Rainfall downscaling,flood modelling and GIS
ModuleExample
Training Application Workshop onExtreme Floods
Srikantha Herath
UNU-ESD

Initiative on Catastrophic Flood RiskReduction
at a Regional Workshop “Ensuring Flood Security for
Sustainable Urbanization in the Asia Pacific Region”,
2003
Bangkok Resolution:

The need for an Asia Pacific Initiative on Catastrophic Flood
Risk Reduction, and pledged support for the mission andgoals of this initiative by representatives from:

Bangladesh, Cambodia, China, Fiji, India,Indonesia, Lao PDR, Malaysia, Nepal, Pakistan,Philippines, Singapore, Sri Lanka, Thailand andVietnam

Program Phase I (Hands on – 3 weeks)¾ Training on GIS
 GIS system freely distributed¾ Setting up and application of Rainfall Downscaling

and forecasting system (DRF)¾ Setting up Flood inundation modelling andApplication (FMS) Phase II (Home country 3 months)¾ Transfer to others¾ Model application and verification with historicalfloods¾ Field survey for data collection

 Phase III(Hands on –b 3 weeks)¾ Risk Assessment: Economic losses and people atrisk

Various data sets from NK-GIAS
Basin boundaryDEMRiver lines

Thiessen polygons

Model set up and results from GIS Links
 The GIS system provides all thefunctionality required forhydrological modelling A special feature of the GIS systemis the ability to handle time series
data.
 Provisions to link static vocational
data to time series GIS data.

Realtime RF system

We use the global forecast(GFS data sets)
Weather Research andForecasting (WRF) Modelof NCAR, USA used fordownscaling
Automated systems
Use for scenario modellingReal-time Rainfall Forecasting and HydrologicalModeling platform at UNU
 Rainfall in selected regions areforecasted, 48h into the future.
 Rainfall products are madeavailable on the web, in a realtime basis.
 Works unattended every day.
Results ready around 17:00HJST (10:00H UT)Inundation Modeling: Damage Assessment andEvacuation
Damage Classification
Rainfall Input

Questionnaire survey& historical data

2D Overland Flow Model
Canopy Interception
Model
Evaporation Model

1D Stream Flow Model
Detailed landcover

Development of fragility(or stage-damage)functionsinformationy

DHM supplies: Flood data oneach grid (depth, duration,velocity)x

3D Richards' Equation for Unsaturated Flow

2D Groundwater FlowDistributed Hydrologic Model

Establish damage
estimation model foreach type of object

Flood Damage
Estimation in eachgrids using establishedmodels for each type ofdamage.

Output: estimateddistributed flooddamage

Damage Estimation ModelOrganizations
 Organized by UNU¾ Resources from: UNESCO-IHE, Monash University,Australia, Nippon Koei Co., Ltd., AIT, Thailand Participants –Professionals from a University andthe organization responsible for flood control trainers¾ China: Tsinhua University, Beijing Municipality¾ Nepal: Institute of Engineering, Department ofHydrology and Meteorology¾ Philippines: University of Philippines, PAGASA(Hydro meteorological Agency)¾ Sri Lanka: University of Peradeniya, Irrigation
Department¾ Viet Nam: Institute of Hydrology and Meteorology,
Department of Storm Control and Dyke ManagemetOutcomes Phase I – Training of trainers on GIS,

Rainfall forecasting and Flood modeling¾ A training text book with examples andstep-by-step manuals to set up and runmodels

 Phase II – Develop extreme flood

scenarios for each country.
 Phase III – A book on case studies andrecommendations
 A Community of researchers andpractitioners working on Extreme Floods

China: Beijing
 For example, on Aug 1st, 2007, the precipitation wasabout 80mm/h at Anhua bridge . After five days, theanother rainfall of 82 mm/h occured at the sameplace. Rainfall resulted in inundation of 3m on theroad.

China


Location: north of Beijing

The main branch ofWenyuhe basinRiver length: 23.7 km

Catchment Area: 210 km2

Beijing Olympic park is
located in this basin

Designed standard: 20years

 Output:Precipitation
WindTemperatureSimulation results: Surface Inundation

Observations
 Many participants were interested inoperational forecasting.
 Paring of educational andresponsible agency participants
proved to be very effective The module can be divided in to 3
sub modules and delivered according
to the needs of each country.

Thank you