AHW26-01

Room:301A

Time:May 27 09:00-09:15

Impact assessment of the Seto-Inland Sea Water Profile Based on CMIP5 Model Ensemble
MORI, Nobuhito1 ; IMAI, Yuki2∗ ; NINOMIYA, Junichi3 ; YASUDA, Tomohiro1 ; MASE, Hajime1
1

Kyoto University, Disaster Prevention Research Instit, 2 Kyoto University Graduate School of Engineering, 3 Kanazawa University, Science and Technology
1.Introduction
This study uses the Regional Ocean Modeling System (ROMS) to project environmental changes of the Seto-Inland Sea inJapan based on the Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble. The IPCC-AR5 WGI (referred to asAR5) was published in September 2013 and made great progress in impact assessment for future climate changes. Uncertaintyof these future projections can mostly be attributed to either greenhouse gas emission scenarios or the precision of the projection
model (e.g. GCM). Emission scenarios such as Representative Concentration Pathways (RCP) have been considered and theuncertainty in the model is assessed by the model ensemble mean, which assumes that results are scattered around the true value(IPCC, 2013). Although there are many impact assessments on global or large scale changes in the coastal ocean environment,
there are few studies on smaller scale changes, for example in Japan. Further, examination of local scale change has not been
consistently discussed in the AR5 large scale impact assessment.
This study analyzed CMIP5 for near-sea surface global and local ocean areas. It also examined the projection of physicalenvironmental changes of the Seto-Inland Sea in Japan by numerical downscaling with CMIP5 forcing.
2.Analysis of CMIP5
CMIP5 was analyzed for present climate named historical, future climate named RCP 4.5W/m2 scenario (RCP4.5) andRCP8.5. It focused on ten ocean areas, including global areas and locations in east Japan (E125 degrees-E136 dgrees, N27degrees-N35 degrees). The objective variables of CMIP5 are atmospheric temperature, cloud fraction, humidity, wind speed, sealevel pressure, shortwave radiation and longwave radiation, which were analyzed by a 61 GCMs ensemble. Spatial distribution ofsea surface temperature (SST) showed a consistent increase overall, with local non-homogeneity; for example, analysis projects
an increase greater than 4 degrees increase in the northwest Pacific. The monthly mean of SST in west Japan was projected tochange with a maximum increase of 3.5 degrees in June and 2.8 degrees in January. The projected increase is higher than that of
the global annual mean. While a constant cloud fraction is projected on the global scale, the model projects a decrease in cloud
fraction in west Japan.
3.Future Change of Water Profile in the Seto-Inland Sea
This study calculated the long-term analysis as 2093 using ROMS as downscaling model with forcing variables from CMIP5
results to project future environmental changes in west Japan’s Seto-Inland Sea. The projection results in present climate condition were compared with observed results (Tanaka et al., 2013) similarly calculated in 2004. Topography data was taken fromJapan GSI, with 1km resolution. Lateral boundary conditions were obtained from FRA-JCOPE. The atmospheric conditions
were implemented using hourly results of CMIP5 analysis for temperature, SLP, short wave radiation, cloud fraction and windspeed. In the summer, the SST shows a remarkable increase of about 1.6 degrees. An increase of the same kind of water profilewas projected in both shallow and deep areas of Hiuchinada and Kitan straits. A difference between the areas is increasing trend
near the sea surface. Remarkable warming near sea surface in Hiuchinada contrasts with constant warming over all layers inKitan straits.
4.Conclusions
CMIP5 analysis projected a decrease in cloud fraction in the western part of Japan despite projecting a constant cloud fraction
on the global scale. Furthermore, although results project an increase in short wave radiation in west Japan. They project a global
average decrease.
Using ROMS with forcing from CMIP5 analysis projected an SST increase of 1.6 degrees in the summer. Finally, the water
profile tends to remarkably increase in shallow water, such as in Hiuchinada.

Keywords: the Seto-Inland Sea, water profile, ROMS, CMIP5, cloud fraction, short wave radiation

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AHW26-02

Room:301A

Time:May 27 09:15-09:30

Study on origin of high- pH spring in Yuzawa Geopark, Akita
HAYASHI, Takeshi1∗ ; HAYASHI, Shintaro1 ; YASUHARA, Masaya2 ; TAKAHASHI, Hiroshi2 ;MORIKAWA, Noritoshi2 ; ASAI, Kazuyoshi3
1

Faculty of Education and Human Studies, Akita Univ., 2 GSJ, AIST, 3 Geo-science Laboratory

Yuzawa Geopark, located in the southeastern part of Akita prefecture, is famous for geothermal activity and various typesof hot springs. In addition, there are many springs that are recharged by huge amount of snow in this area. A high-pH spring(pH>9) is located in a Neogene hill. There is no hydrological study on the high-pH spring. Therefore, this study aims to clarify
the origin and groundwater quality evolution process of the high-pH spring. We will show the results of major dissolved ions andstable isotopes of springs that were collected in September and November of 2014.
The high-pH spring discharges from joint of Neogene clay layer, and white deposit (calcite?) was found in the joint aroundof discharge point. pH and EC of the high-pH spring were 9.7 to 9.9 and 460 to 480 µS/cm, respectively. Groundwater quality
showed Na-HCO3 type. As for δ 18 O and δD, the high-pH spring was located along local meteoric water line (d=20). Considering
the correlation between isotopic ratios and elevation of discharge points that were obtained from the springs that were collected
in wide area of the geopark, elevation of the recharge area of the high-pH spring was estimated more than 400 masl. However,this value was much higher than the elevation of topographical recharge area of the high-pH spring. The results of this study
suggest that the high-pH spring may be recharged by regional groundwater flow system and may have long travel time.
Keywords: high-pH spring, multi tracer, environmental isotopes, Yuzawa geopark

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AHW26-03

Room:301A

Time:May 27 09:30-09:45

A prompt report on influence and change on the river of around Mt.Ontake after eruption(140927)
ASAMI, Kazuki1∗ ; KODERA, Koji2
1

Undergraduate student, Hosei University, 2 Department of Geography, Hosei University

1.Introduction
Mt.Ontake located in the boundary of Nagano and Gifu erupted by phreatic explosion at about 11:53 a.m. on September27, 2014. The volcanic ejecta which occurred by this eruption gets into the lake and the outskirts river of the mountaintop
neighborhood, so naturally influence on water environment is thought about. Therefore our laboratory started a continuation
investigation to check a change of the water environment of a river around Mt.Ontake by the eruption.
2.Survey method
The field work item is AT,WT,pH,RpH,EC. In addition, I performed the water quality measurement of the plumb direction
using ALEC at some spots. Furthermore, I collect water and take a sample home with me and analyze TOC, major dissolved
component in a laboratory.
3.A result and consideration
Volcanic ejecta flowed in Nigori river of the crater south side of Mt.Ontake and Outaki river after the Nigori river junction,and river water was able to observe a cloudy state. From result of a measurement of pH, the around Mt.Ontake river became thevalue before and after 7.0 generally, but showed a value before and after 3.5 and the strong acidity at the cloudy spot. In addition,
the value of the EC is less than 20 mS/cm generally, too, but a value is big at the cloudy spot, and a value called 170 mS/cm isobserved in Nigori river just after the eruption.
There is not a cloudy state, and a value of pH is around 7.0 in the river of the east side of Mt.Ontake. But a value of the ECis slightly big in a part river. In addition, with the Nobunaga Bridge whom there was near a mountain rising to a great heightropeway, pH was around 4.5 values and the value of the EC was relatively big. So I knew that influence of the eruption appearedon the east side of Mt.Ontake particularly in mountaintop neighborhood
The cloudy river water of Outaki river flows into the Ontake Lake made by a dam. As for the surface water of the Ontake
Lake and a spot more downstream than the Ontake Lake, there was no great difference between pH, EC and the whole around
Mt.Ontake river together at the stage of the investigation of October 8 just after the eruption. But when it was on October 31,
a drop of pH and a rise of the EC were confirmed, and a similar change was seen. The volcanic ejecta which flowed into theOntake Lake only deposited in the bottom of a lake at the stage of October 8, but I have lake water cycle in the Ontake Lake fromhere to October 31, and influence of the volcanic ejecta of the bottom of a lake appears in the whole lake, and it can call that sucha water is discharged by the dam, and a change appeared in the downstream water.
4.Conclution
Influence and a change to the quality of the water of the around Mount Ontake river by the eruption became clear. I continue
an investigation and investigate the crater lake of source area and the Mitake mountaintop as much as possible and will examine
influence of the eruption more in future.
Keywords: Mt.Ontake, eruption, volcanic product, Ontake Lake, matter cycle

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AHW26-04

Room:301A

Time:May 27 09:45-10:00

Loading Processes of Chemical Matters in a Forested River Catchment : Observations
and Modeling
MIYAMOTO, Takuto1∗ ; CHIKITA, Kazuhisa2 ; HOSSAIN, Md motaleb1 ; SAKATA, Yoshitaka2 ;OCHIAI, Yasuhiro1
1

Graduate school of science Hokkaido university, 2 Faculty of Science, Hokkaido University

River water is one of the most important natural resource for our live and has much influence for lake and the earth because offast transport velocity. Especially, outflow of chemical matters in river is related with river ecosystem and make lake eutrophication. We targeted Oikamanai river basin, forested catchment in Hokkaido. In this catchment, landuse is 88.3 % forest and 10.6
% farmland. Geology is the Neogene Miocene mud and sand stone, half of which is composed by marine deposit.We got thedata on concentration of chemical matters and time series of discharge, electric conductivity (EC) and MET data. Fresh water’sEC monitoring is new technology, so there are few reports. In this study, we calculated time series of concentration of chemicalmatters and chemical matters load using co-relation of concentration of chemical matters and EC. We analyzed discharge routeusing Tank-model. Using this result, we calculated chemical matters load at each discharge route. We discuss mechanism ofoutflow of chemical matters in forested catchment with these data.
In this study, we targeted Mg2+ , Ca2+ , Na+ , SO4 2− , HCO3 − because they have much influence for EC. As a result of Tankmodel, baseflow is distinguished, 68.3 % and surfaceflow is distinguished in high discharge events. HCO3 − analysis intended
soil water tend to cultivate to underground. HCO3 − was more dissolved in river water in high discharge events, this is insisted
to be caused by river erosion. SO4 2− analysis showed iron pyrites is oxidized in weathered mantle and upper basin and organicmatters is bitten by microbe. Ca2+ , Na+ , Mg2+ analysis suggested ionic exchange with H+ occur in soil.

Keywords: forested river basin, chemical matter, Tank-model, L-Q equation

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AHW26-05

Room:301A

Time:May 27 10:00-10:15

Evaluation of Land cover change and Flow regime change in upper area of Dong Nai riverbasin, Vietnam
TRUONG, Nguyen cung que1∗ ; KONDOH, Akihiko2
1

Chiba university, Graduate school of Science, 2 Chiba university, Center for Environmental Remote Sensing

Vietnam is considered as one of the top countries to be severely affected by climate change, particularly in coastal areas. Thatby 1 m sea level rises, Vietnam would lead to flooding of up to 20,000 km2 of the Mekong river delta and more than 1 million
people would be directly affected in there and it is also predicted economic loss up to 10% GDP (Dasgupta et al. , 2007). Inrainy season a combine of SLR and rainfall increase to make a serious impact on low-lying coastal areas. It is also predictedthat 40,000 km2 of coastal delta region, 90% of the Mekong delta will flood (Eastham et al. , 2008) and temperature is moresignificantly rise in the plateau region (MONRE, 2012).
Dong Nai river and Mekong delta downstream are located in and supplied the major water resources to the whole Southern ofVietnam. Continuous changes in water resources due to climate changes and several controversies about the potential impact ofsediment transport and river flows downstream due to either the cascade hydroelectric power plant system or dam construction in
the upper of Mekong delta being continuous. In addition, water resources from Dong Nai river is the resource that only controlled
by Vietnam. On the other hand, solving the problems of water shortage in the dry season and flood control in rainy season are
also important for issues of water management at Dong Nai river basin. Therefore evaluation of flow regime change by the affectof climate change and human activities is an urgent issue in Vietnam.
That forest area decreased as a human activity is the big problem in Vietnam. In the period from 2002 to 2009, 620 km2of forest land lost on average per year and 250 km2 of forest land was converted to other land use (Vietnam Forest ProtectionAgency, 2010). The main reasons of deforestation are unsustainable logging and agricultural land development (Hoang M.
H. et al. , 2010). In most cases the forest vegetation lost, runoff increases conversely forest vegetation growing, runoff often
decreases (Maita and Suzuki, 2008).
The river flow regime was analyzed from 1989 to 2009 runoff data at 3 observation stations in study area. The Landsat images
in 2014 and 2005 were used to classify to 5 majors of land cover such as the dense-forest, spare-forest, crop-land, bare-land andwater body.
Dong Nai river basin area is 14,713.5km2 with the main land cover types are dense-forest 35%, spare-forest 26% and cropland
24% in 2005. From 2005 to 2014, the large area of forest (both in dense and spare) was converted to crop-land and bare-land; apart of spare-forest had became dense-forest. Especially the majority of bare-land (7%) had been converted into the other land
cove types. The ratio land cover was dense-forest 33%, spare-forest 16% and cropland 39%. We can see that deforestation hasoccurred in the study area from 2005 to present.
As the inflow of Tri An dam, the flow regime at Tri An (basin outlet) slightly increased in all the flow rates of normal
discharge, low-water flow and drought flow but slightly decreased in hosui flow. Flow regime of Ta Lai point, where affected bydeforestation, hosui flow and normal discharge is slightly increased but change trend of low-water flow and drought flow werenot observed. As the inflow of upper stream dam, the flow regime at Da Nhim increased in all the flow rates of hosui flow, normal
discharge, low-water flow and drought flow.

Keywords: Dong Nai river basin, Flow regime, Land cover change

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AHW26-06

Room:301A

Time:May 27 10:15-10:30

Characteristics of groundwater temperature distribution of deep wells in Aizu basin
KANEKO, Shohei1∗ ; SHIBASAKI, Naoaki2 ; UCHIDA, Youhei3
1

Graduate School of SSS, Fukushima University, 2 Faculty of SSS, Fukushima University, 3 National Institute of Advanced Industrial Science and Technology
The Shibasaki Laboratory of Fukushima University has conducted a joint research, ’Analysis on Geological Structure of Quaternary and Hydrological Structure in Aizu basin’ with the Shallow Geothermal and Hydrogeology Team, AIST. The laboratory
has carried out studies on groundwater flow and groundwater temperature. Considering popularization of ground-source heatutilization system, comprehension of groundwater flow will be able to design more efficient system.
In this study, we collected continuous monitoring data of groundwater level and groundwater temperature. We also measured
pumped water temperature and its quality from sprinkling snow-melting wells, and depth-wise temperature at an interval of 2 m
in deep wells.
Groundwater level of deep wells and some shallow wells showed reduction of groundwater levels in winter. This is becausesnow-melting wells were operating. Most of their depths range from 150 to 200 m and their strainers are installed at multiplelayers, so groundwater is pumped from several aquifers. Groundwater temperature of snow-melting wells found to be higher
in the eastern part of Aizu basin. The similar trend was identified in temperature distribution maps prepared by Kaneko et al.
(2014).
There are some snow-melting wells with artesian flow at the periphery of Aizu Basin and their temperatures are higher than
the neighboring snow-melting wells. This is because upward movement of groundwater occurs in artesian wells. In general,
temperature should be higher in the western part of the central Aizu basin which lies in downstream area. However, groundwatertemperature was higher in eastern part.
Moreover, snow-melting wells in the eastern part of the basin showed higher temperature, although there is no artesian flow.
In these places, the thickness of Quaternary system is small and groundwater may be pumped from not only Quaternary systembut also Neogene system.
For further investigation, we will examine chemical composition of groundwater by ion chromatography.

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