A new report has re-echoed the warning that the increasing erratic rainfall caused by climate change will pose a major threat to food security and economic growth, especially in Africa and Asia.

The report, which was made available by the International Water Management Institute (IWMI), said reversing the situation would require increased investment in diverse forms of water storage.

The Director-General of the Sri Lanka-based IWMI, Colin Chartres, said: "Millions of farmers in communities dependent on rain-fed agriculture are at risk from decreasing and erratic availability of water. Climate change will hit these people hard, so we have to invest heavily and quickly in adaptation."

The report argues against over-reliance on single solutions like big dams, proposing instead an integrated approach that combines large and small-scale storage options, including the use of water from natural wetlands, water stored in the soil, groundwater beneath the earth's surface and water collected in ponds, tanks and reservoirs.

The report's lead author and a hydrologist at IWMI, Matthew McCartney, stated: "Just as modern consumers diversify their financial holdings to reduce risk, smallholder farmers need a wide array of 'water accounts' to provide a buffer against climate change impacts. That way, if one water source goes dry, they'll have others to fall back on."

IWMI and its research partners estimate that up to 499 million people in Africa and India can benefit from improved agricultural water management.

The report notes that in response to increased demand for food and power supplies, the governments of developing countries with fast-growing economies have invested heavily in large dams this decade, ending a 10-year lull in their construction. Many of the 50,000 large dams built worldwide since the 1950s are intended to store water for irrigation.