Chihombori et al
Greener Journal of Physical Sciences Vol. 3 (6), pp. 229-246, October 2013.
ISSN: 2276-7851 © 2011 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
Keywords: Water availability; storage capacity; sedimentation; reservoir; catchment; land-use change.