature did not
drop below the 90th percentile of maximum temperature in
the baseline period (36.0 ˚C).

3.3 Extreme wind
The wind climate is very important for the port as the windgenerated waves may limit operations at the port.
Accordingly, the following indices were used for assessingchanges in extreme wind.
1. The average number of days per year with maximum
wind speed (1-hr gust) of more than 15 m/s in the baseline
and future periods,
2. annual exceedance probability of Category 1 andCategory 3 winds (60-sec gust) based on the Saffir-Simpson
Hurricane Scale in the baseline and future periods, and3. annual exceedance probability of 100-year return level
estimated from the baseline period and future periods.
The observed wind speeds are on an hourly scale. Therefore,
an appropriate gust factor must be used to match theestimations with the Saffir-Simpson Hurricane Scale. In thisCRVA study, guidelines from the WMO were applied and agust factor of 1.28 was used [4].

3.4 Sea level rise
The IPCC AR5 projected that the global mean sea-level riserate during the 21st century will exceed the historical rate
observed during the 1971–2010 period for all RCPs. Between
0.26 and 0.55 m of sea-level rise are projected for RCP 2.6
by 2100, and between 0.52 and 0.98 m of sea-level rise areprojected under RCP 8.5 by 2100. Estimates of regional sealevel rise can differ from global estimates. The Second
National Communication Report (NCR-2) used sea-level rise
scenarios from 0.2 m up to 5 m added to mean high tide for
estimating inundation areas in Oman. In this CRVA, sea level
rise scenarios adapted in NCR-2 were considered with highresolution DEM data (5 m × 5 m) in Duqm area.

GP-RSS & SyDE
Tohoku University

was used for downscaling wind speed. Frequency analysis ofclimate variables was performed using the Generalized
Extreme Value (GEV) distribution function.

3.6 Multi-model ensemble
Weighting individual GCM based on model performancehas been used as a way to reduce the unwanted uncertainty inclimate model projections. The rationale is that uncertainties
can be reduced if the results from the better-performing
models are given greater weight in the ensemble when used
to produce probabilistic projections. In this study, different
weights were calculated based on the ability of the GCMs torepresent climate in the baseline period. To compute the
GCM weight, the bias B (%) was found first and then B wasconverted to a weight (W) using the following transformation.
𝐵 = 100−1

𝑊 = 1 + 𝐵/100 , 𝐵 < 0
𝑊=
, 𝐵>0
/

(1)
(2)
(3)

Here PGCM and Pobs are the interest climate variables from
GCM and observations, respectively in the baseline period.
The application of Equation 1 for temperature, rainfall, andwind speed is however different and depends on the extremefeature that we are interested in capturing from GCM.

3.7 Vulnerability and risk matrix
In this CRVA study, likelihoods were assigned based on
consideration of both the historical occurrence and the levelof confidence associated with the climate projections, for the
key hazards. The consequence of a climate change impact
can be identified as either minor, moderate, major, severe, or
catastrophic. Depending on the likelihood of the hazard andthe consequence, a single value for the risk was calculated
based on the guidelines in Fig. 2.

Fig. 2. Risk evaluation matrix

3.5 Climate projections
IPCC AR5 produced climate change projections for a rangeof representative concentration pathways (RCPs) based on
different greenhouse gas (GHG) emissions scenarios. In thisstudy, projections of RCP 4.5 and RCP 8.5 scenarios wereused from 5 general circulation models (GCMs). A stochastic
weather generator (Long Ashton Research Station-Weather
Generator; LARS-WG v5.5) was used to downscale thecoarse resolution rainfall and temperature future projections
at the daily scale to the local scale. The two-parameter
Weibull distribution, which is long been established as a
useful probability distribution for representing wind speeds,

33

4 Results and Discussion
Projections for all emission scenarios indicate that theannual average daily maximum temperature increases in the
future in Duqm area. Under the high emission scenario (RCP
8.5), the maximum temperature in the warmest month isprojected to increase by 1.5 ˚C. An increasing number ofstudies have documented that temperature above a certain
high level remains for a few consecutive days is significantly
associated with human mortality. Figure 3 shows that the
number of heatwaves projected in the 2060-2079 period byboth RCP scenarios is considerably higher than that was

The 10th International Symposium on Water Environment Systems----- with Perspective of Global Safety(Dec. 8th ~ 9th , 2022)

calculated from observed temperatures or projected for the2040-2059 period. When compared with the baseline period,
RCP 4.5 and RCP 8.5 scenarios projected 5.5- and 9.1-times
higher numbers of heat waves in the 2060-2079 period. The
frequency analysis of heat waves estimated that even thoughheat waves did not happen more than once per year during
the 2004-2019 period, heat waves more than twice or thrice
per year are also likely to occur in future climates (Table 1).

Fig.3. Number of heat waves in different periods.
Table 1: Annual occurrence (%) of heat waves.

Baseline (2004-2019)

12.5

0.0

0.0

More
than 3
times
0.0

RCP 4.5 (2040-2059)

4.9

2.0

1.2

0.8

RCP 4.5 (2060-2079)

28.5

20.3

11.4

7.1

RCP 8.5 (2040-2059)

7.7

7.7

2.8

2.1

RCP 8.5 (2060-2079)

41.5

28.1

18.5

10.2

Time period

At least At least At least
1 time 2 times 3 times

GP-RSS & SyDE
Tohoku University

rainfall amounts projected by the RCP 8.5 scenario aresmaller than the rainfall amounts calculated fromobservations for return periods greater than 50-year. On theother hand, RCP 4.5 scenario projected consistently greaterrainfall amounts during the 2040-2059 period. For example,
the 100-year 5-day rainfall from observations is about 385.9
mm (1% AEP), which according to RCP 4.5 in the 2040-2059
period is about 535.5 mm.
A comparison of the temporal variations of droughts
estimated in the baseline period with two of the projectionsin the future is shown in Fig. 5. All four future scenarios
projected that the overall proportion of time spent in drought
would only change marginally. These scenarios however
indicate that extreme droughts are likely possible eventhough such events have not occurred during the baseline
period in Duqm. From all scenarios, RCP 4.5 projected thegreatest changes in the 2060-2079 period compared to theexperienced droughts in the past. When two future periods
are compared, the occurrence of droughts in all categories in
the 2060-2079 period is expected to be higher than in the2040-2059 period. In addition to the potential variations ofmonthly total rainfall, this difference can be attributed to theincreases in evapotranspiration because of greater warmingin the 2060-2079 period than in the 2040-2059 period.

Rainfall intensities projected by the RCP 4.5 scenario fordifferent return periods show only some minor changes(positive changes for return periods less than 50-year andnegative changes for return periods more than 50-year)
compared to the intensities estimated from observations. In
contrast, RCP 8.5 projected consistently higher rainfall
intensities in both future periods. In particular, RCP 8.5 in the2040-2059 period projected approximately 80% increases inrainfall intensity for a 100-year return period (Fig. 4).

Fig. 5. Temporal variation of the droughts.
Fig.4. A comparison of 1-day rainfall intensityfrequency curves.
The 5-day rainfall projections generally have higher rainfall
amounts than the observations for return periods of less than
50-year. In contrast to 1-day rainfall intensities, 5-days

34

A significant change in the days with strong winds (1-hrgust more than 15 m/s) was projected in all future periods
compared to observations in Duqm during the 2004-2019
period (Fig. 6). The greatest of which, the RCP 4.5 scenario
estimated 23 days of strong winds per year in the 2040-2059

The 10th International Symposium on Water Environment Systems----- with Perspective of Global Safety(Dec. 8th ~ 9th , 2022)

period compared to 1.6 days/year observed during thebaseline period in Duqm. Results also showed that thesestrong winds would not likely be strengthened up to
destructive levels on the Saffir-Simpson Hurricane Scale.
According to the comparison of return-level and return
period plots of 60-sec gust wind speed between observations
and future projections, three out of four future scenarios
indicated slightly smaller wind speeds than the estimatedvalues from the observations in Duqm. The RCP 4.5 scenario
alone showed increased wind speeds in the 2040-2059 period
than the observations. Consequently, this scenario projectedthat the AEP of the Category 1 and Category 3 winds will be
increased by 0.64% and 0.15%, respectively.

Fig. 6. The Average number of days per year with amaximum wind speed (1-hr gust) of more than 15 m/s.
In this study, potential inundation areas (IA) were calculated
for a coastal belt of approximately 90 km long. Total IA
ranges from about 6 km2 with a sea level rise under 0.5 m toover 50 km2 under a sea level rise of 5 m which corresponds
to conditions of storm surge due to tropical cyclones.
Depending on the likelihood of the hazard and theconsequence, climate risk was calculated (Table 2) andcategorized as follows.
• R1, Negligible risk: Scenarios do not require further
consideration• R2, Low risk: Controls not likely required• R3, Moderate risk: Some controls are required to reducerisks to lower levels• R4, High risk: High-priority control measures required• R5, Extreme risk: Immediate controls required

4 Conclusions and Recommendations
In accordance with the findings of the risk analysis, several
options were proposed to manage the climate risks. The mostimportant recommendations of those are mentioned below.

GP-RSS & SyDE
Tohoku University• The PMP of 580 mm/day used for designing Jurf and Saaydams has a 285-years return period according to theobservations in the baseline period. The annual exceedance
probability of a such event is about 0.35% (R2 risk).
According to the highest impact scenario (RCP 8.5 in the2040-2059 period), such rainfall event has an annual
exceedance probability of 0.8%. Should SEZAD wish to
reduce the associated risk, the non-overspill crest (NoC) levelof the dam can be increased.
• Similarly, 500-year 24-hour rainfall event in HDS (2010),
which was used for the Drainage network master plan, has an
approximately 100-year return period according to theobservations in the baseline period. The annual exceedance
probability of a such event is about 1% (R2 risk). According
to the highest impact scenario (RCP 8.5 in the 2040-2059
period), such rainfall event has an annual exceedance
probability of 3.2%. Should SEZAD wish to reduce theassociated risk, the embankment level can be increased in
critical places after a detailed study.
• Future designs in Duqm are required to consider the local
rainfall records with a full set of past data and potentialchanges in the future.
• Use flood-proof design and construction methods forindustrial, commercial, and residential complexes and tourist
hotels anticipating both surface flooding and undergroundflooding due to groundwater level rise.
• Implement a groundwater-monitoring program toinvestigate the variation in groundwater level and quality.
• Installing weather stations covering the entire catchment
area and piloting an Early Warning System (EWS) is highly
recommended.

Reference[1] Gunawardhana L.N., Al-Rawas G.A., Al-Hadhrami G.,
Quantification of the changes in intensity and frequency ofhourly extreme rainfall attributed climate change in Oman,Natural Hazards, 92 (2018) 1649-1664.
[2] ISO 31000, 2009: Risk management-principles andguidelines[3] Gunawardhana, L.N., Al-Rawas, G.A., A comparison oftrends in extreme rainfall using 20 years data in three major
cities in Oman. The Journal of Engineering Research, 13(2016) 137-148.
[4] Harper, B.A., Kepert, J.D., Ginger, J.D., Guidelines forconverting between various wind averaging periods intropical cyclone conditions, World MeteorologicalOrganization TD-No. 1555 (2008) 1-64.

Table 2 A summary of climate change risk.
#
1
2
3
4
5
6

Climate Change Parameter
Max Temp Heat Wave: 4 types of impact: M/C,
community health, livestock/agriculture & tourism
High-Intensity Extreme Rainfall: 4 types: Wadis,
Roads, Port & Maintenance
Prolonged Rainfall Intensity >5 days: 3 types:
Roads, Flooding & Structure
Droughts: 3 types: GW, Crops & Ecology
High Winds: 3 types: Port Ops/Coastal Topping,Bldgs/Infra, Dust Impacts on public health
Sea Level Rise: 3 types: Corrosion/damage,erosion/shoreline, loss of freshwater/agriculture

35

Risk: 2040 – 2059
RCP 4.5: 1 x R1 & 3 x R2
RCP 8.5: SameRCP 4.5: 1 x R1 & 3 x R2
RCP 8.5: SameRCP 4.5: 2 x R2 & 1 x R3
RCP 8.5: 1 x R1 & 2 x R2
RCP 4.5: 1 x R2 & 2 x R3
RCP 8.5: SameRCP 4.5: 2 x R1 & 1 x R4
RCP 8.5: SameRCP 4.5: 3 x R2
RCP 8.5: 1 x R2 + 2 x R3

Risk: 2060 – 2079
RCP 4.5: 1 x R2 + 3 x R3
RCP 8.5: 1 x R3 + 3 x R4
RCP 4.5: 1 x R1 & 3 x R2
RCP 8.5: SameRCP 4.5: 1 x R1 & 2 x R2
RCP 8.5: 2 x R2 & 1 x R3
RCP 4.5: 1 x R3 & 2 x R4
RCP 8.5: SameRCP 4.5: 2 x R1 & 1 x R4
RCP 8.5: SameRCP 4.5: 1 x R2 & 2 x R3
RCP 8.5: SameThe 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDE
Tohoku University

Climate Change Adaptation using Managed Aquifer Recharge○ Chaiwat EKKAWATPANIT1*,Chanchai PETPONGPAN1, &Duangrudee KOSITGITTIWONG1
1

Civil Engineering Department, King Mongkut's University of Technology Thonburi, 126 Prachautit Rd.
Bangkok 10140, Thailand.
*E-mail: chaiwat.ekk@kmutt.ac.th

Abstract
Among numerous approaches to responding to hydro-climatic extreme events such as floods and drought, theconjunctive use of surface water and groundwater is one effective option. Flooding can be mitigated by keeping
surplus water during the wet season in the aquifer and, meanwhile, using the groundwater storage to deal with awater deficit issue in the dry season. The purpose of this study is to investigate the Managed Aquifer Recharge
approaches for the holistic management of surface water and groundwater. The SWAT-MODFLOW model isperformed to simulate the surface water-groundwater regime of the vulnerable region in Thailand under the futureclimate scenarios from 2021–2040. The results show that about 2,000 recharge wells can be installed in the mostsuitable areas to inject the water into the aquifer layer. Under the minimum and maximum Green House Gas
emission scenarios (RCPs 2.6 and 8.5), recharging groundwater at 550-900 m3/day causes 22x106 m3 of groundwater
storage while reducing 500x106 m3 of flood volume. From 2031–2040, the groundwater storage can be increased
by 48x106 m3 due to a recharge rate of 1,000–1,400 m3/day under RCP 2.6 and 1,400–1,800 m3/day under RCP 8.5.
The surface water seems to have decreased by 940x106-1,120x106 m3. The achieved approaches can be applied tocreate primary proactive plans in the conjunctive use of water to prepare for climate change impacts in the future.
Keywords: Managed Aquifer Recharge; Surface water-Groundwater simulation; Climate change;
Hydrological modeling.
1 Introduction
The conjunctive use of surface and groundwater relates tothe combined management and development of surface waterand groundwater for sustainable water use in general. The
purpose of this water management strategy is to improve theholistic resilience of water supply, particularly in areas withhigh water availability throughout the seasons, by utilizing
surface water and groundwater systematically. As mainly
focused, groundwater is used to play an advantageous role inwater storage, distribution, and treatment for increasingwater supply coupled with improving water quality anddistribution (Bertule et al., 2017).
In recent years, Managed Aquifer Recharge (MAR) has
become an essential strategy for water resources management
under the rising intensity of climate extremes from climatechange. Groundwater is intentionally recharged into aquifers
for a variety of reasons, including maintaining groundwaterlevel and pressure, storing and recovering water for futureuse, and protecting the environment (land subsidence andsalt-water intrusion prevention). Research regarding MAR interms of economics, governance, operation, risk assessment,
and public acceptance has been undertaken. Over the pastfew decades, the MAR project has been implemented at an
average of 5% per year, but it is not sufficient to respond to
an increase in groundwater extraction (Dillon et al., 2019).
Thus, it is demonstrated that the conjunctive use of surface
water and groundwater plays an increasingly important rolein the climate change adaptation strategy. This study takes
into account the potential of this water resources36

management approach to cause an effective implementation
with the least impact on the local people. The conjunctive useof surface water and groundwater approaches is applied to asimultaneous simulation of surface water and groundwater
under the various climate scenarios in the future by using the
SWAT-MODFLOW model.

2 Materials and methods
2.1 Study area
The study area covers about 55,362 km2 of the Yom and
Nan River basins in northern Thailand by defining the outlets
at runoff stations Y.5 and N.8A (Fig.1). The ground surface
elevation is between 25 and 2,091 m(MSL). The climate
conditions are mainly influenced by the depression,Southwest monsoon, and Northwest monsoon of the South
China Sea, especially during July-September. Over theperiod of 36 years (1981–2016), annual rainfall in the YomRiver basin is almost 1,200 mm, while the Nan River basin
is 1,300 mm. 90% of rainfall in both basins occurs between
May and October, with the highest value occurring in
September at 240-250 mm. Maximum-minimum airtemperatures have similar patterns in that maximum airtemperatures begin an upward trend in January at 32˚C and
hit a peak at 37.3˚C in April, then decrease continuously until
the end of the year. The minimum air temperature increases
from 18.7˚C in January to 25˚C in April, then reduces by 1.5
˚C in October and further drops to the same level as inJanuary in December. Drought events are mainly affected bylong periods of intermittent rainfall that cause severe impacts
on non-irrigated areas as rainfall is the main water source for

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
agriculture. Furthermore, immersed floods are easily caused
by inconsistencies between transportation routes and waterdrained sections. The Yom River basin seems to be more
severely affected by flood and drought issues than the Nan
River basin due to insufficient storage for storing andrecovering the upstream water, while the Nan River basin has
Sirikit dam.

Fig. 1. Yom and Nan River basins, Northern Thailand
2.2 Methods
The SWAT-MODFLOW model, integrating the source
codes of SWAT 2012 Rev.591 with MODFLOW-NWT by
Bailey et al. (2016), was applied to simultaneously simulate
the surface water–groundwater regime. The model wasconstructed by referring to the proposed in Petpongpan et al.
(2021) because the model demonstrated high performance inthe simulation of surface water-groundwater regimes in the
Yom and Nan River basins. The daily river discharges in thecalibration and validation periods have similar patterns andquantities to the observation data at 15 runoff stations. In
addition, the monthly groundwater heads in both thecalibration and validation periods show similar seasonalvariations to the measured data at 14 observation wells.
The study area is spatially analyzed to define a suitable areafor implementing conjunctive use of water in the approach ofManaged Aquifer Recharge (MAR). According to the DGRreport in 2020, the suitability level depends on the geology,
geomorphology, soil permeability, and slope of the area. The
raster files of these variables are overlaid by defining
weighted factors at 0.9 (geology), 0.8 (geomorphology), 0.7(soil permeability), and 0.6 (slope). The watershed area isclassified into four suitability levels, including Unsuitable,
Low Suitable, Moderate Suitable, and High Suitable(Department of Groundwater Resources, 2020).
The future climate conditions depend on the outputs of the
Global Climate Model (GCM), proposed as theRepresentative Concentration Pathways (RCPs) by the
Coupled Model Intercomparison Project 5 (CMIP5). Outputs
for the historical period from numerous GCMs are initially
screened by comparing them with the observation data due todifferent assumptions and formulas of the GCMs. Because of
its significant impact on hydrologic processes, precipitationis the primary concern variable in this case.As proposed in

37

GP-RSS & SyDE
Tohoku University

Petpongpan et al. (2020), MIROC5 has the most similarmonthly rainfall to measured rainfall data in the Yom and
Nan River basins over the period of 1981–2005. Monthly
rainfall intensity presented by MIROC5 provides moresignificant consistency with observation data than the othernine GCMs, whether in quantity or seasonal variation. To
minimize uncertainties, the original outputs of MIROC5 areadjusted to remove the systematic distributional biases froma different grid size between the global scale and regional
scale. It is adequate to adjust biases for only precipitation and
air temperature due to their higher influences on hydrologic
processes than the other variables (Hanasaki et al., 2013).
The bias correction method, namely the Change Factor
Method (CFM) (Zahmatkesh et al., 2015), is applied becauseof its simplicity and straightforward application.
The conjunctive use of surface water and groundwater is
included in the future scenario simulation to find effective
adaptation approaches under various climate conditions in
the future. The Managed Aquifer Recharge method is applied
as the conjunctive use of water approach dealing with water
resources management under the minimum (RCP 2.6) andmaximum (RCP 8.5) GHG emission scenarios throughout
2021–2040. The groundwater recharge wells (dry wells) areindicated for construction near the existing groundwater
pumping wells in the most suitable areas for groundwater
recharge by excluding the forest area to avoid environmental
impacts. During the wet season, the MODFLOW model's
Wells package generates recharge wells to harvest a surplus
water volume in the shallow aquifer layer for reducing flood
volume and water supply in the dry season. The recharge rateis defined as a positive pumping volume by considering the
expected increasing groundwater use in the Yom and Nan
River basins.

3 Results and discussion
In the calibration period (2007–2011), the Nash-Sutcliffe
Efficiency (NSE) and coefficient of determination (R2)values obtained from all 15 calibrated stations in the Yom
and Nan River basins were higher than 0.75. For the YomRiver basin, the highest values of NSE and R2 are at station
Y.16 in the downstream area. The lowest value for both NSE
and R2 is displayed at station Y.6, located in the middle ofthe basin. In the Nan River basin, stations N.60, N.7A, N10A,
and N8A located in the lower part below the Sirikit dam show
higher NSE and R2 values than those obtained at stations
N.75, N13A, and the inflow of the dam in the upstream area.
This is because of the defined outflow release of the dam,which forces a behavior of streamflow in the downstream
area, especially in the dry season (November–April). The
percent bias (PBIAS) values are in a range of -5.2%-12.7%
for the Yom River basin and -6.4%-10.3% for the Nan Riverbasin. Based on their positive PBIAS values, the riverdischarge in the Yom and Nan River basins are mostly
underestimated by 0.8%–12.7%, except for stations Y.1C,
Y.37, Y17, Y5, and the inflow of the Sirikit dam, for which
PBIAS is negative, suggesting that flows are overestimatedby 0.8%–6.4%. The greatest underestimation is 12.7% atstation Y.16 and 10.3% at station N.60 for the Yom and Nan
River basins, respectively. For the validation period (2012–2016), in both the Yom and Nan River basins, almost all
stations show NSE and R2 values greater than 0.65. PBIAS
are between-28.5% and 14.9%. All stations located in the
middle and upper parts of the watershed provide positive

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
PBIAS values, implying that the simulated river discharge inthese areas is underestimated by 1.9%–14.9%. Whereas inlower parts, river discharges are overestimated by 2.2%–
28.5%, referring to their negative PBIAS. The maximum
overestimation is 28.5% at station Y.16, while the maximum
underestimation is 14.9% at station N.13A.
In general, the daily river discharge simulated by the
SWAT-MODFLOW model is very consistent with theobservation data in both patterns and quantity (Fig. 2). The
simulated results are acceptable based on the NSE and R2
values. In the validation period, daily river discharges in thedownstream reaches of both the Yom and Nan River basins
are overestimated, even though they are underestimatedduring the calibration period. This may be due to the effectof calibrating the model to the high discharge rates of thegreat flood year of 2011. Nevertheless, the simulated daily
river discharges obtained in this study present an
improvement to Petpongpan et al. (2020), who simulated
surface water and groundwater of the Yom and Nan Riverbasins via the SWATMOD-Prep interface. Despite thedifference in the numbers of the assessed stations, their study
obtained NSE and R2 values higher than 0.75 during thecalibration period (2007–2011) and higher than 0.60 during
the validation period (2012–2016), which is consistent withthis study. However, the simulated results of their study aremainly overestimated, especially in the Yom River basin.
Most of the stations show a negative PBIAS and the highest
value is -35.6%, which is higher than in this study that theestimated model error on either of these simulations is in arange of ±30%.

GP-RSS & SyDE
Tohoku University

Fig. 3 presents examples of comparing monthly simulated
and observed groundwater heads for simulations with andwithout groundwater pumping. Including groundwater
pumping is more consistent with the observed data than
excluding them, with the no-pumping scenario
overestimating groundwater levels. The monthly
groundwater levels from simulation with pumping have
similar patterns and magnitude of fluctuation compared to theobserved data, likely due to the seasonal drawdown andrecovery patterns caused by the pumps operating during thegrowing season and then being shut off, as well astranspiration in both the growing and non-growing seasons.
These results indicate that the application of groundwater
pumping has a significant impact on groundwater storage in
the aquifer system and is necessary for the accuracy of themodel. The simulated results in some locations and periods
are different from observed data due to uncertainties inapplying a grid-based model to a large-scale watershed suchas grid cell size or spatial variability of inputs. PBIAS values
show a consistent groundwater simulation with Petpongpan
et al. (2020) that the groundwater heads are overestimated in
the calibration period and underestimated in the validation
period. However, the PBIAS numbers obtained in this study
are about twice as low as in their study. Moreover, the NSE
and R2 values provided in this study are greater than 0.80 for
both periods of the calibration and validation, which is higher
than the mainly displayed between 0.71 and 0.80 in the studyof Petpongpan et al. (2020).

Fig. 3. Comparison of monthly groundwater elevationfrom simulation and observation during 2007-2016
The managed aquifer recharge is generated through thegroundwater recharge wells (dry wells) separated into fourparts (Fig. 4). The recharge wells are classified due to theindividual surface hydrological systems and water resourcesmanagement of the Yom and Nan River basins, including a
different potential for groundwater recharge between theupper and lower parts of the watershed area. The lower area
is defined as having higher recharge rates than the upper area
because of greater topographical suitability, surface water
yield, and the number of irrigation projects, which means
more facilities for recharging the groundwater.
Over the period of 2021–2030, the groundwater recharge
rates during the wet season at 550–600 m3/day in the upper
watershed area and 820–850 m3/day in the lower area can

Fig. 2. Comparison of daily river discharge fromsimulation and observation during 2007-2016

38

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
provide more than 22x106 m3 annual groundwater volume
under the scenario RCP 2.6. While, in order to provide thesame amount of additional groundwater volume under the
scenarios RCP 8.5, the recharge rates are increased to 650700 m3/day in the upper area and to 850-900 m3/day in thelower area. Due to these managed aquifer recharge
approaches, the surplus surface water volume can be reduced
by about 530x106 m3 under the scenario RCP 2.6 and570x106 m3 under the scenario RCP 8.5, on average. During
2031–2040, a recharge rate at 1,400, 1,800, 1,200, and 1,650
m3/day in the upper Yom, lower Yom, upper Nan, and lower
Nan River basins, respectively, causes more than 48x10 6 m3
annual groundwater volume and a decrease of 1,120x10 6 m3
surface water volume under the scenario RCP 2.6. Under
RCP 8.5, a 48x106 m3 of groundwater volume can be added
to a 940x106 m3 of surface water volume from recharge rates
of 1,150 (upper) and 1,500 (lower) m3/day in the Yom Riverbasin, as well as 1,000 (upper) and 1,400 (lower) m3/day in
the Nan River basin.

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more contributing to groundwater recharge responding toincrements in air temperature and water demand in the future.

4 Conclusions
Almost 2,000 groundwater recharge wells can be generated
in the highly suitable areas near the existing groundwater
pumping wells for conjunctive use of surface water andgroundwater using the managed aquifer recharge method.
Recharging groundwater with a rate of 550-700 m3/day in theupper and 820-900 m3/day in the lower Yom and Nan Riverbasins during 2021–2030 under the scenarios RCP 2.6 and
RCP 8.5 can produce more annual groundwater storage
volume at 22x106 m3 coupled with a decreasing 530x106570x106 m3 surplus volume of surface water. Under scenario
RCP 2.6 (RCP 8.5), the recharge rate for the upper Yom,lower Yom, upper Nan, and lower Nan River basins is 1,400(1,150), 1,800 (1,500), 1,200 (1,000), and 1,650 (1,400)
m3/day, respectively, to increase a 48x106 m3 of groundwater
volume during 2031-2040. Based on this managed aquifer
recharge, the surplus surface water is reduced to 1,120x10 6
m3 under scenario RCP 2.6 and to 940x106 m3 under scenario
RCP 8.5, on average.

Reference

Fig. 4. Classification of groundwater recharge wells forthe managed aquifer recharge
Under scenarios RCP 2.6 and RCP 8.5, the managed
groundwater recharge rate in the upper Yom River basin islower than the upper Nan River basin, while it seems higher
in the lower area. whereas, under both GHG emission
scenarios, the Yom River basin recharge rates are greaterthan those of the Nan River basin in both upper and lower
areas between 2031 and 2040. In addition, the managed
recharges to the aquifer in the whole watershed area defined
during 2031–2040 under the scenario RCP 8.5 have lower
rates than under the scenario RCP 2.6. Because of the effects
of climate change, a high amount of annual rainfall combinedwith slightly decreasing air temperatures can result in lessgroundwater recharge required. However, due to the limited
capacity of the groundwater recharge wells applied as the drywell method, it might not be able to harvest the targetedamount of water in some years. Therefore, increasing thenumber of recharge wells should be taken into account for

39[1] Bertule, M., Rosendahl, L., Spensley, J., Lærke, S. andNaswa, P., A Practitioner’s Guide to Adaptation
Technologies for Increased Water Sector Resilience, Climate
Change Adaptation Technologies for Water, (2017).
[2] Bailey, R.T., Wible, T.C., Arabi, M., Records, R.M. andDitty, J., Assessing regional-scale spatio-temporal patterns ofgroundwater-surface water interactions using a coupled
SWATMODFLOW model, Hydrological Processes, 30(2016) 4420-4433.
[3] Dillon, P., Stuyfzand, P., Grischek, T., Lluria, M., Pyne,
R.D.G., Jain, R.C., Bear, J., Schwarz, J., Wang, W.,
Fernandez, E., Stefan, C., Pettenati, M., Gun, J.V.D.,
Sprenger, C., Massmann, G., Scanlon, B.R., Xanke, J., Jokela,P., Zheng, Y., Rossetto, R., Shamrukh, M., Pavelic, P.,
Murray, E., Ross, A., Bonilla Valverde, J.P., Palma Nava, A.,
Ansems, N., Posavec, K., Ha, K., Martin, R. and Sapiano, M.,
Sixty years of global progress in managed aquifer recharge,
Hydrogeology Journal, 27 (2019) 1-30.
[4] Department of Groundwater Resources, Managed
Aquifer Recharge approaches in Thailand, (2020).
[5] Hanasaki, N., Fujimori, S., Yamamoto, T., Yoshikawa,S., Masaki, Y., Hijioka, Y., Kainuma, M., Kanamori, Y.,
Masui, T., Takahashi, K. and Kanae, S., A global water
scarcity assessment under Shared Socio-economic Pathways- Part 2: Water availability and scarcity, Hydrology and Earth
System Sciences, 17 (2013) 2393-2413.
[6] Petpongpan, C., Ekkawatpanit, C. and Kositgittiwong,D., Climate Change Impact on Surface Water and
Groundwater Recharge in Northern Thailand, Water, 12(2020) 1029.
[7] Petpongpan, C., Ekkawatpanit, C., Bailey, R.T. andKositgittiwong, D., Improving integrated surface watergroundwater modelling with groundwater extraction forwater management, Hydrological Sciences Journal, 66(2021) 1-18.
[8] Zahmatkesh, Z., Karamouz, M., Goharian, E. and Burian,
S.J., Analysis of the Effects of Climate Change on Urban
Storm Water Runoff Using Statistically Downscaled
Precipitation Data and a Change Factor Approach, Journal of
Hydrologic Engineering, 20 (15).

The 10th International Symposium on Water Environment Systems----- with Perspective of Global Safety(Dec. 8th ~ 9th , 2022)

GP-RSS & SyDE
Tohoku University

Minecraft as a tool for disaster education: A case study of floodinundation in Fukushima, Japan○ Keisuke ONO1*
1

Department of Civil Engineering and Management, Tohoku Institute of Technology,
Miyagi 982-8577, Japan.
*
E-mail: onokeisuke@tohtech.ac.jp

Abstract
Education is key for reducing children’s risks to disasters. This study developed a 1/1-scale flood hazard map in
the game Minecraft, one of the most popular video games among kids. The city data in a 3D format was derived
from Project PLATEAU by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT), and transformed
into a format readable in Minecraft. Finally, the hazard map in Minecraft was developed and compared with a hazard
map in a 2D format. The developed world successfully represented actual topography, shape of buildings and roads,
and flood inundation area in the watershed, where game players can manipulate their avatar and experience theflood hazard in the reproduced virtual 3D world. This result indicated that the flood hazard map in Minecraft canbe a potential tool for disaster education.
Keywords: Minecraft; disaster education; flood inundation area; hazard map
1 Introduction
Floods are becoming more frequent throughout the world ina changing climate. In Japan, serious floods are causing
inundation damage almost every year. As a non-structuralcountermeasure against floods, Japanese river administrators,
such as the Ministry of Land, Infrastructure, Transport andTourism (MLIT), and prefectural governments, designate
potential areas of flood inundation as “flood inundation
areas”, covering 99% of major river streams in the country.
Based on the inundation areas designated, municipalities
prepare and disseminate flood hazard maps to the residents.
Many reports indicate that the hazard map demonstrated ahigh reliability in several historical floods in the country.
Regarding the use of flood hazard maps by citizens,municipalities disseminate the maps in a paper format, makethem available in their city websites, and conduct disaster
drills based on the maps. These activities have improved theunderstanding of flood risk among citizens who have a highdegree of disaster awareness and who are capable to accessto related disaster information. On the other hand, youth
citizen in compulsory education, such as elementary or juniorhigh school students, sometimes have a less awareness or lessaccess to disaster information. Given the basic idea of
disaster prevention and mitigation in Japan is based on a selfhelp and mutual-help, it is important to provide disaster
information in an improved format for the youth, so that they
can understand the flood hazard in their community and makeappropriate decision by themselves in a moment of floods.
Past studies reported the usefulness of video games in city
planning and disaster education. For example, a United
Nations project used the game Minecraft to have citizens
virtually build improvements in their communities [1].
UNDRR made an online game on disaster risk reduction
where students can play multiple disaster scenarios including
tsunami, wildfire, and earthquake [2]. However, these studies
targeted certain scenarios in a fictional area, which unable
students to play the game in their actual life space; thewatershed where their community belong.

40

Education is key for reducing children’s risks to disasters.
Given the fact that appropriate evacuation action depends onthe flood hazard in the areas, it is important to present theflood hazard in a format which is easy for students tounderstand. Therefore, this study developed a hazard map in
the game Minecraft, one of the most popular video games
among kids, where students can learn the hazard posed byflood inundation. As a pilot case study. this study targeted
Koriyama city in Fukushima, Japan, which experienced aserious flood inundation in recent years. Finally, this study
gives an insight of advantages of the developed map,
challenges, and future works.

2 Materials and methods(1) Minecraft
Minecraft is a java base first person multiplayer sandbox
game. Categorized as virtual world game, Minecraft is agame about placing blocks, where player is requires
gathering object to create environment around it at will.
Minecraft is a game that created and published by Mojang,an indie game Developer Company in 2009 for homecomputer and later the mobile version for iOS and android in
2012. Minecraft is the best-selling video game of all time,with over 238 million copies sold and nearly 140 million
monthly active players as of 2021. This study used Minecraft
Java Edition to create flood hazard map in the virtual world.

(2) Dataset
The 3D data of terrain, building shape, road shape, water
body (e.g., rivers and lakes), and flood inundation area, were
downloaded from the website of Association for Promotionof Infrastructure Geospatial Information Distribution. In thewebsite, “Project PLATEAU”, a leading program of 3D city
data by MLIT, disseminate the data for free of charge [3].
The data format is CityGML for terrain, building shape, androad shape, and Geodatabase for water body and floodinundation area.

The 10th International Symposium on Water Environment Systems----- with Perspective of Global Safety(Dec. 8th ~ 9th , 2022)(3) Data transformation
Development of virtual world in Minecraft needs a datatransformation from CityGML and Geodatabase to a format
which Minecraft can import. The data transformation was
conducted by FME Desktop software developed by Safe
Software Inc. This software is the data integration platformthat allows users to connect and transform data between
hundreds of systems, with the best support for spatial data. In
the transformation, all of the 3D data were converted to aformat of Minecraft with a scale of 1/1, where one block
represent an object of 1m3 (1 m x 1 m x 1 m) in the actual
world.

3 Results and discussion
The figure 1 shows an overview of flood hazard map in 2D
format in a website [4] and 3D format in Minecraft. In themap of Minecraft, the virtual world shows ground surface
with blocks of “Grass” (Green), building with blocks of“Podzol” (Brown), road with blocks of “Rocks” (Grey),water body with blocks of “Ice” (Light Blue), and inundation
area with blocks of “Water” (Blue). The world successfully
reproduces the flood inundation area in Minecraft. The
blocks precisely describe the terrain of watershed, the shapesof buildings and roads, and inundation areas overlaid on the
ground, where game players can manipulate their avatar andexperience the flood hazard (i.e., inundation depth) in the
reproduced 3D world. The area of domain modeled was 16
km2, the number of building objects processed was 20000,
and total blocks placed was 100,000,000 blocks,
approximately. The data transformation took about one hourfor the calculation, by a personal computer with Apple M1
Pro chip and 16 GB of RAM.
The flood hazard map in Minecraft was successfully
developed. However, the result raised some challenges asfollows.

GP-RSS & SyDE
Tohoku University

1) The outer edge of inundation area does not follow its
surrounding terrain since the spatial resolution of floodinundation area was 25 m x 25 m.
2) The building has monochromatic and does not represent
actual building color. An integration of texture data ofbuildings in CityGML could enable a better color
representation with colorful blocks.
3) Possible domain of the world is limited to the area of the
Project PLATEAU since the Project has developed the 3D
data in only 56 cities selected in Japan.

4 Conclusions
This case study developed a 1/1-scale flood hazard map inFukushima in the popular game Minecraft, deriving the 3D
data of city from Project PLATEAU by MLIT. The
developed world successfully represented actual topography,
shape of buildings and roads, and flood inundation area in thewatershed, indicating that the flood hazard map in Minecraft
can be a potential tool for disaster education in elementaryand junior high school. As a future work of this study, we
have a plan of on-site lecture in a community school todemonstrate applicability of the developed world for disastereducation.

Reference[1] UN Habitat, Using Minecraft for Youth Participati
on in Urban Design and Governance, https://unhabitat.oro/using-minecraft-for-youth-participation-in-urban-design-aaa-governance[2] UNDRR, Stop Disasters, https://www.stopdisastersg
ame.orghttps://www.mlit.go.jp/plateau/[3] Ministry of Land, Infrastructure, Transport and To
urism, Project PLATEAU, https://www.mlit.go.jp/plateau[4] Ministry of Land, Infrastructure, Transport and To
urism, Portal site of hazard maps, https://disaportal.gsi.g
o.jp

Fig. 1. Comparison of flood inundation map along Ouse river in Koriyama, Fukushima(Left: 2D inundation map derived from a website, Right: 3D inundation map in Minecraft)

41

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDE
Tohoku University

Spatio-temporal projection of the change in sustainability of Kabul River
Basin under SSP scenarios○ Mohammad Naser SEDIQI1*, Daisuke KOMORI1,2
1

Graduate School of Environmental Studies, Tohoku University, Sendai 980-8579, Japan.
2
Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan*E-mail: mohammad.naser.sediqi.p4@dc.tohoku.ac.jp

Abstract
In this study, reliability (Rel), resilience (Res), and vulnerability (Vul) concept, together with the 3-monthstandardized runoff index (SRI-3) and 12-month standardized runoff index (SRI-12), was used to assess thesustainability of the Kabul River Basin due to drought during historical (1975-2014), near future (2020-2059) andfar future (2060-2099). Three downscaled global climate models (GCMs) from Coupled Model Intercomparison
Project Phase 6 (CMIP6) under two shared socioeconomic pathways (SSP2-4.5 and SSP5-8.5) were used to generate
the climate variables. The performance assessment of the basin was based on two thresholds level, which represent
the normal and moderate dryness condition. The soil and water assessment tool (SWAT) model was used to estimate
the surface runoff. The results revealed that the basin would be in an unsustainable condition compared to thehistorical period and would be in a very low performance level when not considering adaptation. The sustainabilityof the Kabul river basin would be low in the far future compared to the near future, and it would be much lower for
SSP5-8.5 compared to SSP2-4.5. The study provides information on driving factors of sustainability in water
resources and help policy makers in planning adaptation to climate change.
Keywords: Sustainability; Standardized runoff index; CMIP6-GCMs; Shared socioeconomic pathways;
Kabul River Basin.
1 Introduction
Drought among other natural disasters has extensive andadverse impacts on the water resources, ecosystem,
environment and socioeconomic development of a country,
particularly in arid regions.
Drought indices are generally used to assess drought events,
including their severities and durations. There are many
drought indices, for instance, the Standardized precipitationindex (SPI), standardized precipitation evapotranspirationindex (SPEI), and standardized runoff index (SRI). Shukla &Wood, (2008) developed the SRI index to assess hydrologicaldrought considering runoff data. The process of calculating
the SRI index is the same as the SPI index and is widely used
due to fewer data requirements and calculation processes.
Global climate models (GCMs) are essential for climatechange and are usually used to project climatic variables(Sediqi et al., 2022). Coupled Model Intercomparison Project(CMIP) is a standard experimental framework developed bymore than 30 institutions worldwide for analyzing the outputsof GCMs. The latest version of CMIP is CMIP6, which isbased on the shared socioeconomic pathways (SSP)
scenarios and includes future climate adaptation andmitigation.
The reliability, resilience and vulnerability (RRV) concept
which was initially introduced by (Hashimoto et al., 1982) isa widely used approach to assess sustainability of a system
under normal or failure conditions. Reliability measures thecapability of the watershed to be in acceptable no drought
condition during a period. Resilience shows the performanceof the basin, where how quickly it bounces back from drought
to the acceptable stage after getting to the failure state.
Vulnerability measures the amount of drought severity. The
critical step in RRV analysis is to introduce the thresholdvalue, which is the transition zone between failure and42satisfactory state, and it gets a different level of performanceby changing the threshold value.
The objective of this study is to assess the change in water
resources sustainability of KRB, using 3-month and 12month SRI for the two future periods based on RRV
framework under different dryness conditions.

Fig. 2: Study area with its topography

2 Materials and methods
The meteorological data, including daily, monthly
maximum (Tmax), and minimum (Tmin) air temperaturesand precipitation (P), were collected from the Ministry ofEnergy and Water of Afghanistan. In this study, the multimodel mean ensemble of three monthly GCMs, namely
ACCESS-CM2, MPI-ESM1-2-LR, and FIO-ESM-2-0, from
CMIP6 which had the highest skill among other GCM
models for climate change assessment over Afghanistan(Sediqi et al., 2022) used to assess sustainability of the basin

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
future periods of 2020-2099 under two (SSP2-4.5 and
SSP58.5) scenarios.
The SWAT model was used in this study to estimate thesurface runoff under future climate change scenarios.
SWAT-CUP was used for calibration during from 2010 to2020. The SRI index can be calculated by using gamma
distribution function (GDF) for fitting monthly runoff datausing the following equation (Thom, 1966).
𝑔(𝑥) =

1−𝛽 𝛼Г Г(𝛼)and NSE=0.7. Therefore, SWAT was calibrated very well forthe runoff simulation.

𝑥𝑥 𝛼−1 𝑒 𝛽 , 𝑥 ≥ 0(1)where Γ is an ordinary GDF, α and β are shape and scaleparameters. SRI index based has been divided into different
categories shown in the table.1
Table 1: SRI index categories
No
Category
SRI Value1
Mild drought-1 ≤ SRI < 02
Moderate drought-1.5 ≤ SRI < -1
3
Severe drought-2 ≤ SRI < -1.5
4
Extremely drought
SRI ≤ −2
we selected two threshold values to assess future river basin
health conditions. First, the SRI index value of -0.1, indicatedthe normal dryness condition. Second, the SRI index value of-0.7 that corresponds to the future average of 20 percent of
the time, was chosen to represent the future droughtprobability condition. The RRV framework can be calculated
as follows:

𝑅𝑒𝑙 = 1 − ∑𝑀
𝑗=1

GP-RSS & SyDE
Tohoku University𝑑(𝑗)Fig.2. Calibration and Validation of SWAT model.
Fig.3 indicated the spatial category of based on SRI-3 andSRI-12 for two future periods and two SSPs scenarios under
the threshold of -0.1 and -0.7, respectively. Under the -0.1
threshold, most of the areas of the basin for SSP5-8.5 has
projected to low sustainable condition, while for SSP2-4.5
during the near and far future, only upstream of the basins
falls under high to very high sustainable category. Under the-0.7 threshold, for SSP2-4.5 and SSP5-8.5, the basin's
sustainability is projected to increase from very low or low tomoderate, high, or even very high.

(2)

𝑇
−1

𝑅𝑒𝑠 = {1⁄𝑀 ∑𝑀
𝑗=1 𝑑(𝑗)}(3)

𝐿 (𝑖)−𝐿𝑠𝑡𝑑 (𝑖)𝑉𝑢𝑙 = 1⁄𝑀 ∑𝑇𝑖=1 { 𝑜𝑏𝑠× 𝐻 × (𝐿𝑜𝑏𝑠 (𝑖) −𝐿𝑠𝑡𝑑(𝑖)

𝐿𝑠𝑡𝑑 (𝑖))} (4)1

𝑆𝑢𝑠 = [𝑅𝑒𝑙 × 𝑅𝑒𝑠 × (1 − 𝑉𝑢𝑙 )] ⁄3(5)

where M is the number of “unsatisfactory states”, d(j) isthe duration of the j-th “unsatisfactory state” (the number ofmonths spent in an unsatisfactory state), T is the total record
duration (here, 12 months), Lobs(i) is the SRI value of the ith month, and Lstd(i) is the threshold (here, threshold=-0.1, 0.7). H is the Heaviside function, which can ensure that the
Vulnerability calculation only involves an “unsatisfactory
state”—if M= 0, then H=0, and if M > 0, then H=1,
The sustainability index was divided into five classes, as
shown in table (2)Table 2: SRI index categories
No
Category
1
Very high2High3
Moderate
4
Low
5
Very low

Sustainability index

Fig. 3. Spatial variability of reliability based on 3-monthand 12-month SRI drought indicator.

4 Conclusions
This study highlights the importance of improving water
resources management for the KRB, where the climate ischanging, and more resources are needed for irrigation due tothe increasing population. RRV approach in this study has
successfully quantified the impact of future climate
variability on watershed sustainability.

Reference

0.81 ≤ Sus < 1
0.61 ≤ Sus < 81
0.41 ≤ Sus < 0.61
0.21 ≤ Sus < 0.41
0 ≤ Sus < 0.21

3 Results and discussion
Fig.1 shows the calibration and validation results at Tangi
Gulbahar station from 2010 to 2020. The result shows that
the R2 increased to 0.84, and NSE increased to 0.74 after
calibration. Validation also has a higher value of R2=0.81

43[1] Sediqi MN, I., Hendrawan, A., & Komori, D. (2022).
Climate Projections Over Different Climatic Regions of
Afghanistan under Shared Socioeconomic Scenarios.
Theoretical and Applied Climatology, 0123456789, 1–22.
https://doi.org/10.1007/s00704-022-04063-y[2] Shukla, S., & Wood, A. W. (2008). Use of astandardized runoff index for characterizing hydrologic
drought. Geophysical Research Letters, 35(2), 1–7.
https://doi.org/10.1029/2007GL032487

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety[3] Hashimoto, T., Stedinger, J. R., & Loucks, D. P. (1982).
Reliability, Resiliency, and Vulnerability Criteria. Water
Resources Research, 18(1), 14–20.

44

GP-RSS & SyDE
Tohoku University

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDE
Tohoku University

Identifying Landslides Using SAR, Optical Imagery and Spatial Indicesin Google Earth Engine○ Sartsin PHAKDIMEK1*, Daisuke KOMORI1
1Graduate School of Environmental Studies, Tohoku University, Miyagi, 980 -0845, Japan.
*E-mail: sartsin.p@gmail.com, sartsin.phakdimek.q3@dc.tohoku.ac.jp

Abstract
The study aims to detect landslides area and type using satellite images, spectral indices, and topography conditionin Ehime prefecture, Japan on 2018. The sentinel-1 and sentinel-2 are utilized to calculate Normalized Difference
Indices (NDIs) and amplitude change detection which detect landslides that apply with classification and regression
tree (CART) on Google Earth Engine (GEE). As result of landslide detection using amplitude change detection anddifferential of spectral indices, the accuracy of the assessment of the landslide detection is sufficient to identify
landslide which are useful for a rapid mapping after landslide event. The accuracy of model can obtain about 67.7885.71% of detection percentage and 55.72-58.76% of quality percentage, which are moderately good for landslide
detection.
Keywords: Landslides; Normalized Difference Indices; Amplitude change; Google Earth Engine.
1 Introduction
Landslides occur anywhere in the world, causing damage tohumans and properties and economic losses. Rapid response
to landslide events is necessary to assess the damage and savehuman life and properties. The detailed landslide inventories
are location, land cover, morphology, type of landslide andtrigger. These are used to improve understanding of landslide
occurrence location, erosion quantification, and secondary
hazards observation (debris flow, landslide dams, Etc.) [1].
Therefore, detecting landslides occurrence, it is necessary todevelop tools with freely available data that can be used tomap the landslide after catastrophic events.
Several studies have used satellite-based optical images,
such as Landsat-8 and Sentinel-2, and aerial images withmanual mapping approaches to provide high-quality
information for landslides, floods, and other types of natural
hazard mapping [2]. They are limited in terms of quick
response because optical imagery requires sunlight and cloudand shadow-free conditions to identify landslides accurately.
The satellite-based synthetic aperture radar (SAR) can
minimize these limitations of optical imagery.
Synthetic aperture radar (SAR) can penetrate clouds andacquire data day and night. That can be beneficial for rapid
mapping of event landslides triggered by intense or
prolonged rainfall, but its limitation is geometric shading anddistortion). The SAR radar amplitude and coherence-basedchange detection can also be used to identify landslides when
there are changes in ground surfaces properties (reflectance,roughness, dielectric properties) pre- and post-landslide
events [3]. The coherence-based change detection methods
work well in urban areas because the coherence is generallyhigh before a landslide event, and the coherence reduces fromdamage after the event. In mountainous areas with dense
vegetation where landslides occur, the amplitude-basedchange detection method outperforms the coherence-based
method. The coherence change is always low, while theamplitude change is apparent.
The main objective of this study was to investigate how
multi-temporal image composite approaches can be used to
improve accuracy of landslide detection in change detection
images on Google Earth Engine (GEE), which combine SAR

45

for minimize limitation of optical image by Sentinel-1 andspectral indices by Sentinel-2 from open-source satellite
images, the classification and regression trees (CART) is
applied to evaluate in the identification of landslide in theclassification phase. As part of this study, landslide
inventories were obtained from previous researches andmanually satellite image identification. Then, this study
explored change detection approaches with machine learning,with sentinel-1 images with VV- and VH-polarized data, andwith NDVI, BSI, and BI in sentinel-2 images.

2 Materials and methods
Study site is Ehime prefecture, Japan. Ehime landslide event
were triggered by more than 400 mm of precipitation on 5 to
8 July 2018. There were 413 landslide disaster sites, and theminimum, mean, and maximum slope angle is 5, 25, and 33
degrees, respectively.
This study uses SAR amplitude data from the Copernicus
Sentinel-1 (S1) satellite constellation. Satellite S1 carries a
C-Band radar sensor with a wavelength of 5.6 cm. The spatial
resolution of the S1 Ground Range Detected (GRD)
Interferometric Wide Swath (IW) product is 20 x 22 m. The
Ground Range Detected (GRD) products on GEE areprocessed to remove thermal noise and are radiometric andterrain calibrated using the SRTM DEM. Potential landslides
examining the change in amplitude, Aratio, defined as thepre-event stack minus post-event stack, Apre – Apost., Apre
– Apost is equivalent to the standard amplitude ratio
approach following Eq. (1).
𝐴𝑝𝑟𝑒𝐴𝑟𝑎𝑡𝑖𝑜 = 𝑙𝑜𝑔10
(1)
𝐴𝑝𝑜𝑠𝑡

where Apre is amplitude of pre-event and Apost is amplitude
of post event. Aratio can be either positive or negative, withpositive values corresponding to a decrease in SAR
amplitude after a landslide event. The SAR amplitudechanges following landslide events because landslides cause
major changes in ground surface properties that alter theradar reflectance, hillslope geometry, roughness, anddielectric properties [3].
Sentinel-2 images have been used to analyze pre- and postlandslide event. The data selection was made based on theThe 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

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cloud cover estimates (<10%) provided by the European
Space Agency (ESA) on the Google Earth Engine (GEE). To
detect landslide by spectral indices, normalized difference
vegetation index (NDVI), bare soil index (BSI), andbrightness index (BI) are calculated by Eq (2) to (4).
(𝑁𝐼𝑅−𝑅𝐸𝐷)𝑁𝐷𝑉𝐼 =(2)(𝑁𝐼𝑅+𝑅𝐸𝐷)(𝑆𝑊𝐼𝑅+𝑅𝐸𝐷)−(𝑁𝐼𝑅+𝐵𝐿𝑈𝐸)

𝐵𝑆𝐼 = (𝑆𝑊𝐼𝑅+𝑅𝐸𝐷)+(𝑁𝐼𝑅+𝐵𝐿𝑈𝐸)(3)

𝐵𝐼 = √𝐵𝐿𝑈𝐸 2 + 𝐺𝑅𝐸𝐸𝑁 2 + 𝑅𝐸𝐷2

(4)

The results of the processing routine indicate a normalized
percentage of the NDVI gained or lost. The rdNDVI is lostas potential landslide and rdNDVI is gain as non-potential
landslide. The differential bare soil index (dBSI) andbrightness index (dBI) take the spectral response before andafter the landslide event. The area with presence of landslides
will appear with negative values. [3,4]Fig. 2. Landslide detection with slope filtering 5 degree
at Ehime landslide events.

Fig. 3. Detection percentage of landslide detection modelwith slope filtering in Ehime landslide event.

4 Conclusions

Fig. 1. Landslide detection framework.

3 Results and discussion
As a result of landslide detection using amplitude change
detection and differential of spectral indices, the accuracy of
the assessment of the landslide detection model was obtained
for the total number of landslides and area detected byclassification and regression tree (CART) based on semiautomatic classification. Wise accuracy for all landslide in
the study area in the Ehime landslide event are provided inFig. 2. The model's accuracy could obtain about 67.7885.71% of detection percentage and 55.72-58.76% of quality
percentage, which are moderately good for landslide
detection. However, the false detection of the model is baresoil areas such as roads, farmland., and urban areas, whichhave shown on the low slope. The slope filtering has been
applied with a landslide detection model to solve this issue.
Figure 3 presented a slope filtering application with alandslide detection model. The 7.5 to 15-degree results werehigh in detection percentage and fitted with actual landslide
scars. The detection percentage of 7.5 to 15 degree of slope
filtering is 80.04-85.71%. For slope filtering 2.5-5 degrees,
the false detection was bare soil area on low area, but theslope filtering 17.5-20 degrees, the detection percentage
decreased by missing detection on landslide area. The
detection percentage of 2.5-5 and 17.5-20 degree of slope
filtering is 67.78-72.65%.

46

Rapid response to landslide events is necessary to assess thedamage and save human life and properties. Therefore, thelandslide detection model is necessary to develop tools withfreely available data that can be used to map the landslide
after catastrophic events. As a result of the amplitude changes
detection, rdNVDI, dBSI, dBI indices, and slope filteringwith classification and regression tree (CART, semiautomatic) on GEE is sufficient to identify landslides which
are useful for rapid mapping after landslide events. The
accuracy of the model can obtain about 67.78-85.71% ofdetection percentage and 55.72-58.76% of quality percentage,
which are moderately good for landslide detection.

Reference[1].Kirschbaum, D. and Stanley, T. (2018) Satellite-based
assessment of rainfall-triggered landslide hazard forsituational awareness, Earth’s Future. 6(3), 505-523,[2] Scheip, C.M. Wegmann, K.W., (2021). HazMapper: A
global open-source natural hazard mapping application in
Google Earth Engine. Nat. Hazards Earth Syst. Sci. 21 (5),1495-1511, 2021.
[3] Handwerger, A. L., Jones, S. Y., Huang, M.-H., Amatya,P., Kerner,H. R., and Kirschbaum, D. B. (2020). Rapid
landslide identification using synthetic aperture radar
amplitude change detection on the Google Earth Engine, Nat.
Hazards Earth Syst. Sci., https://doi.org/10.5194/nhess2020-315.
[4] Alexander, A., Norma, A.D., Hannah, K., Gerhard
Kemper. (2021) Landslide detection in central America using
the differential bare soil index, The international archives ofthe photogrammetry, Remote Sensing and Spatial
Information Science, XXIV ISPRS Congress.

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

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Decadal variations of drought indicators in Indonesia from 1981 - 2020
○ Amalia Nafisah Rahmani IRAWAN1* & Daisuke KOMORI1,2
1 Graduate School of Environmental Studies, Tohoku University, Miyagi 980-8572, Japan.
2

Department of Civil and Environmental Engineering, Tohoku University, Miyagi 980-8579, Japan.
*E-mail: amalia.nafisah.rahmani.irawan.q3@dc.tohoku.ac.jp

Abstract
The Intergovernmental Panel on Climate Change (IPCC) reported that the world’s temperature is expected toincrease by around 1.5C in 2030. One of the impacts of this temperature increase is the variability of the rainfall
pattern and the rainfall amount which is not evenly distributed globally. This condition can lead to more severe
drought disasters in some regions. Because drought event can reduce the water availability, both surface andgroundwater, eventually it will also affect human aspect which has a high dependency on water for various sector
like domestic, industry, agriculture, and so on. Many drought indexes have been developed for drought assessment,
one of them is the Standardized Precipitation Index (SPI) found by McKee et al., in 1993 which only requires longterm precipitation data for the input. Based on probability distribution and normalization, SPI is able to assess the
wet and dry conditions.
This research used SPI-3 to assess various drought indicators including frequency, duration, severity, and intensity
in Indonesia from 1981 – 2020. The precipitation dataset was obtained from the Multi-Source Weighted-Ensemble
Precipitation (MSWEP) which provide monthly precipitation with 0.1 resolution from 1979 – present date. Basedon the assessment, the drought frequency, duration, severity, and intensity tend to increase in the recent decade
especially in South Sumatera and Java Island. However, the worst drought event occurred in 1991 – 2000 where theprecipitation was recorded as the lowest compared to the other decades. This study will be beneficial to assess the
hotspot region to consider the appropriate drought mitigation and preparedness.
Keywords: Drought; SPI; Decadal Variation; Indonesia.
1 Introduction
There are many hazards related to the climate that affecthuman life, one of them is drought. According to the World
Meteorological Organization (WMO), drought can be
defined as a slow on-set phenomenon caused by a lack ofrainfall. Drought is often called a creeping disaster because
unlike floods that occur during relatively short periods oftime, drought impacts build overtime and take a quite longer
time compared to other climatological hazards, for example
floods or landslides.
According to Wilhite [8], there are four types of droughts
which can be understood simply as the deficiency of different
variables of hydrological process. The first one ismeteorological drought which started from the deficiency of
precipitation that could cause less water going to soil andhigher evapotranspiration rate. Over time, the agricultural
drought will occur because of the depletion of soil moisture[3] that affected crop production. Hydrological drought
occurs when there is low water supply on surface andgroundwater. If there is still lack of precipitation, thesocioeconomic drought when demands exceed supply mightoccur and affect the social, economic, and environmental
aspect. From this understanding, many precipitation-based
indexes were developed for drought assessment, one ofwhich is Standardized Precipitation Index (SPI).
SPI was found by McKee et al., in 1993 [4] that it can beused for drought assessment and only needs the long-term
precipitation data (minimum 20-30 years). By using theprobability density function and normalization, the SPI canassess the wet and dry conditions over any regions (drought
occurred where SPI ≦ -1). Another benefit of SPI is the47

temporal versatility so it can be calculated for various
timescale according to user’s interest (WMO, 2012) [9]. In
this research, SPI-3 was chosen as the drought index that
represent not only the rainfall deficiency but also as theappropriate temporal scale to examine drought impact tovegetation [1,2,5]. This research was conducted to assess thedecadal variations of drought event in Indonesia from 1981 –2020. Further study of this research will be beneficial toexamine the hotspot region to consider the appropriate
drought mitigation and preparedness.

2 Materials and methods
The SPI analysis was conducted using monthly
precipitation obtained from the MSWEP dataset overIndonesia with 0.1 resolution from January 1981 –December 2020. Then various drought indicators wereassessed as follows:
1. Frequency
Frequency is the total number of drought event.
According to McKee et al., [4] drought event is defined as aperiod when the SPI value is -1 until it becomes positive.
2. Duration
The duration of a drought event can be calculated as thenumber of months between its start (included) and end month(not included) [6].
3. Severity
Drought severity is the absolute value of the cumulative
SPI values during the drought event [7].
4. Intensity
Drought intensity can be defined as the ratio between
drought severity and drought duration for each drought event

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety[7]. The larger the drought intensity value means more severe
drought event.

3 Results and discussion(1) Drought frequency
Figure S1 in the appendix shows that drought event
becomes more frequent in the recent decades, especially inWest Kalimantan, South Sumatera, and Java Island. However,the period from 1991 – 2000 was the decade with the mostfrequent drought events. According to the precipitation
analysis show in Fig. 1., this is occurred because during that
period the precipitation distribution was the lowest comparedto other decades, especially during the dry season from May– October.

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This drought assessment was conducted to examine thedecadal variation of drought indicators in Indonesia from1981 – 2020. The result showed that the frequency, duration,
severity, and intensity of drought events tends to be longer
and bigger in recent years. However, the period from 1991 –2000 can be categorized as the most extreme drought events
indicated by the most frequent drought events, most longer
drought duration, and most bigger drought severity andintensity. This extreme drought decade caused by the lowest
precipitation distribution compared to other decades,
especially during the dry season.
Based on the result, the Java Island as the main producer ofagricultural product in Indonesia is the region which weshould put more attention into with the characterization ofdrought event in those regions that occurred more frequentcompared to the others, even though with less severity. The
development of appropriate drought mitigation andpreparedness is important to reduce the drought impact,
especially, to ensure the food security in the upcoming
decades where the food demand is expected to increase alongwith the population increase.

References
Fig. 1. Monthly precipitation variability.
(2) Drought duration
Figure S2 in the appendix also shows that drought event
tends to be longer in recent decades, especially in Java Island,
Sulawesi Island, and South Sumatera. The result showed thatthose regions suffered from drought condition with a total of
45 – 65 months or around 37.5 – 55% of its months is adrought month within a decade. Moreover, considering thatthose regions is the main producer of agricultural product(especially Java Island), more attention is needed to reducethe drought impact to agricultural sectors in the future.
(3) Drought severity
Figure S3 in the appendix shows the total of drought
severity for each decade. Like the previous indicators, thedrought severity also has a tendency to become more bigger
in the recent years. But, due to the precipitation variability as
shown in Fig. 1., the period from 1991 – 2000 was a decadewith the biggest total drought severity in Indonesia.
(4) Drought intensity
Lastly, Figure S4 in the appendix shows the drought
intensity for each decade. This result also indicated theaverage of drought intensity for one drought event in a
specific region. The darker blue color indicated that thoseregion during the specific decades suffered from more severe
drought. If we compared it with the result of drought
frequency, we could distinguish the region into two
categories: 1) has more frequent but with a relatively lesssevere drought event and 2) has less frequent but with arelatively more severe drought event.
It can be seen that Java Island as the main producer ofagricultural product is belong to the former category, theregion which suffered from more frequent drought event withless severity. Thus, the attention to adapt and mitigate thedrought impact should be put into those regions. It can beachieved by developing the appropriate drought preparedness
and mitigation system in order to reduce the drought impact
in the future, especially to ensure the food security.

4 Conclusions

48[1] Ali, U.K. (2001). Using the SPI to Analyze Spatial andTemporal Patterns of Drought in Turkey. Drought Network
News (1994- 2001). Paper 49.
[2] Ji, L., & Peters, A. J. (2003). Assessing vegetation
response to drought in the northern Great Plains using
vegetation and drought indices. Remote Sensing ofEnvironment,
87(1),
85–98. doi:10.1016/s00344257(03)00174-3.
[3] Legesse G. (2010), Agricultural Drought Assessment
Using Remote Sensing and GIS Techniques. MSc. Thesis,
Addis Ababa University, Ethiopia.
[4] McKee, T. B., Doesken, N. J. and Kleist, N. J. (1993):
The relationship of drought frequency and duration to timescales. Proceedings, 8th Conference on Applied Climatology,
17-22 January, 1993, Anaheim, pp. 179-184.
[5] Patel, N. R., Chopra, P., & Dadhwal, V. K. (2007).
Analyzing spatial patterns of meteorological drought using
standardized
precipitationindex. MeteorologicalApplications: A journal of forecasting, practical applications,training techniques and modelling, 14(4), 329-336.
[6] Spinoni, J.; Naumann, G.; Carrao, H.; Barbosa, P.; Vogt,
J. World drought frequency, duration, and severity for 1951–
2010. Int. J. Climatol. 2014, 34, 2792–28.
[7] Tan, C., Yang, J., & Li, M. (2015). Temporal-spatial
variation of drought indicated by SPI and SPEI in Ningxia
Hui Autonomous Region, China. Atmosphere, 6(10), 13991421.
[8] Wilhite, D. A. (2000). Drought as a natural hazard:
concepts and definitions[9] World
MeteorologicalOrganization,
2012:
Standardized Precipitation Index User Guide (M. Svoboda,
M. Hayes and D. Wood). (WMO-No. 1090), Geneva.

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

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Appendix

Figure S 1 The decadal variation of drought frequency in Indonesia from 1981 – 2020.

Figure S 2 The decadal variation of drought duration in Indonesia from 1981 – 2020.

49

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDE
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Figure S 3 The decadal variation of drought severity in Indonesia from 1981 – 2020.

Figure S 4 The decadal variation of drought intensity in Indonesia from 1981 – 2020.

50

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDE
Tohoku University

Study of Adaptation Measures for Flood Damage Mitigation
by Adopting Effect of Climate Change○ Tao Yamamoto1, So Kazama1
1

Department of Civil Engineering, Tohoku University, Miyagi 980-8579, Japan.
*
E-mail: tao.yamamoto.b7@tohoku.ac.jp

Abstract
In order to clarify effect of climate change on flood control planning, this study evaluated how the future
reduction of flood damage cost changed by changing the rainfall scenario that served as the basis for flood control
planning. CSIRO-Mk3-6-0 was selected as climate prediction data. There were three target periods, the late 20th
century, the near future, and the late 21st century. Flood inundation simulations were performed using twodimensional unsteady flow model. The river channel elevation was reduced by the depth obtained from floodinundation simulations corresponding to the flood control safety level. This reduced depth was changed based onflood inundation of late 20th century, 21st century under RCP2.6 or RCP8.5. From these analyses, the possibility
has been raised to decrease flood damage by developing flood control level based on future climate.
Keywords: flood control planning; two-dimensional unsteady flow model; maladaptation.
1. Introduction
In recent years, there is concern about the expansion offlood damage due to the effects of climate change in Japan.
As an example, in August 2022, flooding occurred in the
Tohoku and Hokuriku regions, causing inundation andlandslides. The Ministry of Land, Infrastructure, Transport
and Tourism formulated “Integrated flood management” [1].
This is the first initiative to compile an overall vision of flood
control measures through the cooperation of all parties
concerned, based on a bird's eye view of the entire basin,
considering the increasingly severe and frequent disasters
caused by climate change in recent years. In this project,flood control planning will be shifted from planning based on
past phenomena to planning that considers climate change.
Table 1 shows the rate of change in precipitation, etc. due toclimate change as indicated by the Japanese government. A
number of studies have assessed the effects of climate change
on precipitation and discharge [2],[3], but few have estimatedthe effectiveness of flood damage mitigation measures basedon these effects. This study evaluates how the future flood
control effectiveness changes by changing the rainfall
scenario that serves as the basis for flood control planning.

Using this future daily precipitation, an extreme value
analysis using the GEV distribution was conducted todetermine the rate of increase in future extreme value
precipitation. Figure 1 shows the distribution of the rate ofchange in precipitation of the 100-year return period.
The stochastic flood-contributing precipitation distribution
was used as daily precipitation data for the late 20th century.
This precipitation distribution is weighted to make theextreme precipitation distribution have equal probability ofdischarge at any given location. The scales of precipitation
were 30, 50, 100, and 200 return period.
A two-dimensional unsteady flow model was used for theflood inundation simulations. The spatial resolution used was
the fifth order mesh resolution (approximately 250m × 250m). Then, the unit price was set for each inundation depth for

2. Datasets and methods
As climate prediction data, daily precipitation data
downscaled to a 1-km resolution (Regional Climate
Projection Dataset NARO2017-V2.7r, National Agriculture
and Food Research Organization) were used [4]. In thisdataset, CSIRO-Mk3-6-0 was selected, and the two target
scenarios were RCP8.5 and RCP2.6. Three target periods
were considered: 1981– 2000 (the late 20th century), 2031–
2050 (the near future), and 2081–2100 (the late 21st century).
Table 1. Rate of change in precipitation, etc. due toclimate change as indicated by Japanese government
Figure 1. Change rate of 100y return periodprecipitation (late 21st century)

51

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
each land use type, and the damage cost was calculated foreach cell. The details are described in Yamamoto et al. [5].
This study used the method of Tanaka et al. [6] as a method
for expressing flood control levels. The method of Tanaka et
al. was as follows: 1) The depth of the river channel required
to safely flow the 5-, 10-, 30-, 50-, 70-, 100-, 150-, and 200year floods was determined from flood simulations; 2) A
flood control safety level was set for each river section basedon the flood return period; 3) The channel elevation was
reduced by the depth of the channel corresponding to theflood control safety level. In the flood simulation in 1), threestandards for flood control planning were established by
calculating three patterns: late 20th century, late 21st century
RCP 2.6, and late 21st century RCP 8.5. The flood control
safety level in 2) is assumed to be maintained as planned at
the late 21st century, and the flood control safety level was
assumed to be 50% at the late 20th century.

3. Results and discussion
Figure 2 shows Estimated Annual Damage Cost. If flood
control was promoted based on the precipitation at the late
20th century, the damage cost increased by 17.0% under the
RCP2.6 scenario and by 58.3% under the RCP8.5 scenario in
the late 21st century. If flood control improvements weremade based on the precipitation in the RCP2.6 scenario at thelate 21st century, the EADC at the late 21st century would
decrease by 4.3% in the RCP2.6 scenario and increase by
37.3% in the RCP8.5 scenario. If flood control improvements
were made based on the precipitation in the RCP8.5 scenario
at the late 21st century, the EADC at the late 21st century
would decrease by 21.2% in the RCP2.6 scenario andincrease by 7.2% in the RCP8.5 scenario. Future-standard
flood control improvements, which were set up toaccommodate higher discharge, reduced the EADC morethan past-standard flood control improvements.
Even if flood control improvements were based on past
phenomena, EADC would increase due to the effects ofclimate change. Therefore, in order to mitigate EADC in the
future, flood control measures must be based on future
precipitation. On the other hand, there was a large differencein precipitation between the RCP2.6 scenario and the RCP8.5

scenario, and therefore, the cost of flood control was also
expected to differ greatly between the two scenarios.
The average depth of excavation was calculated as a helpful
indicator of cost. The average depth of excavation based on
the late 20th century was 0.39 m, based on RCP 2.6 - late 21st
century was 1.02 m, and based on RCP 8.5 - late 21st century
was 1.84 m. The difference of 0.82 m was caused by thedifferent RCP scenarios. The cost of constructing levees andexcavating river channels to cover this difference in height issignificant. However, the flood control criteria should be
discussed in consideration of the rework required to revise
the flood control plan and the loss of leaving highly
vulnerable areas until the completion of the improvement.
There is also a problem to select which GCM for determining
the future flood control level. Only one scenario was used forthis analysis. Referring to Yamamoto et al. [5], thedistributions and increase rates of precipitation was
significantly different from each GCMs. Therefore it isimportant to select carefully which future predictions we use,
and to use more future predictions as much as possible.

4. Conclusions
When flood control was developed based on the past climate,
flood damage increased due to the effects of climate change.
However, there is a possibility to decrease flood damage bydeveloping flood control level based on future climate.

Reference
[1]

[2]

[3]

[4]

[5]

[6]
Figure 2. Estimated Annual Damage Cost
(EADC)

52

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Tohoku University

Konami, T., Koga, H., Kawatsura, A., Role of predisaster discussions on preparedness on consensusmaking of integrated flood management (IFM) after aflood disaster, based on a case in the Abukuma River
Basin, Fukushima, Japan, International Journal ofDisaster Risk Reduction,Volume 53(2021), 102012.
Iizumi, T., Takayabu, I., Dairaku, K., Kusaka, H.,
Nishimori, M., Sakurai, G., Ishizaki, N. N., Adachi, S.
A., and Semenov, M. A., Future change of daily
precipitation indices in Japan: A stochastic weather
generator-based bootstrap approach to provide
probabilistic climate information, J. Geophys. Res.,
117(2012), D11114.
S. Tezuka, H. Takiguchi, S. Kazama, A. Sato, S.
Kawagoe, R. Sarukkalige, Estimation of the effects ofclimate change on flood-triggered economic losses inJapan, International Journal of Disaster Risk
Reduction, Volume (2014), Pages 58-67.
Nishimori, M., Y. Ishigooka, T. Kuwagata, T.
Takimoto and N. Endo, SI-CAT 1km-grid square
Regional, Climate Projection Scenario Dataset for
Agricultural Use (NARO2017). J Jpn Soc Simul
Technol, 38(2019), 150–154 (in Japanese withEnglish title)
Yamamoto, T., Kazama, S., Touge, Y. et al.,Evaluation of flood damage reduction throughout
Japan from adaptation measures taken under a rangeof emissions mitigation scenarios. Climatic Change
165(2021), 60.
Tanaka Y, Kazama S, Tada T, Yamashita T, Komori
D, Assessment of the risk on flood and storm surgewith flood control facilities. J Jpn Soc Civ Eng Ser B1(Hydraul Eng) 75(2) (2019), I_109–I_114 (inJapanese)

The 10th International Symposium on Water Environment Systems----- with Perspective of Global Safety(Dec. 8th ~ 9th , 2022)

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A data-based modeling approach of rainfall-runoff processes:
its development history and a blueprint for the future○ Yoshiyuki YOKOO1*
1

Faculty of Symbiotic Systems Science, Fukushima University, Fukushima 960-1296, Japan.
*
E-mail: yokoo@sss.fukushima-u.ac.jp.

Abstract
Rainfall-runoff models have been developed for estimating river flows and used for explaining the hydrologicalprocesses that induced flood and drought events by today. Yet, they stand on many assumptions that were notvalidated enough by field measurements or observe data. The author think that this is the critical weakness of current
rainfall-runoff models, because a rainfall-runoff model based on wrong assumptions would derive a right answer
for the wrong reasons. To reduce the weakness, the author’s research group have been developed a data-basedmodeling approach that can simultaneously identify the structure and the parameters of a rainfall-runoff model withleast assumptions. This article attempts to summarize its development history and share a blueprint for the future
for more reliable rainfall-runoff modeling.
Keywords: discharge; storage; recession time constant; calibration; understandings.
1. Introduction
Modeling of natural processes reflects ourunderstandings of the processes to seek for their governingtheories, hence it is a strong measure to advance sciences ofnature together with field measurements. In rainfall-runoff
modeling, most of studies apply existing models and theirvalidities are not verified enough in most of the cases. These
facts would prevent the advances in the theoretical aspects ofrainfall-runoff modeling. Besides, most of the existing
rainfall-runoff models used today have the problem of
uncertainties in their structures and their parameters eventoday. In other words, most of the models are constructedbased on assumptions that are not verified enough. This is thecritical weakness of the rainfall-runoff models used today.
As one of the countermeasures for this problem of
uncertainties, the author’s research group have beendeveloped a methodology to identify the structure and theparameters of rainfall-runoff models. In this short article, theauthor introduces the development history of our data-basedmodeling approach and a blueprint for the future toward thedevelopments of more reliable models for science ofhydrology and its contribution to the society.

2. Development history
The data-based modeling approach of rainfall-runoff
processes was developed based on the inspiration from theunique research by Kirchner [1].
We first tested the original method of Kirchner [1] inorder to test the applicability of the method in Japanesemountainous watershed that has relatively complex rainfallrunoff processes compared to the watersheds tested in
Kircher [1]. In Yokoo et al. [2], we confirmed the original
method of Kirchner [1] estimates watershed-scale storage
only for quick flows after rainfall events.
To adjust the methodology of Kirchner [1] inwatersheds with more complex hydrological processes, werecalled that we would be able to use the filter-separation
method of Hino and Hasebe [3]. We showed our first resultsof the methodology of Kirchner [1] applied after hydrographseparation method of Hino and Hasebe [3] and Kobayashi

53

and Yokoo [4]. The results indicated that we can significantly
improve the estimated changes of storage in Japanesemountainous watersheds. Later we confirmed in Yokoo et al.
[5] that the storage estimations in mountainous watersheds inthe northern Thailand can be significantly improved than theoriginal method of Kirchner [1]. As an application of our
methodology, we compared estimated storage under heavy
rainfall events that caused slope failure in Hiroshima between
the Soil Water Index of Okada and our method in Kobayashi
and Yokoo [6]. There we found that the Soil Water Index isof near surface storage
We then noticed that storage-discharge relationships for
all the separated discharge components can be approximatedas linear relationships rather than the original power-law
relationships from the storage-discharge relationships. Hence
we examined if we can linearize the storage-discharge
relationships for all the discharge components in Chiba et al.
[7]. The results showed that we can approximate by the linear
relationships for all the storage-discharge relationships.
These results suggested that our data-based modelingapproach to identify storage-discharge relationships fordifferent discharge components can be used for identifying
the structures and parameters of the Tank model of Sugawara[8] that employs linear storage-discharge relationships for all
the discharge components.
Based on the above-mentioned expectation, weinvestigated if we can identify structures and parameters of
the Tank model of Sugawara [8]. In the end, we noticed that
we can identify structure and parameters simultaneously if
we identify them from the bottom tank of the Tank model of
Sugawara [8]. We summarized our theoretical investigations
on the simultaneous identifications of structures andparameters of the model in Yokoo et al. [9]. This
achievement allowed us to construct a Tank model of
Sugawara [8] without any trial and errors nor complex
parameter calibrations, which would be an epoch-making
improvement the applicability of the Tank model of
Sugawara [8]. It also allowed our data-based interpretationsof rainfall-runoff processes, which would open a new way toinvestigate rainfall-runoff processes.
One of the examples would be the interpretations ofrainfall-runoff processes that form the unique shape of theThe 10th International Symposium on Water Environment Systems----- with Perspective of Global Safety(Dec. 8th ~ 9th , 2022)

flow duration curve of a watershed. Leong and Yokoo [10],[11] attempted to explain why the shapes of flow duration
curves of watersheds under different climate regions by using
our data-based modeling approach. They succeeded to
explain that different rainfall-runoff processes cause theunique shapes of flow duration curves in watersheds under
different climate regions by using the modeling approach.
Their paper contributed to significantly advance ourunderstanding on the shape of flow duration curves.

studies as exampled in the blueprint for the future, and we arelooking forward to work these studies with you.

Acknowledgments
This work was supported by JSPS KAKENHI (20H00256,
20H02249, 16KK0142, 16K06501, 24760388).

Reference[1]

3. A blueprint for the future
Based on the development history mentioned above, theauthor wants to list up further development directions as a
blueprint for the future of our data-based modeling approachof rainfall-runoff processes.
One of the directions would be using the approach forthe verifications of spatially distributed rainfall-runoff
processes, because the data-based modeling approach was
initially developed for identifying structures and parametersof lumped rainfall-runoff models. The identified model
structure and parameters can contribute to constrain or
identify the structure and the range of parameters of
distributed models. Almost all the distributed models aredeveloped uniquely in terms of structure and parameters,
hence it would be beneficial if we can constrain or identify
the structure and parameters of distributed models from theidentified structure and parameters of lumped models.
As another direction, we can explore storage-discharge
mechanisms at a watershed scale by using the data-basedmodeling approach. Kobayashi and Yokoo (2013) showed an
example to investigate the storage-discharge mechanisms at
a watershed scale. The author think it would be a hint to
explore hysteresis of storage discharge relationships causedby the multiple linear relationship between storage anddischarge. If it rains, a watershed would increase storages ofrainwater from near surface zones to the deeper zones, which
results in increase of discharge to the rivers in the watershed.
On the contrary, rainwater storage would decrease thestorages from near surface zones to deeper zones. Hence, theauthor expects that the simulated total storage and total
discharge at a watershed scale would exhibit hysteresis in thestorage-discharge relationship.
The other direction would be developing a methodology
to partition observed rainfall into evapotranspiration andeffective rainfall to rainfall-runoff processes. Yokoo et al.
(2017) succeeded to estimate effective rainfall but they did
not how to partition it. If we can succeed to partition it, thenour data-based modeling approach of rainfall-runoff process
would be regarded as it was completed. The author is now
working on the development of this methodology.

4. Summary
The author attempted to introduce the development
history and a blueprint for the future of our data-basedmodeling approach of rainfall-runoff processes in this shortarticle. As described in its history, the author’s group has
succeeded to develop and utilize the methodology by today.
Yet, it still need to complete this methodology about rainfallpartitioning near the ground surface, toward further
applications of the methodology. Hence, we would try tocomplete this methodology for conducting its application

54

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Kirchner JW, Catchments as simple dynamicalsystems: Catchment characterization, rainfall-runoff
modeling, and doing hydrology backward. Water
Resources Research 45 (2009) W02429.
[2] Yokoo Y, Kobayashi S, Kawasaki M, Toward
estimations of watershed-scale storage and storage
potential in Japanese mountainous watersheds, Annual
Journal of Hydraulic Engineering, JSCE, 56 (2012),
I_475-I_480. (In Japanese with English abstract).
[3] Hino M, Hasebe M, Identification and prediction of
nonlinear hydrologic systems by the filter-separation
autoregressive (AR) method: Extension to hourlyhydrologic data, Journal of Hydrology, 68 (1984), 181–
210.
[4] Kobayashi S, Yokoo Y, Estimating watershed-scalestorage changes from hourly discharge data in
mountainous humid watersheds: toward a new way of
dominant process modeling, Hydrological Research
Letters, 7 (2013), 97–103.
[5] Yokoo Y, Wattanakarn C, Wattanakarn S, Semcharoen
V, Promasakha na Sakolnakhon K, Soralump S,
Storage under the 2011 Chao Phraya river flood: Aninterpretation of watershed-scale storage changes at
two neighboring mountainous watersheds in northern
Thailand, Hydrological Research Letters, 8 (2014), 1-8.
[6] Kobayashi S, Yokoo Y, Relationship between soil
water index and estimates of watershed-scale storage,
Journal of Japan Society of Civil Engineers, Series B(Hydraulic Engineering), 70 (2014), I_349-I_354 (InJapanese with English abstract).
[7] Chiba T, Yokoo Y, Revision of estimation method ofwatershed-scale rainwater storage and its effect,
Journal of Japan Society of Civil Engineers, Series B(Hydraulic Engineering), 71 (2015), I-289-294 (InJapanese with English abstract).
[8] Sugawara M, Tank model. In Computer models ofwatershed hydrology, V. P. Singh (Ed.), Water
Resources Publications (1995), 165-214.
[9] Yokoo Y, Chiba T, Shikano Y, Leong C, Identifying
dominant runoff mechanisms and their lumped
modeling: a data-based modeling approach,Hydrological Research Letters, 11 (2017), 128-133.
[10] Leong C, Yokoo Y, An interpretation of therelationship between dominant rainfall-runoff
processes and the shape of flow duration curve by using
data-based modeling approach, Hydrological Research
Letters, 13 (2019), 62-68.
[11] Leong C, Yokoo Y, A multiple hydrograph separation
technique for identifying hydrological model structures
and an interpretation of dominant process controls on
flow duration curves, Hydrological Processes, 36(2022), e14569.

POSTER

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

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An overview of sewage treatment for human heath safety in the Song
Dynasty○ Yixiao LIU1*
1

School of Social Development and Public Administration, Suzhou University of Science and Technology,
Suzhou 215009, China*
E-mail: 1720128460@qq.com

Abstract
In today’s globalized world of development, how to remedy water pollution has become a hot topic of discussion.
The importance attached to the issue of pollution reflects the depth of modern human understanding ofenvironmental health. The problem of environmental pollution is not unique to modern society. It is evident fromthe surviving historical texts that the ancient people suffered from environmental pollution as well, and quite
severely. The high economic prosperity of the Song Dynasty was also bound to bring about some pollution problems.
The diversity of sources of pollution was concentrated in the areas of production and life, and many sources ofpollution from production and life had a huge impact on water bodies.
Keywords: Sewage treatment; China history; Song dynasty; Heath safety; Social development
these handicraft production sectors caused a certain amount
1. Introduction
Since ancient times, the development of human society has
been inseparable from water sources. During the Song
Dynasty, there were many rivers and waterways, and not only
did most of the inhabitants live along the rivers, but also mostof the handicraft production sectors were built on the water.
A large amount of domestic and production sewage wasdischarged into the nearby waters without being treated,causing great harm to the environment.

1.1 Domestic sewage
The Song Dynasty saw unprecedented social and economic
development, as well as a significant increase in urbanisation
and a burgeoning urban population. According to Mr. Qi Tao,“the actual populations of Kaifeng and Lin'an in the Northern
Song Dynasty in the first year of Chongning (1102) bothexceeded one million inhabitants.”[1]With a large number ofdensely packed buildings in a limited urban space, the daily
life of the inhabitants had an impact on the public health ofthe city and the surrounding water environment. The frequent
occurrence of epidemics in Song cities was closely related tothe contamination of rivers, waterways, lakes andunderground drinking water. In Bianjing, the capital of theNorthern Song Dynasty, there was a large amount ofhousehold waste in the rivers and drains, causing congestionand pollution. According to “Dongjing Dreams andRecords”: "every spring, the government sent people tosupervise the panning in the city drains, and opened a pit tohold the panned mud, called “mud basin”. Waiting for theofficial to come to inspect the party cover cover, night access,the moon darkness should also take care of." From thedredging of ditches in Bianjing, it is easy to see that theditches were filled with a large amount of dirt, and thissituation was mostly caused by the residents of Bianjing
throwing their daily rubbish into the ditches. This was thecase in the capital city, not to mention the local pollution. The
river in Danyang County, Zhenjiang Province, is often filledwith "dung, especially at the Hu Gong Land Bridge, where it
is as high as the bridge".

of pollution to the surrounding environment during theiroperations. Let's talk about the paper-making industry first.
The paper-making process relied heavily on clarified water
sources to bleach and wash the raw materials, and the “Paper
Recipe” contains information about the waters of the JinjiangRiver in Sichuan during the Song Dynasty, where paper was
made "with the water of the Ronghuatan, so it was good. It isalso water that is suitable." Numerous paper mills were built
along the river to meet the huge demand for paper from allover the country, working day in and day out on both sidesof the river, and the frequent bleaching and washing of thepaper process polluted the surrounding waters. The frequent
bleaching and washing of paper pollutes the surrounding
waters. The pollution caused to the nearby drinking water
sources can be imagined in the long run.
The smelting industry was also more harmful to water
bodies than ever before. The Song Dynasty was rich in goldand silver mineral resources, and there were only three silverproducing places in the country, with fifty-one. The main
method used to pluck alluvial gold in the Song Dynasty is topluck gold from the water or soil at a convenient place near
the alluvial gold deposit, without processing to get the net
gold and stop. Such as “Pingzhou can talk about” in the
Beijing East Road area: "deng, Lai gold pit household, stopwith a large wooden saw cut, leave edge marks, cast sand onit, flood with water, sand to go, gold in the saw, very easy toget". However, this method of panning for gold by impacting

1.2 Production of wastewater
The main sources of pollution from handicraft production
during the Song Dynasty were paper making and printing,mining and smelting and textile printing and dyeing, and

57

Fig. 1. Toilets in Song Dynasty

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
sediments with water is very easy to pollute water sanitation
due to the lack of protective measures. The rivers where gold
panning is carried out contain large amounts of heavy metal
ions, acids and alkalis and suspended solids, which pose athreat to the health and safety of the surrounding populationand the survival of other plants and animals.

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muddy, back into the protection of the Dragon River, spin put
clear water.

2. Governance measures
The development of handicraft industry was relatively rapid
during the two Song dynasties, and according to Mr Ji Ziya,"the development of handicraft industry during the Songdynasty was greatly enhanced in terms of breadth and depth,
composition, division of labour and technological levelcompared to previous generations." However, behind theeconomic prosperity was a damaged environment, as thesmelting and smelting activities of the crafts and the daily lifeof the inhabitants of the two Song dynasties caused a certain
amount of pollution to the nearby waters. These polluted
waters were complex in composition, containing acids,
alkalis and heavy metals, which were not easily degraded.
During the production process, some waste water is also
discharged into the surrounding waters, changing the original
structure of the water bodies. Some toxic and non-degradable
pollutants pose a great threat to the survival of fish andshrimps and other aquatic products in the water, and also
have a certain impact on the health and safety of the residents
on both sides of the river. Due to the limitations of the times
and the development of technology, the Song people
naturally did not understand the composition of waste waterfrom handicraft production, but they were aware of thehazards of sewage. The government of the two Songdynasties reduced the pollution of the waters by setting up
artificial ponds for smelting and dedicated sewage, and byfiltering the printing and dyeing effluent.
In mining and smelting production, artificial pools were set
up to replace the previous direct washing and filtering
operations in the river water. For example, the Song dynasty's
Zhao Yanwei recorded in the <Yunlu Manchu> that during
the Shaoxing period (1131-1162), the Ruiying field in Songxi
County, Jianning Province (now Songxi County, Fujian
Province), in the process of refining fine silver in the silver
mines, "roughly six times overhand, pit households calledover pools, over pools, lead pools, ash pools and the like isalso." As can be seen, the silver ore was panned and filteredby setting up numerous artificial pools, which reduced thepollution of the surrounding waters to a certain extent, as
opposed to working directly in the river. In the early years of
the Northern Song Dynasty, the Jinshui River was pollutedby the waste water discharged from the surrounding dye
houses. A series of measures were put in place by the court
to combat this. In 1015, Emperor Zhenzong of the Northern
Song Dynasty ordered that "short walls be erected on bothsides of the Jinshui River to protect the river from thepolluted water." By setting up short walls, the two banks of
the river were restrained from discharging water to the
Jinshui River. This was followed by the opening of small
ponds and the installation of bucket gates to control the waterand filter the sewage. The west courtyard open pool five, fiveplace the bucket door, put water to fill wash things silk, in theevent of making that open the bucket door, night under the
stack lock closed. If you open a small pool, set the bucket
door, put water to wash the bolt section, when the water is58

Fig. 2. Urban Drainage in Song Dynasty
At the same time, a retreat ditch was dug to drain some of
the waste water from the dyeing and dyeing process to the
Dragon Protection River (a trench outside the palace), thus
reducing the direct pollution of the city's waters. The
domestic sewage was mostly due to the washing and otherwaste water from the daily lives of the residents along theriver, and the frequent encroachments on the water during theSong Dynasty exacerbated the pollution of the waters. The
pollution of the waters caused by domestic waste water andrubbish was much easier to degrade than that caused byhandicraft production. During the Song dynasty, thegovernment discharged sewage from the city to the rivers,
lakes and seas outside the city by repairing the city's drains
and underground ditches, leaving it to degrade naturally. For
example, Meng Yuanlao wrote in his description of theimperial street in Bianjing: "There are two brick and stone
ditches in the fork." Lu You also writes that the dark ditches
in Bianjing City are crisscrossed and extremely wide, "Theditches in the capital are extremely deep and wide, and manydead people hide in them." It can be seen that theunderground sewers in Bianjing were very well developed in
the Song Dynasty. These sewers discharged large amounts ofwaste water directly into the rivers outside the city, thus
reducing the pollution of the waters around the city. The fast
flowing, fast circulating river water itself has a high dissolved
oxygen content, so its self-cleaning ability is also very strong.

3. Conclusions
In terms of the standard of treatment of waste water today,
the Song dynasty has only demonstrated the most basic
treatment techniques in the treatment of waste water, and is
still in a state of natural digestion and decomposition for thetreatment of waste water caused by production and living.
However, there is no doubt that the official response to thepollution problem was positive and relatively less polluting
to the surrounding waters, while at the same time restraining
the expansion of the pollution.

Reference[1] Qi Tao, Ancient Economic History of China, Jinan:
Shandong University Press, December 1999, p. 335.

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

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Performance comparison of Anammox process with EDTA chelation of
Fe (III) and Fe (III) salts addition
Yang Yang1, Li Wen Cao1, Yong Hu1*
1

School of Environmental Science and Engineering, Nanjing Tech University, Nanjing 211816, PR China*
E-mail: huyong333@163.com

Abstract
This study investigated the performance comparison of Anammox process with EDTA chelation of Fe (III) andFe (III) salts addition. Generally, adding iron is one of the strategies to enhance Anammox, which embodied inhigher growth and enrichment of Anammox bacteria and higher denitrification performance of UASB. Although
the low concentration of iron can promote Anammox process, high concentration can inhibit it. This paper willcomplete the research of iron enhanced Anammox and serve as guidance for future engineering application of
Anammox process.
Keywords: Anammox; Iron; Enhancement; Denitrification
1 Introduction
Anaerobic ammonium oxidation (Anammox) has been
deemed to be a novel and promising process for treatinghigh ammonium wastewater in the last decades. Under
anaerobic conditions, the Anammox bacteria use nitrite aselectron acceptor to oxidize ammonia nitrogen to nitrogen.
Compared with traditional nitrification and denitrification,
Anammox has significant advantages of no need for organiccarbon resources, saving aeration and reducing the amountof sludge generated. As a result, it has been considered as
one of the most cost-effective biological denitrification
technologies for wastewater treatment.
However, Anammox bacteria (AnAOB) grow very
slowly, with a long generation cycle of 7–20 days and arequite sensitive to surrounding environment. In view of these
problems, the strengthening of the Anammox process has
always been the most concerned problem. Many strategies
have been conducted to strengthen the Anammox process.
The addition of iron is the cost-effective methods toenhance Anammox process because iron is the mostabundant metal element in the earth, which is widely
available, cheap and easy to obtain.
As a typical organic sequestering agent, EDTA has
continuously attracted much attention for that it canpromote the bioavailability of metal. In this paper, we
compare with two forms of Fe (III) (Fe (III) (chelated by
EDTA) and FeCl3). Firstly, we start up the reactor byaddition of FeSO4⋅7H2O. Then we carried out continuous
experiment to explore the performance comparison of theaddition of EDTA chelation of Fe (III) and Fe (III) salts.
Therefore, two identical reactors were operated and nitrogen
removal performance, sludge characteristic, EPS(extracellular polymeric substances), and community
structure of reactors were investigate

2 Materials and methods
2.1 Experimental setup and operation strategy
Experimental work was conducted in two lab-scale
UASB reactors (R1, R2). The reactor was made ofplexiglass and an effective volume of 2 L. The simulated
wastewater was pumped into the reactor by a peristaltic
pump, and the nitrogen conversion was completed during
the upflow movement. The gas was emitted from the top air
chamber, and the effluent was discharged from the overflow
weir. The reactors were inoculated with Anammox mature

59

granule sludge collected from Jia Yi environmental
Protection Company. The volatile suspended solids (VSS)
concentration of each reactor was 20.4 g/L. In R1 and R2,
the concentrations of iron added into the water were 5mg/L,
respectively, and they were provided in the form of FeCl 3(R1) and Fe (III) (chelated by EDTA) (R2). Operationaltemperature was maintained at 35℃, and hydraulicretention time (HRT) was 24 h.
Operation strategies are summarized in Table1 andwere the same for two reactors. After reaching the stablestate, nitrogen loading rate (NLR) was raised by increasing
the influent nitrogen concentration and/ or HRT. Water
samples were taken to determine the concentrations of
nitrogen compounds. At the end of each phase, the mixed
liquor was withdrawn from the reactors for subsequent
batch tests.
Table1.Experimental conditions of continuous experiments.
NLR
NH4+-NNO2−-N
HRT
Phase(mg/L)(mg/L)(h)(g-N/(L⋅d))
Ⅰ
52.5
69.3
24
0.12
Ⅱ
90.4
119.3
24
0.21
Ⅲ
128.3
169.3
24
0.29
Ⅳ
166.1
219.3
24
0.39
Ⅴ
204.1
269.3
24
0.47
Ⅵ
204.1
269.3
12
0.95
Ⅶ
204.1
269.3
6
1.89
2.2. Synthetic wastewater
The synthetic wastewater was composed of substrates,
trace elements and inorganic solution. Nitrogen resource
was provided by (NH4)2SO4 and NaNO2, and the initial NH4+-N and NO2–-N concentration in influent were 52.5 and69.3 mg N/L respectively. Trace elements were supplied at
a dosage of 0.125 mL per liter of wastewater. One liter of
the trace metals solution contained: 0.5375 mg ZnSO4⋅7H2O,
0.0175 mg H3BO4, 0.2375 mg NiCl2⋅6H2O, 1.2375 mg
MnCl2⋅4H2O, 0.275 mg CoCl2·6H2O, 0.3125 mg
CuSO4⋅5H2O, and 0.275 mg Na2Mo4·2H2O. The inorganic
solution consisted of MgSO4⋅7H2O (102.5 mg/L), NaHCO3(500 mg/L), KH2PO4 (50 mg/L), CaCl2⋅2H2O (108 mg/L),
KCl (570 mg/L). Influent pH was adjusted to 7.2 ± 0.2.
2.3. Analytical methods
Effluent samples were collected every two days, thenfiltrated through 0.45 μm membranes. NH4+-N, NO2−-N,

The 10th International Symposium on Water Environment Systems

NO3–-N were measured according to standard analyticalprocedures (American Public Health Association, 2012).
Sludge volatile suspended solid and suspended solid
contents were detected according to standard methods. Gas
production was measured by gas flowmeter. The pH value
was measured by a handheld pH meter. The composition ofgas was determined by a gas chromatography equipped witha flame ionization detector and a StabiliwaxR-DA capillarycolumn. Sludge samples were collected for elemental
composition analysis using energy dispersive spectroscopy(EDS). According to the previous methods, the functional
genes were analyzed with qPCR and the microbialcommunity was analyzed with high throughput 16S rRNA
gene sequencing.

3 Results and discussion
During the whole experimental period, the two reactors
have been successfully operated for three phases. Phase Ⅰ
and phase Ⅱ was the start-up phase. Phase Ⅲ has begun to
explore the performance comparison of the two reactors.
5

Nitrogen removal efficiency(%)

100

10

(a)

Phase
Ⅱ 55 60Phase
15 20 Ⅰ 25 30 35 40 Phase
45 50
65 Ⅲ

60

40

ammonium removal
nitrite removal
TN removal

20

5Phase Ⅱ

1.5

NLR
NRR

1.0

0.5

0

10 15 20 25 30 35 40 45 50 55 60 65 70

5 10 15 20 25 30 35 40 45 50 55 60 65 70

Time (days)

Time(days)
Phase Ⅰ

Phase Ⅱ

Nitrogen removal efficiency(%)

100

(b)

Phase Ⅲ

80

60

40

ammonium removal
nitrite removal
TN removal

20

Phase Ⅰ

2.0

NLR and NRR(g-N/L/d)(b)

Phase Ⅲ0.0

00

Phase Ⅰ

2.0

80

Tohoku University

gas was N2. The result indicates that the Anammox reactor
was successfully started up. But approximately 3 weeks
start-up time was used to start up R2. At the end of thisperiod, the nitrogen removal rate (NRR) of the two reactors
had stabilized at 0.12 g-N/(L⋅d) and the NH4+-N andNO2−-N removal efficiencies were above 99% and 99.5%,
respectively. During phase Ⅱ, the influent NH4+-N andNO2−-N concentrations were increased to 90.4 mg/L and
119.3 mg/L, the NLR reached to 0.21 g-N/(L⋅d). The
performance of two reactors remained stable.
The start-up period was shorter than reactors with othertypes of sludge and similar to (Ni et al., 2011), showing thatthe inoculation of mature Anammox granules was a goodidea to start-up a new reactor. Nearly complete influent
NH4+-N and NO2−-N were removed from the wastewater,which fully indicated that high activities of Anammox
bacteria were achieved in the reactor.

NLR and NRR(g-N/L/d)(a)

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(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

Phase Ⅱ

Phase Ⅲ

1.5

NLR
NRR
1.0

0.5

0.0

0
0

5

0

10 15 20 25 30 35 40 45 50 55 60 65 70

5 10 15 20 25 30 35 40 45 50 55 60 65 70

Time (days)

Time (days)
Fig.1. Performance of the Anammox granular reactor as a function ofoperating time: (a) R1; (b) R2.

Fig.2. Nitrogen loading rate (NLR) and nitrogen removal rate (NRR) of two
Anammox reactors: (a) R1; (b) R2.

Fig.1and2. show the variation of nitrogen removal
performance, nitrogen loading rate (NLR) and nitrogen
removal rate (NRR) of the two reactors after 66 days ofoperation. During the phase Ⅰ, the influent NH4+-N andNO2−-N concentrations were 52.5 mg/L and 69.3 mg/L,
respectively. NLR was 0.12 g-N/(L⋅d). After approximately
2 weeks start-up time of R1, excellent treatment results
were obtained quickly without big fluctuation. Ammonium
and nitrite have been simultaneously removed. The gas
component analysis indicated that over 99% of the produced

60

4 Conclusions
Generally, the performance of two identical UASB
reactors have been excellent and similar, the result showsthat Anammox reactor was successfully started up. The
inoculation of mature Anammox granules can be a goodidea to start-up a new reactor and the start-up time was 2-3
weeks. The successful start-up of the reactors prepare forsubsequent continuous experiments.

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

Reference
American Public Health Association (APHA), American Water Works
Association, Water Environment Federation, 2012. Standard Methods for
the Examination of Water and Wastewater, 22nd Edition, Standard
Methods.
Ni S Q, Gao B Y, Wang C C, et al. Fast start-up, performance and microbialcommunity in a pilot-scale anammox reactor seeded with exotic mature
granules, Bioresour Technol, 2011, 102: 2448-54

61

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The 10th International Symposium on Water Environment Systems

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Tohoku University

Successful demonstration of a pilot-scale internal circulation reactor
integrated with partial nitritation-anammox for the treatment of real
membrane-manufacturing wastewater○ Yuqin FAN1, Yong HUANG1,2, Dapeng LI1,2, Zhe KONG1,2*
1

School of Environmental Science and Engineering, Suzhou University of Science and Technology,
Suzhou 215009, China
2
National and Local Joint Engineering Laboratory of Municipal Sewage Resource Utilization Technology,
Suzhou 215009, China *E-mail: zhekong@mail.usts.edu.cn

Abstract
A pilot-scale system integrating internal circulation and partial nitritation-anammox successfully treated real highstrength membrane-manufacturing wastewater in this study. With this pilot-scale system, a high chemical oxygen
demand (COD) removal efficiency of 85% and a nitrogen removal of 90% are achieved at an organic loading rateof 6.0 kg COD/m3/d. The nitrogenous organic matters in the internal circulation zone are degraded into ammonia
nitrogen. In the partial nitrification zone, nitrite accumulation is achieved, providing a suitable NH4+-N/NO2--N ratio
for anammox reaction. Partial nitritation is achieved by maintaining an operational temperature at 30-35℃, freeammonia concentration at 5-7 mg/L and dissolved oxygen at 0.4 to 0.7 mg/L with a reflux ratio of 150%. The COD
to nitrogen ratio in the internal circulation effluent is maintained below 3.0 to inhibit nitrite oxidizing bacteria. This
study demonstrates that a pilot-scale system can efficiently remove organic matters and nitrogen from wastewaterof membrane-manufacturing industry.
Keywords: Membrane-manufacturing wastewater; Anaerobic digestion; Partial nitrification; Anammox;
internal circulation; Pilot-scaleat 30-35°C. The IC zone was inoculated with black anaerobic
1 Introduction
Membrane-manufacturing wastewater (MMW) with highconcentrations of biotoxic wastewater discharged during the
production of various membrane products are hazardous to
the environment. Although conventional activated sludge has
been widely used for wastewater treatment, they are
considered less suitable for treating high-strength industrialorganic wastewater. The goal of wastewater treatment is todevelop a sustainable green technology. Anaerobic digestion(AD) can produce CH4 for energy recovery and carbon
emission reduction, while the partial nitritation-anammox
process saves energy consumed by the aeration process andreduces biomass production. In this experiment the MMW
was degraded by AD of organic matter and produced NH4+N, half of the NH4+-N was converted to NO2--N under partial
nitritation conditions and subsequently successfully
denitrifying by anammox process. This study provides new
ideas for the anaerobic treatment of high-strength industrialorganic wastewater such as MMW, and brings solidengineering experience to the promotion of the IC-PN/A
process in practical applications.

granular sludge. The PN zone was inoculated with activatedsludge from the wastewater treatment plant. The AMX zone
was inoculated with anammox granular sludge. The actual
MMW in this study was diluted 10 times and fed into thereactor for reaction. NH4+-N, NO2--N, NO3--N, TN and COD
were measured regularly in the effluent of each zone of thereactor. DO and PH were monitored in real time inside thePN zone using an online monitoring device model (PHS-3T
Digital pH Meter/WTW Multi 9430).
（day）

COD
(mg/L)CODRE(%)

NH4+-N*(mg/L)

I

1050±25

83.3±
3.1

79.3±
10.1

Ⅱ

1520±40

81.5±
2.2

125.6±
4.6

Ⅲ

2023±2282.6±
1.8

156.5±
12.3

Ⅳ

2046±3682.9±
1.9

169.5±
6.8

1

Ⅴ

2550±3783.9±
0.7

198.5±
21.5

1.25

Ⅵ

2550±4284.5±
1.3

206.5±
9.5

1.67

55.6±
13.2

Ⅶ

3051±4785.3±
0.4

168.5±
78.5

2

80.5±
11.1

Stage

2 Materials and methods
2.1 Reactor Setup and Operation
The entire IC-PN/A system has an operational volume of 2
m3 and is equipped with a peristaltic pump, blower and pH
online monitor. A fluidized bed biological filler with a fillingrate of 30% is added to the PN zone. The actual MMW is fed
continuously into the IC, PN and AMX zones. Air is pumped
into the PN zone by a blower for the nitritation reaction.
Finally a percentage of the effluent from the AMX zone isrecycled to the IC zone for enhanced denitrification by meansof an air lift system. The reactor temperature was controlled

62

The operation condition is shown in Table 1.
NH4+-N*:NH4+-N released from IC effluent

HRT
(day)

TNRE
(%)

0.75

_

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

2.2 Sampling and analytical methods
Water samples were measured through the analyticalmethods for water quality and wastewater monitoring (the4th Edition) issued by the State Ministry of Environmental
Protection. The analytical items are NH4+-N, NO2--N, NO3-N, TN, COD, MLSS and MLVSS. The values of pH, DO andtemperature were monitored online with a WTW
multifunctional meter (WTW, Germany).

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treatment process and also contribute to the promotion of the
IC-PN/A process.

3 Results and discussion
This study was divided into seven stages, containing theinitial domestication and the stable operation stage. As shownin Fig. 1, in stage I, the anaerobic digestion sludge achieved
a COD removal efficiency of 79.4-85% at an influent organic
load of 4-6 kg/m3/d, indicating that the sludge graduallyadapted to the MMW and was successfully domesticated.
When the organic load is increased to 8 kg/m3/d, the IC-COD
removal efficiency decreases to 75% and aerobic oxidationof COD occurs in the PN zone. The organic load was restored
to 6 kg/m3/d in order not to affect the subsequent PN/A
denitrification performance, but the subsequent operation
was stable enough to continue the load increase. As the COD
concentration increased, the ammonia nitrogen in the IC
effluent was raised from 80mg/L to 200mg/L. The ammonia
nitrogen conversion efficiency in the PN zone was controlled
at 50-58% by adjusting the aeration. A high FA (5-7mg/L)
was obtained mainly through the combined regulation of highNH4+-N (150-200mg/L) and low DO (0.4-0.7mg/L) in the PN
zone to jointly suppress NOB and obtain a stable nitrite
accumulation efficiency (80%). This process provided
continuous NO2--N/NH4+-N for the subsequent anammox
reaction and the NRE was increased from 57.6% to 90%.
During the experiments it was found that competition for DO
from aerobic heterotrophic bacteria in the IC effluent led to asignificant decrease in NO2--N and NO3--N in the PN effluent
when the COD/TN was above 2.05. Therefore, maintaining astable operation of the IC is a key step in the subsequent
denitrification. Last but not least, the anammox process is
significantly dependent on a stable nitritation process. At
reflux ratios greater than 150%, the NH4+-N in the PN zone
is diluted to 95 mg/L resulting in a weakened NOB inhibitionin the PN zone. Gas lifting reflux sends NO3--N from the
AMX zone back to the IC zone for internal enhanced
denitrification, and refluxes below 150% reduce the overall
denitrification performance of the IC-PN/A. Therefore, aguaranteed reflux ratio of 150% will result in highdenitrification efficiency.
This pilot-scale integrated IC-PN/ a process is the firstreport to investigate MMW treatment. This result provides
solid evidence that the IC-PN/ a system has good potential
for treating actual MMW.

4 Conclusions
This study successfully demonstrates for the first time apilot-scale IC-PN/A system for the anaerobic treatment ofreal high-strength MMW. During the long-term operation,
the entire IC-PN/A system succeeded in the synergetic
removal of both organic matters and ammonia nitrogen,achieving over 85% and 90% removal of COD and TN,
respectively. The division of work is also realized through the
integrated three-stage design of the system. The results of thisstudy provide solid research experience for the futureapplication in practical industrial organic wastewater

63

Fig. 1. Long-term performance of IC-PN/A
Reference[1] Issaoui, M. 2022. Membrane technology for sustainable
water resources management: Challenges and future
projections. Sustainable Chemistry and Pharmacy, 25,
100590.

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

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Tohoku University

Impacts of different Biochar/Ni types on the anaerobic digestion of highsalinity wastewater○ Chen-shun Lu1*, Jin-ming Qiu1 & Yong Hu1
1

School of Environmental Science and Engineering, Nanjing Tech University, Nanjing 211816, China.
*
E-mail: cs999v@163.com.

Abstract
For the anaerobic biological treatment of high salinity wastewater, anaerobic digestion (AD) is currently apossibility, even though elevated salt concentrations can be a major obstacle. To ameliorate the negative effects ofhigh salinity, adding materials has been reported as an effective way. Biochar plays an active role in anaerobic
digestion and high salinity wastewater treatment due to its excellent properties. Due to the different characteristicsof the biochar raw materials, the biochar made by pyrolysis also have different characteristics, and the biocharloaded with nickel ions has been proved to be a possibility of anaerobic digestion. In this study, we focused on theimpacts of biochar/Ni made by pyrolysis of three different kinds of wastes (shrimp shells, pine wood and residual
sludge) on the treatment of high salinity wastewater by granular sludge. Besides, the impacts of different addition
amount and different load nickel ion concentration were also considered. The addition of 2 g/L biochar/Ni canpromote the methane production rate and activity, while the addition of 10 g/L can slightly delay the methane
fermentation. High concentration can strongly inhibit the methane production rate, while the cumulative methane
production is only 56.8% of the unadded.
.
Keywords: Biochar/Ni; Anaerobic digestion; Cumulative methane production; High salinity.
1 Introduction
High-salinity wastewater is produced from various
industries, such as textile-dyeing, tanning, petroleum andfood-processing industries. It is reported that about 5% ofindustrial effluents are saline or high salinity. A variety ofphysical, chemical and biological technologies have been
applied to the treatment of saline wastewater. Compared tophysical and chemical treatment processes, the biologicalprocesses are energy conservation, no secondary pollution
and more convenient. Especially, anaerobic treatment of highsalinity industrial wastewater has attracted considerable
attention over the past decades because of the recovery of net
energy, the reduction to sludge production and the possibility
to handle higher volumetric loading rates if the formation of
granular or immobilized biomass is possible. However, highsalinity is regarded as a stress factor that severely hampers
the performance of biological systems, negatively affecting
biomass retention. High salinity can induce a significant
increase in osmotic pressure, which resulting in a decrease incell activity and eventually leading to cell plasmolysis andcell death.
The effect of biochar as an additive in anaerobic digestion
has become a research hotspot. A variety of biomass types
can be used as feedstock for pyrolysis, and the type of
feedstock selected affects the biochar properties. supporting
bacteria colonies, conducting electron transfer between
species, and adsorbing indirect inhibitors could bemechanisms that biochar uses to promote methanogenesis [1].
The variability of these specific effects is controlled by thephysicochemical properties of the biochar, which is
attributed to the feedstock types and pyrolysis conditions
used for its production. In addition, nickel (Ni) is one of thenecessary nutrient elements for the synthesis of microbial,
which was involved in the synthesis of CO dehydrogenase,64

acetyl-CoA synthase and methyl coenzyme reductase cells in
the process of anaerobic microbial growth and reproduction,and plays an important role in methanogens. The addition ofbiochar and the cations were considered to be effective
strategies in anaerobic digestion, but few studies discussed
their respective roles in the anaerobic treatment of highsalinity wastewater, let alone the combined impacts ofbiochar/Ni.
Thus, this study focused on the impacts of biochar/Ni madeby pyrolysis of three different kinds of wastes (shrimp shells,
pine wood and residual sludge) on the treatment of highsalinity wastewater by granular sludge, and investigated theimpacts of different addition amount and different load nickel
ion concentration.

2 Materials and methods
2.1 Reactor set-up and operation
Two 1 L working volume up-flow anaerobic sludge
blanket (UASB) reactors named R1 and R2 were conducted.
Both reactors were covered with a water jacket to control thetemperature at 35 ± 1 ℃. In the present study, glucose wasadded as the sole organic carbon source to the substrate at aconcentration of 2812 mg/L (COD of 3 g/L). The tworeactors had similar performance and were used as the sourceof batch experimental seed sludge. The concentration of thetotal sodium in the substrate was maintained at 10 g/L.
The operation condition is shown in Table 1
Stage
1
2
3

Table 1 Operation Conditions
Time
HRT
OLR
(days)(d)(g-COD/L/d)
0-57
2
1.5
58-1081
3
109-127
0.5
6

Na+
(g/L)
10
10
10

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
2.2 Biochar preparation
Shrimp shell, pine wood and residual sludge were used to
produce biochar. It was put into quartz tube reactor andslowly pyrolyzed in a tube furnace with a highly purified
nitrogen gas environment. The slow pyrolysis was performedat the temperature of 600 ℃ for 2 h and the heating rate was
10 ℃/min. Samples were washed three times with deionizedwater to remove impurities and dried in the oven at 105 ℃.
The static adsorption experiments were carried out in 1 L
conical flasks. 500 mL of Ni2+ solution with a desiredconcentration and 5 g of shrimp shells biochar (SBC), pine
wood biochar (PBC) and residual sludge biochar (RBC) wereadded into each conical flask. Then conical flasks wereplaced at a constant temperature shaker, where thetemperature and the rotational speed were 30 ◦C and 150
r/min, respectively. After 24 h of adsorption, biochar andsolutions were separated by a suction filter with 0.22 µm
membrane. National standard ( GB) method was used to test
concentrations.
2.3 Batch experiment
Batch anaerobic digestion experiments were carried out in
100 mL serum bottles. Seed sludge is derived from thegranular sludge cultured by UASB. Each serum bottle had 2
g of granular sludge (100 mg VS), 60 mL liquid (glucose andtrace element). Different addition amounts (0, 2, 3.33, 6.67,
10, 13g/L) and SBC loaded Ni (SBC-Ni), PBC loaded Ni(PBC-Ni) and RBC loaded Ni (RBC-Ni) were added into
each serum bottle. Nitrogen was used for air evacuation toensure anaerobic conditions. All digestion bottles wereplaced in a constant temperature incubator at 35 ℃.
2.4 Sampling and analytical methods
Daily biogas production in two UASB reactors wasmonitored with µFlow gas meters (Bioprocess Control
Sweden AB). The determination of biogas composition (CH4,
CO2 and N2) in batch experiment was carried out using a gas
chromatography (GC-2010, Shimadzu). The effluents fromthe two UASB reactors were sampled and analyzed twice per
week for pH, COD, suspended solids (SS). SS were detectedaccording to the Standard Method. The pH value wasdetermined with a pH meter (FE30k), while COD
measurements were performed with COD digest vials(HACH Loveland, CO, USA).

3 Results and discussion

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Fig. 1. The effects of the different amount SBC-Ni on
methane (a), gas production (b)Fig. 1(a) depicts the changes of total biogas produced byanaerobic digestion of high salinity wastewater. After 6 daysof reaction, the total biogas production of 0, 2, 3.33, 6.67, 10,13g/L SBC-Ni were 87.25, 95.88, 96.20, 95.50, 91.83 and69.63mL, respectively. According to Fig. 1(b), the total
methane volumes after the reaction were 45.32, 50.79, 52.04,
51.12, 43.57, 25.73 mL, respectively. Each bottle contained
100 mg VS of seed sluge, so the methane yields were 453.2,
507.9, 520.4, 511.2, 435.7 and 257.3 mL/(g·VS),
respectively. As seen in Fig. 1(b), the addition of SBC-Ni
from 2 g/L-6.67 g/L made the reactor start-up time shorter
than that in unadded, and increased the average CH4 content
by about 10%. The reactor containing SBC-Ni was more
conducive to the enrichment of methanogens in the initialstage. While, the addition of 10 g/L and 13 g/L SBC-Ni candelay the methane fermentation. High concentration canstrongly inhibit the methane production rate, and thecumulative methane production is 56.8% of the unadded.
Nickel (Ni) is an important component of methanogens,cofactor and coenzyme. Although a certain concentration of
Ni has a positive effort on process stability and biogas
production, it takes time for microorganisms to get used to
the Ni contained environment. It is reported that a highconcentration of Ni2+ is toxic to methanogens, which cancause oxidative stress and DNA damage [2]. Besides, theaddition of high concentration biochar is proved that willstrongly inhibit the accumulated methane production ofanaerobic digestion.

4 Conclusions
So far, in this study, the effect of different amount additionof SBC-Ni on anaerobic digestion was studied. The low
addition of SBC-Ni promoted the efficiency and stability of
the whole methane production, and the invigorating effect of
it was mainly concentrated in methanogenesis, while theinhibition effect of high addition amount of SBC-Ni wascomprehensive. Appropriate amount SBC-Ni can be added
into anaerobic digestion systems of high salinity wastewaterfor enhanced efficiencies and improved methanogenesis
inhibition.

Reference[1] J. Pan, J. Ma, X. Liu, L. Zhai, X. Ouyang, H. Liu, Effects
of different types of biochar on the anaerobic digestion ofchicken manure, Bioresour Technol, 275 (2019) 258-265.
[2] X. Li, M. Wu, Y. Xue, Nickel-loaded shrimp shellbiochar enhances batch anaerobic digestion of food waste,
Bioresour Technol, 352 (2022) 127092.

65

The 10th International Symposium on Water Environment Systems

GP-RSS & SyDe

(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

Tohoku University

Effect of aeration intensity on a compact biofilm reactor for rural
domestic sewage treatment in China: pollutant removal performanceand hydrodynamic behavior○ Weiyi WANG1* & Yu-You Li1,2
1

Department of Frontier Science for Advanced Environmental, Graduate School of Environmental Studies,
Tohoku University, Miyagi 980-8579, Japan.
2
Department of Civil and Environmental Engineering, Tohoku University, Graduate School ofEngineering, Miyagi 980-8579, Japan.
*
E-mail: wang.weiyi.s5@dc.tohoku.ac.jp
Abstract
The treatment of rural domestic sewage in China requires the process with low operational cost and easy
maintenance. Thus, the effect of aeration intensity and aeration pattern on the treatment effect of bioreactor needs
to be well investigated. In this study, the pollutant removal performance and hydrodynamic behavior of a compact
biofilm reactor (purification tank) under different aeration conditions were studied. The results show that the gas
rising velocity of 0.066 m/s led to a better pollutant performance and hydrodynamic behavior, compared withvelocity of 0.013 and 0.120 m/s. Besides, under the multistage A/O pattern with step-feed, the average effluent
concentrations of NH4+-N and TN were 3 and 14 mg/L, respectively, which are lower than national discharge
standards of pollutant for municipal wastewater treatment plant (GB18918-2002). The step-feed operation in thesecond anaerobic zone of the purification tank could well solve the problem of insufficient carbon source andstrengthen the nitrogen removal function. Overall, the experimental study and hydrodynamic modelling provide thedirection for the application of full-scale purification tank in rural China.
Keywords: wastewater treatment; domestic sewage; rural China; purification tank; CFD.

1 Introduction
As a compact biofilm reactor, the purification tank is a very
suitable technology for in-situ treatment of rural domestic
sewage, which has the advantages of good impact resistance,solid-liquid separation and simple installation. The effect of
aeration intensity and aeration pattern on the treatment effectof bioreactor is particularly significant.
Effects aeration intensity and aeration pattern on removal ofvarious pollutants were studied by experimental means.
Specifically, the removal performance of pollutants under
three different gas rising velocities was compared, and thenitrogen removal effect under multistage A/O process wasinvestigated. On the other hand, 3-D transient gas-liquid twophase flow CFD model was established to describe thehydrodynamic characteristics of the purification tank at
different gas rising velocities. These studies provide
reference for the practical application of the purification tankin treating rural domestic sewage in China.

resistance of the biofilm in the purification tank, porous
corrugated plate was used as the biofilm carrier withspecific surface area of 70 m2/m3 and filling volume of
60% of each zone. The volume of lab-scale
experimental equipment is 1/66 that of the full-scale
purification tank.
a)
inlet

primary
anaerobic

air pump
settling

secondlyanaerobic

aerobic
outletair pump

Fig.
diagram of lab-scale purification tankb) 1. Schematic
settlingA
O single householdforOA

2 Materials and methods
2.1 Set-up of bioreactor
The purification tank for a single household was
designed to treat the sewage from 5 people's household.
Schematic diagram of lab-scale purification tank forsingle household are shown in Fig.1. Consisted of two
anaerobic zones and one aerobic zone. The volume inprimary anaerobic zone, secondly anaerobic zone andaerobic zone, settling zoon were 14.5, 12.5, 11.5 and
5.0 L. To increase the surface, strength and corrosion

66

inlet
2.2
CFD mathematical model
outlet

The geometry of lab-scale purification tank was set to belength of 0.526 m, width of 0.406 m and height of 0.405 m.
A total of 15 aerators were set, evenly distributed at thebottom of the purification tank. The top of the reactor was
believed to be an air outlet. A schematic of the lab-scale
purification reactor and its computational meshes for the 2D
and 3D geometries are shown in Fig. 2. Due to the complex
flow patterns in the purification tank, the standard k-ε
turbulence model was chosen. The experiment adopted Euler
multiphase flow mathematical model.

The 10th International Symposium on Water Environment Systems

Fig. 2. Three-dimensional computational domain: (a)reactor schematic diagram (b) computational grid

3 Results and discussionb) 120

COD concentration (mg/L)

BOD concentration (mg/L)

The changes of COD in each zone of the purification tankunder different gas rising velocities in the aerobic tank areshown in Fig. 3a. Once the aeration was introduced, the COD
degradation ability was continuously increased along withthe augmentation of aeration intensity. Specifically, COD
was slightly degraded to 84 mg/L at the gas rising velocity of
0.013 m/s, however it was greatly removed at the air velocityof 0.066 m/s with effluent COD concentration of 41 mg/L.
Finally, it is indicated the larger air velocity of 0.120 m/s
cannot greatly contribute to the higher removed COD amount.
The BOD5 changes of each zone in the purification tankunder different gas rising velocities was shown in Fig. 3b.
The changing tend of BOD5 was similar to that of COD.
The effects of aeration intensity on the NO3--N and NH3-N
concentrations were shown in Fig. 3c and 3d. The anaerobic
condition did not change the nitrogen concentration. Alongwith the increase of gas rising velocity in the aerobic zone,
the effluent NH3-N concentration was greatly reduced.
Accompanied by the decreased of NH3, the NO3--N
concentration correspondingly increased, especially up to 16
and 32 mg/L at high gas rising velocity of 0.066 and 0.120m/s (Fig. 3d). The difference of reduced NH3-N and produced
NO3--N concentration was calculated to be 30 and 23 mg/L
at gas rising velocity of 0.066 and 0.120 m/s, respectively.
This means that the more nitrogen was removed at the gas
rising velocity of 0.066 m/s.
a) 140
120
100
80
60

40
20
0

100
80

60
50
40
30
20
10

20

0

0.013
0.066
Gas rising velocity (m/s)

0.120

0

0.013
0.066
Gas rising velocity (m/s)

0.120

b)

c)

d)

The pollutant removal efficiency of purification tank could
be considerably enhanced with increase of aeration intensity.
But the gas rising velocity was suggested to be controlled ina medium level of 0.066 m/s. The pollutant removal andhydrodynamic behavior both performed well under thisaeration intensity. Besides, appropriately increasing the gas
rising velocity could not only reduce the bubble size, but also
increased the turbulence between the gas-liquid phases.

0

0.013
0.066
Gas rising velocity (m/s)

0.120

30
25
20
15
10
5
0

0

a)

4 Conclusions

40

d) 35

70

indicating that the liquid phase distribution was not uniform.
When the gas rising velocity arrived at 0.013m/s, the flow
uniformity became better, but no eddy current was formed.
Furthermore, when the gas velocity further increased to
0.066m/s, the fluid in the purification tank had the besthydrodynamic behavior being uniform. This phenomenon
indicates that the gas velocity in the purification tank played
an important role in the flow field distribution in the tank.
The velocity of 0.120 m/s contributed to smaller vortex at the
top of purification tank relative to velocity of 0.066 m/s.
Since the vortex at the bottom of the biofilm carrier was morefavorable for the renewal of the biofilm attached to the carrier,so the gas rising velocity of 0.066 m/s was suggested to be
adopted.
Regarding with the hydrodynamic behavior, the gas risingvelocity also played an important role. Firstly, the bubbles
produced by aeration gather near the aerator and are cut andevenly distributed in the whole tank under the help of biofilm
carrier. But the weak aeration with gas rising velocity of
0.013 m/s did not make a strong positive effect on thehydrodynamic behavior. Besides, the bubble size wasrelatively large, not conducive to the contact and masstransfer of gas-liquid two phases. When the gas risingvelocity increased up to 0.066 m/s, the gas phase could passthrough the biofilm carrier. Overall, appropriately increasing
the rising velocity can not only reduce the bubble size, butalso increase the turbulence between the two phases.

60

0.120

NO3--N concentration (mg/L)

NH4+-N concentration (mg/L)

c) 80

0.013
0.066
Gas rising velocity (m/s)

Tohoku University

Fig. 4. The liquid flow field diagram under anaerobic
condition (a) and aerobic condition with gas risingvelocities of 0.013 m/s (b), 0.066 m/s (c) and 0.120 m/s (d)00GP-RSS & SyDe

(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety+

Fig. 3. Changes of COD (a), BOD5 (b), NH4 -N (c) andNO3--N (d) concentrations in different zones ofpurification tank under three gas rising velocities
The liquid phase flow field in the purification tank withdifferent gas rising velocities is shown in Fig. 4. Bycomparing the flow charts under different gas risingvelocities, when there was no aeration in the tank, a breakpoint appeared in the flow chart inside the biofilm carrier,

67

Reference[1] P. Jin, Efficient nitrogen removal by simultaneous
heterotrophic nitrifying-aerobic denitrifying bacterium in apurification tank bioreactor amended with two-stage
dissolved oxygen control, Bioresource Technology, 281(2019) 392-400.

The 10th International Symposium on Water Environment Systems

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(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

Tohoku University

Effect of up-flow anaerobic sludge blanket reactor treating methanolic
wastewater by adding complex accelerant○Juntong Ha1*, Liuying Song2, Qin Yu2 & Yu-you Li1,2
1 Department of Frontier Science for Advanced Environment, Graduate School of Environmental Studies,

Tohoku University, Miyagi 980-8579, Japan.
Department of Civil and Environmental Engineering, Tohoku University, Graduate School ofEngineering, Miyagi 980-8579, Japan
Abstract
In this study, to improve the efficiency of anaerobic digestion(AD) in an up-flow anaerobic sludge blanket reactor(UASB reactor) treating methanolic wastewater, we investigated the effect of adding a complex accelerant
containing nutrients and amino acids. The experiment was divided into two parts: batch experiment and long-term
continuous experiment. Firstly, the effect of the accelerant on the enhancement of anaerobic bacterial activity wasverified by batch experiments. The results showed that the accelerant had a positive effect on microbial activity.
Secondly, We used a lab-scale UASB reactor for the long-term continuous experiment to investigate the effect ofaccelerant on the performance of the reactor under different organic loading rates, and we also observed the effecton the sludge granulation. The experiments showed that the addition of the accelerant was able to operate stably athigh loading conditions (OLR up to 30gCOD/L/d) with a COD removal rate of over 90%. Furthermore, the additionof the accelerant also had a positive effect on the granulation of sludge. Finally, we hypothesized that the additionof an accelerant could diversify the metabolic pathway of methanolic wastewater.
2

Keywords: Anaerobic digestion; Methanolic wastewater; UASB reactor; Accelerant; Sludge granulation.
1 Introduction

2 Materials and methods

In recent years, with the process of industrialization andmodernization, as well as the acceleration of economic
globalization and the increase in chemical sales, the massive
discharge of industrial wastewater has become a serious
environmental problem. However, as a traditional waste
treatment technology, due to incineration and landfill,greenhouse gas emissions, and soil pollution is notenvironmentally friendly. Therefore, there is a strong
recognition of the importance of developing environmental
waste treatment technologies to achieve carbon-neutral andsustainable societies, which could reduce CO2 emissions,recover resources, save energy and create energy.
Anaerobic digestion(AD), with its carbon-neutral
properties, is also widely used for the treatment of industrial
wastewater containing large amounts of organic matter.
Although AD technology is being seen as a method ofgenerating energy from waste-based biomass resources, ADof methanolic wastewater suffers from bottleneck problems,such as lack of nutrients, sludge run-off, unstable operation,and so on. Methanol is been well known as a major
component of various chemical industries and has a large
annual discharge. In the meantime, methanolic wastewater
has great potential for reuse because it is easily converted tomethane, and does not require hydrolysis in the AD process.
However, the current on-site UASB reactors are sufferingfrom difficulties in forming granular sludge when methanol
is the only substrate and a large amount of granular collapse
and discharged outside the system, which severely limits its
wide application in the anaerobic treatment of methanol[1].
In this study, to improve the efficiency of AD in the UASB
reactor treating methanolic wastewater, we investigated theeffect by adding a complex accelerant that was obtained fromthe Ajinomoto plant and rich in trace metal elements andamino acids.

2.1 Batch experiment
Sludge was obtained from the UASB reactor that treatsbeer wastewater on-site. The concentration of the methanol
was 1.88 g-COD/L. A total of 80 ml of buffer, nutrient
solution, accelerant(127mg/L), tap water, substrate, andsludge were mixed in serum vials (volume 120 ml), whichwere tightly closed with rubber stoppers and aluminum seals
and then blown with nitrogen gas to create an anaerobic
environment, and batch experiments were carried out at 35°C.
The additional amount of accelerant(0.04%,0.5% of CODbase) added in the different serum vials was varied. All
experimental sets were run in double. An additional set ofserum vials as blank was employed without accelerant added.

68

2.2 Long-term continuous experiment
A UASB reactor with a working volume of 6 L wasoperated at 35°C conditions. Table 1 shows the operating
conditions of the UASB reactor during one-year operation,organic loading rate(OLR) was increased by a step-wise
reduction in hydraulic retention time(HRT), and the effect ofaccelerant on reactor operation stability was investigated,furthermore, the particle size distribution of the sludge wasmeasured periodically.
Table 1 Operation Conditions.
Phase
Durationtime(d)HRT(h)
OLR(gCOD/L/d
Methanol(gCOD/L)
Accelerant(gCOD/L)
Total(gCOD/L)

1
1
91
20
4
3
0
3

2
92
129
2
0

3
130
155
1
1

4
156
179

5
180
204

6
205
220

7
221
248

8
249
294

9
295
309

8

4.3

5

3.6

2.4

2.4

4

7

10

17

14

20

30

48

3

3

3

3

3

3

3

5

0.0
4
3.0
4

0.0
4
3.0
4

0.0
4
3.0
4

0.0
4
3.0
4

0.0
4
3.0
4

0.0
4
3.0
4

0.0
4
3.0
4

0.0
7
5.0
7

The 10th International Symposium on Water Environment Systems

3.1 Batch experiment in different amounts of accelerant
As shown in Table 2, the blank group had the highest
methane production rate of 133 mL/gVS/d, while it reached
108 and 76 mL/gVS/d in the amount of 0.04% and 0.5%
accelerant respectively. On the other hand, the lag phase wasshorter than the blank group under the condition of 0.5%
accelerant added. These results indicate that the accelerant
had a positive effect on microbial activity.

Blank

60
Accelerant 0.04％

11 h

4

5

6

7

8 h 4.3h 5h 3.6h

8

9

2.4 h

2.4 h

100

20
CH4%

80

CO2%

CH4生成速度
15

60
10
40
5

20

Methane production
rate（L/L/d）

Biogas content（%)

3

20 h

0

Accelerant added

2000
1500
1000
500

AK6.5

AK4.8

Accelerant added

5100
4100
3100
2100
Influent

Effluent

200

250

100

Accelerant added

100
95
90
85
80

30
Accelerant0.5％(gCOD/L/d)

60

40

20

2

20 h

1100

COD removal rate(％)

80

1

HRT

0

OLR

Methane accumulation (mL)90

Alkalinity(mg-CaCO3/L)

3 Results and discussion

Phase

0
2500

COD(mg/L)

All samples of influent and effluent were analyzed after
being filtrated through Millipore filter units with 0.45µm
pore size. The composition of the biogas(CH4, CO2)wasmeasured once daily using a gas chromatograph with a TCD
detector (Shimazu, GC-8A). The volatile fatty
acids(VFAs)were quantified by gas chromatography(Agilent
6890 series)

50

Tohoku University

Accelerant added

2.3 Sampling and analytical methods

70

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(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

50
40
30
20
10

10

0
0

0
0

50

100

150

200

250

300

Time（h）

Fig. 1. Batch progress data.
Table 2 Results of fitting the batch progress data withthe modified Gomperz model

Blank
Accelerant
0.04％
Accelerant
0.5％

The maximum
potential of CH4
production(mL-CH4/gVS)
258

Maximum CH4
production rate
(mL/gVS/d)

Lag
phase
(d)

133

4.8

278

108

4.2

343

76

3

50

100

150

300

Fig. 2. Long-term performance of methanolic
wastewater treatment by adding accelerant.
3.2 Effect on sludge granulation
To investigate the effect of the accelerant on sludge
granulation, the particle size distribution of the sludge wasmeasured periodically. Table 3 shows a summary of themedian diameter (D50). It can be seen that the particle size
increases significantly along the longitudinal direction of thereactor. In addition, the particles formed in the reactor did notcollapse and no sludge uplift was observed.
Table 3 Comparison of median diameter (D50) results

350

Time
Top(µm)

3.2 Long-term experiment with UASB reactor treatingwith synthetic methanolic wastewater
Fig.2 shows the results of a long-term continuous
operation of the UASB reactor for approximately one year.
Accelerant started to be continually added from phase2. The
pH and CH4 content were stable in the range of 7.2-7.5 and
83% respectively from phase 1 to phase 8. The methane
production rate also increased progressively with increasing
OLR. During this period, no VFA was detected in the effluent,indicating stable operation is achieved. However, in phase9,
when the OLR was increased to 48 gCOD/L/d, there was adecreasing trend in pH, and alkalinity and the CH4 content
decreased to 75%. In addition, the rate of methane production
gradually began to decrease. Although there was little change
in the NH4+-N concentration in the effluent. However, theCOD concentration in the effluent increased to an average of
800 mg/l and the COD removal rate decreased from 90% to80%. Besides, the accumulation of VFA was detected in thisphase.

69

72d 109d

126d 156d

175 d 192d 248d 280d

123

125

63.4

81.1

76.8

139

538

579

Medium(µm) 383

316

370

314

369

697

610

440

Bottom (µm) 579

560

533

561

578

650

620

543

4 Conclusions
Through batch experiments, we observed that the additionof 0.5%(COD base) accelerant could reduce the lag phase,but did not increase the rate of gas production. As for the
long-term experiment, stable operation can be achieved evenunder high OLR conditions (up to 30g COD/L/d) with a COD
removal rate of over 90%. However, when the OLR was ashigh as 48g COD/L/d, it resulted in the accumulation of VFA
in the reactor and began to operate unstably. The addition ofan accelerant can promote sludge granulation andproliferation, and also inhibits sludge collapse.

Reference[1] Xueqin LU, Biocatalysis conversion of methanol tomethane in an up-flow anaerobic sludge blanket (UASB)
reactor: long-term performance and inherent deficiencies,
Bioresource technology198(2015), 691-700.

The 10th International Symposium on Water Environment Systems----- with Perspective of Global Safety(Dec. 8th ~ 9th , 2022)

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Predictive numerical modeling of landslide susceptibility:
A case study for Uma Oya catchment, Sri Lanka.
○ Abeygunasekara HASHANI1*, Kazama SO1
1

Department of Civil and Environmental Engineering, Tohoku University, Miyagi 980-8579, Japan.
E-mail: hashani.anuttara.abeygunasekara@dc.tohoku.ac.jp*

Abstract
Predicted landslide susceptibility offers vital input to effective disaster risk management. Landslide susceptibility is an
important consideration referring to the central highlands in Sri Lanka, given the unique combination of climatic and hydrogeological conditions it is featured with. Provided the unique spatio-temporal configuration, the applicability of a global model
to predict the landslide susceptibility becomes less effective, which requires much adaptation. Numerical modeling poweredwith globally evaluated climatic data combined with some field data provides an effective solution to model the corresponding
landslide-inducing environment and predict the slope stability conditions within the local settings. The study suggests thevalidity and the applicability of the suggested approach to numerical modeling of slope stability within the target region, thus
contributing to the fact that landslide triggering conditions are much sensitive to the input feature variables defined by bothglobal climatic conditions and local hydro-geological settings.
Keywords: landslide susceptibility; slope stability; numerical modeling; disaster risk management

1 Introduction
Landslides are catastrophic events induced by various
causes. The factors that induce landslides include bothnatural and anthropogenic processes. Rainfall and thegeomorphology of a specific location act together todetermine the slope stability of the ground leading to thegeneration of a slope failure. Ground water table acts asignificant role in shaping the slope stability of the ground.
The weight induced by the increased water table tend to
induce much weight on the sliding plane which causes theland to slide along the sliding plane. Accordingly, the rainfall
acts a significant role in determining the slope stability of theground.

Comprehensive understanding of the processes related tohydrology cycle is much important which enables
understanding the related mechanisms and causative factors
behind the disaster events. With application to the landslides,
the extreme rainfall events cause the precipitation to exceed
the infiltration capacity of the ground, which in turn generatesurface runoff that is added to the surface water channels
shaped by the topography of the terrain. The water that is
infiltrated is subjected to either interflow or deep percolation.
The interflow is added to the stream network while the waterthat is deep percolated causes the ground water recharge.
Provided the properties of the deep aquifers, and the state ofequilibrium, the ground water recharge or discharge may
occur in between the aquifers and the surface water resources.
The research is intended to investigate the predictability oflandslide susceptibility within the region, by numericallymodeling the regional hydrological processes. Accordingly,
the proposed methodology is a stepwise approach i.e., tomodel the dynamics of the water table within the region andthen use the same to evaluate the dynamics of the slope
stability to predict the likelihood of a landslide event.

2 Materials and methods
Numerical model was developed to simulate the relatedhydrological processes to evaluate the dynamics of slope
stability within the study region.
Step 1: Rainfall runoff model
The study period was set to 2015-2016 based on theavailability of input data for the study region. Daily values
for the precipitation measured at 15 rainfall gauges andminimum and maximum temperature measured at one
temperature gauge were used to the net effective precipitation
using the following equations.
𝐸𝑓𝑓𝑒𝑐𝑡𝑖𝑣𝑒 𝑃𝑟𝑒𝑐𝑖𝑝𝑖𝑡𝑎𝑡𝑖𝑜𝑛 = 𝑅𝑎𝑖𝑛𝑓𝑎𝑙𝑙 – 𝐸𝑣𝑎𝑝𝑜𝑡𝑟𝑎𝑛𝑠𝑝𝑖𝑟𝑎𝑡𝑖𝑜𝑛 (1)(2)
𝐼𝑛𝑓𝑖𝑙𝑡𝑟𝑎𝑡𝑖𝑜𝑛 = 𝑀𝑖𝑛(𝐸𝑓𝑓. 𝑃𝑟𝑒𝑐𝑖𝑝𝑖𝑡𝑎𝑡𝑖𝑜𝑛, 𝐼𝑛𝑓𝑖𝑙𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦)
𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑟𝑢𝑛𝑜𝑓𝑓 = 𝑀𝑎𝑥(0, 𝐸𝑓𝑓. 𝑃𝑟𝑒𝑐𝑖𝑝𝑖𝑡𝑎𝑡𝑖𝑜𝑛 − 𝐼𝑛𝑓𝑖𝑙𝑡𝑟𝑎𝑡𝑖𝑜𝑛) (3)(4)
𝐼𝑛𝑡𝑒𝑟𝑓𝑙𝑜𝑤 = 𝐼𝑛𝑓𝑖𝑙𝑡𝑟𝑎𝑡𝑖𝑜𝑛 − 𝑔𝑤𝑅𝑒𝑐ℎ𝑎𝑟𝑔𝑒(5)
𝐵𝑎𝑠𝑒𝑓𝑙𝑜𝑤 = 𝑔𝑤𝑅𝑒𝑐ℎ𝑎𝑟𝑔𝑒 − 𝑔𝑤𝑆𝑡𝑜𝑟𝑎𝑔𝑒
𝑆𝑡𝑟𝑒𝑎𝑚𝑓𝑙𝑜𝑤 = 𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑟𝑢𝑛𝑜𝑓𝑓 + 𝐼𝑛𝑡𝑒𝑟𝑓𝑙𝑜𝑤 + 𝐵𝑎𝑠𝑒𝑓𝑙𝑜𝑤 (6)𝑔𝑤𝑆𝑡𝑜𝑟𝑎𝑔𝑒 = 𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑟𝑢𝑛𝑜𝑓𝑓 + 𝐼𝑛𝑓𝑖𝑙𝑡𝑟𝑎𝑡𝑖𝑜𝑛 − 𝑆𝑡𝑟𝑒𝑎𝑚𝑓𝑙𝑜𝑤(7)Figure 1: Study Area - Uma Oya basin, Sri Lanka

70

The 10th International Symposium on Water Environment Systems----- with Perspective of Global Safety(Dec. 8th ~ 9th , 2022)

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4

Then the landuse distribution of the region was analyzed torecategorize the existing landuse classes, which were used as
the basis to determine the infiltration capacity of each unit ofground within the grid.
Provided the effective rainfall intensity exceeds theinfiltration capacity of the ground, the surface runoff isgenerated, in terms of infiltration-excess overland flow.
Besides the mass balance of water budget was used to derive
the formulae to model the daily water table within the study
region.
Step 2: Relation to the landslide susceptibility
The evaluated temporal series of groundwater table was
evaluated against various landslide occurrences recorded
within the study period to identify the behavior of the watertable within the designated period as simulated by the model.
The attempt was focused on mapping the slope stability of
the ground with the dynamics of the water table.

3 Results and discussion
Temporal series of factor of safety evaluations werecompared with the known examples obtained from theground surveys to evaluate the accuracy of the model results.
Thus, Table 1 shows the regions that were identified as themost susceptible to landslides, which could be verified
against the historical landslide records obtained from the
National Building Research Organization, Sri Lanka.
Moreover, the zonal statistics calculated for the same indicatethat the majority of the landuse within these regions are thehomesteads and tea cultivations.
Table 1: Most landslide-susceptible regions within AOIAdministrative Division
Code
Major Landuse
Kandegedara Town
27A
Tea cultivation
Bandarawela Estate
65B
Home gardens
Hapuwalakumbura
73A
Tea cultivation
Hindagoda
78K
Home gardens
Dematawelhinna
82B
Home gardens
Medagama84
Tea cultivation
Besides the results were analyzed for the associated trends
in the characteristics of the landside inducing environments.
The same indicated a variety of combinations of the related
attributes that have contributed towards defining a landslide
event. Table 2 highlights few of such trends that could beobserved within the landslide inducing settings.

Figure 2: Regions with landslide occurrences

Conclusions
The climatic conditions tend to create a significant
contribution towards shaping the landslide inducing
environments, whereas the extreme rainfall events,
temperature variations, landuse distribution and more
importantly the local geomorphology are among thestimulators.
Assessment of landslide susceptibility is of utmost
importance regarding the prevention of the significant losses
and the management of risks associated with the disasters tominimize the associated losses. Improved predictability ofthe various scenarios of risks favor to improve thecommunity-wide awareness, alertness and the preparedness
which will in turn improve the community resilience against
the downturns caused by the disastrous events.
The study is expected to contribute towards the related
research community in its effort to map the relationshipbetween the dynamics of groundwater table and thevulnerability of the land to slope failures through numericalmodeling. Secondly the numerical model provides the basis
for further analysis by offering a structured numerical modelthat is conveniently be improved and adapted to a variety of
scenarios in future research work.

References

Major Landuse
Gradient of Terrain

2015/1/5
2015/1/6

Max Diff in WT(m)Attributable Regions

2015/1/2
2015/1/3

Characteristics

2015/1/1
2015/1/2

Table 2: Characteristics within the susceptible regions

3.97
65B
78K
Homestead
Low

1.58
73
84
Tea
High

16.28
27A
73A
Tea
High

[1] L. Chen et al., “Meta-learning an intermediate
representation for few-shot prediction of landslide
susceptibility in large areas,” International Journal ofApplied Earth Observation and Geoinformation, vol. 110, p.
102807, Jun. 2022, doi: 10.1016/j.jag.2022.102807.
[2] Ö. Ekmekcioğlu and K. Koc, “Explainable step-wisebinary classification for the susceptibility assessment of geohydrological hazards,” Catena (Amst), vol. 216, Sep. 2022,
doi: 10.1016/j.catena.2022.106379.
[3]A. Paetzold, C. Yoshimura, and K. Tockner, “Riparian
arthropod responses to flow regulation and river
channelization,” Journal of Applied Ecology, vol. 45, no. 3,
pp. 894–903, Jun. 2008, doi: 10.1111/J.13652664.2008.01463. X.

71

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDE
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Validation of a watershed storage effects
for the analysis of climate change○ Sora MARUTA1, -Seiki KAWAGOE1*
1Faculty of Symbiotic Sciences Systems, Fukushima University, 960-1296 kanayagawa1, Fukushima, Japan.
*
E-mail: kawagoe@sss.fukushima-u.ac.jp.

Abstract
Climate change has led to an increase in precipitation and the number of rivers exceeding their flood levels in all
regions of Japan. It is pointed out that the amount of precipitation and the frequency of flooding will continue toincrease in the future, and there is concern that the number of disasters that cannot be prevented simply by improving
river channels will increase. In recent years, basin-based flood control measures have been promoted in Japan toreduce flood damage throughout the entire basin, and estimating the effect of water storage outside the river channel
can help in the planning of basin-based flood control measures. In this study, data on off-channel water storage
capacity for rice paddies, parks, and school reservoirs were collected on a national scale, and their functions were
evaluated. In Fukushima Prefecture, the contribution of internal and external water storage was determined inconsideration of future population changes, and priority areas were selected for countermeasures.
Keywords: Watershed management, Off-channel storage, Storage effectiveness.
1 Introduction
It has been confirmed that the amount of precipitation andthe number of rivers exceeding the flood risk level haveincreased due to climate change. According to the IPCC
Sixth Assessment Report, there is no doubt that humanactivities are contributing to global warming, and extreme
events are expected to become more severe in the future [2].
In order to prevent flooding as much as possible, it isimportant to understand the amount of storage in the river
basin in addition to the in-channel flow rate. In a study on
off-channel storage, Shimura (1982) calculated the storage
effect of rice paddies for the whole of Japan, covering an areaof 3.17 million m3 of rice paddies in 1975 [3]. For floodinundation analysis including off-channel storage, Kawaike
et al. (2018) conducted a flood inundation simulation in the
Nakahama treatment area in Osaka City, including offchannel storage in residential areas, schools, and parks, andmentioned the calculation of maximum inundation depth andinundation reduction effects [4]. Thus, while there are
analyses that calculate storage in rice paddies throughout
Japan and that anticipate off-channel storage effects for
specific areas, there have been no calculations of off-channel
storage and its functional evaluation for the entire country.
Therefore, in this study, we compiled data on off-channel
storage on a national scale and evaluated its function. Basedon the data, we attempted to understand the changes in water
storage contribution due to future socioeconomic changes inFukushima Prefecture, and to select priority areas forcountermeasures.

2 Materials and methods
Target off-channel storage options were selected, and thestorage volume for each option was estimated on a watershedbasis. Three off-channel storage options were selected: ricepaddies, parks, and schools, and data were obtained fromnumerical geographic information. For rice paddy storage,
the land structure was classified into three types: plain,sloping, and fan-shaped land. The depth of waterlogging was72

set to 30 cm, 10 cm, and 20 cm, respectively. For park andschool storage, the storage volume was calculated by setting
the required waterlogging depth to 60% of the park andschool yard area and 30 cm. The maximum hourly
precipitation and mean temperature (warm-season normal,
analysis period: 1991-2021) data were obtained from
AMeDAS stations, and the equations were derived. The
obtained regression equation was applied to the mean
temperature of the warm-season normal of the mesh climate
value 2010 to obtain an estimate of the maximum hourly
precipitation for a 1 km mesh with spatial resolution.
Population data from the socioeconomic scenario developedby Chen et al. [2] were used to evaluate the contribution ofinternal and external water storage to population change
within the watershed. SSP1 and SSP5 were selected as theupper and lower limits of the scenarios, and were alsoclassified into three time periods: 2015 (base year), 2050, and2100.

3 Results and discussion
The amount of storage in rice paddies, parks, and schools
in Japan was about 3.68 billion m³, 0.34 billion m³, and 0.05
billion m³, respectively. The storage in parks and schools is
estimated to be about 340 million m³ and 0.5 billion m³,
respectively, and storage is expected in the Tokyo, Chukyo,
and Kansai areas (Figure. 1). The storage effect in space andtime was calculated, and it was found that the storage effectwas high on the northern Japan side, while the effect was not
so great on the Seto Inland Sea side in the Chugoku region(Figure. 2).
The area with no population as of 2015 was 33.9% of all
watersheds. The proportion of watersheds with no population
did not change for both SSP1 and SSP5, basically indicatingthat watersheds with a population distribution as of 2015
tended to increase or decrease in population. Thus, it was notpossible to determine the changing water storage
contribution by the unpopulated areas. The off-channel
storage in these unpopulated watersheds and watersheds withsignificant population decline contributes to the storage ofThe 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
water for the reduction of outside water. On the other hand,storage in watersheds where the population will increase in
the future or where the rate of population decrease is small
will contribute to water storage to mitigate internal water
damage in addition to external water reduction. Therefore,
areas where the population is increasing or where thepopulation decrease is relatively small were selected aspriority areas.
In SSP1 and SSP5, there were some areas where thepopulation will increase in 2050 (Figure. 3). These areas havea high return on investment in terms of both external andinternal water supply, and should be prioritized forcountermeasures. In addition, since the population will
decrease in all watersheds by 2100, it is necessary to takefuture operations into consideration.

GP-RSS & SyDE
Tohoku University

(a)

(b)

Fig. 3. Relationship between the rate of change of basin
population (%) and total storage (m³) for each SSP.

4 Conclusions
Among paddy field, park, and school storage, paddy fieldstorage was found to be the most effective off-channel
storage option. In the case of park and school storage, it was
found that there are watersheds in the Tokyo, Chukyo, andKansai areas that can be expected to be effective. The
watersheds with the largest total storage volume were locatedin the northern part of Japan, which is consistent with thewatersheds with high storage effectiveness.
In the analysis in Fukushima Prefecture, there werewatersheds where the population will increase in 2050 for
both SSP1 and SSP5. These watersheds can be considered aswatersheds that function for both water storage to mitigate
internal water damage and to reduce external water.
Therefore, the focus should be on measures for off-channelwater storage.

Fig. 1. Each storage potential map.

Reference[1] MEXT, JMA, Report of Working Group I of the IPCC
Sixth Assessment Report Summary for Policymaker (2022).
[2] Shimura, H., Evaluation of flood control function of
paddy fields and rice paddies, Journal of Agricultural Civil
Engineering Society, Vol.50(1), pp.25-29, (1982).
[3] Kawaike, K, Nakagawa, H, Mitigation Effects of OnSite Storage Facilities on Pluvial Inundation in Highly
Urbanized Area：Journal of Japan Society of Civil Engineers,
Ser. B1 (Hydraulic Engineering), Vol.74, No4, pp. I_15371542, (2018).

Fig. 2. Water storage effect ratio distribution.

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The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDE
Tohoku University

Assessment of the chemical compositional characteristics
as mass movements in granite zone
○ Yuki KUSAKABE1，Shiho YABUSAKI2 and Seiki KAWAGOE1
1Faculty of Symbiotic Sciences Systems, Fukushima University, Fukushima 960-1296, Japan.
2
Research Institute for Humanity and Nature, Kyoto 603-8047, Japan.
*E-mail: kawagoe@sss.fukushima-u.ac.jp.

Abstract
In this study, Actual mass movements in the Granite Zone (Abukuma highland during Hagibis) were verified
environmental conditions. In particular, we focused on the chemical composition that may in-duce the degree of
geological weathering. The mass movement cases were databased from satellite (Sentinel-2B). Spatial information
based on numerical geographic information and chemical analysis of runoff were used for data on environmental
conditions. The results show that the relation-ship between cumulative precipitation and slope gradient can indicate
a large or small collapse rate. However, the chemical analysis of elemental runoff indicated that the amount of Ca
from feldspar and Mg from biotite, which are leached from the granite during weathering, were also involved. The
amount of these elements released from the granite varies depending on the geology and topographic position of the
granite.
Keywords: Geological weathering, hagibis, sentinel-2, icp-ms and climate change
1 Introduction
In this study, the mass-movement distribution of awatershed was obtained for the Abukuma Highlands (Fig. 1),
where many mass movements were caused by Typhoon East
Japan in 2019. The chemical composition of the runoff in thewatersheds where mass movements occurred was also
determined, and the chemical characteristics of thewatersheds were clarified. From these analyses, thefollowing (1) and (2) are aimed to be achieved.
(1) To organise the environmental conditions for mass
movements contributing to sediment and flood inundation.
(2) To clarify the runoff characteristics of the chemicalcomposition that may induce the degree of weathering of thegeology.
As putting these into practice and clarifying the chemical
knowledge, it may be possible to derive the degree of
weathering without relying on knowledge from geologicalmaps. Such knowledge can be used for early urban relocation.
This can avoid the damage from excessive combined waterand sediment events that have been observed in recent years.
Therefore, they provide an effect as a measure for watershed
flood control.
In the East Japan Typhoon of 2019, mudflows and slope
failures occurred frequently in these weathered zones,
especially in the massified areas, and large amounts of
sediment were washed away. Massification is a simultaneous
physical and chemical reaction between the fracture of
granitic rocks and the reaction of water entering the fracturesurface. In granitic rocks, for example, feldspars tend to
become clayey while quartz, the main element, remains
unchanged. The degree of weathering can be easily
determined by looking at changes in the chemicalcomposition of the feldspar. The main elements in feldspar
are Al, Si, Ca, Na and K, but Al and Si are not easily dissolved
out, so kaolin minerals (Al2O3, 2SiO2) remain in the clayedzone. On the other hand, Ca, Na and K are easily dissolvedin acidic water. The biotite contained in the rock is easily
weathered, causing the dissolution of K distributed in theinterlayer of the biotite. In addition, weathering also leaches
Fe and Mg to form kaolin minerals. Considering the above
processes of chemical compositional changes due toweathering, it may be possible to determine the degree of
weathering from the dissolution and efflux of Ca, Na and K
from feldspar and Fe and Mg from biotite[1].

74Fig. 1. Study area map

2 Materials and methods
The analysis in this study consists of (1) extractive analysis
of mass movement distributions, (2) comparative verificationof watershed environmental conditions with case studies, and(3) comparative verification with the chemical compositionof runoff in the watersheds. The spatial unit of analysis was
set to small watersheds, covering 30 watersheds distributedin the Abukuma Highlands.
(1) Extractive analysis of mass movement distributions
Satellite imagery was used to develop information on thespatial distribution of mass movements. Sentinel-2B wasused as the dataset for satellite imagery. The images extracted
to extract examples of mass movements during the East Japan
Typhoon of 2028 were taken on 14 November 2018 and 9
November 2019. Two indices were used to extract mass
movements: the normalized vegetation index NDVI, whichindicates vegetation activity, and the grain size index GSI,
which indicates bare areas. These indices were compared todetermine the distribution of mass movements.
(2) Comparative verification of watershed environmental
conditions with case studies
To understand the environmental characteristics of mass
movements, the relationship between each environmental
condition and numerical geographic information wasdetermined. This comparative study revealed the conditions

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDE
Tohoku University

Fig. 3. relationship between
slope angle and cumulative precipitation

Fig. 2. Satellite image analysis results map
under which mass movements were likely to occur in the
granitic zone. The conditions examined were vegetation, soil,
surface geology, slope gradient and cumulative rainfall
during the East Japan Typhoon of 2019(12-13 October 2019).
The basin average cumulative rainfall is based on data
developed by Kawagoe (2022)[2]. Comparison andverification of various information showed that a generalrelationship was established between vegetation with few
regional differences in the Abukuma Highlands, surface
geology other than soil, slope angle, and cumulative
precipitation during the East Japan Typhoon of 2019 and thecollapse ratio of the sub-watersheds. Therefore, this paper
describes the results of the comparative verification of
surface geology, slope gradient and cumulative precipitation.
(3) Comparative verification with the chemicalcomposition of runoff in the watersheds.
The chemical composition of the runoff water from thecatchment area, including the mass movement, wascompared with the chemical composition of the water fromthe case study. The chemical composition data were obtained
from surface water sampling and results analysed byinductively coupled plasma mass spectrometry (ICP-MS).
Sampling of runoff was carried out when no precipitation
had been observed for five days, in order to obtain thechemical composition of runoff from base rock that had beencleared of the effects of surface runoff. In order to remove theinfluence of land use, such as agricultural land, sampling
points were set up in mountainous areas within the catchment.
Flow observations were carried out simultaneously withsampling.

3 Results and discussion
The points of mass movement determined from the indicesobtained by satellite image results are shown in Fig.2. Massmovement is characterized by the fact that it occurs evenly
on the slopes of the entire watershed in the northern
Abukuma Highland area. In addition, the eastern margin of
the watershed is concentrated at the valley head (zero-ordervalley). The collapse ratio (the ratio of mass movement area
to catchment area) for each catchment was organized, andwas found to be higher in the upper reaches of the Gofukuya,
Shin, Uchigawa, Yamabunyu and Uchigawa Rivers in thenorthern Abukuma Highlands.
The relationship between slope angle and cumulative
precipitation is shown in Fig.3, where a particularly clear
relationship is demonstrated as a comparative study between
the catchment environmental conditions and the case study.

75

Fig. 4. relationship between
failure ratio and chemical element runoff
This information is also supplemented with information on
geology and failure ratios. higher failure ratios with higher
cumulative precipitation and steeper slopes. However, somegeological features do not fit the linear relationship. For thisreason, a simple relationship was determined between thechemical composition of the runoff from the geology, In therelationship with the discharge of Ca and Mg, which isregular depending on the geology. The results are shown in
Fig.4. The results show generally similar correlation
coefficients between slope gradient and cumulative
precipitation. This suggests that the influence of thegeological interior has the same effect as that of the surface
and precipitation.

4 Conclusions
The results show that, although the relationship between
cumulative precipitation and slope gradient can generally
explain the size of the collapse rate, in basins where this
explanation does not apply, the tendency for the discharge offeldspar-derived Ca and biotite-derived Mg, which areleached from the granite as a result of weathering, to be
involved. Therefore, the possibility of inducing the degree of
weathering by the amount of Ca and Mg leached from theriver was also revealed. However, these results are findings
based on a case study of a specific area. Therefore, further
validation by expanding the area of comparison is an issue
for the future. In addition, it is also necessary to verify the
specific domain in accordance with changes over time.

Reference[1] M. F. Thomas : Some Geomorphological Implications of
Deep Weathering Patterns in Crystalline Rocks in Nigeria，Transactions of the Institute of British Geogra-phers, No. 40,
pp.173-193,1966.
[2] S.Kawagoe et al: Disaster characteristics of Fukushima
prefecture by the 19th typhoon, Journal of JSCE, Series B1(hydraulic Engineering), Vol.76(1), pp. 329-345, 2020.

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDE
Tohoku University

Population Movement caused by Flood Damage at City Level
Ayaka Okamoto1, So Kazama, Hayata Yanagihara
1

Department of Civil and Environmental Engineering, Tohoku University, Miyagi 980-8579, Japan.
*
E-mail: okamoto.ayaka.s3@dc.tohoku.ac.jp

Abstract
Flood disasters have been pointed out to have an impact on population decline in Japan. For this reason, it isimportant to estimate the future decline in population due to flood disasters. The results of these population estimates
can be used as basic data for land use planning and economic activity planning based on flood disasters. Therefore,
the objective of this study is to estimate the future population decrease caused by flood disasters. For this purpose,
population loss due to flood disasters is estimated for each region and for Japan as a whole. First, we examine thepopulation decline in cities that were severely damaged by floods in the August 2014 rainstorms. As a result, we
could not confirm the impact of flood damage on population decline at the city level. Accordingly, it is necessary
to analyze population loss by subregion and 500-meter resolution in the future. In Fukuchiyama City, which suffered
the most damage, the population tended to decrease in the areas along the river. This suggests that floods are likely
to have an impact on population decline. Based on these results, we will analyze population decline in the case offlood disasters of various sizes, such as the torrential rains in July 2020 and the East Japan Typhoon in 2019.
Keywords: Population movement; Flooding; City level
1 Introduction
Japan has entered a society with a declining population,
which is a serious problem. Previous studies have indicatedthat flood disasters have an impact on the declining
population in Japan. According to a report by theInternational Displacement Monitoring Centre (IDMC),
floods and typhoons account for approximately 76% of the
population decline due to natural disasters in Japan between
2008 and 2020 (Figure 1). Considering the above, it isimportant to estimate the future population decline caused byflood disasters, taking climate change into account. This isbecause future population estimates are used as basic data fornational land policy. In order to estimate the population
decline due caused by flood disasters, it is necessary to model
the population decline caused by it. In previous studies,models have been developed for population estimationconsidering flood risk applicable only to specific regions 2)
and for the analysis of population movements caused byflood inundation in different countries around the world3). On
the other hand, there is no model for population decline
caused by flood disasters that can be applied to a wide area.
For that reason, it is not possible to estimate the future
population decline caused by flood disasters taking climatechange into account in the current situation. Therefore, theobjective of this study is to understand the actual situation of
population decline caused by flood disasters in Japan. The
results obtained from this study will be used as basic data fordeveloping a model of population decline caused by flood
disasters and for estimating the future population decline
caused by flood disasters, taking climate change into account.
The results of this study will make it possible to predict future
population decline caused by flood disasters.

analyzed population movements by subregion (town, street,street name, etc.) using the total population by sex for theyears 2000, 2005, 2010, and 2015. Currently, actual
population data are available from 1995 to 2020. I n thisstudy, the number of population decline caused by flood
damage is determined for the "August 2014 Torrential
Rainfall". Figure 2 shows the relationship between cities andthe amount of flood damage. The amount is calculated using
the amount of damage to general assets by city, town, andvillage, by cause of flood damage, from the 2014 Flood
Damage Survey. Specifically, damage from flooding isdefined as damage caused by breaches of embankments,
overflows at embankments, overflows at no-embankment
areas, internal flooding, and internal flooding in depressions.

(2) Method
In this study, the number of population decline caused byflood disasters is estimated from actual population data. An
overview is shown in Figure 3. The actual data include
natural population movement as well as population decline
caused by disasters. The number of population decline causedby flood disasters is estimated by subtracting the projected
population decline in the absence of the flood from the actual
population decline based on the number of population decline
in the past. The flood hazards covered in this study are thevarious types of flood hazards listed in the National Flood
Survey.

24%
Percentage of Population
Displacement
due to Disasters in Japan(2008-2020)

76%

2 Materials and methods(1) Data
We obtained actual population data (2000, 2005, 2010, and2015) from the National Population Census data. First, we

76

Flood/Typhoon

Landslides, etc.

Fig. 1. Percentage of Population Movement due toDisasters in Japan4).

The 10th International Symposium on Water Environment Systems

Tohoku University

160

160
140
120
100
80
60
40
20
0

140

Flood damage (billion yen)

Flood damage (billion yen)

GP-RSS & SyDE

(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

120
100

80
60
40
20
0
0

City name

5000

10000

15000

20000

25000

30000

35000

40000

Population decline (number of people)

Fig. 4. Flood Damage and Population Decline.

Fig. 2. Cities and Flood Damage.

3 Results and discussion
Figure 4 shows the relationship between flood damage andpopulation decline in 13 cities. Population decline was
examined for the top 20 cities with the highest flood damage,but for seven of these cities, population decline could not becalculated in the GIS. One of the reasons for this is that the
key codes for each municipality have changed due to the
Heisei Era's great merger and other factors. Key codes are thelink codes between boundary data and statistical data, and are
required when charting population data in QGIS. Therefore,
some cities were unable to estimate their population in 2015
in the absence of a disaster. In consequence, only 13 cities
are plotted in Figure 4. As can be seen from the figure, theeffect of flood damage on population decline could not be
confirmed. This suggests that it is necessary to examine
population decline at the sub-region and 500-meter
resolution. Sub-regions are smaller units than municipalities,
such as town. Figure 5 shows the number of population
decrease in Fukuchiyama City using QGIS, a cross-platform
open source software with functions for viewing, editing, andanalyzing geographic information systems. The blue lines
indicate rivers in the direct Class 1, designated Class 1, andClass 2 river areas. The red portion indicates an increase inpopulation, while the blue portion indicates a decline in
population. The figure shows that the population tends todecline more in the areas along the rivers. Thus, it is clearthat flooding has a negative impact on population decline.
This suggests that floods are likely to have an impact on
population decline.

Flooding(2014)ー・ー

Number of population decline
caused by flood disasters： Population without flooding(Estimated based on historical population decline)

・： Actual population
2000

In this study, we analyzed population decline in 20 cities
with large flood damage amounts for the August 2014
torrential rains. As a result, it was found that it is difficult tograsp the population decline caused by flood disasters in eachmunicipality. In addition, due to the Heisei Era's great merger,
some areas have changed from the past to the present, andkey codes have also been changed. Therefore, it is difficult toaccurately calculate the number of population decline in eachmunicipality using QGIS. Thus, it is effective to study
population decline in small areas or at 500-meter resolution.
We would like to use the results of this study to develop amodel of population decline caused by flood disasters.

[1] Murai et al., Characterization of population loss due toflooding based on population projections, Japan Societyof Hydrology and Water Resources, 2019.
[2] Imai et al., Development of a population distribution
estimation model for future time series for land use
policy evaluation considering flood risk, Journal of City
Planning, Vol. 50, No. 3, pp. 656-662, 2015.
[3] Kakinuma et al., Flood-induced population
displacements in the world, Environmental Research
Letters, Vol.15, 124029, 2020.
[4] International Displacement Monitoing Centre (IDMC).

Population movement at a given point

1995

4 Conclusions

Reference

Population◆

Fig. 5. Estimated number of population decline
caused by flooding in Fukuchiyama City.

2005

2010

2015 [Year]

Fig. 3. Estimation of the number of population losses
due to previous flood disasters.

77

The 10th International Symposium on Water Environment Systems

GP-RSS & SyDE
Tohoku University(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

Innovative ensemble approach of spatial prediction of flood using
bivariate index of entropy and support vector machine models○ Kumudu Madhawa KURUGAMA1*, So KAZAMA1 & Chaminda SAMARASURIYA2
1
2

Department of Civil and Environmental Engineering, Tohoku University, Miyagi 980-8579, Japan.
Department of Earth Resources Engineering, University of Moratuwa, Katubedda 10400, Sri Lanka*
E-mail: kurugama.arachchige.kumudu.madhawa.r4@dc.tohoku.ac.jp

Abstract
In this study, we propose a novel ensemble method for improving the accuracy in flood susceptibility mapping
using index of entropy (IoE) and support vector machine (SVM). The proposed method was implemented with four
SVM kernels, like linear (LN), polynomial (PL), radial basis function (RBF), and sigmoid (SIG). A spatial database
was created with twelve flood conditioning factors(FCFs) and a flood inventory map with 445 flood locations,produced using historical documents, satellite images and extensive field survey. First, the correlation between
classes of each flood conditioning factor with flooding was evaluated using IoE. Following that, SVM wasconducted using the results of the first step. Area under the curve (AUC) and seed cell area index(SCAI) methods
were used to evaluate the performances of the models. The highest success and prediction rates of 94.82% and95.81% and lowest SCAI values of 0.18, 0.878 for very high and high susceptibility classes were achieved byensemble IoE-SVM(RBF) model. Among all the applied methods, both the individual EBF and SVM(RBF) methods
achieved the lowest accuracies. It can be concluded that, using ensemble methods, a more detailed assessment of
the flooding and conditioning factors can be performed, thereby increasing the accuracy of the final map.
Keywords: flood susceptibility; index of entropy; geographic information system (GIS); support vector
machine(SVM); ensemble modelling
1 Introduction
Floods are among the most devastating of natural disasters
and may cause immeasurable damage. Assessment of floodrisk and hazard has gained significant attention in recent
years from geoscientists, engineering professionals, as well
as from the public and local governments in various regionsof the world. Numerous studies have used a variety oftechniques to map flood-prone areas [1].
In Rathnapura district, the most devastating floods haveoccurred during following years 2003, 2008, 2012, and 2017
resulting hundreds of fatalities and economic losses. In thecurrent research, a GIS based, ensemble technique of IoE andSVM models is utilized to map the flood prone regions at
Rathnapura city, Sri Lanka, and the main goal of this research
to examine and compare the efficiency and precision of
proposed ensemble method with standalone IoE and SVM
methods.

2 Material and Method
2.1 Study area

Rathnapura city is located in the western province, Sri Lanka
and lies between the latitudes 6° 55' 51"N and 6° 28' 36"N,and longitudes 80° 10' 37"E and 80° 36' 57"E. The altitude
ranges from 4-2174 m above mean sea level. Climaticcondition of Rathnapura city is hot, humid, and cloudy withmore than 3100mm average annual rainfall and averagetemperature ranges from 71°F to 93°F.
2.2 Data and feature selection
A total of 445 flood locations were chosen as the floodinventory which was created based on satellite data, historical
documentary sources and extensive field survey. Later thesepoints were randomly divided into two sections as 70% (312points) and 30% (133 points) for training and testing
purposes, respectively. Twelve FCFs with 30m spatial grid
resolution were considered. They are altitude, curvature,aspect, slope, normalized difference vegetation index(NDVI),
topographic roughness index(TRI), topographic wetness
index(TWI), distance from river, distance from road, land
cover(LULC), soil, and rainfall.
To avoid overfitting, evaluation of correlations between theflood conditioning factors is an essential. The varianceinflation (VIF) and tolerance (TOL) were used to examine
the multicollinearity among the factors in this study.
2.3 IoE method
The method proposed by [2]. The weight of parameters isdefined by entropy level that indicates the extent of disorderin the environment, then the weight will determine which
factor is more significant in occurrence of flood. The
following seven equations represent the various steps in thecalculation of index of entropy model. See Eq.1 and Eq.2
𝐴𝑓

Pij = 𝐴
Fig. 1. Study Area

78

𝑡

(1)

(Pij) =

𝑃𝑖𝑗
𝑆𝑗

∑𝑗=1 𝑃𝑖𝑗(2)

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
Af : Area of the factor class after primary reclassification
At : Area of flood within the given factor class(Pij) : Probability density
Hj and Hj max represent entropy values (Eq 3 and Eq4).
𝑆𝑗

Hj = ∑𝑖=1(𝑃𝑖𝑗 ) 𝑙𝑜𝑔2 (𝑃𝑖𝑗 )𝑗 = 1, … 𝑛

Hj max = 𝑙𝑜𝑔2 𝑠𝑗
Sj : Number of classes
Hj , Hj max : Entropy values
Ij : Information coefficient
Ij =𝐻𝑗 𝑚𝑎𝑥 − 𝐻𝑗
𝐻𝑗 𝑚𝑎𝑥(5)

GP-RSS & SyDE
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2.5 Model performance evaluation
As statistical measures, the specificity, sensitivity, andaccuracy were used to evaluate the performances of the
trained models. These indices reflect the ability of the model
to correctly differentiate the flood pixels from the non-flood
pixels. The seed cell area index (SCAI) was used to compare
the ratio of the density of the flood locations and the areas ofthe susceptibility classes in this study.

(3)
(4)

𝐴𝑟𝑒𝑎 𝑒𝑥𝑡𝑒𝑛𝑡 𝑜𝑓 𝑠𝑢𝑠𝑐𝑒𝑝𝑡𝑖𝑏𝑖𝑙𝑡𝑦 𝑐𝑙𝑎𝑠𝑠𝑒𝑠(%)

𝑆𝐶𝐴𝐼 = 𝐼𝑛𝑣𝑒𝑛𝑡𝑜𝑟𝑦 𝑜𝑓 𝑓𝑙𝑜𝑜𝑑 𝑖𝑛 𝑒𝑎𝑐ℎ 𝑠𝑢𝑠𝑐𝑒𝑝𝑡𝑖𝑏𝑖𝑙𝑖𝑡𝑦 𝑐𝑙𝑎𝑠𝑠𝑒𝑠(%)
Wj = Ij x Pij(6)

Wj :represents the weight of each parameter
The final flood susceptibility map was prepared bysummation of weighted multiplications of the secondarily
reclassified parametric maps, see (7).
FSI = ∑𝑛𝑖=1(𝑓𝑎𝑐_𝑟𝑒𝑐𝑙2) ∗ 𝑊𝑗
(7)
Where factor_recl2 is the value in a particular pixel after
reclassifying the parametric map of the conditioning factors.
2.4 SVM method
The SVM algorithm is a cogent prediction machine learning
method based on the structural risk minimization principle
and statistical learning theory. The model creates a
hyperplane in the original space of the coordinates between
the points of the two classes. The hyperplane is classified in
the central part of the peak edge. Separating hyperplane canbe expressed as;yi((𝑤. 𝑥𝑖 )+b) ≥1-ξi(8)
where w ∶ norm of normal hyperplanexi : vector of each input spaceb : offset of the hyperplane from the origin
ξi : positive slack variables
Lagrangian multipliers can be used for determine the optimal
hyperplane as;
1

Minimize ∑𝑛𝑖=1 𝛼𝑖 − 2 ∑𝑛𝑖=1 ∑𝑛𝑗=1 𝛼𝑖 𝛼𝑗 𝑦𝑖 𝑦𝑗 (𝑥𝑖 𝑥𝑗 )(9)

Subject to ∑𝑛𝑖=1 𝛼𝑖 𝑦𝑖 = 0, 0 ≤ 𝛼𝑖 ≤ 𝐶(10)Where αi ∶ Lagrange multipliers,
C : is the penalty,
ξi : slack variables
In the case of non-separation of a hyperplane, input data may
be transformed into high dimensional feature space using
non-linear kernel functions. New data is classified using
decision function:g(x) = 𝑠𝑖𝑔𝑛(∑𝑛𝑖=1 𝛼𝑖 𝑦𝑖 𝐾(𝑥𝑖 , 𝑥𝑗 ) + 𝑏)
(11)
where K(xi , xj ) is the kernel function.
Table 1 Different SVM kernel types
KernelEquation
Variables
LN
K(xi , xj ) = xi T . xj
PLγ, dK(xi , xj ) = (−γxi T . xj + r)dγ
SIG
K(xi , xj ) = Tanh(−γxi T . xj + r)d2
RBF
γK(xi , xj ) = exp (−γ||xi , xj ||)

79

(12)

Finally, to validate the analytical outcomes, the popular AUC
method was used. In this study, training and testing dataset
were used to determine success and prediction rate curves
which reflect the goodness of fit and prediction power of themodels, respectively.

3 Results
3.1 Multicollinearity analysis
Table 2 presents the results of multi-collinearity analysis of
the twelve FCFs. When VIF > 5 or TOL < 0.1, the factor has
multiple collinearity problems and needs be eliminated.
Table 2 Results of multicollinearity analysis
Conditioning Factor
Tolerance
VIF
Altitude0.3076
3.2514
Aspect0.76211.3125Slope
0.5005
1.9979TRI
0.43052.3224Soil
0.82991.2049LULC
0.90851.1005Dist.River
0.60631.6493Rainfall
0.6474
1.5444
Although altitude had the highest VIF(3.2514) and lowest
TOL(0.3076), neither of these values exceeded the thresholdvalues(5 and 0.1, respectively.) indicating the absence ofmulticollinearity among the eight FCFs. Thus, all eight FCFs
were used in modeling.
3.2 Analyzing the weights derived from each method
The weights of entropy for each FCFs were calculated
based on the aforementioned equations. For an example, thetabulated values of the rain are shown in Table 3. According
to the findings, in the case of altitude, the class intervals of
4–22m, 22-47m, and 47-88 m were found as highly
susceptible regions indicating flood occurs predominantly
in low-altitude areas rather than on mountain tops. Slopeclasses within the range 0º–8.6 º, nearly flat with low
elevation showed higher relationship on flooding. Mainly flat
aspect exhibits the highest effect on flooding. Distances of up
to 150 m from the river had the most significant impact on
flooding. Further, the distance range of 150-300 m also foundto be important indicating long coverage and spread ofalluvial floods over the studied area. Since the type of soil
has an apparent influence on drainage, water storage,
permeability, this factor was used in this study. According to
the results Alluvial soil type had the greatest influence on
flooding. Rainfall is a major trigger in flood formation, andflooding will not occur if this factor is not present. Therefore,
the most significant rainfall classes were found to be ranging
from 3640-3850mm. LULC is a critical component in

The 10th International Symposium on Water Environment Systems

FactorTable 3 IoE calculation result for rainfall weight
No.of
flood
Pij
(Pij)
Hj
Hj maxpixelspoints27810256
0.91260.18841.69
2.32
286992106
1.67390.3455303519139
2.07550.428427338011
0.18240.037627201900.00000.00001414012312
4.84441.0000Class

Rainfall2863-3640
3641-3735
3736-3850
3851-3996
3997-4486

Summation

identifying vulnerable areas prone to floods. According to theresults, waterbodies, homesteads, and paddy classes showed
higher effect on flooding. The friction exerted on the waterflow by the underlying surface is determined by TRI where
lowest classes of 0.9-15, 15-26 were the most significant on
flood occurrence.
Pij of Elevation

Pij of Aspect420-667

Pij of Slope

Pij of TRI

Pij of Distancefrom river
4
3
2
1
0

59.0-86.6

54.0-59.0

50.3-54.0

46.9-50.3

43.6-46.9

39.0-43.6

34.2-39.0

26.1-34.2

0.9-15.0

Wj

Fac_recal2

0.27

0.26

3
4
5
2
0

Table 4 Prediction performance of SVM models based on
validation dataset
Model
Specificity
Sensitivity
Accu.
SVM-rbf0.90980.93980.9286
IoE+SVM-rbf
0.97740.96990.9737
IoE+SVM-poly
0.95490.9474
0.9511
IoE+SVM-sig
0.96990.9474
0.9549IoE+SVM-ln
0.92480.9624
0.9436

Table 4 SCAI values of the flood susceptibility classes
Model
Very Low Mod High
Very
low
erate
High

Pij of Soil
6
5
4
3
2
1
0

Pij of LULC
10.00
8.00
6.00
4.00
2.00
0.00

15.0-26.1

29.1-73.6

23.1-29.1

19.3-23.1

16.1-19.3

13.5-16.1

10.9-13.5

6.3-8.6

8.6-10.9

0-3.7

6.00
5.00
4.00
3.00
2.00
1.00
0.00

3.7-6.3

4.00
3.50
3.00
2.50
2.00
1.50
1.00
0.50
0.00

Ij

According to SVM results, highest sensitivity, specificity,
and accuracy of 96.99%, 97.74% and 97.37% was obtained
for the ensemble IoE and SVM model with RBF kernel,
respectively. Lowest sensitivity, specificity, and accuracy of
93.98%, 90.98% and 92.86% were obtained from standalone
SVM model with RBF kernel. SVM model with Sigmoid
kernel obtained higher accuracy compared to linear andpolynomial kernel models.
To generate the flood susceptibility maps, the floodprobability indices obtained from SVM models has to beclassified into different zones of susceptibility. Natural
breaks classification method which follows the Gauss normal
distribution, was used to classify the probability index into 5
susceptibility classes as low, low, moderate, high, and veryhigh(Fig. 3.).

667-2174294-420222-294

171-222128-171

47-88

88-128

4-22

6.00
5.00
4.00
3.00
2.00
1.00
0.00

22-47

6.00
5.00
4.00
3.00
2.00
1.00
0.00

GP-RSS & SyDE
Tohoku University(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

IoE
SVM-rbf
IoE+SVM-pol
IoE+SVM-rbf
IoE+SVM-sig
IoE+SVM-ln

Pij of Rainfall
2.00

1.50
1.00
0.50
0.00

Fig. 2. Distribution of flood in each factor classes basedon probability density(Pij)
The ensemble method was applied using all four SVM
kernels. Cross validation technique was used to derive kernelparameters. The final step involved the derivation of four
flood probability maps. In addition, another flood probability
map was generated using a stand-alone SVM -RBF kernel.
The individual SVM was performed using the original FCFs,
which were not classified by the IoE results.

80

59.21
250.19148.30283.75151.89
54.74

66.02
9.39
7.47
7.47
6.24
4.69

18.45
10.04
2.78
2.02
4.12
2.41

2.29
1.36
1.07
0.878
1.87
0.98

0.21
0.20
0.19
0.18
0.19
0.19

Lower SCAI values indicate a higher flood susceptibility
and vice versa. This approach is helpful in evaluating theconsistency and effectiveness of the models. SCAI values ofvery high, high, and moderate susceptibility classes were
found to be lower in the ensemble IoE and SVM model withrbf kernel than the other four models. Thus, the IoE and SVM
model with rbf kernel model was found to be the mosteffective model for analyzing flood susceptibility in the studyarea.
To evaluate the reliability of the derived susceptibility
maps, an accuracy assessment was performed using the AUC
method. The AUC results showed that the highest prediction(95.81%) and success (94.82%) rates were achieved by theensemble IoE+SVM (rbf) method. The individual SVM (rbf)and IoE methods produced lower success and prediction ratesas (SVM-rbf:86.17% success rate and 84.90% prediction
rate; IoE: 82.57% success rate and 81.78% prediction rate)
relative to all four ensemble methods. The IoE+SVM (ln)The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDE
Tohoku University

IoE

SVM (rbf)

IoE+SVM (ln)IoE+SVM (poly)

IoE+SVM (rbf)

IoE+SVM (sig)F ig. 3. Flood Susceptibility maps

CUMULATIVE PERCENTAGE OF
FLOOD PIXEL(%)

4 Conclusions

Success Rate

100

A unique ensemble IoE-SVM approach was utilized toevaluate flood susceptibility in the Rathnapura city and its
surrounding, Sri Lanka. Bivariate and multivariate statisticalanalysis performed using IoE and SVM respectively. FourSVM kernels were used to build the ensemble models andtheir impacts were also evaluated. The accuracy of themodels was assessed through ROC curves and SCAI. The
lowest SCAI values were obtained for very high, high andmoderate flood susceptibility classes in the case of ensemble
IoE+SVM(rbf) model. According to AUC results, highest
accuracies were obtained for ensemble IoE+SVM(rbf) modelwith 95.81% and 94.82% for prediction and success rates,
respectively. Lowest accuracies were obtained for theindividual IoE and SVM(rbf) models. It can be concluded
that the integration of the standalone methods improved
their performances. We hope that this research will be useful
to policymakers as a framework for taking proper
measurements in prior identification of flood prone regions
and minimizing the adverse effects of flooding.

IoE(82.57%)
SVM-RBF(86.17%)
IoE_SVM-LN(91.27%)

50

IoE_SVM-POLY(92.57%)

IoE_SVM-SIG(93.10%)
IoE_SVM-RBF(94.82%)

0
0

20

40

60

80

100

PERCENTAGE OF FLOOD SUSCEPTIBILITY INDEX RANK(%)

Prediction Rate

CUMULATIVE PERCENTAGE OF
FLOOD PIXEL(%)

100

IoE(81.78%)
SVM-RBF(84.90%)
IoE_SVM-LN(90.98%)

50

IoE_SVM-POLY(93.87%)
IoE_SVM-SIG(94.40%)

Reference

IoE_SVM-RBF(95.81%)[1] Dano, U., Balogun, A., Matori, A., Wan Yusouf, K.,
Abubakar, I., Said Mohamed, M., Aina, Y. and Pradhan, B.,
Flood Susceptibility Mapping Using GIS-Based Analytic
Network Process: A Case Study of Perlis, Malaysia,
Water,2019, 11(3), p.615.
[2] Constantin, M., Bednarik, M., Jurchescu, M. and Vlaicu,
M., Landslide susceptibility assessment using the bivariate
statistical analysis and the index of entropy in the Sibiciu
Basin (Romania). Environmental Earth Sciences,2010, 63(2),pp.397-406.

0
0

20

40

60

80

100

PERCENTAGE OF FLOOD SUSCEPTIBILITY INDEX RANK(%)

Fig.4.Success and prediction rate curves
model showed lower success and prediction rates as 91.27%
and 90.98% among all ensemble models, respectively. Basedon the obtained accuracies, the integrated IoE and SVM (rbf)technique can be utilized as opposed to the standalone
approaches.

81

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDE
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Understanding drought risk in the coastal region of Bangladesh using
gridded meteorological data
○Sheikh Hefzul Bari1, Noor-E-Ashmaul Husna2 and Yoshiyuki Yokoo1
Graduate School of Symbiotic Systems Science and Technology, Fukushima University , Japan.
2
Bangladesh University of Engineering and Technology, Bangladesh.
*E-mail: shbari.bd@gmail.com.

1

Abstract
The coastal region of Bangladesh is prone to different hydro climatological calamities. Drought has recently beenrecognized as one of them. To understand the long-term drought scenario of this area, we derived SPI (Standardized
Precipitation Index) and RDI (Reconnaissance Drought Index) indices using 100 years of gridded meteorological
data. Drought indices show that the region has experienced moderate to extreme drought in the past. In many cases
time series of indices show a dry and wet cycle. Non-parametric Mann-Kendall test shows statistically significant
trend in annual initial RDI. Which is a climate change indicator for this area. The trend result identifies that grid 5,
6, and 10 (Southwestern part) have a greater tendency of drought.
Keywords: Coastal Bangladesh, Drought, Reconnaissance Drought Index, Climate change, Water security.
1 Introduction
Due to the global climate change effects frequency ofdroughts are likely to increase in recent years. This will also
affect Bangladesh, especially the coastal region. This regionis already susceptible to numerous natural calamities.
Increasing drought events might stress the already existingfood and water security issues. As drought was identified asa barrier to accessing safe drinking water in the southwestern
coastal region [1]. Assessing drought risks, vulnerabilities,
and hazards is crucial to putting mitigation and adaptation
into action to decrease the effects of the drought. Because alack of comprehensive knowledge about drought behavior ina specific region frequently causes difficulties in decisionmaking [2] in the relevant field. Besides, the groundwater
deficit is causing concern due to rising demand. Droughtinduced surface water depletion will hasten groundwater
over-exploitation, particularly during the cropping season.
Also, the growing threat of salinity will impose additional
stress on the existing water resources. The combined effects
pose a serious threat to Integrated Coastal Zone Management(ICZM) approach as well as the Integrated Water Resource
Management (IWRM) approach.

For the coastal region of Bangladesh, the grid centers wereassigned a number ranging from 1 to 12 for convenience(Figure 1).
The Standardized Precipitation Index (SPI) [4] andReconnaissance Drought Index (RDI) [5] were used to assess
the severity of drought occurrence in the study area. The RDI
employs PET (potential evapotranspiration) in addition torainfall, which is expected to improve drought detection
efficiency. The RDI has three forms: initial value ( 𝛼𝑘 ),normalized RDI (RDIn), and standardized RDI (RDIst). The
initial value is aggregated using a monthly time step and canbe calculated monthly, seasonally, or annually. Because theStandardized RDI and SPI perform similarly, the results areinterpreted similarly. The initial form of RDI is equivalent toAridity Index, enabling it to use as a climate change indicator.

2 Materials and methods
The coastal zone of Bangladesh lies within the tropical zone
between 21-23° N and 89-93° E. The area is characterized
by a massive network of rivers, with a large number ofislands among channels where horrendous tropical cyclones
are common [3].
River flow reductions during the dry season have asignificant negative impact on river morphology and salinity
in coastal Bangladesh. Recurring drought events, as well as
reduced flow volume of major rivers, drying of water
channels, and depletion of groundwater tables from overexploitation, exacerbate the area's water crisis, particularly
during the dry season.
Estimation of drought indices requires rainfall andtemperature data. High-resolution 0.5 degree by 0.5 degree
gridded monthly land surface air temperature andprecipitation data from 1910-2010 was collected fromNOAA (National Oceanic and Atmospheric Administration).

82

Fig. 1. Coastal region of Bangladesh.
PET was estimated using Thornthwaite method [5,6]. Nonparametric Mann-Kendall [7] test was used to identify thetrend. While spatial distribution of Mann-Kendall Z scoresand severe drought events were computed using Empirical
Bayesian Kriging (EBK) in ArcGIS.

3 Results and discussion
The annual SPI and RDI data reveal a wet cycle. For
example, grid twelve RDI time series, which includes major

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
flood and drought events (Figure 2). Similar cycles wereobserved using the 6-month SPI and RDI although there aresome interruptions in the cycle where the SPI and RDI values
approach zero or became negative for a short time. The
indices respond more slowly to short-term precipitation
variation as the time scale increases from six to twelve
months, and cycles of positive or negative values become
more visible. Several flood events occurred during the cycleof positive SPI and RDI values, while this area wasexperiencing a long-wet period. Following the wet period, along dry period influences agricultural production.
Several noticeable drought events occurred during the cycleof negative SPI and RDI values. The sharper negative
inclination of RDI12 compared to SPI12 reveal a possible
increasing trend of temperature in this area. Based on theoverall analysis of SPI and RDI, grid six (the Southwesternpart) was identified as the most vulnerable.
The occurrence of the negative indices value displays that theregion has suffered from comparatively more serious drought
in recent times than that in the past years. Analyzing the timeseries plot of the drought indices, four major droughts and at
least twenty moderate drought events were detected.
It was discovered that the frequency of negative SPI and RDI
values is relatively low at grid eight. This could be interpreted
based on where it is. For the time being, this region is lesssusceptible to meteorological drought risk. Overexploitationand sea level rise, on the other hand, makes it vulnerable tosafe drinking water access.
RDI was found more sensitive to drought events while SPI
were to flood event. This slightly better performance of RDI
could be the use of evapotranspiration in RDI index
calculation. Therefore, using RMSE, the relative
performance of SPI and RDI were calculated. The results
were satisfactory. RMSE was calculated between RDI and
SPI by using the following equation:
𝑅𝑀𝑆𝐸 = √2∑𝑁𝑖=1(𝑅𝐷𝐼𝑖 − 𝑆𝑃𝐼𝑖 )𝑁

GP-RSS & SyDE
Tohoku University

Fig. 2. Annual RDI series at grid 12 with 3year moving average. The X-axis denotes thehydrologic year (1910 denotes 1910-11hydrologic year and so on).
In general, this study has shown that most of the coastal
areas were affected by drought but the severity andoccurrence of this phenomenon are greater in the western
coastal part, especially at grid five and six. Therefore, future
research on these regions should be prioritized to improve thewater resource management and development programs andto resolve the socio-economic and agricultural problems
faced by the people in this part of the country.
In general, the SPI and RDI series show almost similar
results. But in some cases, RDI was found more sensitive tothe dry period and SPI was found more sensitive to the wet
period. The SPI is a widely used drought monitoring index.
Mainly, due to its fewer data requirements. However,meteorological drought depends not only on rainfall but also
depends on evapotranspiration, temperature, and otherclimatic parameters. On this basis, the RDI could be a
promising alternative to best represent the drought scenario.
It is seen that drought severity is increasing in the coastal areaof Bangladesh. Apart from the impacts that drought can
impose on natural resources and the environment, hugeeconomic losses are likely to happen. To overcome thedrought effects comprehensive and coordinated planningshould be taken.

Reference

Here, N= Length of each SPI or RDI time scales.
Trend analysis of the dry six months (October - March) RDI
series exhibited a negative trend except at grid twelve. Only
grid twelve showed an increasing trend. In contrast, trend
analysis of the annual RDI series showed a significant
negative trend at all grids except grid eight. From both the six
months and annual RDI trend analysis results, we canconclude that there is an overall annual moisture deficiency.

4 Conclusions
The goal of this study was to present an analysis of thecharacteristics and recurrence of droughts in the coastal
region of Bangladesh. According to the findings, thesouthwestern coastal zone is more vulnerable to drought. The
Mann-Kendall trend test showed a significant negative trendinterpreting possible increment of drought phenomenon in
the future and possible climate change.

83[1]. Abedin, M.A., Habiba, U., Shaw (Eds), R., Water
Insecurity: A Social Dilemma. Emerald Group Publishing,
2013.
[2]. Mishra, a. K., Desai, V.R., Drought forecasting using
stochastic models, Stoch. Environ. Res. Risk Assess. 19(2005), 326–339.
[3]. Alam, E., Collins, A.E., Cyclone disaster vulnerability
and response experiences in coastal Bangladesh, Disasters,
34(2010), 931–954.
[4]. Mckee, T.B., Doesken, N.J., Kleist, J., The relationshipof drought frequency and duration to time scales, 1993, 17–22.
[5]. Vangelis, H., Tigkas, D., Tsakiris, G., The effect of PET
method on Reconnaissance Drought Index (RDI) calculation,
J. Arid Environ. 88(2013), 130–140.
[6]. Thornthwaite, C.W.,An Approach toward a Rational
Classification of Climate, Geogr. Rev. 38 (1948), 55–94.
[7]. Mann, H.B., Nonparametric tests against trend, Econ. J.
Econ. Soc. 13(1945), 245–259.

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

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POTENTIAL OF IRRIGATION RESERVOIRS FOR FLOOD PREVENTION
AND EVALUATION OF THE REDUCTION RATE OF FLOOD DAMAGE
COST FOR EACH PREFECTURE○ Atsuya IKEMOTO1*, So KAZAMA1, Takeo YOSHIDA2, Hayata YANAGIHARA1
and Yoshiya TOUGE1

1

Department of Civil and Environmental Engineering, Graduate of School of Engineering, Tohoku
University, Miyagi 980-8579, Japan.
*
E-mail: ikemoto.atsuya.s1@dc.tohoku.ac.jp
2 National Agriculture and Food Research Organization
3 Water Resources Research Center, Disaster Prevention Research Institute, Kyoto University

Abstract
In order to grasp the potential flood prevention of the irrigation reservoir, the flood inundation model was performed
for the whole of Japan assuming that the maximum reservoir capacity can work. In addition, the rate of change ininundation depth with and without reservoirs was calculated. The results suggest that effectiveness of flood control
using by reservoir is expected in Kagawa, Hyogo, Osaka, Hiroshima and Saga. In addition, effectiveness of flood
control using by reservoir is not expected in Kanto region.
Key Words: flooding, flood inundation analysis, reservoir
1 Introduction
In Japan, water control focus on each water system. The
river basin management[1] is finalized river plannning,rainwater storage and infiltration facilities, landuse
regulation and forecasting to prior release in dams. The
project uphold utilization of agricultural land, facilities for
agriculture;patty field, reservoir is upholded. Storage ofrainwater and floodwater on agricultural land and facilities
for agriculture is expected to reduce flooding disaster. To
help water control which is expected to utilize agriculturalland and facilities for agriculture, flood damage mitigation
effect using agricultural land and facilities for agricultureneeds to be measured. Tanakamaru et al.[2] and Yoshisako etal.[3] studied the flood control effectiveness of reservoirs in
Hyogo and Hiroshima prefectures. However, studies
evaluating the effect of reservoir utilization on flood damage
reduction across Japan are rare. The purpose of this study is
to examine the effectiveness of the use of reservoirs in Japanin reducing the damage caused by flood inundation. Floodinundation analysis is conducted considering the reservoir
capacity to achieve the purpose. The study focusedparticularly on areas with large changes in inundation depth.

2 Materials and methods
The rainfall data which is used for flood inundation analysis
in this study is the stochastic flood-contributing distributionof fifth-order made by Yamamoto et al[4]. A two-dimensional
unsteady flow model[5] in Cartesian Coordinate System isused for flood inundation analysis, which has been appliedand shown to be valid for the Naruse River basin, which wasseverely damaged by the East Japan Typhoon 2019 [6].
The inundation analysis is conducted for gamut in Japan at
a time. The two-dimensional unsteady model is uniformly
applied to river and floodplain. The mesh size is fifth-order.
The inundation analysis is conducted on condition thatrainfall-intensity of the stochastic flood-contributing
distribution is steady for 24 hours. The resistance of house is84

taken in account by assuming that house area is not gotten
flooded in the two dimensional model. The value of Manningcoefficient is same as Yamamoto et al. [7]. The proportion ofhouse in each cell is calculated in the same way as
Yanagihara et al.[6]. The proportion of Land for building use
is 0.411. Other parameter values in analysis are same asprevious researches. When the analysis is conducted by using
elevation data of fifth-order mesh, occurence of unlikely
inundation as real phenomenon in dip is noted. Dips are
removed by in the same way as Yanagihara et al. [6].
Tanaka et al. [8] established the level of flood control safety
for each river section by mapping the planned scale of thewater system to the data of the type of manager of the river
section. Tanaka et al. [8] used data which is about the planned
scale of the water system and the type of the river section todecide the level of flood control safety for each river. The
assigned flood control safety level is reflected by calculating
excavation depth at which a flood of that scale can be safely
discharged each river section. The excavation depth iscalculated by inundation analysis. The level of flood control
safety is assumed to be 50% of the planned level of flood
control maintenance, because the flood control structures arein the middle of improving in Japan. In this study, method
which is improved is applied the inundation analysis. The
way of improved is following. The manager of the river
section was allocated by using order stream of Strahler in thisstudy. Connection order stream of Strahler and the data of thetype of manager of the river section was decided that is
consistent with the type of manager of the river section in
Digital National Land Information[9] for every first-classriver and second-class river. The level of flood control safety
for each river section was allocated as previous studies[7],[8].
The reservoir data in Japan is provided by National
Agriculture and Food Research Organization. Someirrigation dams are not listed in the reservoir data in Japan.
So the irrigation dams are added to reservoir data in Japan
from the dam data(W01-05) in 2014 Digital National Land

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

1.0

1.0

0.0

0.0

Fig.1 Rate of inundation depth change ( Hokkaido )GP-RSS & SyDE
Tohoku University

Fig.2 Rate of inundation depth change (Tohoku, Niigata )

1.0

1.0

0.0

0.0

Fig.3 Rate of inundation depth change( Kanto, Chubu, Kinki )Fig.4 Rate of inundation depth change( Chugoku, Shikoku, Kyushu, Okinawa )図 4 中国・四国地方，九州地方，沖縄県の浸水深のInformation[9]. The dam data stored in the Digital National
Land Information download services.

expected in Kanto region. This study intend in the future toconsider water system basis and municipality basis.

3 Results and discussion

ReferenceIn this study, the inundation analysis is conducted thatsimulates damage due to the 200 year return period. The
analysis is conducted that considers reservoir capacity or not.
After analyzing, rate of inundation depth change is calculatedby the following equation.
r = D / Dres（1）
where r is rate of inundation depth change, D is inundation
depth which does not consider reservoir capacity, Dres isinundation depth which considers reservoir capacity. The rateof inundation depth change is shown in Fig.1, Fig.2, Fig.3,
and Fig.4. The size of rate of inundation depth is white toblack gradient. Fig.1, Fig.2, Fig.3 and Fig.4 shows that areas
which have big rate of inundation depth change distributenear estuary. This indicates that reservoir capacity andreservoir distribution mainly affect downstream. In addition,
prefectures such as Kagawa, Hyogo, Osaka, Hiroshima andSaga are distributed a lot of big rates of inundation depthchange. In these prefectures, effectiveness of flood control
using by reservoir is expected. The other, the distributions
areas that big rates of inundation depth change are small in
Kanto region, such as Kanagawa, Tokyo, Tochigi, Ibaraki,
Gunma, Saitama. This suggests that effectiveness of flood
control using by reservoir is not expected in Kanto region.

[1]

4 Conclusions
The purpose of this study is to examine the effectiveness of
the use of reservoirs in Japan in reducing the damage causedby flood inundation. The results suggest that effectiveness offlood control using by reservoir is expected in Kagawa,
Hyogo, Osaka, Hiroshima and Saga. In addition,effectiveness of flood control using by reservoir is not

85

[2]

[3]

[4]

[5]

[6]

[7]

[8]

[9]

Council for Social Infrastructure Development: Waterrelated Disaster Countermeasures in Light of Climate
Change: Shift to Sustainable "Basin Flood Control" to be
Carried Out by All Stakeholders throughout the Basin
Report, 2020.
Tanakamaru, H. et al.: Simple estimation method of flood
mitigation effect of irrigation ponds, IRRIGATION,DRAINAGE
AND
RURAL
ENGINEERINGJOURNAL, Vol. 88,No. 9,pp.23-26,2020.
Yoshisako, H. et al.: Flood Peak Mitigation Effects by
Irrigation Ponds Group of Valley type in the Mukunashi
River
Valley,Hiroshima
Prefecture,
Japan,IRRIGATION,DRAINAGE
AND
RURAL
ENGINEERING JOURNAL, Vol. 81,No.3,pp.205214,2013.
Yamamoto, T. et al. : Evaluation of flood damage
reduction through-out Japan from adaptation measurestaken under a range of emissions mitigation scenarios,
Climatic Change, Vol.165, Article number: 60, 2020.
Machida, S. et al. : EVALUATION OF FLOODDAMAGES FOR CLIMAIE CHANGE, Proceedings of
the Symposium of Global Environment, Vol. 15,pp. 155160,2007.
Yanagihara, H. et al. : CHANGES IN FLOODDAMAGE THROUGHOUT JAPAN DUE TO
CLIMATE CHANGE AND LAND-USE CHANGE
USING SHARED SOCIOECONOMIC PATHWAYS,
Journal of Japan Society of Civil Engineers, Ser. G(Environmental Research), Vol. 77,No. 5,pp. I_33I_42,2021.
Yamamoto, T. et al. : Estimation of the mitigation and thelanduse control for climate change based on the flood
analysis in Japan, Journal of Japan Society of Civil
Engineers, Ser. G (Environmental Research),Vol. 76,No.
5,pp.I_141-I_150,2020.
Tanaka, Y. et al. : Assessment of the risk on flood andstorm surge with flood control facilities. J Jpn Soc Civ
Eng Ser B1 (Hydraul Eng) 75(2):I_109–I_114 (inJapanese).
Ministry of Land, Infrastructure, Transport and Tourism(MLIT) (n.d.-b) Digital National Land Information
download services : https://nlftp.mlit.go.jp/ksj/ Accessed
22 Oct 2020.

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

GP-RSS & SyDE
Tohoku University

The Survey of Extreme Flood Events in The Downstream Area of
Citarum Watershed, Indonesia as Preliminary Study of Hazard
Assessment and Socio-hydrology Approach○ Muthiah SADIDAH1* & Daisuke KOMORI1,2
1Graduate School of Environmental Studies, Tohoku University, Miyagi 980-8579, Japan.
2Department of Civil Engineering, Tohoku University, Miyagi 980-8579, Japan.
*

E-mail: muthiah.sadidah.t2@dc.tohoku.ac.jp

Abstract
Citarum River, the longest river in West Java, is one of the most strategic rivers yet one of the most flood-pronerivers throughout history. Based on National Agency for Disaster Countermeasure of Indonesia (BNPB), Karawang
regency is the most flooding-prone area in Citarum watershed with the highest number of flood events compared tothe upper areas. This research aims to prepare data of socio-hydrology study by analysing three extreme events inthe target area which occurred in 2013, 2014 and 2021. The human-flood interaction is assessed in the target areaby discussing societal vulnerability and exposure to flood risk. The study of the interplay between social andphysical processes is conducted based on 2007 until 2014 precipitation data from Yanto et al., 2017 and damages
data reported by local News. The result shows that there is a sign of “adaptation effect” in the study area. This result
supported the existence of the dynamics of human-flood system in the target area. This research hopefully will beable to be a starting point of the further study of flood hazard and socio-hydrological assessment in Citarum
Watershed.
Keywords: Flood; Human-flood; Adaptation-effect; System dynamic; Socio-hydrology; Hazard
1 Introduction
The International Disaster Database reported that in the last
21 years, flood is the major disaster event in The World withtotal 3656 events. The situation appears to get worse related
to the facts that rapid urbanization continues to increase thenumber of people living in floodplains and flood levels mightrise up due to climate change [Hinkel et al., 2014; Jongman
et al., 2014]. Reviewing 20 years of NASA satellite data,
researchers discovered that between 58 and 86 million more
people might be found residing in floodplains worldwide
between the years 2000 and 2015. During that time, major
floods had an impact on more than 255 million individuals atleast once [Tellman et al., 2021].
The interaction between social and physical processes stilllacks a fundamental understanding while there has been a lotof studies assessing flood risks quantitively. Consequently,
the dynamics emerging from this interaction cannot be well
explained by the current analytical frameworks [DiBaldassare et al., 2015]. Seeking to achieve greater insights
into causal relationships within human-water systems,
process socio-hydrology employs nonlinear, organic thinking(i.e., systems thinking; Sivapalan et al., 2012). System
dynamics (SD), a branch of systems thinking (Ford, 1999),
was introduced by Forrester (1961) to support studies related
to representing complex systems and analyzing theirdynamic behavior (Hjorth and Bagheri, 2006).
“Adaptation effect” is a first type dynamics discussed in thisresearch, which is associated with the relationship between
the frequency of flood events and societal vulnerability. This
term explains that the more frequent flooding happens themore decreasing the societal vulnerability is. Based on an
empirical study, the impacts resulted by flood are decreasing
while there was a similiar event happened not long before [DiBaldassare et al., 2015]. For example, despite having similar86

magnitudes, the 1995 Meuse River flood caused substantiallyless damage than the one in 1993 [Wind et al., 1999].
A second type of dynamics is “levee effect” which is
explained by a decrease in risk awareness when flooding
becomes less frequent because of the introduction (orreinforcement) of structural protection measures (White,1945). A previous study explained that increasing the levelsof flood protection can generate a sense of satisfaction amongprotected people, which can reduce preparedness, thereby
increasing vulnerability (Tobin, 1995). An example of levee
effect was described in the case of New Orleans (1930’s2005), where the construction and raising of levees caused
frequent, minor flooding to become infrequent but
catastrophic disasters [Kates et al., 2006].
The aforementioned two types of dynamics arises from theinteraction between physical and social processes which havebeen considerably studied in many floodplains around theworld. Nevertheless, conventional methods are not able tocorrectly explain these dynamics. For instance, the current
methods would logically imply that flood-rich periods would
result in more flood damage. However, the adaptation effect(the case of 1995 Meuse River flood) that has been explained
before shows that this is not always the case. Anotherexample, current research consistently indicates that putting
flood prevention systems in place would result in less flood
damage but the levee effect explains (such as the case of New
Orleans happened in 1930’s-2005 explained before) that thisis not necessarily the case [Di Baldassare et al., 2015]. Sociohydrological modeling is a tool to explore and to have better
understanding in the dynamics of human-flood system
explained before hence our ability to interpret flood riskchanges over time can be improved thereby better policies
and measures that will decrease the negative impacts offloods can be developed [Di Baldassare et al., 2013].

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
This research is a part of socio-hydrology study which aims
to prepare data of socio-hydrology study by pairing up eventsin the target area to examine the hazards and exposure
resulted. Pairing up events is important for sociohydrolocical study as it helps gain better understanding ofinteraction and feedback mechanism between hydrologicaland social processes in the target area.

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Measures have been taken to reduce the risk over theintervening period.
Besides maximum precipitation. The probability of riverdischarge is one of the typical indicators of the scale of riverflooding. However, due to data limitation, the analysis using
river discharge will be employed in the further discussion.

2 Materials and methods
This research surveyed extreme flood events in 2013, 2014
and 2021 in Karawang regency, West Java, Indonesia. This
area was chosen based on the database of The National
Agency for Disaster Countermeasure of Indonesia (BNPB)
and Citarum official website. Based on the data, the total
number of flood events in Karawang from 1980 until 2021 is
at least twice as much as the number in upper regencies.
Hazard assessment of this research is supported by gauge
observation data of daily gridded precipitation from 1985
until 2014 over Java Island, including West Java sourced
from Yanto et al., 2017. On the other hand, human-floodinteractions are assessed in respect to exposure such as thenumber of victims and vulnerability such as the preparednessof the nearby society.

3 Results and discussion(1) The transition of flood hazard and flood exposure
N/A N/A

Fig. 2. Karawang Flood Victims 2007-2021
As it can be seen in Figure 2 the flood events happened in2013, 2014 and 2021 resulted great damages of 66,746;
185,000 and 52,527 victims, respectively. The damages aremuch higher compared to those in other years. Hence, thesethree flood events are considered extreme cases within the
study period in Karawang.
As shown in Figure 3, the annual maximum daily
precipitation in Karawang from 2007 until 2014 depicts afluctuative trend with the highest value occurred in 2014.
As it can be seen, the extreme cases discussed using Figure
2 are supported by hazards shown in Figure 3. The maximum
daily precipitation of 2013 and 2014 is higher than that inother years which is around 45 mm and 51 mm, respectively.
However, due to data limitation from Yanto et al.,2017 thedata of 2021 precipitation was gathered from Kompas news,
it is reported that the daily rainfall in 2021 at least reached 50
mm. These facts conclude that the hazards data of 2013, 2014
and 2021 support the extreme flood cases shown in Figure 2.
Figure 4 depicts the return periods based on maximum daily
precipitation calculated using Log Normal distribution.
Based on this figure, the extremes cases of 2013, 2014 and2021 in Karawang with the value of rainfall hazards 45 mm,
51 mm, and 50 mm have the estimated magnitude of floods
in terms of return periods of 4, 6, 8 return periods respectively.

87

Fig. 3. Annual maximum daily
precipitation in Karawang

Fig. 4. Return Periods(2) Extreme events comparison
The flood events that happened in 2013, 2014 and 2021
resulted in great damages of 66,746; 185,000 and 52,527
victims, respectively. The damages are much higher hence
these three flood events are considered extreme cases within
the study period in Karawang.
As it is shown in Figure 2 the damages of the 2021 flood in
Karawang were much lower than those in 2013 and 2014
even though their magnitudes do not show great difference.
This condition may consider “adaptation effect” which
relates to the observation that the occurrence of more
frequent flooding is often associated with decreasing societal
vulnerability. The effect we can see in Figure 2 is there is apossibility that explains that the experience of floods in 20132014 and every year after may have reduced flood damages
in 2021. This condition might have happened due to theincrease of preparedness such as evolving early warning
system, fixing emergency management and so on. The
increasing preparedness is what really happened in Karawang
as it is reported by Regional Disaster Management Agencyof Karawang regency (BPBD) that in 2019 they has installed
an early warning system tool that is directly connected to thedisaster warning alarm at the BPBD office. So that thehandling of disaster preparedness can be directly handled by
the officers.

4 Conclusions
The estimation of the dynamics which comes from theinteraction between human and flood has been applied in
Karawang regency, West Java, Indonesia. The result showsthat there is a sign of “adaptation effect” in the study area.
“Adaptation-effect” is one type of system-dynamic arisingfrom human-flood interaction. As it is stated by Baldassare
et al., 2013, interaction and feedback mechanism betweenhydrological and social processes in the floodplain area iscomplex. Therefore, it is needed to conseptualise humanflood interactions through socio-hydrological modeling. The
role of this model is to be a tool to explore possible future
trajectories of flood risk so that the government andstakeholders can improve policies and measures that will
decrease the negative impact of flood hazard itself.

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
Reference[1] Di Baldassarre, G., Viglione, A., Carr, G., Kuil, L.,
Salinas, J.L. and Blöschl, G., 2013. Socio-hydrology:
conceptualising human-flood interactions. Hydrology and
Earth System Sciences, 17(8), pp.3295-3303.
[2] Di Baldassarre, G., Viglione, A., Carr, G., Kuil, L., Yan,
K., Brandimarte, L. and Blöschl, G., 2015. Debates—
Perspectives on socio‐hydrology: Capturing feedbacks
between physical and social processes. Water Resources
Research, 51(6), pp.4770-4781.
[3] Hinkel, J., D. Lincke, A. T. Vafeidis, M. Perrette, R. J.
Nicholls, R. S. J. Tol, B. Marzeion, X. Fettweis, C. Ionescu,
and A. Levermann (2014), Coastal flood damage andadaptation costs under 21st century sea-level rise, Proc. Natl.
Acad. Sci. U. S. A., 111(9), 3292–3297, doi:10.1073/
pnas.1222469111.
[4] Hjorth, P. and Bagheri, A., 2006. Navigating towards
sustainable
development:Asystemdynamics
approach. Futures, 38(1), pp.74-92.
[5] J. Forrester. 1961. Industrial Dynamics The MIT
Press, Cambridge, MA and Wiley, New York.
[6] Kates, R. W., C. E. Colten, S. Laska, and S. P.
Leatherman (2006), Reconstruction of New Orleans after
Hurricane Katrina: A research perspec tive, Proc. Natl.
Acad. Sci. U. S. A., 103(40), 14,653–14,660,
doi:10.1073/pnas.0605726103.
[7] Livneh, B. and Rajagopalan, B., 2017. Development ofa gridded meteorological dataset over Java island, Indonesia
1985–2014. Scientific data, 4(1), pp.1-10.
[8] Sivapalan, M., Savenije, H.H. and Blöschl, G., 2012.
Socio-hydrology: A new science of people and water. Hydrol.
Process, 26(8), pp.1270-1276.
[9] Sukowati, K.A.D. and Kusratmoko, E., 2019, August.
Analysis of the distribution of flood area in Karawang
Regency using SAR Sentinel 1A image. In IOP Conference
Series: Earth and Environmental Science (Vol. 311, No. 1, p.
012085). IOP Publishing.
[10] Tobin GA (1995) The levee love affair: a stormy
relationship?
Water
ResourBull
31:359–367.
https://doi.org/10.1111/j.1752-1688. 1995.tb04025.x[11] White, G. F.: Human Adjustments to Floods,
Department of Geography Research, Paper no. 20, 29, The
University of Chicago, Chicago, 1945.
[12] Wind, H. G., T. M. Nierop, C. J. de Blois, and J. L. de
Kok (1999), Analysis of flood damages from the 1993 and1995 Meuse Floods, Water Resour. Res., 35(11), 3459–3465,
doi:10.1029/1999WR900192. Levermann (2014), Coastal
flood damage and adaptation costs under 21st century sealevel rise, Proc. Natl. Acad. Sci. U. S. A., 111(9), 3292–3297,
doi:10.1073/ pnas.1222469111.

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The 10th International Symposium on Water Environment Systems

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(Dec. 8th ~ 9th , 2022)

Tohoku University----- from the Perspective of Global Safety

Evaluation on high-altitude snow observation for snowmelt flood
forecasting○ Shoichi KUROSAWA1･2* & So KAZAMA1
1

Department of Civil Engineering, Graduate School of Engineering, Tohoku University, Miyagi 980 -8579,
Japan.
2 Mitsui Consultants Co., Ltd, Tokyo 141-0032, Japan.
*
E-mail: kurosawa@mccnet.co.jp
Abstract
In order to contribute to flood prevention activities and damage minimization against flood disasters exceeding theplanned scale, provision of more accurate flood forecast information is required. This includes not only summer
floods caused by rainfall, but also snowmelt floods in early spring. This paper presents the results of a study to
improve the accuracy of flood forecasting by observing snow cover at high altitudes, taking the Yoneshiro River as
an example.
Keywords: Flood forecast; Snowmelt flood; Snow depth observation; Snow depth gauge; Snowmelt model.

In recent years, in order to contribute to flood prevention
activities and damage minimization against flood disasters
exceeding the planned scale, provision of more accurate
flood forecast information is required. However, many flood
forecasting systems currently in operation target summer
floods caused by rainfall, and the problem is that they cannot
be applied to snowmelt floods in early spring. For this reason,snow observations were carried out at high altitudes so thatfloods including snowmelt floods can be predicted
throughout the year, and using those values, accuracy
improvement was studied using the flood forecasting model.
In this paper, the Yoneshiro River was used as an example.
Yoneshiro River is a river with a catchment area of 4,100 km2,
which originates from Mt. Nakadake located on the border of
Akita, Aomori, and Iwate prefectures, flows through thenorthern part of Akita prefecture from east to west, andempties into the Sea of Japan. (Fig. 1)

2 Implementation of snow depth observation
A snow depth gauge was installed at Mt. Moriyoshi Ani Ski
Resort (1,167m above sea level) (November 2017). In
addition, since the ski resort is famous for frost-covered trees(Japan's top three frost-covered trees), a Teflon-coated snow
depth gauge sensor was manufactured, and countermeasuresagainst low temperature such as use of an observationequipment that can withstand temperatures of up to -25°C
and heating equipment were implemented. The initial statusof the observation is shown in Fig. 2, Fig. 3. In early February,
the sensor part became covered in frost and some missing
data were confirmed, but observation has been consistentsince early March. (Fig. 2, Fig. 3)

snow was observed at Ani ski resort, and the snow melted on
May 11, one month later than the observed value at low
altitude, showing a clear difference between the two. From
this situation, it was judged appropriate to use the snow depth
observation value at high altitudes, for snowmelt flood
forecasting. (Fig. 4)

AomoriYoneshiro River●Ski resort

89←The sensor
part is in astate of a
frost-covered
tree.

Fig. 1. Location Map ofYoneshiro River.

Fig. 2. Photos of the sensor. Top: At the beginning of
the snowfall, Bottom: Early February.
300

200

100

Ski resort
Missing
max=248cm
data↓
Missing data↓↓↓

0
11/22 12/22 1/21 2/20 3/22
Fig. 3. Ski Resort Observation Values(November 2017 to March 2018).

3 Snow depth observation results
Snow observation of the Yoneshiro River is carried out by
the Japan Meteorological Agency AMeDAS at low altitudes.
According to the annual AMeDAS snow depth data, snow
melting begins at low altitudes around mid-March, and tends
to melt at all the low altitude AMeDAS around early April.
Comparing the ski resort (elevation 1,167m) and Aniai(elevation 120m) from March to May 2018, the snow at Aniai
disappeared on April 6, but at this point, about 150 cm of

Iwate

Akita

snow depth (cm)1 Introduction

4 Reproduction results of the flood forecastingmodel
The basic runoff model is the distributed runoff model inwhich kinematic wave method is applied to the groundThe 10th International Symposium on Water Environment Systems

GP-RSS & SyDE

(Dec. 8th ~ 9th , 2022)

Tohoku University----- from the Perspective of Global Safety
surface and Darcy's law is applied to the underground layer,
so that the permeation process of rainfall and snowmelt canbe expressed.

A result has been obtained that the reproducibility of riverdischarge will improve by building a snowmelt model basedon high-altitude observation values. The reason for this is thatthe snow cover distribution (snowmelt amount) thatremained in the mountains could be roughly reproduced.
On the other hand, new observation issues have emerged,
such as data delivery delays even after maintenance andinspection, due to deterioration of the equipment installed
and severe situation where the sensor part was covered with
frost.
Until 2019, the observation equipment consisted of (1)sensor unit, (2) data logger, (3) communication unit, and (4)battery.
In particular, it has been determined that the data delivery
delay was caused by the communication unit, so the datalogger and communication unit have been updated to an
integrated type. Before the update, the data logger and thecommunication unit operated separately, and the two devices
were connected using a USB connector, so it is possible thatthey were affected by the outside air (temperature drop), andstable operation can be expected after the device update. (Fig.
6, Fig. 7)

Fig. 4. High and low altitude observations (2018).
In addition, the amount of snowmelt on the base was set at
2.0mm/day, and the amount of snowmelt on the surface wasdetermined by the degree hour method, and was assigned toeach 1km mesh of the distributed runoff model. The
following is the formula for calculating the amount ofsnowmelt. In addition, as a method of correcting the snow
observation data (density difference), correction of theamount of snow water (assimilation method [1] [2]) was
incorporated.
〇SM＝K×T＋2.0/24
T: hourly average temperature (℃)
K: snowmelt coefficient (mm/℃･hr).
The snowmelt coefficient K was set to a constant value
during the snow cover period, and was set so as to coincidewith the AMeDAS (Aniai) snowmelt day in the basin. In
addition, the air temperature was corrected against altitudewith a temperature lapse rate of 0.006°C/m.
As the model reproduction result, the river discharge wascompared with each observed value. Originally, thereproducibility of flood forecasting is confirmed by riverwater level, but in order to include the influence of snowmelt
in the evaluation, the river flow rate at Junisho where theoutflow area is prominent was compared with the observed
value. (Fig.5)
As a result, although the snowmelt discharge could not be
reproduced due to the lack of flow volume in the calculationthat did not consider the amount of snowmelt, it was possible
to reproduce the peak water level etc. by considering theamount of snowmelt, and it was judged that the snowmelt
model was generally appropriate.
Junishoachievement

No model (calculated)

↑↑

↑↑↑

Fig. 6. Equipment configuration (until 2019).

Fig. 7. Updated equipment configuration (from 2020).

6 Conclusions

With model (calculation)

350
300

250
200
150

100
50

5/1

4/28

4/25

4/22

4/19

4/16

4/7

4/4

4/1

4/13

the effect of the model

0

4/10

river discharge （ｍ3／ｓ）

400

Fig. 5. Reproduction results of river discharge (Junisho).

5 Results and discussion90

It has been concluded that the reproducibility of the riverdischarge will improve by using the observed value of the ski
resort and combining it with the snowmelt model and the
distributed runoff model. For this reason, stable observationis also important, and we believe that it is necessary to takecountermeasures against missing measurements by covering
the entire sensor with a windbreak plate that takes into
account the direction of the wind.

Reference[1] 柏俊輔，朝岡良浩，風間聡， 積雪深データ同化による融雪出水解析，水工学論文集，55，2011.
[2]風間聡，広域における積雪全層密度推定に関する研究,水工学論文集，41，1997.

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety

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Satellite and UAV derived vegetative roughness in Nanakita river: caseof Typhoon Hagibis○ Andre FORTES1*, Masakazu HASHIMOTO2 & Keiko UDO1
1

Department of Civil and Environmental Engineering, Tohoku University, Miyagi 980-0845, Japan.
International Research Institute of Disaster Science, Tohoku University, Miyagi 980-8572, Japan.
*E-mail: andre.araujo.fortes.p6@dc.tohoku.ac.jp

2

Abstract
Typhoon Hagibis hit Japan on October 12, 2019, causing severe floods. Hydraulic models are powerful tools forflood control strategies but depend on several input parameters. With the riparian vegetation strongly related to the
Manning roughness coefficient in these areas, many studies aim to quantify the effect. Remote sensing techniques
facilitated the acquisition of vegetation parameters, which enabled hydraulic models that adopt a dynamic Manningvalue that better represents the vegetation relationship with roughness. The objective of this study is to recreate thetyphoon event with a dynamic Manning model that considers the vegetation parameters to calculate the roughness.
The dynamic approach presented more accurate results when compared to the traditional static approach. The results
suggest that the proposed dynamic Manning model can be a powerful tool for river management, capable ofaccurately representing the vegetation effect on flow dynamics.
Keywords: Flood modeling; Manning’s coefficient; Remote sensing; Vegetative roughness; Typhoon 19.
1 Introduction
On October 12, 2019, typhoon Hagibis hit Japan, causing
flood in many rivers in the territory [1]. To protect the
population and mitigate the damage of the floods, rivermanagement uses hydraulic models for flood control
strategies. But these models have a dependency on uncertain
parameters like the Manning roughness coefficient.
The Manning value depends on a variety of factors [2], andamong all factors, vegetation is the primary determinant of
the roughness value [3]. Many studies have related thevegetation parameters with the roughness in different flow
conditions, relating the friction factor with the vegetation
density expressed by the leaf area index (LAI) when thevegetation is emergent [4], and relating the roughness to thedegree of submergence of the plants, which is defined by theratio of water depth over the plant height, in submerged
vegetation scenario [5].
Studies that implement roughness as a dynamic variable
related to vegetation are important but acquiring detailed
vegetation parameters in large areas is a difficult task.
Vegetation identification and parameters acquisition
became possible with remote sensing techniques from UAV
and satellite imagery. Parameters like the canopy height havebeen obtained by combining machine learning techniqueswith UAV imagery [6] while other parameters, like the LAI,
with satellite images [7].

Fig. 1. Study area.

91

The study area of this study is a 2 km stretch of the Nanakita
river, a class B river with 45 km of length in total and acatchment area of 229 km2. Figure 1 shows the 2 km stretch
location inside the river catchment area.
The objective of this study is to recreate the typhoon eventin the 2 km stretch using a dynamic roughness model thatuses both the vegetation height and the LAI to calculate theManning value.

2 Materials and methods
The typhoon event was recreated using a 2D unsteadyhydraulic model that uses continuity and momentum
equations as governing equations [8]. The input parameters
are the topography, the upstream discharge and the Manningvalues in channel and floodplain.
The topography digital elevation model (DEM) was createdwith 10 m resolution by interpolating 21 cross sections
provided by the Miyagi prefecture. The discharge used in the
upstream of the stretch was obtained with RRI model [9].
Three simulations were performed to recreate the event. A
static model (SM) was performed with Manning values of
0.022 and 0.038 for channel and floodplains, respectively.
For the other two simulations, a subroutine to calculate theManning in the vegetated grid cells was created. The
Manning calculation was done in the submerged state ofvegetation using the degree of submergence relationship withthe roughness found in [10]. The data was used to create aformula with regression analysis, shown in Eq. (1).
(1)
𝑛 = 0.084 ∗ (𝑆𝐷)−0.98 + 0.023
Where n is the Manning coefficient and SD is the degree ofsubmergence of the vegetation.
In the emergent state, Darcy-Weisbach friction factor was
calculated based on the LAI value in the grid cell with theformula proposed by Järvelä [4], shown in Eq. (2) andconverted to Manning by Eq. (3).
𝑢 𝑥
𝑓 = 4𝐶𝐷𝑥 𝐿𝐴𝐼 ( )
(2)
𝑢𝑥
(3)
𝑛 = √𝑓 ⁄8𝑔ℎ−1/3

The 10th International Symposium on Water Environment Systems(Dec. 8th ~ 9th , 2022)----- with Perspective of Global Safety
Where CDx is the vegetative drag coefficient, x is a speciesspecific parameter, ux is the minimum velocity used toacquire x and u is the flow velocity.
The full dynamic model (FDM) considered both emergent
and submerged Manning calculation, and the partial dynamic
model (PDM) used only the submerged state, where the water
was blocked in the vegetated cells while the vegetation was
still emergent.
The vegetation location and height were obtained by a
combination of UAV 3D point cloud data and machinelearning, for more details, refer to [6].
The LAI with 10 m resolution was obtained by downscaling
the LAI from MODIS (500 m) using machine learning and
Sentinel-2 images, like the methodology used in [7].

3 Results and discussion
The simulated event with the SM produced a similar waterlevel profile to the observed. Regarding the dynamic models,the FDM achieved results more accurate than the SM and thePDM. The FDM and SM peak water level profile were very
similar, with the FDM presenting the best result. The RMSE
of SM and FMD were 0.141 and 0.137, respectively. The
PDM produced the largest RMSE of 0.189, with the waterlevel profile higher than the observed. Figure 2 shows thewater level profiles of the SM, FDM and PDM over the
ground level and with the right and left banks.
The overestimation of the inundation produced by the PDM
was due to the use of only the submerged Manningcalculation routine. By blocking the water flow in thevegetated grid cells while it was emergent, a fast
accumulation of water occurred in these locations, leading to
the increase of the water level profile. The similar result of
the FDM and SM means that the proposed emergent andsubmerged Manning calculation routines combined produced
an equivalent overall Manning value that substituted thestatic Manning of 0.038 in the floodplains previously
calibrated and proposed by Miyagi prefecture. This isimportant because the FDM can shorten the trial-and-error
process of calibration of the static model, and it correctly
verifies the effect of the vegetation on the floodplainroughness.
With the FDM, it is possible to perform sensitivity analysis
on the vegetation LAI and height to assess the appropriate
amount of vegetation in the floodplains in order to provide
the safety of the nearby residents while maintaining theecological properties of the environment.

Fig. 2. Simulated and observed water level profiles.

92

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4 Conclusions
Remote sensing is an important tool to provide data in riverenvironments. Both UAV and satellite can provide
vegetation parameters with moderate resolution to be used inhydraulic modeling.
The proposed dynamic Manning model considering both
emergent and submerged vegetation obtained more accurate
results than the traditional static Manning model. Although,the simulated water levels from the FDM and SM were very
close, which suggests that the floodplain roughness value of
0.038 was appropriate. This also suggests that the FDM has
the advantage of not requiring the same time-consuming
process of calibration and represents well the effect of thevegetation in the roughness. The results suggest that the
dynamic Manning model can be an important tool for rivermanagement.

Reference[1] Kazama, M., Yamakawa, Y., Yamaguchi, A., Yamada,S., Kamura, A., Hino, T., and Moriguchi, S., Disaster reporton geotechnical damage in Miyagi Prefecture, Japan caused
by Typhoon Hagibis in 2019, Soils Found., 61 (2021) 549565.
[2] Cowan, W., Estimating hydraulic roughness coefficients,
Agricultural Engineering, 37 (1956) 473-475.
[3] Ebrahimi, N. G., Fathi-Moghadam, M., Kashefipour, S.
M., Saneie, M., and Ebrahimi, K., Effects of Flow andVegetation States on River Roughness Coefficients, Journalof Applied Science, 8 (2008) 2118-2123.
[4] Järvelä, J., Determination of flow resistance caused bynon ‐ submerged woody vegetation, Int. J. River BasinManage., 2 (2004) 61-70.
[5] Nikora, V., Larned, S., Nikora, N., Debnath, K., Cooper,G., and Reid, M., Hydraulic Resistance due to Aquatic
Vegetation in Small Streams: Field Study, J. Hydraul. Eng.,
134 (2008) 1326-1332.
[6] Fortes, A., Hashimoto, M., Udo, K., Ichikawa, K., andSato, S., Obtaining Riparian Vegetation Characteristics fromUAV Optical Imagery 3D Point Cloud Data, in: Proceedingsof the 39th IAHR World Congress, (2022) 4855-4862.
[7] Gokool, S., Kunz, R.P., and Toucher, M., Deriving
moderate spatial resolution leaf area index estimates fromcoarser spatial resolution satellite products, Remote Sens.
Appl.: Soc. Environ., 26 (2022) 100746-100758.
[8] Hashimoto, M., Yoneyama, N., Kawaike, K., Deguchi,T., Hossain, M. A., and Nakagawa, H., Flood and SubstanceTransportation Analysis Using Satellite Elevation Data: A
Case Study in Dhaka City, Bangladesh, J. Disaster Res., 13(2018) 967-977.
[9] Sayama, T., Ozawa, G., Kawakami, T., Nabesaka, S.,
and Fukami, K., Rainfall–runoff–inundation analysis of the2010 Pakistan flood in the Kabul River basin, Hydrol. Sci. J.,
57 (2012) 298-312.
[10] Japan Institute of country-ology and engineering,
Manual of plans for river channel (in Japanese), Sankaidou(2002).