Impact of land use and land cover changes on water flows: a case of Malagarasi river catchment in Tanzania
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Date
2009
Authors
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Publisher
Sokoine University of Agriculture
Abstract
Malagarasi River catchment represents one of the largest and most significant
transboundary natural ecosystems in Africa. The catchment constitutes about one third of
the catchment area for Lake Tanganyika. There is growing concern: however, regarding
land degradation in the catchment, particularly deforestation affecting the natural resource
base and the river flow. This study utilized remote sensing and geographical information
system tools, climatic data, available hydrological data and local resident's perception to
determine the magnitude of the land-use and cover changes in the Malagarasi catchment.
and the effects of changes on the river flows over the past 28 years. The results revealed
that there has been considerable land-use and cover change. For the period under study
(1984/86 and 2000/02). the analysis revealed an annual increase in forest cover and water
areas by +3.24% and +2.95% per year respectively while, settlement/cultivation increased
at +1.05% per year. Meanwhile, woodland and wetland vegetation/marsh declined by -
0.09% and -2.51 per year respectively. The analysis of mean monthly flow indicated
variations in peaking. The peak How has changed from May for 1975-1980 to April for
1981-2002 periods. Early attainments of peak flow are related to the observed variations
attributed to land use and cover change. The trend analysis on annual rainfall indicated no
significant differences at 95% level of significance. The principal causes for land use and
land cover change were found to include deforestation, forest reserve encroachment,
expanding agricultural activities and population growth. Given the significance of the
stream flow to the local people, a set of measures aimed at enhancing groundwater
recharge are required to sustain the water resource and maintain a balanced dry-season
flow in the catchment. Generally, an integrated catchment management approach.
whereby the whole of the catchment can be holistically viewed and managed, would be
desirable.
Description
Dissertation
Keywords
Land use, Land cover changes, Water flows, Malagarasi river catchment, Tanzania