Keywords: arid climate, semi-arid regions, drought frequency, extreme events, frequency analysis, deceedance probability, distribution function, plotting positions, historical information, droughts, drought estimation, Tunisia, drought management, risk assessment, water resources, resource management, water management
Frequency analysis of droughts using historical information – new approach for probability plotting position: deceedance probability
This paper presents a new statistical approach for droughts estimation. The conducted frequency analysis uses for the first time the 'Deceedance' Probability using historical information. The developed approach was applied for the first time in Tunisia. The annual rainfall was fitted to eight distribution functions. A rigorous evaluation of the historical information, in terms of completeness and authenticity, is undertaken. It is shown that Weibull's formula matched with the Log-Normal-III and Log-Pearson-III distributions gave the highest fit. These results are of practical relevance to water resources managers in arid and semi-arid regions for applications in droughts management and risk analysis.