Monitoring of Water Utilization and Water Balance on Agriculture Fields in Nganjuk, East Java, Indonesia

In the dry season, water shortage has occurred in Nganjuk, East Java, Indonesia. The northern area of Nganjuk irrigation blocks was drier than southern area, and downstream in southern area was drier than upstream area. Regardless the water shortage, the farmers of these areas would like to increase productivity, cropping intensity and fanner's income by using shallow and deep wells. In the future, the utilization of groundwater for irrigation can be impact to land subsidence and can compete with other uses of groundwater such as domestic and industrial. The estimation of groundwater uses for irrigation is required for sustainable water resource management and farmers prosperities. Monitoring stations were installed in Nganjuk to analyze water balances. Shallow groundwater levels were monitored at four irrigation blocks. The discharge rates were monitored in river reaches of upper. middle and lower streams. The monitoring data of groundwater showed the tendency of recharge in rainy season and uptake in dry season. However, in southern area Mrican-Kiri block, the tendency was not clear. Groundwater levels in the southern area (Mrican-Kiri and Kuncir-Bodor blocks) were higher than those in northern area (Widas and Ketandan•Tretes blocks) in dry season. The rainfall and discharge rate data showed that the infiltration and percolation were high in the beginning rainy season. Base flows were increased in second month of the rainy season and peak discharge was around 6 mm d-I in the upper stream and approximately 2 mm d-l in whole watershed.