Flood Warning Systems in Sri Lanka Current situation for DRR

Transcription

1 Flood Warning Systems in Sri Lanka Current situation for DRR S.B.Weerakoon Department of Civil Engineering, University of Peradeniya, Sri Lanka Asian Water Cycle Symposium, 1 2 March 2016,Tokyo

2 A2: Flood simulation/forecast system Real time data of rainfall at selected stations and water levels at selected rivers/reservoir gauging stations received, and warnings issued. 120 stations Need for early warning systems based on forecast of inundations/water levels derived from basin runoff models

3 A2: Weather warning/forecast system World Meteorological Organization World Weather Information Service Official Forecasts Weather warnings (mainly rainfall, wind,..) are issued

4 A3:What are the criteria for issuing the flood warning? Pre-defined water levels at selected gauging stations, e.g. major flood, minor flood etc. A4: Channels (from whom to whom) and technical means of communicating the flood warning to the local communities and to disaster management authorities. Electronic media, telecommunication systems A5: Flood awareness raising and preparedness activities (including training of using the system ) part of the System? Through programmesof Disaster Management Centre, Ministry of Disaster Management

5 Though real-time data is acquired, flood/inundation forecast and early warning based on basin model analysis are yet to be mainstreamed for DRR Such exercises are done at universities/research instututions, and some examples are given here: 1. Rainfall Forecasting and Flood Inundation along the Lower Reach of Kelani River Basin S.B Weerakoon 1, Srikantha Herath 2, Gouri De Silva 1 1 Department of Civil Engineering, University of Peradeniya, Peradeniya, Sri Lanka 2 United Nations University, Shibuya-ku, Tokyo, Japan

6 Kelani River Basin Elevation distribution (DEM) Flood inundation in Colombo and suburbs createheavyeconomicdamages 6

7 Weather forecasting for flood warning - to provide early warning on rainfall and floods Rainfall forecasting using downscaling of regional climate model data by Weather Research and Forecasting (WRF) model Inundation modeling in the lower Kelani basin using FLO-2D model Also, flood inundation analysis were done under changing climate.

8 Graphical output of WRF model Input data downloaded from NCAR web site

9 Validation HEC HMS was used to compute inflow into the lower basin at the upstream Time series of observed and simulated flow at the D/S gauging station during May 2010 flood F = 73% Observed Inundation extent (from DMC data) Simulated Inundation extent

10 Results Inundation extents due to 50 year return period rainfall under A2 scenario Inundation extent correspond to 50 year return period rainfall under B2 scenario Inundation extents due to 100 year return period rainfall under A2 scenario Inundation extent correspond to 100 year return period rainfall under B2 scenario

11 2. Flood modeling in the Kalu Ganga Basin (AWCI) Gouri Silvaetal, UNU,UoP Eheliyagoda Dediyawala # PUTUPAULA Geekiyankanda # ELAGAWA Galatura Group Halwathura Estate RATNAPURA # Gonapinugala Ratnapura Lellopitiya Estate Alupola Estate Watapotha Estate Welandura Estate Balangoda Horagoda Veddagala Panilkanda Lauderoale Group

12 KaluGnagabasin. Weather modeling by WRF for Arrangement flood prediction of threeand domains flood warning Gouri Silvaetal, UNU,UoP Domain 01 Domain sizes Domain 01: 1350km x 1350km (27kmx27km cell) Domain km x 450 km (9kmx9km cell) Domain 01 Domain 02 Domain km x 150 km (3kmx3km cell)

13 3. Flood inflows to DeduruOyaReservoir for anticipatory flood water management Sampath, UoP, UNU Deduru Oya Reservoir

14 DeduruOyariver basin and nested domains for WRF model downscaling HEC-HMS Rainfall Runoff Model was developed to generate current and future inflows at Deduru Oya reservoir site.

15 DisasterMitigationinSriLanka - Response to flood disasters for recovery (attended by State and NGOs, Donors) - Disaster Risk Reduction (Yet to be givenneededattention)

16 Thank you