Climate change effect on water balance for water critically in upper Bogowonto Watershed, Indonesia

Abstract

Abstract The impact of climate change has hit Indonesia, especially in Central Java Province. Based on rainfall data between 1981-2017, there has been a trend of changes in intensity and a shift in rainfall patterns with an increase in temperature of 1.04°C/year. The focus of this study is in Bogowonto Watershed is located in Purworejo Regency, where the development of land cover has been increased and affected water demand in the area around the study location. The purpose of this study was to determine the conditions of rainfall due to climate change based on land cover conditions. The analytical method in this study is related to water availability with FJ. Mock and climate change with GCM with RCP scenario. The results obtained are: (1) The condition of annual rainfall in Bogowonto Watershed is still in the moderate category, with an annual rainfall of 2064.3 mm. Annual rainfall fluctuations are in adequate amount (200-500 mm per year); (2) The calculation of the WHC value of 104.92 shows that the ability of the land in the study area to store and bind water is low due to the type of soil that has shallow to moderate soil solum and the structure of the soil is kersai and sandy. Types of vegetation cover in the form of secondary crops with shallow parakaran zones also affect the value of WHC; (3) Meteorological water balance analysis can be concluded that the availability of water from rainfall in this area is quite high; (4) Water criticality index has a value of 0.66 which is included in approaching critical if water resource conservation is not carried out; (5) based on the results of climate change that occurs, for the next 40 years there will be changes in the intensity and pattern of rainfall distribution if climate change cannot be controlled and (6) The carrying capacity of Bogowonto watershed needs to be maintained by promoting plantation of useful vegetation in surrounding area of watershed.