Hydrogeology Conceptual Model of Ponorogo-Ngawi Groundwater Basin in Ngawi Regency

The Ponorogo-Ngawi groundwater catchment area encompasses seven regencies in Central and East Java. Ngawi Regency, the largest rice producer in East Java (6.39 tons/ha), uses groundwater from the groundwater catchment area for irrigation. Increased agricultural productivity has been linked to the growing demand for groundwater. Excessive groundwater extraction can reduce both quantity and quality. To maintain groundwater availability, the Ngawi Regency requires proper planning and management. This study aimed to comprehend the water flow patterns within aquifers by creating a conceptual hydrogeological model. Geological and hydrogeological analyses were also conducted. The geological analysis is based on mapping and borehole data, whereas hydrogeological analysis relies on well measurements, water-quality tests, and water-balance analyses. The hydrogeological conceptual model of the research area describes the lithology as comprising lava, claystone, limestone, tuff, volcanic breccia, sandstone, and alluvium. Volcanic breccia and sandstone act as aquifers. The research area features confined and unconfined aquifers, with the groundwater level elevation in the research area ranging from 43.3 to 611.62 m above sea level. Groundwater flow patterns move from Mount Lawu towards the Bengawan Solo and Madiun Rivers and from the northern hills towards the Madiun River, with a groundwater recharge of 604 mm per year.