Within Southern Africa, many archaeologists publish their theses and dissertations in the African Archaeology Series of the British Archaeological Reports (formerly Cambridge Monographs in African Archaeology). Although BAR monographs are not peer reviewed, the series takes postgraduate research out of the “gray literature” and into the public domain. Otherwise, many African theses and dissertations are not readily available.
Musindo's research is a contribution toward understanding Great Zimbabwe—a national monument, World Heritage site, and source for the name of the Republic of Zimbabwe. Because of Great Zimbabwe's importance, there is a vast literature—most recently on contested interpretations of dating, spatial organization, population numbers, and the dichotomy between elite and commoners. Ignore the review of these current debates (Chapter 2), and read the original papers. Musindo does little justice to the complexity of these issues.
Musindo's own contribution focuses on the availability of water for the town residents. She uses various GIS tools (digital elevation modeling, hydrological modeling, and cost surface modeling) to examine water sources, transport routes, and management. These tools have not been used before, and her research makes a welcome contribution. Like people living in the area today, Great Zimbabwe people relied on springs, streams, and rivers for domestic use and on rainfall for agriculture. She and others have not found evidence for irrigation.
Surprisingly, there is only one spring (Chisikana) in the residential area. This is clearly insufficient for 18,000 people at its peak (my estimate—note that half would have been children) or even 5,000 (Musindo's reading of Chirikure's calculations, p. 7). Musindo claims that her analyses favor a lower population number (pp. 102–103). For this to be the case, however, she would need data on daily average consumption in rural areas and on average discharge of local springs and other sources. As it is, my population estimate is based on hut counts. The task is to determine how the large population survived.
To offset the limitations of the one spring, Musindo believes the numerous dhaka (soil) pits were water reservoirs. Only toward the end does she allow that these pits were the source of building material for houses. This misunderstanding must be clarified immediately. These pits were unquestionably the source for the hundreds of residential houses that existed during Period IV (AD 1285–1550/1600): I found some 39 in just one 33 m2, and remnants are visible in many other areas. For house materials, different pits yield different soil types: those at the base of Zimbabwe Hill have red, decomposed granite, whereas those on the edge of the wetland have white and yellow clays. Roger Summers used the color differences in 1958 to reconstruct a relative sequence of structures inside the Great Enclosure. Had these pits been dug for water, they would be surrounded by soil mounds, in the same way that ancient mines in Zimbabwe are. Furthermore, their primary function as a source of dhaka is why they are located on the edge of the marshland. Otherwise, they would have been flooded at a relatively shallow depth. Nevertheless, many pits hold water during the rainy season (September to March), and those with clay bottoms probably held water throughout wet years. Indeed, their secondary use as water reservoirs could have made the difference to the town's sustainability. This is a new and important finding.
The wetland (matoro) at the base of Zimbabwe Hill, where several pits are located, was created by the downslope flow of the Chisikana spring. Consequently, it is as old as the spring itself. Presumably, this can be counted in millennia. Musindo, however, claims that Zimbabwe people created the wetland as part of water engineering. The clays from some pits and the artificial causeway across the wetland at the “Watergate” obviates that claim. The use of the wetland for gardens, on the other hand, must surely have taken place and can be understood in terms of water management. Some other claims for water engineering are equally overstated. The stone terraces on Zimbabwe Hill, for instance, were not constructed to manage downhill flow (p. 101) but to support the houses of Zimbabwe elite. Furthermore, it is unlikely that people constructed the Outer Perimeter Wall to protect water sources and control access (p. 100). Equivalent walling exists at many other Zimbabwe settlements, and they all designate the west-front entrance to the muzinda—the leaders’ area. Specific studies such as this one are important, but ultimately, Great Zimbabwe should not be considered in isolation.
Like cities elsewhere, Great Zimbabwe's sustainability was tied to natural resources, including rainfall. Southern Africa has been steadily drying over the last 100 years, so recent rainfall data for Great Zimbabwe do not apply to Period IV. Musindo's research would benefit more from Stephan Woodborne's Limpopo baobab data. Overall, Great Zimbabwe is in a relatively high rainfall zone on the southeast escarpment, and an annual average of 800 mm is not unreasonable for most of the fourteenth and fifteenth centuries (more springs?). Droughts must have occurred, but their impact would have been much less than in the Limpopo Valley to the south. Indeed, an extended drought between about AD 1300 and 1310 contributed to the demise of Mapungubwe and the rise of Great Zimbabwe. Although traditional leaders in drier areas, such as Botswana, moved their capitals from time to time because of water problems, the first population reduction at Great Zimbabwe at about AD 1450 occurred during a wet period. Local politics rather than environmental deterioration was therefore probably the cause of Great Zimbabwe's abandonment.
If monument authorities allow it, some pit walls need to be excavated to the bottom to investigate possible fluctuating water levels. Furthermore, the entire monument area should be examined for evidence of extinct springs and check dams. And then there are the calculations needed to determine water budgets. Musindo's research lays a useful foundation for these future endeavors.
