| Abstrak/Abstract |
Wadaslintang Reservoir located in the District of Purworejo Central Java Indonesia with the cathment area is 192.58 km2. It’s was built in 1989 with a capacity of 443 million m3 and provide the water for various needs such as irrigation, fishery, power house, industry, household consumption and others. In dry season, amount of water will be reduced and cause the water need can’t be fulfilled especially for irrigation. To solve that problem, needs to arrange a good water resources management and it’s required a good instrument to measure water availability accurately.This research aim to predict the water availability upstream of Wadaslintang Reservoir by make a rainfall zonation base on the rainfall data availability that measured in fours of rain gauge in different elevation at upstream watershed of the reservoir. Rainfall zonation implemented using principal of Thiessen Method and the annual water availability calculated with Tank Model using rainfall and climate data fromthe year 2001 to 2010.The result show that the largest area of rainfall zonation is Wadaslintangwith area 63.44 km2, Limbangan with area 51.14 km2, Kaliwiro with area 43.73 km2 and Sumberejo with area 34.21 km2. The total annual water discharge of that area is 353.31 million m3, where the highest water discharge is from Limbangan area with water amount is 103.39 million m3, and then Wadaslintang is 102.69 million m3, Kaliwiro is 81.32 million m3 and Sumberejo is 65.91 million m3. |
