Munro Lecture - 'Climate change, groundwater depletion and the decline of Great Zimbabwe'

Recent research on archaeological, geo-hydrological and climate change provide baseline data to address the decline of Great Zimbabwe. The ancient city was located on an aquifer, fed by water from surrounding granite hills, percolating into adjacent etchplains, and then discharged through springs. Geoarchaeological research identified earthen depressions (dhaka pits) within Great Zimbabwe as water reservoirs (Pikirayi et al. 2022, 2023). Their dredging is coeval with declining temperatures in equatorial and eastern Africa during the late sixteenth and mid-eighteenth centuries, characterised by widespread droughts reportedly, "more severe than any recorded drought of the twentieth century" (Verschuren et al. 2000). Jasechko et al. (2024) demonstrates widespread, accelerated and significant groundwater-level declines, especially in regional aquifers. For Great Zimbabwe, dredging of dhaka pits to harvest water from underlying fractured zones implicates its depleting aquifer. With groundwater resources vital to its ecosystem, climate change and increased withdrawals may have triggered diminishing water levels, depleting the pits, negatively impacting on the ancient city.

Professor Innocent Pikirayi

Innocent Pikirayi is Professor of Archaeology and deputy dean responsible for research in the Faculty of Humanities at the University of Pretoria, South Africa. His research focuses on the development of complex societies in southern Africa since 1000 AD. He was visiting Professor at the Centre for Urban Network Evolutions (UrbNet), Aarhus University, Denmark in 2019, and was appointed as an honorary research associate at the McDonald Institute for Archaeological Research, University of Cambridge, 2020-2023.

Professor Pkirayi is a member of the World Archaeological Congress (WAC), the Society of Africanist Archaeologists, the Shanghai Archaeology Forum, the Association of Southern African Professional Archaeologists, the South African Archaeological Society, the Integrated History and Future of People on Earth, the Royal Society of South Africa, and, the Academy of Science South Africa. In September 2017, he was appointed ambassador of the journal Antiquity: A Review of World Archaeology, to develop locally relevant strategies to mentor young scholars in Africa. He is editorial advisor for Azania: Archaeological Research in Africa (Routledge), African Archaeological Review (Springer), Antiquity (Cambridge Core), Post-Medieval Archaeology (Taylor & Francis), Anthropocene Review (SAGE), the Global Colonialism book series and Decolonizing Archaeology and Heritage book series (University Press of Colorado).

His most recent publications include; ‘Climate-smart harvesting and storing of water: The legacy of dhaka pits at Great Zimbabwe, Anthropocene’, 2022, ‘Landscape sequences and Iron Age settlement in southern Africa: Managing soils and water in the Greater Mapungubwe landscape’, In Sulas, F., Lewis, H. and Arroyo-Kalin, M. (eds), Inspired Geoarchaeologies: Past landscapes and social change - Essays in honour of Professor Charles French, 2022; ‘Community-Based Approaches in the Construction and Management of Water Infrastructures among the Chagga, Kilimanjaro, Tanzania’, Land, 2023; ‘On the Origins of Khami: Evidence from the Henry Balfour Collection’, in Nimura, C., O’Sullivan, R. and Bradley, R. (eds), Sentient Archaeologies: Global Perspectives on Places, Objects and Practice; 2023; ‘Archaeology, Current Political Climate, and Climate Change, the Past Not as Prelude from an African Perspective: A Response to Pyburn,’ Archaeologies: Journal of the World Archaeological Congress, 2023; and, ‘The conundrum of Great Zimbabwe’, Journal of Urban Archaeology, 2023.