Author:

Keywords:

extreme value analysis; generalised Pareto distribution; Lake Victoria basin; parameter estimation; rainfall extremes; uncertainty analysis, Science & Technology, Physical Sciences, Water Resources, extreme value analysis, generalised Pareto distribution, Lake Victoria basin, parameter estimation, rainfall extremes, uncertainty analysis, PARTIAL DURATION SERIES, CORRELATION-COEFFICIENT TEST, ANNUAL MAXIMUM SERIES, SPATIAL INTERPOLATION, INFORMATION-THEORY, HYDROLOGIC EVENTS, HIGH-RESOLUTION, BIAS CORRECTION, VARIABILITY, PRECIPITATION, 0406 Physical Geography and Environmental Geoscience, 0905 Civil Engineering, Environmental Engineering, 3707 Hydrology, 3709 Physical geography and environmental geoscience, 4005 Civil engineering

Abstract:

Uncertainty in the calibration of the generalised Pareto distribution (GPD) to rainfall extremes is assessed based on observed and large number of global climate model rainfall time series for nine locations in the Lake Victoria basin (LVB) in Eastern Africa. The class of the GPD suitable for capturing the tail behaviour of the distribution and extreme quantiles is investigated. The best parameter estimation method is selected following comparison of the method of moments, maximum likelihood, L-moments, and weighted linear regression in quantile plots (WLR) to quantify uncertainty in the extreme intensity quantiles by employing the Jackknife method and nonparametric percentile bootstrapping in a combined way. The normal tailed GPD was found suitable. Although the performance of each parameter estimation method was acceptable in a number of evaluation criteria, generally the WLR technique appears to be more robust than others. The difference between upper and lower limits of the 95% confidence intervals expressed as a percentage of the empirical 10-year rainfall intensity quantile ranges from 9.25 up to 59.66%. The assessed uncertainty will be useful in support of risk based planning, design and operation of water engineering and water management applications related to floods in the LVB.