The Impact of Land Use on Hydrological Characteristics and Erosion Rate of Cilutung Watershed with SWAT Model

Abstract

Cimanuk watershed will be affected directly by the dynamics of Cilutung watershed as one of its tributaries. Cimanuk is one of the watershed areas in West Java Province, that is categorized as a critical potential due to erosion and vegetation damage. This study aims to simulate hydrological conditions and erosion rates for each sub-watershed. This research uses several variables: 1) soil type; 2) topography; 3) land use; and 4) climate (temperature, rainfall, solar radiation, wind speed, and relative humidity). Analysis conducted is Hydrology Response Units (HRUs) and statistical analysis. Variable physical characteristics are processed by the overlay method for HRUs analysis. Statistical analysis showed the values of R2 and NSE were 0.48 and 0.32. Based on the calibration and validation results, the values of R2 and NSE are 0.75 and 0.46. This shows a satisfactory and acceptable model. The runoff value tends to show a moderate category between 50-80 in the category of Coefficient of Flow Regime and this is precisely proportional to the rate of erosion. Each sub-watershed shows a high runoff value, tends to produce high erosion rate as well and its reverse. The rate of erosion indicates 175.0 tons/ha / year in the medium category.

Determination of Flood Susceptibility Index Using Overlay-Scoring Data Method based on Geographic Information System (GIS) in Semarang City, Central Java, Indonesia

“…Guidelines for the use of flooded area space (Directorate General of Spatial Planning, 2003), the factor of natural conditions with the shape of a plain or basin is one of the characteristics of areas prone to flooding or inundation. The slope affects the number and speed of runoff, surface drainage, land use and erosion (Fadhilah et al, 2018). It is assumed that with more slope, then the runoff flow will be slow and the possibility of inundation or flooding becomes greater while getting steeper the slope will cause surface runoff to be fast and not inundate the area, so the risk of flooding is small.…”