|LE DUC, TRUNG - Mekong River Commission Secretariat|
|GASSMAN, PHILIP - Iowa State University|
Submitted to: International Agricultural Engineering Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/12/2008
Publication Date: 1/1/2009
Citation: Rossi, C.G., Srinivasan, R., Jirayoot, K., Le Duc, T., Souvannabouth, P., Binh, N., Gassman, P.W. 2009. Hydrologic evaluation of the lower Mekong River Basin with the Soil and Water Assessment Tool model. International Agricultural Engineering Journal. 18(1-2):1-13.
Interpretive Summary: The Mekong River basin serves over 60 million people and has an average annual runoff of 475,000 million m3. A Water Utilization Program was developed by the Mekong River Commission so that an agreement between the countries impacted by the Mekong River water would use the river for development in a sustainable and equitable manner. The Lower Mekong basin includes the four downstream riparian countries of Laos PDR, Thailand, Cambodia, and Vietnam. The SWAT (Soil and Water Assessment Tool) Hydrological Model has been applied to generate the runoff for each subbasin, a total of 138 subbasins, covering the areas upstream of Kratie, catchment areas around the Great Lake, and some part in Vietnam. Due to its successful simulations the SWAT model can be used as a water management tool for large river basins such as the Mekong River Basin.
Technical Abstract: Recently the Mekong River Commission (MRC) has developed a computer package so-called Decision Support Framework (DSF) under the Water Utilization Programme (WUP). The development was aimed to implement the 1995 Agreement on the Water Utilization with sustainable development and equitable manner of the four riparian countries. Within the package, there are five main parts, including Knowledge Base (KB), three Simulation Models, and Impact Analysis Tools (IATs), and the information can be internally transferred between each other. However, this paper has been scoped with the Hydrological and Basin Simulation Model of the package. The SWAT (Soil and Water Assessment Tool) Hydrological Model has been applied to generate the runoff for each sub-basin, total 138 sub-basins, covering the areas upstream of Kratie, catchment areas around the Great Lake and some part in Vietnam. Firstly, the SWAT model parameters for the headwater catchments were calibrated against gauged flows, then transferred to the ungauged sub-basins based on proximity and similarity of soil types and land uses. SWAT calibration for the sub-basins of instream reaches and mainstream was also considered. The evaluation results for model calibration show that the Nash-Sutcliffe efficiency monthly efficiency values generally range between 0.8 and 1.0 at all of the key monitoring stations. The SWAT model version 2003, which is embedded inside the Decision Support Framework (DSF), is one of the first official hydrological models to be used to simulate the Lower Mekong River Basin. The Mekong River basin is the largest area the SWAT model has attempted to hydrologically simulate. Due to its successful simulations of gauged and ungauged subbasins, the SWAT model can be used as a water quantity management tool for large river basins such as the Mekong River Basin.