Hubungan Geomorfometri dengan Bentuklahan dan Penggunaan Lahan (Studi Kasus: DAS Cileungsi-Citeureup, Kabupaten Bogor).

Abstract

The image interpretations for landform mapping are mostly carried out visually, since the landforms can’t be indentified solely from land cover spektral. To reduce the subjectivity of visual interpretation, the quantitative analysis of geomorfology (geomorphometry) is expected to facilitated for landform’s identification and delimitation objectively. TWI (Topographic Wetness Index) and TRI (Terrain Ruggedness Index) are some of geomorphometric analysis that can be attempted to that purpose, especially for erosional and depositional landforms. This study took place in the Cileungsi- Citeureup Watershed, Bogor Regency, and aims to: (1) determine the type and distribution of landform in the study area, assess the value of TWI and TRI, and understand the relationship between landforms to TWI and TRI; (2) determine the type and distribution of land cover/land use and to understand the relationship between land cover/land use to TWI and TRI. The method for landforms and land use mapping is visual interpretation and on-screen digitization respectively on Shuttle Radar Topography Mission (SRTM) hillshade (30m resolution) and IKONOS imageries. The TWI and TRI were assessed from SRTM’s digital elevation models (DEMs) using SAGA and ArcGIS softwares. The result shows that the landforms of study area can be divided into 24 types, and based on the morphography and morphogenesis the dominant landforms are denudational hills. The relationship between landforms and TWI is illustrated by the distribution of TWI’s dry class on mountainous areas, the moderate class covers almost all of landforms, and the moderately to wet classes covers the valley and plain landforms. As for the relationship to TRI, it is illustrated by the dominant distribution of TRI’s rough class on the mountainous landforms, the moderate class on the hillslopes, and the smooth class on the plains landforms. According to the land use interpretation and classification, it can be divided into 5 type where the mixed gardens and dry field crops are the most widely types, respectively 45.31 km2 (25.70%) and 42.08 km2 (23.86%) of study area and covering the hilly areas. In relation to TWI and TRI, the mixed gardens and dry field crops spread out dominantly in the moderately dry TWI areas and in the moderately smooth TRI areas.