INCORPORATION OF SNOW AND GLACIER MELTPROCESSES IN RRI MODEL FOR ESTIMATING PEAKRIVER DISCHARGES AND INUNDATION ANALYSIS IN
NEELUM RIVER BASIN
Dr. Mohamed Rasmy Abdul Wahid2
Toshio Koike3

Irfan Ullah Khan1
MEE15629
ABSTRACT

There is no hydrological model that can produce inundation by simulating rainfall, snow and glaciermelt
together. In this study, Neelum river basin was studied where extreme monsoon weather events
augmented by snow and glacier melts trigger the flood frequently and cause damages because of narrow
flood plain, residential and commercial activities within the flood plain. There is considerably lessground rainfall information in the Neelum basin for it is a transboundary basin having only one rain
gauge at Muzaffarabad. Therefore, the RRI-snow-Glacier (RRI-SG) model was developed in Gilgit
basin that has three rain gauges inside the basin. The snow and glacier melt algorithms were incorporated
in RRI Model based on degree-day method and satellite snow images. After having confidence that thenew model was working well, the model was applied in Neelum river basin to analyse the flood 2010.
In order to address the non-gauging and transboundary issue of the basin, satellite observed rainfall(GSMaP-NRT) was corrected by a method proposed by JAXA based on ground rainfall data. The model
simulation results showed that the new developed RRI-SG model is a simple, effective and easily
applicable to produce flood warning and inundation by simulating the combine effects of rainfall, snowand glacier melts. Lastly, the inundation analysis of the Neelum River basin was accomplished using
RRI-SG Model and validated using remote sensing technique. A flood hazard map for Muzaffarabad,
based on a 100-year return period future extreme event, was developed. The results showed that boththe banks of the Neelum River are under risk of future extreme events.
Keywords: RRI Model, Snowmelt, bias correction, Flood Plain Management
INTRODUCTION AND BACKGROUND
About 85% of the annual flows of Indus River is due to snow and ice melts while 11.5% of the total areaof Upper Indus Basin i.e. 22,000 Km2 is covered by perennial glacial ice (Hewitt, 2001). Like othermany developing countries, Pakistan is also facing impacts of floods. In Pakistan, generally heavy
concentrated rainfall during Monsoon period cause the flooding. However, in Northern areas of thecountry, heavy rainfall events augmented by snow and glacier melts cause the river flooding. The main
reasons for flood damages are either poor or absence of integrated flood risk management in many floodprone basins.
The main objectives of the study were;• To incorporate and investigate the combine effects of rainfall, snow and glacier melts in RRI model.
• To accomplish the inundation analysis of River Neelum for better flood plain management,adaptation and mitigation.
For this study, Neelum river basin was selected as a study area. It lies in the North East of Pakistan. Itis a part of Mangla Basin and a transboundary basin for some of its part lies in Indian held Jammu
Kashmir. The River Neelum originates from a lake known as Vishansar Lake, in Indian held Jammu
Kashmir. The mouth of Neelum River lies in Muzaffarabad City at Domail. The basin topography ismostly mountainous, covered with thick forests.
1. Deputy Director (M&E), Physical Planning & Housing Department, Government of AJ&K, Pakistan
2. Senior Research Associate, ICHARM, Tsukuba, Japan
3. Director, ICHARM, Tsukuba, Japan1

Key information of Neelum River Basin are appended in Table I.

Table I: Study area information
Neelum River BasinRiver Flow Gauging Station
LatitudeLongitude
ElevationofGauging
StationDrainage Area
Mean Elevation
No.
ofMeteorological
Stations

Muzaffarabad
34o22’3’’N
73o27’47.88’’E
670 m
7278 Km2
3363 m01 (Installed by PMD)
Muzaffarabad
670 m

Fig 1: Location of Study Area in Pakistan(Source: Author created using GIS Tools)
METHODOLOGY AND THEORY

Rainfall Runoff Inundation model is a two dimensional model that can simulate rainfall-runoff and floodinundation simultaneously (Sayama et al., 2012). The flow on the slope grid cells is calculated with thetwo dimensional diffusive wave model, while the channel flow is calculated with the one dimensional
diffusive wave model. The model simulates also lateral subsurface flow, vertical infiltration flow andsurface flow. The vertical infiltration flow is estimated by the Green-Amp model (RRI User’s Manual).
However, the model does not include the snow and glacier melt processes. Therefore, snow and glaciermelt processes based on the Degree day method were incorporated in the model. Temperature at eachcell was calculated from the following equation based on the observed average temperature andTemperature Lapse Rate (TLR).
Lapse Rate= −𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒………………………….…………………. (A)𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝐸𝑙𝑒𝑣𝑎𝑡𝑖𝑜𝑛

Snow and glacier melts (mm/day) at each grid cell, if snow count was one, was calculated from thefollowing relation;
Melt = (Ta-Tb) X DDF ………………….…………………………. (B)
Where DDF=Degree Day Factor, Ta= mean daily air temperature in °C and Tb= base temperature in °C
Where value of Degree Day Factors (DDF) for snow and glacier were set as 2 mm/°C/day.
The model source code was modified toensure that both the snow and glaciermelt at each cell, calculated as per above
mentioned physics, were added to theground observed rainfall (mm/day ormm/hr) and model was run to simulate
the 2010 flood event in the study area. Inorder to tackle the transboundary basin
and under gauging issue, Near RealTime Global Satellite Mapping ofPrecipitation(GSMaP_NRT)
wascorrected by a method proposed by
Japan Aerospace Exploration Agency(JAXA) based on ground rainfall data.
Fig 2: Study Methodology
2DATAInundation analysis is one of the objective set for this study therefore, Rainfall-Runoff Inundation (RRI)
Model was used for this study. The original model requires topographic and precipitation data as its
basic inputs. The model does not consider the snow and glacier melt processes. As discussed earlier, thestudy area also receives the snow during winter season therefore the model was required to be modified
by incorporating the snow and glacier melt processes based on degree day method and satellite snowdata. Therefore, in addition to basic inputs, MODIS snow cover data, glacier cover data and temperature
were also required for this study.
Topographic Data
Digital Elevation Model for Asia was acquired
from United State Geographical Survey (USGS)
HydroSHEDS to delineate the study area. The
study area was delineated using GIS techniques.
Then ASCII format files of DEM, flow direction
and flow accumulation for the study area wereprepared.
Precipitation Data
Fig 3: Digital Elevation Model of Neelum River
Basin (HydroSHEDS)

There is only one meteorological station in thebasin at Muzaffarabad, therefore, ground rainfall
from Eight basin outside laying rain gauges wereused initially.
Snow and Glacier Cover Data
Snow Cover data was obtained from Moderate
Resolution
Imaging
Spectroradiometer(MODIS). The MODIS/Terra Snow Cover EightDay L3 Global 500 m Grid (MOD10A2) for year
2010 were used for this purpose. Out of the eightbands, only first band was used. Glacier Data wasacquired from International Centre for Integrated
Mountain Development (ICIMOD).

Fig 4: Location of Meteorological Stations inStudy Area
Jan 01, 2010

Feb 10, 2010

Mar 06, 2010

Apr 07, 2010

May 01, 2010

June 18, 2010

July 04, 2010

Aug 13, 2010

Sep 06, 2010

Oct 08, 2010

Nov 01, 2010

Dec 03, 2010

No Snow

Snow

Fig 5: Snow Cover Maps for Study area (MODIS)3

Fig 6: Glacier Map of Neelum River Basin(ICIMOD)RESULTS AND DISCUSSION
0RRI Simulations in Gilgit River Basin
1500

5Discharge m3/sec

Rainfall mm/day

From the MODIS snow cover maps for the study
10area, it was clear that snow melt was also 1000contributing to the Neelum river runoff,
15therefore, incorporation of snowmelt process in 500
20RRI model was required. However, since
025
Neelum river basin has very less ground rainfall
Apr-08Jun-08Aug-08
Sep-08inside the basin even in Pakistan’s territory,
Avg Basin RainObs Discharge
therefore, the RRI-SG model was developed inRain+Snow
Rain+Snow+GlacGilgit basin which is a part of upper Indus river
basin and has three rain gauges inside the basin.
Fig 7: Observed and simulated discharge hydrographs
The results are shown in Fig 7.
at Gilgit Station (Ground Rainfall, snow & Glacier)0

RRI Simulations in Neelum River Basin

6000

Fig 9: Observed and simulated discharge hydrographs
at Domail Station (Ground Rainfall, snow & Glacier)02000

0Dec-09

Corr. GSMaP Avg BasinRainfall
Q_obs

Nash= 0.650

Final calib RRI Sim

50

4000
2000

1000Dec-09

150
Apr-10Jul-1050
100150
Apr-10Jul-10

Oct-10Corr. GSMaP Avg Basin Rainfall
Q_obs
Corr. GSMaP+Snow+Glac

Oct-10

Fig 11: Final Calibrated RRI-SG Simulation

Discharge m3/sec

4000

06000
Rainfall mm/dayDischarge m3/sec

6000

Rainfall mm/day

Discharge m3/sec

Discharge m3/sec

Rainfall mm/day

Having confidence that the model was working
50
Basin Avg Rainfall
well, it was applied in the Neelum river basin. 4000
Nash= - 0.45
Q_obs
RMSE=464
Fig 8 shows RRI simulation based on ground
Rain only_ka=0.1d0
rainfall only that shows there was100
2000
underestimation during March to June becausesnow melt was not considered. Figure 9 shows
the RRI-SG model simulation based on ground0150
Dec-09Apr-10Jul-10
Oct-10
rainfall, snow and glacier melt together.
However, due to less glacier cover map, theFig 8: Observed and simulated discharge hydrographs
contribution from glacier melt was notat Domail Station (Ground Rainfall only)
prominent.
Since, most of gauges were outside the basin,
0therefore, GSMaP-NRT was corrected based on 6000
JAXA’s correction method. The method proved
to be effective to obtain good rainfall
Nash= 0.3307
50Gr. Basin Avg Rainfall
RMSE=314
distribution maps inside the basin with the help 4000
Q_obsof basin outside lying rain gauges. RRI-SG
Gr. Rain0+S_G Inter
simulation for bias corrected GSMaP-NRT, 2000
100
snow and glacier melt together is shown in fig
10.
0150
After that, through sensitivity analysis, theDec-09
Apr-10Jul-10
Oct-10model was calibrated and validated. The fig 11
and 12 show the results.

Fig 10: Observed and simulated discharge hydrographs
at Domail Station (Corr. GSMaP, snow & Glacier)4

Flood Inundation analysis in Neelum Basin

Discharge m3/sec

In order to achieve the second objective of this 4000
study, inundation output from the RRI model
was used to produce the flood inundation mapfor the year 2010 in Muzaffarabad and its 2000
surrounding areas. For validation, modified
gradient based remote sensing technique wasused which although showed overestimation
0but similar pattern of inundation was observed.
Nov-08The results are shown in fig 13 and 14.

Corr GSMaP Basin Avg
Q_obs

Nash= 0.450

Year 2009

Mar-09Jun-09Rainfall mm/day-50100

Sep-09Fig 12: RRI-SG Model Validation (2009)

Frequency Analysis results
Annual Maximum Rainfall data for period(2001- 2010) for Muzaffarabad, Balakot andAstore Rain gauge stations were used tocalculate 100 year return period extreme
rainfall events based on Gumbel andGeneralized Extreme Value distributions andcunnane method.
Future Flood Inundation

Fig 13: Flood 2010 Inundation in Muzaffarabad andsurrounding areas on July 30, 2010

Finally, based on the results of frequency
analysis of future extreme event, the inundationfrom the model was obtained and flood hazard
map for Muzaffarabad city and its surroundings
based on 100-year return period event wasdeveloped. Figure 14 shows the 100-year floodhazard map for Muzaffarabad and its
surrounding areas. Its shows the flood plain of
the river is under risk of a future flood.

Fig 14: Validation of flood 2010 inundation bymodified gradient based method (MOD9A1, 8-daycomposite 500 meter July 8 to Aug 4, 2010)

Fig 15: Flood Hazard Map for Muzaffarabad and surroundings (100 Year return period)

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RECOMMENDATIONS
The following are the few recommendations based on this research.
i.
Integrated Flood Risk Management in the flood plain of Neelum River is required. Therefore,
Early Warning System and contingency planning should be ensured. In addition to that, policies
and strategies regarding existing and future settlements should be formulated.
ii.
Awareness regarding future possible flood risk and early evacuation may be raised among thecommunity. In addition to it, early evacuation drills may also be conducted.
iii.
The RRI-SG model should be applied in the whole Indus River basin for flood forecasting,inundation analysis and detail damage assessment purposes.
iv.
A suitable number of meteorological observatories at suitable locations should be installed forflood forecasting purposes.
v.
Effectively collaborated institutional arrangements in AJ&K are necessary for observing
meteorological and river flow data, forecast and carrying out countermeasures against.
ACKNOWLEDGEMENTS
All the praise and glory to Almighty Allah Who is the most merciful and beneficial. First of all, I
would like to express my gratitude to Japan International Cooperation Agency (JICA) for providingme this mammoth opportunity of my entire life.
This dissertation would not have been possible without the support, worthwhile knowledge andsuggestions of many personalities. I have been privileged to accomplish this research under the kindsupervision of Associate Professor Dr. Mohamed Rasmy. I acknowledge with my deepest gratitude
his endless support, expert guidance, encouragement and motivation in exploring new horizons ofresearch.
I would also like to express my heartedly indebtedness to sub supervisor Prof. Toshio Koike for hisguidance, incredible patience, thoughtful questions, comments and valuable suggestions. A timeto-time meeting conveyed with an internationally reputed Professor like him proved a milestone inachieving the objectives set for this study.
In addition, I am deeply thankful to co-supervisors Dr. Morimasa Tsuda and Dr. Liu Tong for theirvaluable knowledge and suggestions. I am grateful to Mr. Takashi Shirai and Miss Yukie Okawa,
who were always readily available to support me with their best.
Last but not the least, I want to thank to all of my family members and specially my mother andwife for their unconditional love. Their support and prayers always made it possible the way I
wished.
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