Ring dike system to harness floodwater from the Mekong River for paddy rice cultivation in the Tonle Sap Lake floodplain in Cambodia

Located in the floodplain of the Mekong River and the Tonle Sap River, Batheay irrigation
system and its reservoir directly receive floodwater from the Mekong. The Batheay reservoir
formedby a ring dike functions as botha reservoir anda paddy field. In thewet season, the ring
dike prevents floodwater fromentering the reservoir and rainy season rice is growninside the
dike. After harvesting, the gateson the ring dike are openedto receive floodwater. The water is
stored inside the dike for cultivating dry season rice outside the dike. In this paper, the
irrigation system is studied as a model site for future development of the floodplain of the
Tonle Sap Lake of Cambodia. Specifically, this paper is concerned with the study of water
balance and analysis of the hydrologic components of the Batheay irrigation system, and the
effectiveness of the ring dike system. The study found that floodwater of the Mekong River
contributed about 74% to the total inflow to the Batheay reservoir. Contributions to the total
water supply of reservoir water, floodwater remaining in the fields, and precipitation were 73,
12, and 15%, respectively. The efficiency of the systemwas found to be 92%. The dike system is expected to be a paradigm for the floodplain of the Tonle Sap Lake.