Author(s): Ngo Le An; Ilyas Masih
Linked Author(s):
Keywords: Reservoir operation; Sesan; SWAT model; WEAP model; Hydrologic regime
Abstract: The transboundary Sesan river sub-basin is the “hot-spot” area for reservoir development the Lower Mekong region with 7 reservoirs built in Vietnam territory and 2 reservoirs going to be built in Cambodia territory. The operation of these reservoirs will cause changing of the flow regime the detailed assessment of which is necessary for developing integrated water management strategies. This study examines the impacts of the reservoirs on the hydrologic regime. The analysis is based on SWAT model application for simulating river flows for gauged and ungauged catchments that was input into the WEAP model which was used for water balance estimation and reservoir operation. The result of SWAT model is the “base scenario” which is used to compare with “reservoir scenarios”. The WEAP model is established to estimate the water balance including irrigation activities and hydro-power generation. Two reservoir operation scenarios are selected for the study as the maximum hydro-power capacity generation with (W) and without (WO) taking into account the minimum flow in downstream at the Vietnam border with Cambodia. The results of the study show that both “reservoir scenarios” will cause the volume of flow increase in dry period (December-June) from 20% (WO) to 40% (W) on average, and reduce in high flow period (July-November) from 3% (WO) to 8% (W). The month with highest flow in base scenario is September but it changes to August (W) or July (WO) with the tested reservoir scenarios. The results also show that the full hydropower generation capacity can be achieved only three months from July to September in most of the years. During October to June, hydropower cannot be generated to full capacity due to limitations of water availability and storage. Regardless of lack of information, the study shows the reasonable assessment of the impacts of the tested reservoir operation scenario on the hydrologic regime while using SWAT and WEAP models. This study can be developed to assess the impact of climate change and evaluating more options for reservoir operations and water allocation in the context of transboundary rivers in the region.
Year: 2014