Abstract
Since the watershed of the Mekong River is situated under the typical monsoon climate, the Mekong River presents a distinct variation in its water levels between the dry and rainy seasons, and causes heavy inundation in the Delta area along the river every year. In order to analyze the inundation process and for agricultural practice, this study tried to establish three models: the Mekong Runoff Model, Tonle Sap Lake Water Balance Model and Delta Water Balance Model. The Tank Model consisting of 4 columns and 3 layers with a ground water layer was employed to calculate the runoff of the Mekong River and its sub catchments from Pakse to Kompong Cham. It was also used to estimate the inflow to the Tonle Sap Lake from its catchments. The daily water balance of the lake was formulated based on the relationship between the storage volumes and water levels of the lake surface. The deltaic area was divided into four zones, and the water balance of each zone was formulated by considering the zone's inflow/outflow between rivers and flooding areas. A combination of these three models could provide a basic framework for modeling the Delta inundation.
