Gis Based Analysis of Land Use /Land Cover, Land Degradation and Population Changes. (A Study of Boru-Metero Area of South Wello, Amhara Region)
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Date
2003-06
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Addis Ababa University
Abstract
The North-Central high lands of Ethiopia have been exploited over centuries
and their present status is alarming. A subsistence rain fed production using
obsolete methods characterizes agriculture the predominant economic activity
of the area. The study area which cover about 3088ha of South Wello found in
Tehuledere Wereda known as Boru-Metero is one of the representative area of
the highlands in the region where its land use and land cover has significantly
changed due to demographic pressure.
Today in many parts of the North-central highlands, cultivated and grazing
lands are commonly seen dissected by gullies and gorges of different sizes.
Almost all natural forests have been cleared irrespective of slope steepness and
are now under cultivation without proper land management. The size of
farmland per household is very low due to population growth. Because of these
and other factors the rural population of the region and the study area are
vulnerable to food shortage every year.
The study is designed to address the above interwoven problems in the area
related mainly to land use/land cover, land degradation and human population
pressure. Accordingly two main objectives were designed: first, establishing the
current status and trends in changes of population distribution, land use/land
cover changes and identifying areas severely affected by the changes. Second,
identifying the causes and consequences of temporal and spatial changes in
population distribution, land use/land cover changes and land degradation.
In order to fulfill the above objectives, assessment of land use/land cover
changes in relation to population growth was done using the available aerial
photographs of 1936,1965, 1986 and 1994.
An-in-depth investigation of each aerial photographs of the study area was
carried out using different raster and vector GIS soft wares such as
photogrammetric workstation known as VIRTUOZO, ERDAS Imagine ver.8.3
Map/Info ver.4.1 Arc/view ver.3.2 and others. In order to support those GIS
technologies analogue instruments such as Procom-2, pocket Stereoscope, field
camera, handheld GPS-45 and others were used. With the help of these
technologies and field assessment, land use/land cover changes taking
vegetation cover as an indicator was investigated and rural population of the
area was also estimated from the stated aerial photos and mapped for each
year.
The 1936 aerial photographs of the Italians was interpreted for sample area of
Borur Sellassie and Gora area and separately compared with the recent 1994
aerial photographs to evaluate land use land cover changes, land degradation
and population distribution. While the 1965, 1986 and the 1994 aerial
photographs were applied for the whole study area. All the stated year aerial
photographs were converted in to digital formats using the above stated soft
wares and then geo-referenced, land cover types identified are digitized.
The result shows that, cultivated land in Boru-Metero increased from 44.86
percent in 1965 to 49.44 percent and 49.62 percent in 1986 and 1994
respectively. In this respect the change of crop land was not significant because
the areas suitable for cropland was already farmed by the 1980’s and since.
Conversely, the natural vegetation cover declined from 3.43 percent in 1965
and became 2.74 percent in 1986 and 2.59 percent in 1994. The most significant land cover change found was the increasing of tree farming of
Eucalyptus trees. It was only 1.63 percent coverage in 1965 and increased to
4.71 percent in 1986 and 4.63 percent in 1994. This change was the result of
the aforestation and enclosure of hill side program done in the 1980’s as well as
the increasing of financial income gained from the selling of fuel wood and poles
that initiate farmers to plant Eucalyptus trees around their homestead and on
their farms.
The result of land use/land cover changes investigated on aerial photographs of
1936 in the sample areas of Boru sellassie shows that, cropland which was
50.83 percent coverage in 1936 increased to 64.25 percent in 1994, which was
69.51 additional hectare within 58 years difference. This indicates that there
was an expansion of farmland since the 1936 in the area.
The analyzed result for Gora area shows that, the cover of natural forest
(dominated by Juniperous procera) declined from 18.22 percent in 1936 to 7.70
percent in 1994. The area coverage of natural forest in 1936 shows about 130.9
ha and declined to about 55.1ha in 1994. Therefore, the natural forest cover
cleared within 58 years was 57.91 percent of the cover existed in 1936 around
Gora area.
The investigation of rural population done from the stated aerial photographs
show a population of 5404 in 1965, 8050 in 1986 and 9774 in 1994 settled in
Boru-Metero. Based on this the population density of the study area shows 175
persons/km2 in 1965, 261 persons /km2 in 1986 and 317 persons /km2 in
1994.
Population density regarding the sample area of Boru Sellassie area in 1936
shows 298 persons/km2 and increased into 628 persons/km2 in 1994. On
similar trend the population density of Gora area during the 1936 accounted
about 44 persons/km2 and increased to about 364 persons/km2
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Keywords
Geography and Environmental Studies