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flood Modelling of Kalu-Ganga river basin

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Presentation on theme: "flood Modelling of Kalu-Ganga river basin"— Presentation transcript:

1 flood Modelling of Kalu-Ganga river basin
H. K. Nandalal Department of Civil Engineering University of Peradeniya Peradeniya Sri 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 by utilizing modern technology like Geographic Information Systems (GIS), Remote Sensing (RS) and flood modeling

3 Outline of the Presentation
Study area Data used Software used Application of Software HEC-HMS HEC-RAS ENVI

4 Study Area Kalu-Ganga river basin in Sri Lanka
Total catchment area is 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

7 Data used TIN Model of the Study area Contour Data LIDAR DATA

8 Data used Locations of rainfall and discharge gauging stations

9 Data used Satellite images
Raw Images (Dry Date, 03 March,2008) ALOS – PALSAR (HH) Raw Images (Wet Date, 03 June,2008) ALOS – PALSAR(HH)

10 Data used Data Collection and Data-basing…

11 Application of HEC-HMS
Rainfall –Runoff Modeling

12 Application of HEC-HMS
Basin model developed using HEC-GeoHMS

13 Application of HEC-HMS
Results of the verification runs to compare the simulated flows and the observed flows of the calibrated HEC-HMS model

14 Application of HEC-RAS
Flood Modeling

15 Application of HEC-RAS
Geometric Data: HEC-GeoRAS export Stream C/L River banks Flow paths

16 Application of HEC-RAS
Discharge data obtained from HEC-HMS Mawakoya Elagawa Junction Mawakoya/Kalu Ganga Kuda Ganga Junction Kuda Ganga/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

17 Application of HEC-RAS
HEC-RAS output

18 Application of HEC-RAS
HEC-RAS output

19 Application of HEC-RAS
Flood Hazard Maps from HEC-RAS

20 Verification of model result by satellite data
Raw Images (Dry Date, 03 March,2008) ALOS – PALSAR (HH) Raw Images (Wet Date, 03 June,2008) ALOS – PALSAR(HH)

21 Band Math Image (WET-DRY)
(Difference dB image Wet - Dry) Mask

22 Flood extent resulted by satellite data

23 Comparison of the Flood extent derived from HEC-RAS model and Satellite image

24 Final Flood Hazard Maps

25 Thank you for your patience.

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