DETERMINING THE EFFECTS OF LAND USE AND LAND COVER CHANGES ON SIZE OF LAKE BOGORIA USING GIS AND REMOTE SENSING

Abstract

Land cover and land use changes in the Lake Bogoria catchment area have had diverse influence on the lake. The aim of this study was to determine the land use and land cover changes that have affected the size of Lake Bogoria using GIS and Remote Sensing. Data was obtained from LANDSAT (1986 and 2000) and ASTER images (2008). A combination of geographic information systems and digital image processing software were used to process the images and determine the percentage change in the identified land use/land cover classes. IDRISI-software was used to create the change maps. Spatial data analyses covering the period of 1986 and 2008 indicated an extensive change of land cover characters that have really affected the lake. The study showed decrease in the size of the lake from 32.76 km2 (1986), 32.07 km2 (2000) to 30.59 km2 (2008). A significant correlation in the change map between the increase of cultivated area from 610.27 km2, 624.82 km2 to 734.17 km2 (1986, 2000 and 2008), built up area from 56.80 km2, 58.65 km2 to 63.97 km2 (1986, 2000 and 2008) and the size of the lake was obtained. Increase in the two land cover types had negative effect on the size of the Lake as a result of over abstraction of water by farmers for irrigation. Results showed fluctuations in shrub (551 km2, 225.37 km2 and 620.57 km2), Forest (74.21 km2, 70.50 km2 and 146.34 km2) and grassland (138.55 km2, 465.39 km2 and 637.84 km2) in the three years respectively. There was general decrease in bare ground (231.7 km2, 214.35 km2 to 21.30 km2) as a result of increased infrastructure and farming. The study recommends the need of Intergrated River Basin Management Approach for long-term conservation of rapidly declining natural resources and development of a framework for decision makers who can promote conservation of such threatened and unprotected habitats.