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SEDIMENT YIELDS ESTIMATION AND IDENTIFICATION OF THEIR SOURCES
IN LAKE TANGANYIKA BASIN
The Case of Mulongwe Sub Catchment
Uvira City
D
RCongo
Ongezo Muzaliwa Séverin
University of Dar es Salaam, College of Engineering and Technology,
Department of Water Resources Engineering.
Université Officielle de Bukavu (UOB) / DR Congo, B.P 570 BUKAVU
ABSTRACT
Soil erosion / sedimentation are
immense problems that have threatened water resources
development in the Tanganyika basin, particularly in the northwest of Lake Tanganyika
(Mulongwe sub catchment in Uvira City). This study was conducted in Mulongwe sub
catchment (DRCongo
) to set up and calibrate model, to estimate the sediment yields in
the sub catchment and identify the sediment sources. The required input data for this study were
Digital Elevation Model (DEM) with spatial resolution of 30x30m, Land use/cover an
d soil
map for the year 2004. Eight types of land use/cover have been determined and two types
of soil in the study area. The hydro meteorological observations were set up around the
Mulongwe sub catchment. Stream flows and s
ediment loads were monitored from two
years 1999 and 2004 at Mulongwe gauging site on the main Mulongwe River. Sediment
sources have been determined by fing printing method and water chemistry.
Model performance evaluation statistics for calibrating daily
stream flow and sediment were
satisfactory with NSE and R2 greater than 0.62 and 0.71 respectively. For the validation the
NSE and R2 were also greater than 0.56 and
0.63 respectively. Sediment erosion rate were in the range of 0.17
-
5.23tons/ha/yr with av
erage
of 0.53tons/ha/yr and average amounts of 6,096tons/yr for sediment yields. The sediment
sources should be the weathering of rocks, tectonic effects and anthropic activities in the
study area.
Key words: Sedimentation, Erosion, AVS
WAT2005, Weathering and Landslide