Small-scale water solutions are a key to increasing agricultural productivity in the face of climate change, says water expert David Molden.
In 2007, the Intergovernmental Panel on Climate Change (IPCC) issued a dire warning that climate change could halve crop yields in some African countries by 2020.
The prediction has since become controversial, with even an IPCC scientist reportedly saying he could not see supporting data. But there is growing concern about the impact of increasing drought on agricultural output in Sub-Saharan Africa, where 95 per cent of farmlands are rainfed and whererates of soil fertility loss are alarming.
Just a two or three week dry spell can bring disaster to many of the world's small farmers. And with increasing rainfall variability predicted by climate change experts,it is becoming too risky for farmers to invest in fertilisers, seeds and good soil management practices.
There is a tried and tested way of reducing this risk: assure a reliable supply of water and farmers will invest and their yields will go up. Evidence shows that better water and soil management can increase grain productivity despite climate change.
But how is it done?
In part, it means rolling out large-scale irrigation schemes. But, with high costs per hectare and per beneficiary, large schemes are costly and slow to develop, and relatively few farmers would benefit from improved production.
For example, scenarios from the Comprehensive Assessment of Water Management in Agriculture suggest that even doubling the irrigated area in Sub-Saharan Africa would help provide only about ten per cent of the continent's food supply.
To improve water security for those who need it most the rural poor we need a broader range of solutions.
One place to start looking is the 'informal' water sector, which is especially vibrant in Asia. People who have not been well served by government water services have already taken matters into their own hands, often stimulating small-scale private sector development.
Motorised pumps, the most influential technology in water for agriculture in the last 20 years, are just one example. People buy a reasonably priced pumpset, go to a water source such as groundwater, a river or drain, and pump water to their fields when they need it.
Long flexible pipes are another. They are now found all over the Indian countryside, and also China, where they are called 'white dragons'. They allow people to pipe water over relatively long distances from the source and either use it on their fields or sell it.
While pumps and pipes require investment, operation and maintenance, the water itself is free, and there is little need to interact with others in the community or with the government. It sounds easy.
Indeed, several other innovations have sprung up from this informal sector including ingenious water harvesting structures, low-cost sprinklers and drip systems, the application of clays such as bentonite to conserve soil moisture, and the safe use of urban wastewater for irrigation.
Water storage will also be particularly important to cope with climate change and more variable rainfall. We need to consider a range of options from ponds and small on-farm reservoirs to groundwater and soil moisture.
Drought insurance and post-harvest technologies such as food storage are complementary approaches to better water storage.
The advantage of small-scale, individual approaches is that they can be quickly installed with short payback times to a greater number of small-scale farmers. They can also involve the private sector and stimulate 'spontaneous' uptake, rather than uptake driven by donors, which is often slow and expensive.
Bottlenecks to progress
But these innovations are not being taken up at the speed or scale necessary across regions where they are badly needed, such as Sub-Saharan Africa.
This is largely because a lot of other elements have to be in place. Knowing the right technology or agricultural practice is simply not enough. Many water technologies are not available in local markets or not affordable by small-scale farmers.
Agricultural inputs such as seeds and fertilisers are similarly unaffordable. Even if they aren't, limited access to markets means that small-scale farmers cannot guarantee to sell their extra produce.
An agricultural water management solution must account for a range of factors beyond technology or agricultural inputs. There is a role for the private sector in financing, maintaining and marketing sustainable agriculture, such as microcredit schemes that help farmers access what they need.
There is also still an important role for the government. Policies and investment can help the development and uptake of small-scale technologies. For example, reducing tariffs on imported pumpsets or other irrigation and soil improvement technologies may lower costs to an affordable level.
Finding the balance
There is a downside. Increasing water use at one place will affect someone elsewhere in a river basin. The action of thousands of small-scale users adds up. Uncontrolled extraction may lead to falling groundwater tables, shrinking rivers, and competition and conflict over water.
It is relatively easy to control or regulate one large irrigation scheme, but managing groundwater resources used by millions of small-scale pumpers is a logistical nightmare, as can be seen in India.
So the challenge for water governance is to stimulate the development of affordable solutions while also managing water and land for sustainability. It is vital that policymakers plan and regulate the right policies for sustainable water management.
The good news is that any action taken now to improve water security for food production will ultimately help us cope with climate change.
David Molden is deputy director general for research at the International Water Management Institute in Colombo, Sri Lanka.