Browsing by Author "Ndomba, Preksedis Marco"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Estimation of soil erosion in the Pangani basin upstream of Nyumba ta Mungu reservoir
    (University of Dar es Salaam, 2001) Ndomba, Preksedis Marco
    The Universal Soil Loss Equation (USLE) was used to estimate soil erosion in the Pangani Basin upstream of Nyumba ya Mungu reservoir located to the North-Eastern part of Tanzania using data from reconnaissance surveys such as Geo-referenced soil, land use and topographic maps. The R-factor (rainfall Erosivity) was estimated using empirical equation proposed by Wischmeier and Smith et al, 1978 as rainfall intensity data was insufficient to evaluate average annual R by usual procedures, using data from three rainfall recording gauges. The K-factor (soil erodibility) was determined using data derived from Physiography map of Tanzania (De E.PAUW, 1984). The LS-factors (slope length and steepness) were determined from a digital elevation model (DEM) of the basin. The C-factor (crop and management) was determined from the land use and farming system maps, obtained from the Institute of Resource Assessment (IRA) and Ministry of Agriculture (Mlingano Soil Research Service) respectively. The P-factor (Soil conservation practice) was taken to have a value of 1, for the whole basin, with the assumption that the entire population in the basin does not practice the soil conservation programs. A raster-based Geographic Information System (GIS) was used to calculate soil loss and volume of sediments deposited into Nyumba ya Mungu Reservoir over years. The results obtained from soil loss models (equations) using GIS in the upstream of Nyumba ya Mungu reservoir were compared to measured amount of sediments deposited into reservoir by echo-sounding technology. The result obtained from this study indicates that the mean potential soil erosion in the basin is 24 t/halyr. And about half of this average erosion finds its way into Nyumba Mungu Reservoir. Generally, there is a need for detailed research to determine appropriate USLE parameters.
  • No Thumbnail Available
    Item
    Modeling of erosion processes and reservoir sedimentation upstream of Nyumba ya Mungu reservoir in the Pangani Basin
    (University of Dar es Salaam, 2007) Ndomba, Preksedis Marco
    The electric power shortages experienced by Tanzanians during the late 1990`s have been attributed to reservoir sedimentation by same sources. This research works was motivated to study on the problem in one of highly regulated watersheds by human activities. Nyumba Ya Mungu Reservoir catchment in Pangani river basin, located in North-eastern part of Tanzania was therefore selected as a case study. Since there were no compelling methods and tolls to research on the problem, this study developed a conceptual framework for the purposes: The framework comprised of conceptual model and network properties and yield fluxes monitoring sites across the basin. The result from the study indicates that soil loss levels in the upland catchments are high above the recommended standards. However it should be noted that the main transferable output from this study is the developed methodological framework and not the absolute figures of sedimentation rate. Finally, the author would like to recommend a wide application of the developed conceptual framework for comprehensive understanding of the sedimentation problem both in Tanzania and elsewhere.