Review the water balance of the Sempor Irrigation Area in Kebumen Regency

Abstract The Sempor Reservoir has a Catchment Area of 4,231 hectares. The catchment area of Sempor Reservoir has undergone land use change from green areas to residential areas, resulting in erosion. Erosion causes sedimentation in the reservoir, which affects the reservoir’s storage capacity. This study aims to review the needs, availability, and water balance in the Sempor Irrigation Area. The F.J. Mock model was chosen to calculate the water availability in the catchment area of Sempor Reservoir. This method estimates discharge from rainfall. The calculation results show that the highest water availability occurs in the first period of January, amounting to 5.20 million m 3 , while the highest water demand in the Sempor Irrigation Area occurs in the first period of May, amounting to 6.97 million m 3 . The Sempor Irrigation Area experiences a water deficit of 38 million m 3 . The catchment area of Sempor Reservoir can only meet 60% of the total needs of the Sempor Irrigation Area. Therefore, proper management of the Sempor Reservoir is necessary to maintain its storage capacity.