Analysis of Drought Progression Physiognomies in South Africa

Abstract

The spatial-temporal variability of drought characteristics and propagation mechanisms in the hydrological cycle is a pertinent topic to policymakers and to the diverse scientific community. This study reports on the analysis of drought characteristics and propagation patterns in the hydrological cycle over South Africa. In particular, the analysis considered daily precipitation and streamflow data spanning from 1985 to 2016, recorded from 74 weather stations, distributed across South Africa and covering the country’s 19 Water Management Areas (WMAs). The results show that all the WMAs experience drought features characterized by an inherent spatial-temporal dependence structure with transition periods categorized into short (1⁻3 months), intermediate (4⁻6 months), long (7⁻12 months) and extended (>12 months) time-scales. Coupled with climate and catchment characteristics, the drought propagation characteristics delineate the WMAs into homogenous zones subtly akin to the broader climatic zones of South Africa, i.e., Savanna, Grassland, Karoo, Fynbos, Forest, and Desert climates. We posit that drought evolution results emanating from the current study provide a new perspective of drought characterization with practical use for the design of drought monitoring, as well as early warning systems for drought hazard preparedness and effective water resources planning and management. Overall, the analysis of drought evolution in South Africa is expected to stimulate advanced drought research topics, including the elusive drought termination typology.

Keywords

• drought propagation physiognomies
• hydrological drought
• clustering
• drought termination