An oasis in the desert: The transformative power of sand dams
It is 5 AM on a Saturday morning in March. The sun does not rise for another hour in Kipico, Kenya, but David Mutisya Sila is awake and walking out the front door of his home to go work on his farm.
It is cool in the morning so he is bundled up in a shirt and jacket. They will be on the ground before 9 AM when the temperature rises above 90 F. Mr. Mutisya gathers what he needs and begins to walk down the hill, past his farm plot and on to the nearby river. He fills the gas-powered water pump he carried with fuel, hooks up the pipes and starts the motor.
Water pulled from the river travels upward to the farm to irrigate the kale, spinach, and fruit trees that are growing. Other farmers are still asleep. They will soon wake up and take tea before tending to their fields.
Mr. Mutisya works hard every day, just like so many in this region of Kenya. But he has something that most people do not — access to water throughout the year.
Just 5 kilometers down the river, farmers are not in a rush to start their day. The short rain season ended in December and did not bring as much water as hoped. Their farms sit empty, waiting for the long rainy season to start within the next month. Again, they hope that it will bring enough rains to ensure healthy crops this year. In the meantime, the riverbed sits dry.
Their neighbor, Mr. Mutisya, does not have this concern. He has access to water year-round from the riverbed thanks to a sand dam he helped build in 2012.
A decade ago, this land was unused. Today, it is an exemplar of abundance.
“These crops let me buy sugar, flour, that pump and so much more,” David said.
Kipico is located in a semi-arid region of Kenya. When it rains, rivers and streams rush with water. Once the rain stops, it takes only a few months before the once-full rivers are just sand. Underneath the sand is water. So, people must dig scoop holes to get water.
The effects of climate change make things more difficult for people in this region. The rainy seasons are less reliable and do not last as long. This year opened with yet another warning of drought in parts of Kenya due to below-average rainfall. The short rain season from November to December did not produce as much rain as anticipated.
But there is a way to push back against the impacts of climate change. In fact, it is possible to enable abundance in the face of desolation. Sand dams are a low-cost solution to the problem that brings year-round access to water, which in turn regenerates the environment and a community.
Old technology brings renewal
Sand dams are not your average dam. Rather than hold back a reservoir of water, sand dams allow most water to continue downstream. What they gather, as the name implies, is sand. And in that sand is water.
The Water Project works with communities in Makueni, Kitui and Machakos counties of southeast Kenya to utilize sand dams to address their water needs. It is possible to build multiple sand dams along the same river and support multiple communities.
Community members provide labor and local materials, such as rocks and sand, to the process. Oftentimes, more than 30 people work all day 6 days a week for 3 weeks to complete a dam that extends up to 100 meters and is up to 6 meters high.
When the rains come, water rushing down the riverbed carries sand, dirt, and rocks as it rushes downstream. The sand dams are built low so almost all of the water passes by, but the sand builds up behind the wall. That sand can extend up to 1.5 km beyond the dam, holding water for people to access. It may take a few rainy seasons for the dams to fill with sand, but once they do they have the potential to provide year-round access to water for people living nearby.
As much as 35% of the mass behind a sand dam is water. It is easily accessed by constructing a well adjacent to the riverbed behind the dam. Once a dam is mature, people can collect all the water they need from the well.
What makes sand dams ingenious is their minimal environmental impact downstream, the fact that the sand reduces the rate of evaporation of water, and the sand acts as a natural filter for the water.
Sand dams are not a new technology. In eastern Kenya, there are some dams that are a half-century old.
“All the people who built this are no longer alive,” said one farmer upon passing a dam built in the 1960s.
But, the older dams have not withstood over time. Over time, lessons learned have improved the construction of sand dams. Better cement is used. The wings on the sides extend farther. Hydrological advances in understanding make it easier to know where and how to build the most effective sand dam for in a river channel.
When built the right way, the impacts are remarkable.
A 2008 study measured the economic gains from sand dams in Kitui County, one of the places where we work. Its authors found that the sand dams they observed not only reduced vulnerability in the region but increased the average income of farmers using the dams by $120.
Sand dams are life-changing.
Abundance of water
David uses a pump, that he bought from money made through increased crop production, to irrigate his crops. The lack of water access before the dam’s completion caused David and other community members to turn away from traditional irrigation methods that relied on regular water access. Today, he is deploying those methods to grow kale (sukuma) and other crops.
“The money is not here,” he said, pointing to the ground.
“The money is 10 meters down. It is not possible without hard work. You have to dig down deep to get it.”
That hard work is supplemented by the availability of water from the nearby sand dam. It means that David now plans for what he wants to grow each year without worrying about whether there will be enough rains. And he does not have to worry about whether sudden hard rains will strip his land because it was too dry. Consistency allows David to plan into the future in ways he never could before.
He worked side-by-side with community members who formed a self-help-group as a part of the project. The Water Project partners with these community-based groups on projects for up to five years and continue to stay in touch well beyond the completion date of the last project.
These groups are the leaders from start to finish. They determine where to place the dams and wells. They manage the water points as they see fit.
In the case of David’s group, animals are banned from going to the river. People can freely walk down and cut whatever vegetation they need to carry back and feed to their livestock. Doing so keeps the water free from contamination and has helped preserve many of the plants growing in its vicinity.
Lessons like that are then shared between groups. When groups begin the process of constructing new dams and wells, they are bussed to meet with an experienced group. Sometimes, more than two groups are brought together. The communities can then share ideas and lessons learned from each other. And just as important, the new groups can see how their hard work will benefit them and their families.
“When we were working here we were not serious,” said David while reflecting on the construction of the dam in 2012.
“But now we see the impact of what we were doing. Water is life. Water is everything.”
David hopes that we will see something different the next time we visit because he expects his farm to continue to change. He plans on expanding further up the hill to plant even more crops that he will sell to continue to improve his life.
The lives of countless people, like David, are transformed by sand dams. It is truly remarkable how such a simple technology has such a significant impact.
