Remote Sensing and Gis Techniques in Land Use Land Cover Mapping and Change Detection in the Main Ethiopian Rlft (Mer) Between Koka and Ziway
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Date
2005-07
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Addis Ababa Universty
Abstract
Land use/land cover change investigation of the study area between 1973 and 2002/5 was
conducted using remote sensing and geographic information system (GIS) controlled by
ground truthing. The study area is about 560km2 located in the main Ethiopian rift (MER)
with in the Orommia Regional Government state and can represent mountain degradation of
the rift valley of Ethiopian
The research was conducted with the objective of creation of historical and the current
LULC maps and LULC change map of 1973-2002/5. The maps were derived utilizing
standardized digital remote sensing classification techniques using three multitemporal
Landsat scenes acquired on Jan 30, 1973(MSS), Jan 21, 1986 (TM), and Feb 30, 2002
(ETM+). Classification accuracy was determined to be sufficient by means of employing
standardized accuracy assessment measures.
According to the statistics calculated from the land use and land cover change data between
the 1973 and 2002/5, the intensively cultivated and Urban lands have been expanded by
18710 ha and 555 ha which is 128.43% and 411.11% increase respectively. On the other
hand, the wooded cultivated/grass land, the shrub grass land, the wet land and water boMes
show decrease by 14779 ha (58.86%), 4478 ha (64.46%), 432 ha (7.98%), 229 ha (6.05%)
respectively. The degraded shrub Grass Land also showed an increase by 518 ha (386.57%)
between 1986 and 2002/5.
The population growth was certainly the most important factor causing the observed land
cover change because of the increase of demand ofland for cultivation, settlement and trees
for fuel and construction purpose. As a result, large areas, which were once under wood and
shI1lb cover, are now exposed and affected by sheet and rill erosion which in turn resulted in
formation of big gullies and hence loss of farmlands.
If current trends are allowed to continue damage to the natural resource base will continue
and land lost due sheet and gully erosion will increase. The increase in run off and low water
retention due to low land cover further intensify the sheet erosion and rill and gullies to widen and deepen which therefore degrade the agricultural land more than the present
condition. The sediments removed are channeled to the lakes and cause sedimentation and
pollution. The increase in the length and depth of the gullies associated with the lUgged
topography, nature of the soil, low vegetation cover of the area, together with the rainfall
that come after a long dry period might cause serious land slide which is observed by soil
fall occurring in the area.
Introducing alternative energy sources such as biogas should be encouraged to reduce
dependency on natural vegetation for fuel. On the other hand, Planting of trees individually
or in group in the mountainous areas and in the areas which are degraded so that out of usage
for agriculture will add to the rehabilitation process and also satisfy need of wood for fuel,
constlUction and could compensate for low coverage of woodland and at the same time
reduce erosion currently affecting the environment.
Educating the society concerning optimum use of natural recourses, conservation systems
and their benefits and continuing the current efforts of introducing family planning to make
the people aware of consequences of population pressure should be carried out intensively.
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Keywords
Sensing and Gis Techniques