Author:

Keywords:

Peak flows, Extremes, Rivers, Nile basin, Lake Victoria basin, Statistical analysis, Science & Technology, Physical Sciences, Water Resources, extreme value analysis, flow extremes, floods, QDF, regionalization, analyse des valeurs extremes, extremes de debit, crues, regionalisation, NILE BASIN, SHRINKAGE, INFERENCE, TAIL, 0406 Physical Geography and Environmental Geoscience, 0905 Civil Engineering, 0907 Environmental Engineering, Environmental Engineering, 3707 Hydrology, 3709 Physical geography and environmental geoscience, 4005 Civil engineering

Abstract:

This paper focuses on a regionalisation attempt to partly solve data limitation problems in statistical analysis of high flows to derive discharge-duration-frequency (QDF) relationships. The analysis is based on 24 selected catchments in the Lake Victoria basin (LVB) in Eastern Africa. Characteristics of the theoretical QDF relationships were parameterized so as to capture their slopes (γevd) of extreme value distributions (EVD), tail behaviour (β) and scaling measures (αs). To enable QDF estimates to be obtained for ungauged catchments, interdependency relationships between the QDF parameters were indentified and regional regression models were developed to explain the regional difference in these parameters from physiographic characteristics. In validation of the regression models, from the lowest (5 years) up to the highest (25 years) return periods considered, the percentage bias in the QDF estimates range from -2 % for 5 years return period up to 27 % for 25 years.