LAUSR

The Lembata Regency, which is located on Lembata Island in eastern Indonesia, is a region with high water scarcity. Appropriate efforts should be made to ensure the drinking water supply in the area. A water supply-demand analysis is needed to determine the condition of water sources (surplus or deficit). Water supply is determined based on rainfall data, while water demand is calculated based on domestic, nondomestic and irrigation needs, including evapotranspiration. Evapotranspiration is calculated using the Thornthwaite method. The results showed that a water deficit would exist in the Lembata Regency in 2033 for seven months per year (May to November), although the amount of accumulated water in one year would still be surplus. Therefore, it is recommended to store water in a raw water reservoir during the rainy season for use during the dry season. The minimal total reservoir capacity is 95,000,000 m3, and the reservoir should be spread among watersheds in Lembata. The raw water reservoirs need to be lined with a geomembrane to prevent lost water from seeping into the soil.