Abstract:
Any hydropower project requires an ample availability of stream flow data. Unfortunately, most of
the hydropower projects especially small hydropower projects are conducted on ungauged river
and consequently hydrologists have for a longtime used stream flow estimation methods using the
mean annual flows to gauge rivers. Unfortunately flow estimation methods which include the runoff
data method, area ratio method and the correlation flow methods employ a lot of assumptions
which affect their uncertainty. This study was conducted on Bua River in Malawi to unveil the uncertainties
of these flow estimation methods. The study was done on a well gauged catchment in
order to highlight the variations between the observed, true stream flows and the estimated
stream flows for uncertainty analysis. After regionalizing the homogenous sites, catchments using
L-moments, an uncertainty analysis was done which showed that the area method is better followed
by the correlating flow method and lastly the runoff data method in terms of bias, accuracy
and uncertainty.
