HYDROLOGICAL DYNAMICS AND IMPACTS IN THE PEATLAND WATERSHED OF SOUTH SUMATRA, INDONESIA

Abstract

Climate change and human activities, such as El Niño, agricultural drainage, and deforestation, have caused hydrological problems in peatlands. This study employed remote sensing to assess hydrological dynamics, variations in the moisture stress index, and vegetation health in the peatland watershed of the Sugihan–Saleh Peat Hydrological Unit from 2005 to 2024. Hydrological modelling, utilizing the Soil Conservation Service Curve Number approach, revealed variations in surface runoff and water storage across land cover types. The study area experienced a significant water deficit during El Niño events. Furthermore, reducing tree cover during these extreme drought seasons led to increased runoff in the following years. Due to restoration activities, the area of bare land/sparse vegetation decreased slightly from 37.69 ha in 2015 to 28.42 ha in 2024. Tree cover generally increased from 3,932.67 ha in 2015 to 7,646.74 ha in 2024, improving soil infiltration and lowering runoff. Bare land/sparse vegetation contributed the most to surface runoff, 29%. In contrast, the area of tree cover, dominated by peat forest, had the lowest runoff contribution (6.6%) and the highest storage capacity. The study highlights the moisture retention in tree-covered areas, with surpluses in rainy seasons and deficits in dry seasons, particularly during El Niño events. Conservation areas show better moisture conditions and better water resource management. Long-term monitoring and modifying cultivation practices are needed for peatland sustainability.