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flood Modelling of Kalu-Ganga river basin. 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 - PowerPoint PPT Presentation
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FLOOD MODELLING OF KALU-GANGA RIVER BASIN
H. K. NandalalDepartment of Civil Engineering
University of PeradeniyaPeradeniyaSri Lanka
2
Introduction
Problems related to flooding have greatly increased over recent decades because of
population growth development of extensive infrastructures in close proximity to rivers
It is importance to find solutions byutilizing modern technology like Geographic Information Systems (GIS), Remote Sensing (RS) and flood modeling
3
Outline of the Presentation
Study areaData usedSoftware usedApplication of Software
HEC-HMSHEC-RASENVI
4
Study Area
Kalu-Ganga river basin in Sri Lanka
Total 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.
5
Study Area
Study concentrates on the lower reaches of the river Area of interest is nearly 500 km2 This includes 5 Divisional Administrative Divisions (DSD)
6
Data Used
LIDAR DATAContour Data
TIN Model of the Study area
Data used
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Data used
Locations of rainfall and discharge gauging stations
Raw Images (Dry Date, 03 March,2008) ALOS – PALSAR (HH)
Raw Images (Wet Date, 03 June,2008) ALOS – PALSAR(HH)
Data used
Satellite images
Data Collection and Data-basing…
Data used
Rainfall –Runoff Modeling
Application of HEC-HMS
Basin model developed using HEC-GeoHMS
Application of HEC-HMS
Results of the verification runs to compare the simulated flows and the observed flows of the calibrated HEC-HMS model
Application of HEC-HMS
Flood Modeling
Application of HEC-RAS
Geometric Data: HEC-GeoRAS export
Stream C/L River banks Flow paths
Application of HEC-RAS
Discharge data obtained from HEC-HMS
Elagawa
Mawakoya
Kuda GangaJunction Kuda Ganga/Kalu Ganga
Junction Mawakoya/Kalu Ganga
Flow (m3/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
HEC-RAS output
Application of HEC-RAS
HEC-RAS output
Application of HEC-RAS
Flood Hazard Maps from HEC-RAS
Application of HEC-RAS
Raw 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
Mask(Difference dB image Wet - Dry)
Band Math Image (WET-DRY)
22
Flood extent resulted by satellite data
Comparison of the Flood extent derived from HEC-RAS model and Satellite image
Final Flood Hazard Maps
Thank you for your patience.Questions?