Chihombori et al
Greener Journal of Geology and Earth Sciences Vol. 1 (1), pp. 007-012, August 2013.
ISSN: 2354-2268 © 2013 Greener Journals
Manuscript Number: 062113682
Causes and Rate of Reservoir Sedimentation Due to Changes in Catchment Management. A Case of Marah Dam in Masvingo Province of Zimbabwe
*1John Chihombori, 2Kosamu Nyoni, 3Daniel Gamira
1Agritex Officer- Ministry of Agriculture Mechanisation and Irrigation Development
Great Zimbabwe University
P.O. Box 1235, Masvingo, Zimbabwe.
2Lecturer – Faculty of Agriculture and Natural Sciences, Great Zimbabwe University.
3Lecturer-Faculty of Education, Great Zimbabwe University.
*Corresponding Author’s Email: elijahnyoni @ yahoo.com,
Cell No: +263 775087075
The paper sought to analyse the rate of reservoir sedimentation due to changes in catchment management within the catchment area of Marah dam in Masvingo province of Zimbabwe. To do this, the study evaluated the current capacity of the dam based on current sedimentation rate as well as the lifespan of the dam under the current management practices. In order to obtain the rate of sedimentation, the formula (LTD/6) was used. The parameters T and D were measured using an Automatic level, Theodolite and staff. The depth of the reservoir was found to be 16m and the throwback was also found to be 840m. Calculations done pointed to an increase in the rate of sedimentation with a marked increase of 49.9% from 2000 to 2006, giving an average sedimentation rate of 8.3% per annum. The lifespan of the dam was also found to be about 12 years. This meant that the lifespan of the irrigation scheme dependant on the dam had a lifespan less than the 12 years. It was recommended that the Environmental Management Agency be involved and also that the community formulate catchment management strategy so that there is continuity and sustainability of Marah irrigation scheme.
Keywords: Water availability; storage capacity; sedimentation; reservoir; catchment; land-use change.