Spatial Statistics of Extreme Weather Events in the SADC Region: A Proposed Theoretical Review

Extreme events of climatic nature such as floods, heat waves and cold waves have become more frequent worldwide in recent years than in the past decades. Many studies have attempted to model these extreme events using various geohazards, environmental, mathematical, and statistical techniques without conclusive findings. Extreme value theory (EVT) is a well-established branch of statistics used to study extreme or rare events. Several studies that have applied EVT to climatic events modelled these events using at-site and regional approaches. These approaches have performed fairly well but lacked the ability to address the spatio-temporal nature associated with climatic events such as precipitation, floods, droughts, wind and heat waves. Other EVT studies have attempted to extend these studies to multivariate extremes, but still within either the at-site or regional realisations. The present study looks at the possibility of application of spatio-temporal extreme value theory to the complex extreme value events in the Southern African Development Community (SADC) region in a changing climate. This study is motivated by the existence of spatio-temporal variability of extreme weather events in the SADC region revealed from the previous studies, particularly with reference to the 1991/1992 severe droughts in the SADC region, the year 2000 disastrous floods in the region and the recent 2019 disastrous floods caused by Cyclone Idai which affected parts of Malawi, Mozambique, South Africa, and Zimbabwe. Although the present study is theoretical and does not present empirical findings in its current form, it proposes and discusses in detail EVT techniques such as hierarchical modelling for spatial extremes and extension to spatio-temporal processes with reference to precipitation in the SADC region.