Potential Climate Change Effects on the Okavango River Basin

The Okavango River basin of Southern Africa is the second largest inland wetland region on earth, and as such supports a huge diversity of ecological habitats. It is also an important source of water for the people of Angola, Namibia, and Botswana, providing invaluable resources for agricultural and household use. There are currently plans in place for pipelines and irrigation from the river to better utilize the basin’s resources. However, as this study suggests, global climate change will almost certainly impact the available water from the basin, perhaps jeopardizing these future plans. Because the magnitude of future temperature change cannot be divined, the researchers in this study used a total of 6 possible estimates for warming scenarios: increases of 1, 2, 3, 4, 5, and 6°C. Each of these scenarios showed a different effect on the monthly flow and rainfall in the Okavango River, but to differing degrees and with differing signs. What seems certain is that some change will occur in the Okavango basin, and the degree of this transformation will result from the magnitude of climate change. In order to prepare for this change, it will be essential for the three nations directly affected by the Okavango river to make an integrated water management plan, and to quantify the impacts of development intervention in the basin. Tensions over water resources could cause not only famine, but also political unrest and even violent conflict in the region. Soil and water conservation (SWC) technologies may play a large role in the development of the basin as farmers attempt to maximize the supply of water they get from the area (Ringler et al. 2011) . At the same time, these plans must take into account the fragile ecological systems that the basin supports. The only thing that the people who rely on the water resources of the basin can rely on is uncertainty and transformation, and further studies should be undertaken to better plan for a changing future in this essential region.

Hughes, D. A., Kingston, D. G., Todd, M. C., 2011. Uncertainty in water resources availability in the Okavango River basin as a result of climate change. Hydrology and Earth System Sciences 15, 931–941. [GSSS: uncertainty Okavango (2011)]

Although scientists cannot be sure what the precise effect of climate change will be on the Okavango River basin, predictive models have allowed some striking possibilities to be outlined. In three of the scenarios, very substantial changes to the magnitude of river flows on the order of 30% result from temperature increase. Additionally, in at least two of the models there is a change in the timing of the season of discharge, the “wet season.” In fact, at temperature increases over 4° C, there is an almost complete loss of the wet season in the basin, due to increased evaporation and decreased rainfall and flow. Even using a relatively conservative estimate of a 2°C increase in temperature by the year 2065, significant changes in flow and discharge are predicted. These impacts are probably underestimations, a fact that makes it even more apparent how essential it will be for the region to prepare itself for change in under a drying climate change scenario.

Different areas of the Okavango River basin have physical characteristics such as geology, vegetation, and soil composition that affect rainfall-runoff response. Thus not every specific area in the region will feel the effects of climate change to the same degree, or even experience the same “symptoms.” The numerous deltas of the main river will also be affected in a trickle-down (no pun intended) effect. These climate models must therefore be understood in terms of interactive physical processes that make up the projected changes. In the same manner, further studies should be conducted in order to determine critical thresholds in rainfall and river flow to sustain ecological environments. Previous research had collected some data on water resource estimations, such as monthly rainfall and runoff, but there is still a dearth of data regarding evaporation, stream flow, and discharge. Particularly in light of the significant changes that are inevitably approaching with global climate change, data collection and further analysis will be invaluable in maintaining the physical, ecological, and anthropological stability of the Okavango River basin.

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