Land-use and land-cover change in Lake Ziway watershed of the Ethiopian Central Rift Valley Region and its environmental impacts

Abstract

Assessing land use and land cover (LULC) change in Lake Ziway watershed is important to evaluate the degradation of ecosystems and their environmental processes caused by the ongoing increase in human pressures. The present study analyzed the long-term LULC dynamics in the Lake Ziway watershed, which covers 7300 km2 in the Ethiopian Central Rift Valley region. Three Landsat Satellite Image Series - Landsat MSS (1973), Landsat TM (1989) and Landsat Enhanced ETM+ (2018) - were the main input data from which three LULC maps were produced by employing Remote Sensing Techniques and Geographical Information Systems. The satellite data were supported by Google Earth and information gathered from informal discussions from local elderly people who are knowledgeable aboutthe area. The results over the last 45 years show that the major LULC changes in the study watershed have been the expansion of cultivated, agroforestry and settlement areas and the corresponding reduction in woodlands. Cultivation, agroforestry, and settlement LULC categories increased by 45%, 10.9%, and 141.4%, respectively. These changes are attributable to a combination of the ever increasing human population and the subsequent demands on environmental resources like agricultural lands, commercial and domestic fuelwood and charcoal. Other factors include poorly defined ownership arrangements and weak enforcement strategies on the existing land use policy. This has created open access mentalities among communities and intensified LULC changes in the watershed. Awareness raising and provision of technical training about conservation interventions should be provided to communities in the watershed.This study provides information for corrective measures to protect further degradation and irreversible losses that might happen to the biotic and abiotic resources in Lake Ziway watershed.