INTEGRATING GEOARCHAEOLOGICAL APPROACHES AND RAINFALL MODELLING AS A PROXY FOR HYDROLOGICAL CHANGES IN THE SHASHE-LIMPOPO BASIN, SOUTH AFRICA

摘要

This paper focuses on the role of hydrological changes and the societal decline of southern Africa's earliest state society, the Mapungubwe state (AD 2200-1300) in the Shashe-Limpopo basin. The rise and demise of Mapungubwe has long been linked to significant climate changes such as increased rainfall that would have supported intensive agro-pastoral activities and demographic growth, later declining . due to the onset of drier conditions. Accordingly, during the Little Ice Age (1300-1850 AD), drier and cooler climate resulted in environmental deterioration, ultimately leading to the abandonment of Mapungubwe. This model is based on archaeological survey records and oral histories, with very limited regional climatic/environmental data. This paper presents three types of datasets: historical records; modern rainfall patterns, including field observations made from geoarchaeological records of soil sequences; and chemical analyses (Inductively Coupled Plasma Atomic Emission Spectroscopy) to examine climate variability and social complexity in Iron Age southern Africa using historical ecology frameworks. The integrated analysis of these datasets indicates that hydrological changes in the Shashe-Limpopo basin are highly influenced by seasonal variability and distribution of rainfall. The proposed alternating periods of high and low rainfall in the present study suggests the potential for flooding episodes of differing severity, while geoarchaeological data indicate an active landscape with alternating sequences of profile development and soil disturbance. Therefore, environmental deterioration cannot simply be avoided by migration. In fact, where heavy rains in the catchment area cause flooding, they also bring both moisture and deposit rich silt, valuable for the growth of vegetation and crops. Instead, the argument put forward is that many aspects, both cultural and environmental factors, influenced societal decline in the Shashe-Limpopo basin.