wcm.02.2026.279.286

The Wanagama Forest represents a notable success in the rehabilitation of degraded karst landscapes. This restoration effort has not only enhanced vegetation cover but also contributed to the development of a favorable microclimate that supports ecological functions and human well-being. Over time, the forest has played an important role in improving water availability, which is essential for meeting the needs of nearby communities. Karst regions, including Wanagama, are typically characterized by limited water retention capacity and are highly vulnerable to seasonal drought, particularly during prolonged dry periods. Despite its recognized success in land restoration, studies focusing on the hydrological dynamics of the Wanagama Forest remain relatively scarce. Therefore, this study aims to (1) assess the water balance, (2) evaluate the drought index, and (3) determine the runoff coefficient within the rehabilitated forest area. The analysis applies the Thornthwaite-Mather approach to estimate water balance components, alongside calculations of the dryness index (la) and runoff coefficient (C). The results indicate an increasing trend in annual water surplus, reaching approximately 15.654 mm/year, accompanied by a rise in water deficit of about 9.014 mm/year. The calculated drought index of 1.15% suggests that the area experiences low drought stress and can be classified as having a non-critical water condition. In addition, the runoff coefficient ranges between 0.3 and 0.5, indicating a moderate proportion of rainfall contributing to surface runoff while a substantial amount infiltrates into the soil.