Examining Trends of Hydro-Meteorological Extremes in the Shire River Basin in Malawi

This study, therefore, aimed at examining trends and frequency of these hydro-meteorological extremes in the Shire River Basin in Malawi. Daily scale data from 1961 to between 2005 to 2015 were collected from 22 rainfall stations, 12 temperature stations and 10 river discharge station within the study area. The hydro-meteorological extremes were analyzed using annual maximas and annual minimas of the daily hydro-meteorological data. Significance and direction of trends in these extreme indices were examined using the non-parametric Mann–Kendall test statistic. The Peak-Over-Threshold (POT) approach, applying the Generalized Pareto Distribution (GPD) was used to analyze the distribution of the extremes. Study results have shown that temperature extremes have an increasing trend which is significant at 5% significance level. In terms of streamflows, both the peak and low flow extremes have shown a decreasing trend, which is consistent with the decreasing trends observed in rainfall extremes. Analysis of frequency of extreme events has shown that extremely high rainfall events have a high probability of occurrence while streamflow extremes will not occur frequently. These findings have provided key insights that are key in understanding the temporal occurrence of hydro-meteorological extremes in the basin, which are of benefit to the regional water resources planning and development.
Source: Physics and Chemistry of the Earth, Parts ABC - Category: Science Source Type: research