Regional analysis of low flow regimes in Tanzania.

The main objective of this study was to develop models for the estimation of low flow parameters at ungauged sits. In order to achieve this, low flow studies were carried out using sixty three river basins in Tanzania. Low flow statistics and base flow indices were derived. Flow duration curves were grouped into homoegeneous groups using regionalization techniques. Regional predictive equations were developed to estimate such low flow measures and indices as the annual average yield, and average flow exceeded by ninety five percent of average discharge, the predictor variables included the annual average rainfall, area of catchments, base flow index. The benefits that may be derived from the results of the studies include being able to make estimates of low flow parameters at ungauged sites for the purposes of determining waste-load allocations, siting treatment plants and sanitary land fills, and for decisions regarding inter basin transfer of water and allowable basin withdrawals, and possibly for the purpose of determining the minimum downs release requirements from hydropower, irrigation, water supply and cooling plant facilities.