Sand dams

Hello!

As I mentioned last week, this post is dedicated to telling you about a new technology that I have been learning about this semester called sand dams (http://www.sanddam.org/). Sand dams are a new, up and coming technology that can be used in drought-prone regions or places where harnessing and storing water is difficult. The construction of sand dams helps in recharging aquifers (or ground water) so that wells and hand pumps in the area can extract water from the ground. Here is a picture of what a sand dam looks like:

Sand dams are dams that are built across seasonally dry river beds. The area must be appropriately selected, preferably with large boulders or rocks on either side of the river beds to serve as supports for the dam. Initially, you build a dam that is only a few feet high. When it rains, some of the water will be retained to form a reservoir. More importantly though, all of the sediment that is being carried by the rainwater will be blocked from continuing downstream from the dam. As the sediment builds up, water will continue to flow over the dam. The dam is only supposed to affect a maximum of 10% of streamflow so that communities downstream can continue to use the water for sanitary and irrigation purposes. The following year, another addition to the sand dam is made to make it a little bit higher. When the river floods again, some of the water will remain in the area, sediment will build up, and more water will flow over the dam. The idea here is to create a reservoir and give the water the chance to be absorbed into the ground to recharge the aquifer. The picture below gives you an idea of how a sand dam is built:

By having all of the sediment build up, this will facilitate the storage of water, and will also clean the water as it gets absorbed into the ground. To extract water, wells can be built around the area. There is also a pipe that is built into the sand dam in the initial stages, so that water being retained by the dam can be accessed. A filter is placed on one end of the pipe to prevent sediment and sand from blocking the pipe. The water that comes out of the pipe is otherwise clean and ready to use! This video shows you how to build a sand dam and talks about all of the technology's beneficial impacts (on the reduction of water-borne diseases, the increase in vegetation and school attendance rates). I highly recommend you watch it:

Isn't it incredible? The more I am learning about this technology, the more I want to continue learning about it and hopefully get the chance to apply it one day. Who knows, I may even be able to start a sand dam project next year in Huacho when I am working with the local water utility! Only time will tell. But please, tell your friends and spread the word, because this is a very useful, cost-effective, yet under-used technology. The more people find out about it and learn about it, hopefully it will be implemented to a greater extent as a simple solution to drought and water shortage issues!

See you again next week! And Happy St. Patty's Day!

Sheila