Browsing by Author "Ngana, James Omari"

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    Estimation of flood peaks with limited hydrological data: the case study of Mbeya - Rukwa catchments
    (University of Dar es Salaam, 1978) Ngana, James Omari
    In developing countries, it is a common occurrence to be called upon to estimate flood peaks with different recurrence intervals in ungagged watersheds. This is usually the case because of the small density of the hydrologic stations in these areas. In the succeeding pages, an attempt has been made to estimate flood peaks with different recurrence intervals in Rukwa Region. Like many other developing countries, rainfall data was the only data available for a considerable length of time. Stream flow data was hardly available for a considerable length of time. Stream flow data was hardly available for a period longer than three years. Initially, similarities were drawn up between Rukwa Region and Mbeya Region. The former is a less gauged Region and the latter is fairly well gauged neighbouring Region. Firstly, statistical analyses were carried out in Mbeya selected catchments to determine the 10 year flood. Next, the TRRL flood model, a model which utilises mainly the basin characteristics, was used to estimate again the 10-year flood. Comparisons were made between the two approaches and conclusions drawn. As another attempt to estimate floods of longer recurrence intervals, a regional frequency curve was derived from Mbeya selected catchments. From this curve, floods of larger recurrence intervals can be worked out for the studied areas and for the ungagged catchments in Mbeya Region. Since in the first place, similarities were established between these two neighbouring Regions, the established results in Mbeya could reliably be utilized in Rukwa Region as well. From the TRRL flood model and the regional frequency curve approaches, the 10-year floods for the two selected Rukwa catchments were calculated. Comparisons from these two methods were drawn and assessment made. The last chapter reviews all the results and conclusions achieved and final recommendations are presented