Landuse/Cover Dynamics and Selection of Suitable Site for Water Harvesting Structure: The Case of Ziquala Watershed, Wag Himra Zone
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Date
2010-06
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Addis Ababa University
Abstract
The study area Ziquala Watershed located at a distance of about 760 km from the capital
Addis Ababa city covers an area of about 759 km' . It is one of the drought p;one areas in the
country. It is found in drought prone areas of the Wag Himra Zone. The area is charocterized
by scarcity of water even during the rainy seasons. Agriculture predominantly animal rearing
is the main stay of the area. Water harvesting structures are extremely important to conserve
precious natural resource like, soil and water, which is depleting day by day at on alarming
rate. GIS offers a powerful tool for mapping potential sites for rainfall harvesting. Selection of
suitable sites for artificial recharge and water harvesting structures needs a large volume of
multidisciplinary data from various sources. Remote sensing is of immense use for natural
resources mapping and generating necessary spatial database required as input for GIS
analysis. The most affecting factors on mapping the poten tial sites: landuse, soil, geological
formation, drainage density and slope respectively. The main objective of this study is to
evaluate the landuse/cover change and select and mop suitable sites for different water
harvesting structures tor Ziquala watershed. Landuse/cover was prepared using supervised
classification of Landsat imageries of three different years. Post classification analysis was
used to reveal the change in landuse/cover during the study periods. During 1988-1999
period more change occur on bareland decreasing by -32.63% and bush land/shrub land
increasing by 28.53%. The water harvesting structures considered for this study area are
check dam, farm pond, semi-circular bund and contour bund. Multi-criteria evaluation (MCE)
method was used to identify suitable sites for WHSs. Weight was given based on their
relative importance for individual WHS. Check dam with 48.33% has higher coverage
fallowed by contour bund, semi-circular bund and farm pond having 2.8%, 1% and 1%
coverage respectively. The remote sensing and GIS technique proved to be effective for
generating thematic layers, facilitating, analysing and derivation of database management
and results.
Key word: GIS, Landuse/cover change, MCE, Remote sensing, suitability, Water harvesting
Description
Keywords
GIS, Landuse/cover change, MCE, Remote sensing, suitability, Water harvesting