Assessment of Land Degradation Using Gis Based Model and Remote Sensing in Bishan Guracha-Adilo Subcatchments, Southern Ethiopia
No Thumbnail Available
Date
2007-07
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa Universty
Abstract
This study is aimed at assessing the spatio-temporal changes of land use / land cover and
identifying land degradation area in the form of soil erosion in Bishan Guracha-Adilo
subcatcments. The three landsat images (1973, 1984 and 2000) were classified into five
major land use / land cover classes based on supervised classification of 2000 image.
Post classification change detection among three classified images was conducted.
Accordingly, classes classified as intensively cultivated and degraded / barren lands were
expanding in areal coverage at the expense of others. However, moderately cultivated,
wood and grazing lands of the study area became reduced in size in the time span of 1973
to 2000. On the other hand, NDVI images analysis comparison also done to look into the
vegetation/ land cover degradation or change between 1984 and 2000 images, its result
implies a decline in land cover taking the standard deviation variation in to account.
Universal Soil Loss Equation (USLE) model was used for estimation of soil erosion
amount by computing each input mostly on the basis of the adapted methodology of the
previous researches for Ethiopian highlands. The estimated annual soil loss for the study
area ranges from 0.02 to 133.2 t/ha/yr. These values were classified in to six classes or
degree of soil erosion depending on the calculated soil erosion amount. Of which the last
class having greater than 30 t/ha/yr, which is 2470 ha (6%) is considered to be as priority
(spot) zone of the study area. In contrary, about 86% of the study area experiences annual
soil loss less than 10 t/ha/yr. The estimated annual soil loss was evaluated against land
use/ land covers classes, slope gradient and drainage density. Slope gradient and drainage
density have got positive relationship with soil loss but land use / land covers did not
show distinct pattern of relationship with that of the estimated annual soil loss of the
study area. In connection with the two-subcatchments’ more vulnerability to estimated
annual soil loss, comparison has been made by considering areal size being exposed to
different degree of the annual soil loss. This could result in making Bishan Guracha River
subcatchment as more vulnerable to high soil erosion by taking its large percentage of
area under greater than 30 t/ha/yr.
Key words: Land degradation (soil erosion), USLE, post classification change detection,
land use/ land cover classes, estimated annual soil loss.
Description
Keywords
Land degradation (soil erosion), USLE, Post classification change detection, land use/ land cover classes, Estimated annual soil loss