Studi keseimbangan air di pulau Jawa

ABSTRACT Java as one of five principal islands in Indonesia, is only 6.9 % of the total area. However there is 60 % of total population or about 115 millions. Therefore Java is the most important island and the most developed area. This condition induces the increase in water demand, while the water availibility is constant or decrease. Study of water resources development in Java needs data of water balance. The study of water balance consist of calculation of the water availibility and of the water demand. According to the regulation of the Ministry of Public Works, Java is divided into 15 river territories or SWS. These 15 SWS are divided further into 28 river basin (DPS). The water balance is analysed in each DPS. This water balance analysis is made by assuming that : no reservoir or pond for water storage, no water transfer between basins, priority order for water demand is domestic, non domestic and industry as the first and followed by river maintenance, fish, livestock and irrigation. Monthly water balance in each DPS for every five year period are calculated through 1995 to 2020. The results of the study show that for annual basis consideration, Java is surplus of water about 64.5 billion m3/year in 1995. In the predicted year of 2020 the surplus of water is about 60 billions m3/year. For monthly basis consideration most of DPS is deficit of water in dry season. By increasing the irrigation efficiency from 0.5 to 0.65, we will be able to save about 31.3 billion m3/year