Notes to broadcasters
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The following script outlines one possible solution to water scarcity during the dry season: the groundwater dam. Groundwater dams store water underground, rather than on the surface. Water that is stored in the soil does not evaporate like ponds and streams. It is clean and healthy – parasites will not contaminate underground water. The key is to find ways to capture wet season rainfall underground. There are many ways to do this, both traditional and modern; but whatever method is used, the principle is the same: slow down the flow of water as it runs downhill.
Each region will have its own traditional solutions, based on its own unique needs for water, its soil structure, its climate, and its social structure. You will want to do some research on the needs and capacities of your area to make the script relevant.
The groundwater dam requires a fair amount of labour to complete, but the technology is not difficult, and the rewards are considerable. This script is intended to show how one community was able to build a groundwater dam to solve their water problems. It is not meant to provide step by step instructions to build a groundwater dam. Further technical details on how to build and maintain the groundwater dam are available in the resource materials listed at the end of this script. You might want to do further research and let your listeners know where they could obtain more information.
Good morning [afternoon, evening
]. This is Gikuyu, and I’m here with Adongo to talk about how our village built a groundwater dam and solved our dry season water problems.
Good morning [afternoon, evening
I’ll start by explaining why we built the dam. During the dry season, the rivers and wells in our village dry up. We have no water for our cattle, and very little for ourselves. We used to take our cattle to the hills every year. It was a long and tiring journey, and we wanted to find a better solution.
]: We heard about another village that had built a groundwater dam under a dry riverbed. They no longer had to move their cattle every year. They were able to stay in one place. They were even growing a few vegetables in the dry riverbed! Their cattle were healthy, and they had good drinking water all year round.
It was a little hard to believe, but we were willing to try anything. So we visited the village and saw the dam. It was simple, but the villagers had achieved remarkable results. They told us that a groundwater dam is better than a surface dam in many ways. It’s simpler to build and it costs much less. You can use building materials that are available right in your village. And water doesn’t evaporate when it’s underground.
That’s right. And the water is cleaner and safer — parasites that cause sickness can’t breed underground. You don’t have problems with mosquitoes and snails.
After talking to elders in the other village, we decided to talk to other experts. We got all the information we needed. And to our surprise, we realized that we could build it ourselves.
Yes, that was a wonderful surprise! The experts told us to look for a place where there was green vegetation all year round on the riverbed and along the banks of the river. This is a sign that there is water underground. When we found such a place, we dug a few holes by hand to make sure that there was a layer of bedrock not too far from the surface. Then we were ready to start digging.
We started work near the beginning of the dry season. It was a lot of work! The builders took the lead, and almost everyone else in the village helped. Even the children helped! We dug a trench all the way across the dry riverbed. We dug right down to the bedrock, and then built a wall of brick and stone. The top of the wall was about one metre under the surface of the riverbed.
It’s also possible to use clay soil for the dam wall instead of brick and stone; as long as the clay is well compacted. The important thing is to use materials that are completely waterproof, so no water gets through.
Yes, we had to be very careful to make it watertight. We also built walls on each side of the riverbank to prevent the dam from eroding and to make sure that the water didn’t flow around the dam when the river valley was flooded.
In a surface dam, the water is stored on the surface, in a lake or pond. But in a groundwater dam, the water is stored underground, beneath the dry riverbed. Even though the river dries out in the dry season, there is still water in the ground under the riverbed.
We placed a pipe in the downstream wall of the well. The pipe leads to a pump on the side of the riverbank. There, we can pump water for drinking, for livestock, and for whatever else we need. It doesn’t give us an unlimited supply of water, so we have to be careful and use water wisely. But it’s changed the life of our village.
]: Both our cattle and our people are healthier! But there are also benefits that we didn’t expect! Before we built the dam, children often had to walk a long way to find water during the dry season, especially the girls. They missed a lot of school, and were behind in their studies. Now, fetching water is much easier and takes less time. [Proudly
] My daughter is doing much better in school this year.
Building the dam was a lot of work. It took many people working during the entire dry season to finish the dam. We had to finish all the construction during the dry season to avoid flooding. It was not a difficult task, but it had to be done right. And we did it!
Thank you for listening to our story. Perhaps it can help your village as well. This is Adongo ____________, saying good morning, [afternoon, evening
Good morning, [afternoon, evening
– END –
- Contributed by Vijay Cuddeford, researcher/writer, North Vancouver, Canada.
- Reviewed by Chris Reij, International Cooperation Center, Vrije Universiteit, Amsterdam, The Netherlands.
- Shenkut, Mesfin. Rainwater Harvesting with Subsurface and Sand Dams.
- Raju, Dr. K.C.B. “Groundwater Dams.” Catchwater. Apr. 2000. Centre for Science and Environment. Centre for Science and Environment, 41, Tughlakabad Institutional Area, New Delhi 110061. Tel: 26066854, Fax: 29955879.
- Nissen-Petersen, Erik. Water from sand-rivers. 23rd WEDC Conference Durban, South Africa, 1997.
- “Sand dams regenerate baragoi.” Kit Newsletter. Intermediate Technology Development Group (ITDG).
- ITDG East Africa, PO Box 39493, Nairobi, Kenya. Tel: +00 254 20 2719313, Fax: +00 254 20 2710083, Email: firstname.lastname@example.org
- ITDG Zimbabwe, Number 4 Ludlow Road, Newlands, Harare. Tel: +00 263 4 776107, Fax: +00 263 4 78815, Email: email@example.com
- “Sub-surface dams, small dams, and sand dams.” Sourcebook of Alternative Technologies for Freshwater Augmentation in Africa.
- “Subsurface Dams.” WaterAid. WaterAid, Prince Consort House, 27-29 Albert Embankment, London, UK SE1 7UB.
- Falkenmark, Malin, Patrick Fox, Gunn Persson, and Johan Rockström. Water Harvesting for Upgrading of Rainfed Agriculture.