Pengaruh Generalisasi Unit Lahan pada besarnya Erosi (Studi kasus di DAS Air Nelas, Propinsi Bengkulu)
Abstract: The research aims to
identify the effect of land unit generalisasion on the erosion at the Air Nelas
catchment area in Bengkulu Province. Land unit generalisation is one step to be
done in arrangin RTL-RLKT (Rencana Teknik Lapangan-Rehabilitasi Lahan dan
Konservasi Tanah; Field Planning for Soil Rehabilitation and Conservation) conducted
by Balai Pengelola DAS (formerly Balai RLKT).
Method applied by conducting digital analysis using GIS Program to
calculate erosion of the catchment area with USLE (Universal Soil Loss
Equation) formula. Comparison analysis was done between the result of erosion
before and after land unit generalisation. Land unit generalisation is a
process to eliminate land unit having area 1 cm2 on map or 25 hectares on the
field at the scale of 1:50.000. The instruction to run generalisation in
ArchInfo GIS program is ELIMINATE. Land unit generalisation is done to simplify
map analysis manual by avoiding land unit which is very small in the area.
The research result showed that for the whole Air Nelas catchment area
the erosion rate was 601,279.49 ton/ha/year before generalisation and
267,907.54 ton/ha/year after generalisation, indicating that there was a
33,371.95 ton/ha/year difference or 55.44% as the effect of land unit
generalisation process. When the observation was mainly at the area of
rehabilitation and conservation, there were categorical changes of the erosion
i.e. from Moderate to Heavy or Very Heavy and vice versa. The change was
varying between 148,244.82 ton/ha/year (Moderate to Very Heavy) and 79,470.62
ton/ha/year (Very Heavy to Moderate). Overall, the erosion was increaasing aas
65,335.90 ton/ha/year (11,01%) for the whole category in area where
rehabilitatin and conservation have to be conducted. Those changes would affect
the plan which determine recommendations to be taken in rehabilitation and conservation
of catchment areas, as well as change in the project location and budget.
Keywords: generalisation, land
unit, erosion
Penulis: Bambang Sulistyo
Kode Jurnal: jpkehutanandd080006
