The MRC Mekong Flood Forecasting and MRC Flash Flood Guidance Systems

Transcription

1 MEKONG RIVER COMMISSION The MRC Mekong Flood Forecasting and MRC Flash Flood Guidance Systems NGUYEN TIEN KIEN Regional Flood Management and Mitigation Centre Phnom Penh, Cambodia

2 Outline 1. Operational data for flood forecasting in the RFMMC 2. MRC River Flood Forecasting System 2.1 Unified River Basin Simulation model 2.2 ISIS Hydrodynamic model 2.3 Delft - FEWS 3. MRC Flood Guidance System 4. Conclusions and Individual Plans

3 MEKONG RIVER COMMISSION 1. Operational data for flood forecasting in the RFMMC

4 Data Availability Daily Satellite Rainfall Estimates (SRE) and Numerical Weather Prediction (NWP) gridded data Daily rainfall manual data from 131 stations (as of May 2009) Water level manual data from 49 stations (12-hrly and daily) AHNIP telemetry data (hourly) from 20 stations HYCOS telemetry data (15 min) from 34 stations GTS rainfall data from 112 synoptic stations coving the entire Mekong River Basin

5 Daily receiving of hydro-meteorological data from the four riparian countries: - telemetry system - SMS (manual) data through a software package : HydMet management software The HydMet is the primary database management system by which rainfall and water levels observations are collected from the riparian countries and collected for use within the new flood forecasting system. The HydMet is installed in the main national line agencies of the MRC Member Countries and the RFMMC.

6 MEKONG RIVER COMMISSION 2. MRC River Flood Forecasting System (MRCFFS)

7 URBS Delft FEWS ISIS

8 ISIS + Regression URBS 22 Stations in the mainstream 1. Chiang Saen 2. Luang Prabang 3. Chiang Khan 4. Vientiane 5. Nong Khai 6. Paksane 7. Nakhon Phanom 8. Thakhek 9. Mukdahan 10. Savannakhet 11. Khong Chiam 12. Pakse 13. Stung Treng 14. Kratie 15. Kampong Cham 16. Phnom Penh Bassac 17. Phnom Penh Port 18. Prek Kdam 19. Koh Khel 20. Neak Leung 21. Tan Chau 22. Chau Doc

9 Unified River Basin Simulator (URBS) Semi-distributed non-linear hydrologic network model Ability to model spatial & temporal variability of rainfall Specifically tailored for flood forecasting Combines: - rainfall-runoff model - runoff-routing model

10 URBS (con t) 52 URBS models, covering > 740,000 km 2 and represented by over 2,217 subcatchments, were developed and calibrated: - 49 runoff routing models are linked together - 3 channel routing models: Chiang Saen to Kratie Tonle Sap system Kratie to Tan Chau/Chau Doc.

11 ISIS Hydrodynamic Model ISIS is a generic 1D model for the simulation of unsteady flow in channel networks. The ISIS model within the FFS starts at Stung Treng to the South China Sea, including the Tonle Sap Lake and Floodplain, the Cambodian floodplains and the Vietnamese Mekong Delta. The extent of downstream boundaries of the model are at the mouths of the Mekong (and the West Sea). Tributary inflows supplied to the model are obtained from the URBS.

12 Delft-FEWS as a data management and modeling platform. FEWS collates rainfall and water level inputs, runs the set of URBS models, manages the model results and publishes the flood forecasts. FEWS Stand alone system : data in the database is not shared with others, but whole database can be copied FEWS Client-serve (on-line) system: - central location to do the calculations and to store the data - users in different offices are connected via RFFMC network, synchronising with the central database when they need data

13 MEKONG RIVER COMMISSION 3. MRC Flash Flood Guidance System (MRCFFG)

14 Background The MRCFFG system has been developed by the U.S. Hydrologic Research Center (HRC) through a program funded by the U.S. Agency for International Development (USAID) - Office of US Foreign Disaster Assistance (OFDA). Completely set up and installed at the RFMMC in early September, The MRCFFG is designed to provide flash flood guidance information on a small basin scale across the four riparian countries MRC. The primary mission of the MRCFFG system is to provide realtime informational guidance products pertaining to the imminence of potential small-scale flash flooding throughout the region of application.

15 MRCFFG System MRCFFGs is a diagnostic system for flash floods to produce forecasts and ultimately warnings for flash floods. It is not a predictive system The system provides warnings for flash floods from intense rainfall events through the use of satellite and gauge-based rainfall estimates. A user-friendly interface provides quantitative real-time diagnostic information that may be used by the forecaster in conjunction with other local forecast information.

16 MRCFFG System Design Overview The RFMMC receives data from 4 riparian countries Various models are applied These data together with Satellite rainfall data are processed inside the Computational Server The products are provided to dedicated national agencies on the Dissemination Server

17 MRCFFG Dissemination Server User Interface to provide organized and convenient access to downloadable data products for local acquisition to facilitate preliminary product review in order to focus forecaster attention on urgent points of interest relating to potential flash flooding to facilitate the quality control and operational management efforts of forecasters and system administrators

18 MRCFFG Operational Output Products

19 HE MAP Hydroestimator satellite precipitation, un-biased corrected rainfall for 1, 3, 6, and 24 hour accumulations Mean areal precipitation for each basin for 1, 3, 6, and 24 hour accumulations based on bias-corrected satellite rainfall estimates

20 Average Soil Moisture (ASM) Soil water saturation fraction for the upper zone of the Sacramento Soil Moisture Model for each of the MRCFFG subbasins. Updated every 6 hours at 00, 06, 12 and 18 UTC.

21 Flash Flood Guidance (FFG) the amount of rainfall of a given duration (1 6 hours) over a small basin needed to create minor flooding (bankfull) conditions at the outlet of the basin.

22 Flash Flood Threat (FFT) the amount of rainfall of a given duration in excess of the corresponding FFG value. The FFT, when used with existing or forecast rainfall, is an index that provides an indication of areas where flooding is imminent or occurring and where immediate action is or will be shortly needed.

23 The system can detect the storm activity and compute the change of soil moisture

24 The FFG can show potential critical flash flooding The system can identify FFT in some areas

25 MEKONG RIVER COMMISSION 6. Conclusions and Individual Plans

26 Conclusions The MRC Mekong FFS is user-friendly, flexible, robust in flood forecasting and provides a platform for the incorporation of new models. The availability and quanlity of both hydrological and meteorological (rainfall) data as inputs for models are highest priority because of deciding factors for forecast result and accuracy. Facets of the models and modelling system need to require refinement. The RFMMC will maintain and operate the MRCFFG servers. Even though the both FFGCS and FFGDS servers are designed to be fully automated, there will always remain a critical need for ongoing observation and quality control. The RFMMC will be required to perform frequent observations of the MRCFFG system processing to ensure that the system s automated features are working properly.

27 Individual Plans Improvement of forecast rainfall by using data from different sources may provide higher frequency and better accuracy. Improvement for model calibration by updating the rating curves and other parameters at stations along the Mekong mainstream to be supported by Line Agencies, especially at main forecast stations. Since the current system is capable in producing medium-term forecasts up to 10 days, in advance, forecasts can be made available to a designated national flood forecasting agencies for their internal uses. A second forecast cycle and product dissemination as appropriate during critical flood conditions should be initiated which would provide valuable additional information for Member Countries. Preparation for MRCFFG implementation during flood season 2010.

28 THANK YOU VERY MUCH FOR YOUR ATTENTION