Groundwater Management Based on Vulnerability to Contamination in the Tropical Karst Region of Guntur Spring, Gunungsewu Karst, Java Island, Indonesia

摘要

The purpose of this study was to examine the most suitable groundwater vulnerability method and formulate karst groundwater vulnerability management based on the distribution of the resulting vulnerability class. The most suitable groundwater vulnerability method was selected with a tracer test as well as by analysing its compatibility with the conditions of the study site, distribution of the vulnerability classes, spatial autocorrelation and comparison with other studies. The study was conducted on Guntur Spring, which is one of the tropical karst springs located in the western region of Gunungsewu Karst, Java Island, Indonesia. This perennial spring is used by approximately 1,000 people. This spring has the potential to be polluted due to the characteristics of the catchment area, which typify the connectivity between the surface and subsurface flow systems. The management of the Guntur Spring catchment was based on the distribution of vulnerability classes that are also adapted to the geomorphological, hydrogeological and land-use conditions. The analysis showed that EPIK is the most suitable method compared with COP, PI and PaPPIKa. The recommended management of the karst groundwater vulnerability included: (1) creating a protective structure at swallow holes; (2) reforestation and erosion management of thin soils on the crest of the karst hill; (3) addition of multilayer vegetation coverage to the upper, middle and bottom layers of the cockpit karst; (4) land-use and fertiliser limitations in the karst valley; and (5) restrictions on land use that produces pollutants around the lineaments, underground rivers and recharge points.