Hydrological Response to Land Use/Land Cover Projection in Cisadane Watershed, Indonesia

Abstract

The Cisadane Watershed is in a critical state, which has resulted in the expansion of residential areas upstream of Cisadane. Changes in land use and cover can impact a region's hydrological characteristics. The Soil and Water Assessment Tool (SWAT) is a hydrological model that can simulate the hydrological characteristics of the watershed affected by land use. This study aims to evaluate the impact of land use change on hydrological characteristics and variations in inflow and outflow to develop optimal recommendations for land use in the Cisadane sub-watershed using different scenarios. The models were calibrated and validated, and the results showed satisfactory agreement between observed and simulated streamflow. The main river channel is based on the results of the watershed delineation process, with the watershed boundary consisting of 85 sub-watersheds. The hydrological characteristics showed that the maximum flow rate (Q max) was 12.30 m³/s, and the minimum flow rate (Q min) was 5.50 m³/s. The study area's distribution of future land use scenarios includes business as usual (BAU), protecting paddy fields (PPF), and protecting forest areas (PFA). The BAU scenario had the worst effect on hydrological responses due to the decreasing forests and paddy fields. The PFA scenario provided the best hydrological response with a significant reduction in surface flow, lateral flow, and groundwater due to increased water infiltration, as well as increased water yield and evapotranspiration. Therefore, it is vital to maintain green vegetation and conserve land to support sustainable water availability.