Water balance evaluation in Penanggungan hamlet Wanayasa sub district Banjarnegara, district Central Java province

A key issue of watershed management in Indonesia is massive forest conversion in the upstream area. Forest conversion to agricultural land occurred in the Merawu watershed. Penanggungan Hamlet located in the upstream area of Merawu watershed, where the economic resources is potato (Solanum tuberosum L) farming. The agricultural and domestic water needs are supplied by 5 springs water in the surrounding areas. Intensive farming needs a large portion of water. Inefficient water utilization pattern and the El Nino phenomena may raise water competition among agricultural and domestic sectors in Penanggungan. Deficit water was occurred in the Penanggungan Hamlet, particularly in the dry session. The purpose of this study is to evaluate the water availability based on regional water balance and design the drought mitigation. Regional water balance focused in terms of demand and supply. The water demand covers daily household needs such as cooking, bathing, toilet, washing dishes, laundry, cleaning the floor, washing vehicles, watering yards, and drinking. The demand likewise comes from farming sectors for irrigation and pesticide application. The demand calculated for one year. A water need census in Penanggungan was conducted to acquire data on the amount of water per sector. Water supply calculated from the discharge of 5 springs for one year. Prediction of water needs used three parameters i.e., population, total household and agricultural water needs. This study reveals that the water demand in Penanggungan Hamlet is surplus until 2031 but in 2032 until then it experiences a deficit. © Published under licence by IOP Publishing Ltd.