Dakar — Drastic water loss in West Africa's River Volta basin - covering Benin, Burkina Faso, Côte d'Ivoire, Ghana, Mali, and Togo - could deprive millions of people of food and hydropower in coming years due to climate change, researchers predict.

Higher average temperatures, seen to be rising by up to 3.6 degrees Celsius over the next century, and reduced rainfall could see water flows in the basin drop by 24 percent by 2050, and 45 percent by 2100, according to a new study by the International Water Management Institute (IWMI).

By 2050 there would be enough water for only 50 percent of current hydropower production, the study found. Ghana's Akosombo dam, the world's largest man-made lake, currently generates 1,020 megawatts.

The roughly 24 million people living in the basin are mainly dependent on agriculture, which accounts for around 40 percent of the region's economic output. This population, however, is expected to reach 34 million by 2015, up from 19 million in 2000, adding to pressure on water resources.

Matthew McCartney, the study's lead author, told IRIN climate change effects were already being felt in the basin.

"Climate change warning signs in the Volta Basin are an upward trend in mean annual temperature," he said. "Because of the natural variability, rainfall trends are much harder to assess than temperature, but there is some evidence of declining trends in rainfall, at least over Ghana."

Climate change would make planned additional water storage in the basin unattainable.

In the absence of climate change about 78,000 hectares would be irrigated and 11,800 gigawatt hours per year of hydroelectric power would be generated in the coming years, explained Tim Williams, IWMI's director for Africa. But, he said, climate change would mean that "only about 75 percent of the irrigated area will be possible and only about 52 percent of the potential hydroelectricity will be generated by 2050."

"We do notice two trends: The increasing demand on the available water resources which is population driven - that is already affecting the water availability. On top of that there is anecdotal evidence by farmers who point to shifts in the onset of rains as well as variability within the season in terms of frequency of dry spells within the growing season," he told IRIN.

The study's predictions are based on a moderate impact scenario which the report says are "relatively conservative, but not overly cautious...

"In general, climate change predictions point to extreme weather events. A middle impact climate change scenario mimics the way nature works in a long period of time," Williams said.

Solutions

Improving ground water by filling local aquifers with water from the local rivers or reservoirs as well as relatively simple solutions such as building small ponds on farms, or roofed water tanks are important for sustaining water supply, said the study.

Cooperation by the riparian states on future dam projects and incorporating climate change impact in those developments are other ways of ensuring that water from one of the world's largest river basins continues to sustain lives.

Robert Zougmoré, programme leader of Consultative Group on International Agricultural Research (CGIAR) West Africa, said offering reliable weather and climate information would help farmers plan better to avoid losses due to extreme weather conditions.

"If we are able to provide communities with up-to-date weather forecasts, this can help farmers on how to effectively manage their farms without suffering much of the effects of climate change.

"If a farmer knows that the rainy season will have above-normal rainfall he will, for instance, decide to grow rice rather than millet," he said.

However, the study noted that climate change was not a priority in many sub-Saharan African countries. "In many countries there has been almost no systematic evaluation of the possible implications of climate change for water resources and it is given little consideration in the planning of future water resources development."

Uncertainty about climate change impact, the fact that predictions tend to be in the distant future and that the priorities for many sub-Saharan African governments are mainly basic service provision, discourage timely climate change adaptation, the researchers argued.

"In the Volta, riparian states need to develop 'no regrets' options for water planning and management that are socially and economically viable over a range of possible climate futures. They also need to think much more about more integrated water planning and management across the whole basin, with all the states cooperating rather than the piecemeal ad hoc water resource development that has occurred to date," said McCartney.

IWMI's Williams, however, said African governments were gradually becoming more aware of the dangers of climate change, "but the rate and magnitude of climate change adaption response is not yet sufficient."

[ This report does not necessarily reflect the views of the United Nations. ]