H K Nandalal Department of Civil Engineering University of Peradeniya Peradeniya Sri Lanka Introduction Problems related to flooding have greatly increased over recent decades because of population growth ID: 786301
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Slide1
flood Modelling of Kalu-Ganga river basin
H. K. NandalalDepartment of Civil EngineeringUniversity of PeradeniyaPeradeniyaSri Lanka
Slide2IntroductionProblems related to flooding have greatly increased over recent decades because of
population growth development of extensive infrastructures in close proximity to riversIt is importance to find solutions byutilizing modern technology like Geographic Information Systems (GIS), Remote Sensing (RS) and flood modeling 2
Slide3Outline of the Presentation Study area
Data usedSoftware usedApplication of SoftwareHEC-HMSHEC-RASENVI3
Slide4Study Area
Kalu-Ganga river basin in Sri Lanka4Total catchment area is 2719 km2
Entire basin lies within the wet zone.Average annual runoff is around 7600
MCM
.
Catchment experiences average annual rainfall of 4000
mm.
Slide5Study Area
5Study concentrates on the lower reaches of the riverArea of interest is nearly 500 km2
This includes 5 Divisional Administrative Divisions (DSD
)
Slide6Data Used
6
Slide7LIDAR DATA
Contour Data
TIN Model of the Study area
Data used
Slide8Data used
8Locations of rainfall and discharge gauging stations
Slide9Raw Images (Dry Date, 03 March,2008) ALOS – PALSAR (HH)
Raw Images (Wet Date, 03 June,2008) ALOS – PALSAR(HH)
Data used
Satellite images
Slide10Data
Collection and
Data-basing
…
Data used
Slide11Rainfall –Runoff Modeling
Application of
HEC
-HMS
Slide12Basin model developed using HEC-
GeoHMS
Application of
HEC
-HMS
Slide13Results of the verification runs to compare the simulated flows and the observed flows of the calibrated
HEC
-HMS
model
Application of
HEC
-HMS
Slide14Flood Modeling
Application of
HEC
-RAS
Slide15Geometric Data:
HEC-GeoRAS
export
Stream C/L
River
banks
Flow
paths
Application of
HEC
-RAS
Slide16Discharge data obtained from
HEC
-HMS
Elagawa
Mawakoya
Kuda Ganga
Junction Kuda Ganga/Kalu Ganga
Junction Mawakoya/Kalu Ganga
Flow (m
3
/s) data at\Return Period
10yr
20yr
50yr
100yr
Elagawa
1062.6
1319.7
1798.1
2605.5
Junction KudaGanga/ Kalu Ganga
1455.7
1836.9
2524.4
3743.3
Mawak
Oya
97.5
122.2
174.4
245.5
Junction Mawak Oya/Kalu Ganga
1079.5
1340.5
1828.5
2647.7
Kuda Ganga
414.4
555.3
817.1
1260.7
Application of
HEC
-RAS
Slide17HEC
-RAS
output
Application of
HEC
-RAS
Slide18HEC
-RAS
output
Application of
HEC
-RAS
Slide19Flood
Hazard Maps
from HEC-RAS
Application of
HEC
-RAS
Slide20Raw Images (Dry Date, 03 March,2008) ALOS – PALSAR (HH)
Raw Images (Wet Date, 03 June,2008) ALOS – PALSAR(HH)
Verification of model result by satellite data
Slide21Mask
(Difference dB image Wet - Dry)Band Math Image (WET-DRY)
Slide22Flood extent resulted by satellite data
22
Slide23Comparison of the Flood extent derived from
HEC
-RAS model and Satellite image
Slide24Final Flood Hazard Maps
Slide25Thank you for your
patience.Questions?