Groundwater Recharge Assessment using Geographic Information System APLIS Method in Donorojo Karst Area, Pacitan

Karst aquifers can be a source of water supply, especially for the community in Donorojo District, which is one of the areas with the worst drought crisis in Pacitan Regency and requires a sustainable solution to the problem of water needs. Therefore, the study and management of karst formations are very important because of their abundance and potential in forming subsurface aquifer karst aquifers. The recharge rate is one of the basic parameters in the management of the consumption and maintenance of this resource. In addition, the distribution of aquifer locations, aquifer characteristics, and the quality of groundwater forming the aquifer need to be known. This study aims to assess aquifers in the Karst area of Donorojo, Pacitan based on recharge rate and spatial distribution. The APLIS method can estimate surface recharge rates and present the results as a map of the spatial distribution of aquifer recharge rates by utilizing a Geographical Information System (GIS). The results of the analysis using the APLIS method, the groundwater recharge rate in the Donorojo Pacitan karst area is divided into 4 classes, namely very low, low, moderate, and high. Almost the entire Donorojo karst area has a high groundwater recharge rate, this means that the area needs to be used as a groundwater protection zone and it is important to carry out good groundwater management, especially to overcome the problem of drought.

Application of the APLIS Method for Groundwater Vulnerability Assessment in Rote Island Karst Areas

The karst area on Rote Island dominates more than 60% of the Island. The land surface conditions in karst areas are generally dry, while below the subsurface is the potential for abundant water resources. This study aims to assess groundwater vulnerability using the APLIS (Altitude, Pendiete/Slope, Lithology, Infiltration, and Soils) method that will integrate with Geographic Information System (GIS) technique. The parameters used are elevation, slope, lithology, infiltration zone, and soil type. Slope and elevation are obtained from DEM maps, the soil is obtained from soil type maps, while lithology and infiltration zone are obtained from geological maps. The lithology and the infiltration zone in APLIS method analysis have a high role in determining the level of groundwater vulnerability. The groundwater vulnerability in Rote Island was divided into four classes: very low in the Northeast, low in the South, moderate in the East and North, and high in the East and West part of the Island. It explains that a high level of groundwater vulnerability in Rote Island needs to be used as a groundwater protection zone.