Store More Water, Experts say

According to the Sri Lanka-based International Water Management Institute (IWMI) which issued the report, these changes have dire consequences for feeding an ever-expanding global population; this is especially true in areas of Africa and Asia where millions of farmers rely solely on rainwater for their crops. In Asia, 66% of cropland is rain-fed while 94% of farmland in sub-Saharan Africa relies on rain alone, according to IWMI.

These are the regions where water storage infrastructure is least developed and where nearly 500 million people are at risk of dire food shortages, the report cautions. In sub-Saharan Africa, existing water storage is equal to less than 26,400 gallons (100 cubic metres) per person. Compare this to 1.3 million gallons (5,000 cubic metres, which is enough to fill two Olympic-size swimming pools) per person in the US, according to Colin Chartres (director general of IWMI). "Climate change will hit these people [in Africa and Asia] hard, so we have to invest heavily and quickly in adaptation", said Chartres in a statement. "We've missed the boat on climate change mitigation," he told National Geographic News.

How can these regions adapt? According to Chartres, the solution is to fund a diversity of water storage projects, from small-scale rainwater tanks and larger-scale dams to systems that artificially recharge groundwater aquifers, to improving the soil so it can hold more water. "If we can capture some of these big events, like what is happening now in Pakistan, we can channel it back into wells and old irrigation reservoirs and tanks", Chartres said. Stored water in times of drought can "make all the difference between chronic hunger and steady progress towards food security," Matthew McCartney, the report's lead author and a hydrologist at IWMI, said in a statement. "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," he added.

Small-scale efforts have delivered some positive results when planned with the participation of both politicians and farmers, according to IWMI. For example, small collection basins have boosted maize yields in times of rain or drought in Zimbabwe. In India's Rajasthan State, 10,000 water harvesting structures that help to recharge groundwater now irrigate 34,600 acres (14,000 hectares) and feed 70,000 people. Chartres adds that decision-makers in India, where there is expected to be a 50% gap between water demand and supply by 2030, are starting to fund storage projects because they realise the long-term economic benefits of a secure supply.

While the early results seem positive, some experts argue that decision-makers have to diversify even beyond storage. "Storing water is not an end in itself," said Sandra Postel, director of the Global Water Policy Project and National Geographic's freshwater fellow. "It is a means to meet food, energy and drinking water needs. The key goal of climate adaptation should be to build resilient ways of meeting these needs in an equitable and environmentally sound fashion." A more holistic approach includes conservation and efficiency improvements, Postel explained.

The need to feed and provide electricity for growing populations has brought about a resurgence in big dam building. Despite controversy over these projects, which have been associated with significant environmental damage, the displacement of tens of millions of people and the loss of an income for hundreds of millions of fishers and farmers downstream, Chartres says they are an inevitable part of the picture. "We're not going to stop dams with the demand for energy. It's green energy. We should be asking how to make them more sustainable."

IWMI recommends that dam builders more carefully weigh the social and environmental consequences against the economic benefits. Postel agrees with IMWI that large dams are one of many viable solutions, but she cautions that when planning for larger scale projects in the face of climate change, planners have to take a landscape or watershed approach to storing and managing water. "We are going into a period with greater uncertainty and variability, so you want to build in resilience. If you construct dams of any size, you want to invest in watershed protection, for example." A well-forested riverbank or thriving wetland can slow floodwaters, reduce erosion and protect dams from becoming clogged with silt - a problem that reduces dam capacity and value.

Source: National Geographic