The water budget of a headwater catchment containing a dambo

Abstract

Dambos, seasonally saturated wetlands, are common in the headwaters of many southern African rivers. It is widely believed that they play an important role in regional hydrology. However, there have been very few studies of the natural processes occurring within catchments containing dambos, and their hydrological functions are not well understood. This paper describes a study conducted to determine the water budget of a small Zimbabwean catchment containing a single dambo. The results indicate that: a) rainfall dominates, and inflow from the surrounding catchment comprises only a small percentage (ca. 12%) of the total water input to the dambo; b) dry season flow is typically only a small proportion (ca. 14%) of the water stored within the dambo and potentially available to flow at the end of the wet season. These findings have important implications for agriculture and water resource management in the region; loss of water to evaporation rather than to river flow indicates that water within some dambos could be put to productive use in growing crops with little impact on dry season river flows.