an Integrated Approach for the Spatial and Temporal Variability Analysis of Wetlands: a Case of Central Rift Valley Lakes, Central Ethiopia
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Date
2013-06-06
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Addis Ababa University
Abstract
Alteration in the hydrological system and ecological situation within CER is highly seen from
mid 1970s due to both anthropogenic and natural factors. Humans usually and very
dramatically accelerate natural processes often unintentionally but usually in the course
activities like agriculture, industry and urban development. An attempt has been made to
assess and map the spatial and temporal variability of these changes with respect to driving
forces and to determine water resource including wetland priority areas for conservation and
management purpose based on tendency of the land use and direction of denudation using
Remote Sensing and GIS techniques.
Landsat satellite images having different sensors, meteorological data, hydrological data are
possible data sources were used in order to accomplish the study. Satellite imageries of 1973,
1986, 2000 and 2011 were used to map LULC and change detection analysis. In addition to
this, specifically delineation of wetlands and mapping of wetland types using criterion layers
satellite imagery analysis has been adopted. The change detection shows a cultivated land is
increased by 42% from 1973 to that of 2011, whereas wetlands/water bodies (small part of an
area) are reduced by 4% which has great impact on ecological diversity and hydrology of the
area. The major possible causes identified for destruction of wetlands, fluctuation of lakes
level and its volume within CER are climate variability, poor land use system, imbalance of
water inflow and outflow to/from the lakes, deforestation and overgrazing, diversion of river
canals and water abstraction for irrigation purpose, water abstraction for soda ash extraction
and sedimentation to the lakes. The result from an integration analysis showed that
hydrological and ecological system is in a dynamic disequilibrium to which the outlook
seems very bad. However, to alleviate these problems the best solution is to create awareness
towards wetland ecosystem value for the resident communities and to formulate/regulate
policy on wise use of water resources including wetlands for its protection and conservation.
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Keywords
Cer, Lake Abiyata, Langano, Ziway, Lu/Lc, Satellite Imageries, Wetland