Modelling patterns of past inundation processes combining geoarchaeology and morphometric hydrological analysis in the Shashe-Limpopo Basin, South Africa

Abstract

Riverine and valley systems across the globe have been central to the development of past urban centres. By AD 900, the Shashe and Limpopo Rivers seem to have facilitated the interaction and integration of early farming communities in southern Africa. This paper focuses on the application of geoarchaeological perspectives made available by the subsurface environments and the development of advanced morphometric models to understand human behavioural patterns under various climatic conditions in the Shashe-Limpopo basin. Mapungubwe emerged between AD 1220–1300 as the earliest Iron Age state system in the middle Limpopo valley, practising floodplain agriculture together with surplus wealth generated from long-distance trade that bolstered social and political transformations. At about AD 1290, Mapungubwe began to decline and was subsequently abandoned due to erratic rainfall patterns in the region. Despite the general absence of relevant palaeo-environmental proxies, Mapungubwe's dominance lasted to about the 13th Century. The reasons for Mapungubwe's decline remain contested. The role played by changing climate variability is a possible proximate cause. Uneven distribution of rainfall and flooding seem to have resulted in low agricultural productivity in the Shashe-Limpopo Basin and led to the movements of people towards better-watered regions. This paper aims to show how advanced morphometric hydrological analysis of inundation regimes (riverine modelling) and evidence from geoarchaeological records on buried soil sequences can be used as tools to evaluate human responses against the ever changing and deteriorating environmental conditions in southern Africa.