BEBERAPA SKENARIO PENGGUNAAN LAHAN UNTUK PERBAIKAN KONDISI HIDROLOGI DI DAERAH ALIRAN SUNGAI CIDURIAN (Land use scenarios for hydrological conditions improvement in Cidurian Watershed)

Cidurian Watershed is one of the watersheds in Java Island that is classified as a watershed to be restored. The performance of Cidurian Watershed, from upstream to downstream, is classified as poor. This research aims to 1) assess the hydrological characteristics of Cidurian Watershed using the SWAT (Soil and Water Assessment Tool) hydrological model; 2) assess the hydrological performance based on the prepared simulation scenarios; and 3) formulate successful strategies of Land and Forest Rehabilitation for Cidurian Watershed based on the best scenario. Various land use and management scenarios were simulated using SWAT to estimate their impact on the hydrological characteristics of the Cidurian Watershed. The applied scenarios are as follows: 1) Implementation of Spatial Planning of Banten and West Java Province; 2) Implementation of Forest and Land Rehabilitation with vegetative planting and; 3) Implementation of Forest and Land Rehabilitation for vegetative planting and combined with Soil and Water Conservation measures. The calibration and validation of the model showed a satisfactory category with NSE values of 0.53 and 0.50, respectively. All scenarios result in a better improvement on hydrological responses compared to the existing conditions in 2020. The surface runoff and sediment yield decreased and the lateral flow and base flow increased. The scenarios reduced the value of the Annual Flow Coefficient and Flow Regime Coefficient. Implementation of Forest and Land Rehabilitation and Soil and Water Conservation is the best scenario with Annual Flow Coefficient and Flow Regime Coefficient values 0,27 and 22.40.