Groundwater vulnerability zonation using Aplis and Foster method in The Ponorogo-Ngawi groundwater basin

Abstract

In 2021, Ngawi district became the largest rice producer in East Java. Groundwater is the main water source used for irrigation purposes. Lack of management for developing necessary irrigation wells has resulted in uncontrolled groundwater use, potentially reducing groundwater quantity and quality. This study aims to analyze groundwater vulnerability zones. An assessment was conducted using the Aplis and Foster methods, and their parameter classes can be customized to match the conditions of the research area. The Aplis method considers five parameters: altitude (A), slope (P), lithology (L), infiltration (I), and soil (S). The Foster method considers four parameters: aquifer response characteristics (RA), aquifer storage characteristics (DS), aquifer thickness (s), and groundwater depth (h). The vulnerability values obtained using the Aplis method ranged from 30 to 131 and were divided into four classes: low, moderate, high, and very high. The Vulnerability values obtained using the Foster method ranged from 10 to 15 for the low and moderate classes. A non-technical approach through the strict application of permits and restrictions on groundwater usage is a basis for formulating policies related to groundwater management in the research area.