[en] The Tonle Sap Great Lake and the Mekong River in Cambodia have huge floodplain suitable for rice-based farming system and potential water resources for farming. Studies to exploit the flood and the water resources of the lake and the river have not been well conducted yet. Batheay irrigation system is located in the floodplain of the Tonle Sap River and the Mekong River. In this research, the irrigation system is studied as a model site for future development of the floodplain of the Tonle Sap Great Lake and the Mekong River. Batheay reservoir directly receives floodwater from the Mekong. It functions as both a reservoir and a paddy field. In wet season, dike around the Batheay reservoir prevents floodwater from entering the reservoir. Rainy season rice is grown inside the reservoir. After harvesting, gates around the reservoir are opened to receive floodwater. The water is stored for cultivating dry season rice outside the reservoir. In this work, we attempt to study water management of the Batheay irrigation system by analyzing water use pattern in the irrigation system and uncover effectiveness of the system. A development scenario for the floodplain of the Mekong River is then proposed.
