Land Use/Land Cover Dynamics and Soil Degradation Assessement Using Remote Sensing and Gis: A Case Study of Jima Arjo Woreda (Western Ethiopia)
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Date
2009-06
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Addis Ababa Universty
Abstract
This study is aimed at assessing the spatio-temporal dynamics of land use/ land cover and soil
degradation in Jima Arjo Woreda. Three different time landsat images (1973, 1986 and 2001)
were classified into 7 major land use/cover classes through supervised classification: farm land,
dense forest land, degraded forest land, open woodland, grassland, wet land and bare land.
Post-classification change detection among the image data has been conducted. Accordingly,
farmland and bare land has expanded with 15326.6ha and 769.897ha, respectively. Although the
expansion is not continuous; open woodland increased by 6825.2ha and grassland by 6392.4ha
over the period. However, vegetations particularly dense forest and the degraded forest land and
wetlands were reduced greatly at varying rates of change per annum. Dense forest dropped down
by 1686.5ha, degraded forest land reduced by 4264.7 and wetland by 8184.1ha.
Land use/cover distribution across various slope categories and susceptibility to change has also
assessed from the final state of the study period (2001) image data. With respect to land
use/cove – slope distribution, steep slopes were made cultural landscapes (agricultural and
settlement areas). Farm lands, particularly the intensively cultivated farms, were evident on
steep slopes (above 250) and more than 60% of slopes above 120 were shared by the farmlands.
Five levels of susceptibility to change: extremely susceptible, highly susceptible, moderately,
low and none susceptible areas have been identified based on factors of accessibility, proximity
to towns and rivers, agroclimate, soil, slope and the type of land cover in the area. Vegetations
are signified as the most susceptible classes. This has been realized in that 94.1% of the high to
extremely high susceptibility level has been shared by dense forests.
Soil Loss has been estimated using USLE model on the basis of the adapted methodology and
parameters for Ethiopian highland conditions. The estimated soil loss for the study area ranges
from 0.35 – 184.4t/ha/yr with mean annual loss of 20.6t/ha. Highly sever soil loss (>60t/ha/yr)
has been recognized over 5.9% in the area. This is more evident on the farm lands. The low soil
loss (<1t/ha/yr) experienced over 10% of the area where vegetations (particularly the grassland
and dense forest land) were recognized.
Key Words: land use/land cover dynamics, land use/cover susceptibility to change, soil
degradation, USLE, Annual Soil Loss Estimation
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Keywords
Land use/land cover dynamics, Land use/cover susceptibility to change, Soil degradation, USLE, Annual Soil Loss Estimation