Enhancing the Climate Resilience of Semiarid River Systems and Their Catchments

Responses of river systems to climate change are highly variable, depending on the nature of regional climate forcing and on catchment properties. This is particularly the case with semiarid river systems where annual rainfall is low and seasonally distributed. This study considers the factors that give rise to the geomorphological sensitivity experienced by semiarid river systems, with a particular emphasis on sub-Saharan Africa, and then identifies the elements of (1) semiarid river systems and (2) semiarid river catchments that contribute towards their resilience to climate forcing. This is achieved through considering the workings of these river systems and their relationships to catchment properties, including soils, ecosystems, sediment dynamics, and the role of extreme events such as floods. The results of this analysis show that a systems-based approach, where semiarid rivers are described in the context of their contributing catchments (which is not commonly done), provides the best framework to understanding catchment vulnerability and resilience to climate forcing. This information can be used in predictive modelling of integrated semiarid river systems, including patterns of sediment export, hazard risks, and pollution management.