Preliminary assessment of water balance at Mayang watershed, East Java

Abstract

Mayang watershed is prone to hydrological disasters. The watershed is subject to flooding events during the rainy season, and potentially prone to drought risk during the dry season. This study aims to assess the sustainability of water balance on the watershed using the Water Evaluation and Planning (WEAP) model. Supply water comes from rainfall. Demand is calculated based on the need for irrigation, domestic, urban, industrial, and livestock uses. The unit of time to calculate the water balance is ten days. In one month it is divided into three periods. WEAP modeling is based on current water requirements. The results showed that from 2002 to 2019, the available water resources were not able to meet all water demand throughout the year. Unmet demand occurs from May 2nd to December 2nd. From December 3rd to May 1st, the Mayang river and its tributaries were able to supply the water for all demand sites up to 100%.