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.
Global climate change has increased the uncertainties and risks that have always been inherent in agriculture, especially in regards to the availability of water resources for crops. In response to this heightened jeopardy, some experts have advised the promotion of soil and water conservation (SWC) technologies for farmers. SWC technologies include bunds (structures to control runoff and reduce erosion), grass strips, tree planting, irrigation, and water harvesting structures such as dams and ponds. Farmers must weigh the risks of adopting a new technology with the potential gains in crop yield in order to decide if implementing a particular SWC technology will be beneficial. This study creates a mathematical model to assess the impact of SWC techniques in 5 ecologically different regions of the Nile Basin in Ethiopia. After running statistical analysis, the model suggests that all of the SWC options studied have large positive impacts on crop output in low-rainfall areas, while only waterways and tree planting have an impact in high-rainfall areas. In addition, irrigation alone has no effect or results in lower yields in both high- and low-rainfall areas of the country, but when it is combined with other SWC technologies, large positive impacts can be seen in all regions. This finding should lead us to consider that the answer to water management in the face of climate change will not be a “silver bullet” solution, but rather the result of interactions between many different technologies. The results from this statistical model may be used to give advice to farmers in Ethiopia, improve targeting of SWC techniques to certain areas, and provide insight for policymakers, NGOs, and other development agencies in order to help farmers adapt to changing water resources in the face of global climate change.–Nora Studholme
Kato, E., Ringler, C., Yesui, M., Bryan, E., 2011. Soil and water conservation technologies: a buffer against production risk in the face of climate change? Insights from the Nile basin in Ethiopia. Agricultural Economics 42, 593–604.
In order to build an accurate statistical model, researchers used diverse data from 50 households across 5 regions of Ethiopia, resulting in a total sample size of 6,000 plots. Researchers then separated the regions based on historical rainfall patterns, so that the impact of different technologies could be observed in disparate ecological environments.
The model assumes that farmers are risk-averse and want to maximize their profits. The equation is set up to show how farmers might maximize utility using different levels of SWC inputs. In order to account for the fact that different crops might be produced in larger or smaller quantities, the success of the inputs is based on the value of the crops produced per hectare of land on a plot. In addition, the statistical model controls for soil type, plot size, human capital, and fertilizer. After running the numbers, a positive coefficient from the equation means that the inputs have risk-increasing effects, while a negative coefficient implies risk-decreasing effects.
Each region was affected differently by SWC technologies, and the degree to which the innovations helped them was also variable. Grass strips and soil bunds have more risk-reducing results in low-rainfall areas, while some techniques, such as rainwater harvesting and irrigation, require a certain amount of rainfall to be viable. Even within the same rainfall area, some SWC technologies produced different results. This could be because of differing chemical properties of the soil, availability of nutrients, the needs of a specific crop, or other physical characteristics. What is clear is that it is important to investigate effects of SWC technologies with a specific region in mind in order to determine the best way to reduce risk in the face of climate change.
This statistical model and the results it has already produced will be valuable resources for farmers and policymakers as water resources become more jeopardized and droughts, floods, and other climate-driven events continue to plague the world. SWC technologies have great potential to mitigate the effects of climate change on water resources, and thus improve agricultural yields and food production worldwide even in these unstable ecological times.