Many regions that suffer acutely from drought actually enjoy substantial rainfall; the trouble is that it rains torrentially for very short periods, so most of the water is lost as run-off.
By building reinforced concrete walls across seasonal rivers, sand dams not only trap some of the water but also huge volumes of sand. The water is trapped within the sand, so it doesn’t evapourate, stays fresh for long periods and is filtered, so it can be extracted and drunk safely.
Huge quantities of water can be stored very cheaply in this fashion – up to 40 million litres per dam – yet sand dams are designed to capture only a small proportion of the overall flow. This means that, unlike traditional dams, sand dams don’t end up starving downstream communities of water.
This pioneering innovation could have a huge impact. Families in arid regions are often forced to live a nomadic existence; women and children spend many hours every day travelling just to collect water. That’s bad for maintaining education and building financial stability.
Excellent Development has so far arranged the construction of almost 1,000 dams, always with the full backing of local communities. Now they are installing smart meters to gather clear evidence of the scale of the benefits. Their longer term goals are ambitious: to help build 10,000 dams for 5 million people by 2025, and 1 million dams for 0.5 billion people by 2040.
We’re delighted to be supporting them with a grant at this stage of their work. That should help to persuade larger funders, such as the Gates Foundation, to finance construction at scale.
To learn more about sand dams please visit: www.excellentdevelopment.com