Catchment Area Analysis of Guntur Karst Spring Gunung Kidul Regency, Java, Indonesia

Abstract

Karst area has abundant potentials and distinctive characteristics. Its prospective resources are associated with karst aquifer. This condition makes the local people highly dependent on karst groundwater sources, especially in dry seasons. However, in this landscape, water is stored abundantly in the hardly accessible underground flow system. Therefore, drought is a persistent hazard in a karst region. These conditions can be identified by examining the water recharge and delineating the catchment's boundaries as the determinants of water resource potential in karst areas. The boundaries can be approached through the water balance method. The principle of water balance can be used to identify water distribution and storage in a catchment area. The primary data were the water level recorded automatically and the flow velocity Guntur Spring. The secondary data were rainfall statistics from 4 nearby rainfall stations and temperature records from 5 nearby meteorological stations. This study was conducted at a karst complex in Girijati Village, Purwosari District, Gunungkidul Regency. This study aimed to (1) identify the characteristics of Guntur Spring water recharge and (2) estimate the catchment area of the spring using the water balance approach. During the six months of the observation, the spring recharge zone received 1,658.6 mm of rainfall, lost up to 862.6 mm of water by evapotranspiration, and produced a discharge of 88.28 L/s at the spring. Based on the water balance calculation, the catchment area was 30.7 Ha. The nomogram and the topography-based delineation around Guntur Spring also affirmed this finding.