Presentation on theme: "Hydrological Modeling for Upper Chao Phraya Basin Using HEC-HMS UNDP/ADAPT Asia-Pacific First Regional Training Workshop Assessing Costs and Benefits of."— Presentation transcript:
Hydrological Modeling for Upper Chao Phraya Basin Using HEC-HMS UNDP/ADAPT Asia-Pacific First Regional Training Workshop Assessing Costs and Benefits of Adaptation: Methods and Data March 11-14, 2013 Dr. Dilip K. Gautam RIMES, AIT Campus, Bangkok
Hydrological Model A model is a simplified representation of reality. A mathematical model consists of series of equations defining the system we are dealing with. The function of model is to convert the given input into an output. A hydrological model is the mathematical representation of the response of a catchment system to hydrologic events during the time period under consideration. Hydrological phenomena are extremely complex, highly non-linear and highly variable in space and time. A model is needed to predict the watershed runoff for the design and management of water resources utilization and flood control projects.
Hydrological Model Outputs for Climate Change Impact Assessment Simulated flow peaks, volumes and hydrographs at the outlets of subbasins and the points of special interest such as reservoirs, weirs or other hydraulic structures Simulated long flow sequences for water budget and drought analyses Simulated extent of flooded areas for different precipitation events and various antecedent basin conditions
Hydrologic processes that need to be captured by the model Single-event precipitation-runoff transformation Continuous precipitation-runoff transformation Snow accumulation and melt Interception, infiltration, soil moisture accounting Evapotranspiration Regulated reservoir operation
HEC-HMS US Army Corps of Engineers, Hydrologic Engineering Center’s Hydrologic Modeling System software Designed to simulate both single event and continuous rainfall- runoff process Simulates precipitation-runoff and routing processes, both natural and controlled HEC-HMS uses a separate model to represent each component of the runoff process including: runoff volume; direct runoff (overland flow and interflow); baseflow; channel routing.
Key Components of Model Runoff Volume models: separate infiltration from pervious surface, runoff from impervious surface, compute the direct runoff volume Direct Runoff models: transform direct runoff volume from excess precipitation into fast component of flow Base Flow models: compute slow subsurface drainage component Routing models: compute flow attenuation and translation over channel Reservoir models: flow regulation
Data Required Digital Elevation Model (DEM), land use, soil types and other physiographic data Precipitation, temperature data Evaporation/evapotranspiration data Discharge, Water level and Rating curve data Channel and reservoir hydraulic data Generated sequence of meteorological data representing various scenarios of future climate
Upper Chao Phraya Basin, Thailand Catchment Area = 105553 sq. km.
Dams and Reservoirs Bhumibol dam in the Ping River (Storage 13462 MCM) Sirikit dam in the Nan River (Storage 9510 MCM) Kwae Noi dam in Kwae Noi River (Storage 766 MCM) Kiew Kor Mha dam in Wang River (Storage 171 MCM) Kiew Lom dam in Wang River (Storage 112 MCM)
Data preparation using HEC-GeoHMS Delineate catchment and river network Obtain catchment characteristics data (area, slope etc) Make Thiessen polygon Obtain Thiessen weights Prepare basin file
Conclusions Semi-distributed physically based deterministic hydrological models are powerful tools for assessing climate change impact on water resources. Continuous modeling approach could be taken to assess the impact on flow volume. Care should be taken to interpret the results as there are lots of uncertainties in the model inputs, parameters and structure of the model. Uncertainties associated with climate models will also be carried over.
Thank You ! Dr. Dilip K. Gautam, Senior Hydrologist, RIMES E-mail: firstname.lastname@example.org@rimes.int Website: www.rimes.int