Sand Dams

Sand dams are an incredibly good idea...

A couple people from EMU are staying with Wes and Lois (an elderly EMM couple that hosts the meals at the guest house) and they were going to Kola so I went with them. 

We left at 0700 in hopes of beating the Nairobi traffic. We failed. Wes knew a back way which would not have so much traffic; it didn't, but Wes did not know it as well as he thought and got disoriented (which is quite easy when there are practically no signs). With my limited knowledge of the area I was able to direct him to a road from which we could return to a main road, but then at an intersection Wes thought he knew a better way to get where we wanted to go and so my suggestions were not taken. Unfortunately, we again found ourselves on a road on which we did not want to be and despite my suggestions that turning around may be a good idea, the driver drove bravely on. We sat in traffic for another hour and finally found our way back to the main road. We then drove in circles for half an hour, since the navigator did not understand the directions we had been given and I, after having been ignored once more, had decided that there was no point in my offering assistance.

Finally, after driving into and out of the airport parking and making four wrong turns, we finally got back on the correct road and proceeded on our way. 

We were going to visit Jacob and Alvera Stern, a couple from MCC who are helping with a sand dam project. They work with Utooni Development Organisation (UDO) which finds communities that have formed self-help groups which want to build a sand dam. UDO provides the cement, reinforcing bars, consultation, etcetera, and the self help group provides the labor, sand, stone, and water (which sometimes has to be carried for miles). The dam then represents significant investment of time and labor so the community will take responsibility for maintaining it.

The location of the dams is very specific; they must be built in a sandy, seasonal riverbed that has a rock bottom. They are built in series, since one dam captures only about 2% of the river's water. After a dam is built it fills with sand, and the sand captures water, while silt flows over the sand. Behind the dam is usually around 40% water and 60% sand, and sand prevents surface evaporation, which can be up to 70 inches per year. The sand prevents mosquitoes from breeding, since there is no water on the surface. It also filters the water and greatly decreases the presence of parasites and disease.

 The water that flows in the river.

The water coming out of the dam, after being filtered through the sand.

 To retrieve the water, a pipe can be put at the base of the dam, (as has been done in the picture above) or people can simply dig scoop-holes in the sand behind the dam.

Jacob Stern loves to talk and knows everything about what he does, so I learned lots of stuff about the sand dam projects; as we walked up the stream for several hours, seeing total of five dams, Jacob kept up a running commentary, telling us more than I thought there was to know on the subject.

We also went to see the first sand dam built in the area: built by UDO's founder. It has been extended six times and is now over twenty feet tall.

The sand trapped above a dam.

The dams that we went to see are all made by one self-help group. It is the most active group in the area; they have built thirteen dams in two years. The group has 27 members but when they start a dam, 150 people show up and they can finish a dam in three days.

Another project they encourage is terracing. The terraces slow down the water: decreasing runoff.

Digging the terraces is backbreaking work but they dramatically increase crop yields, especially if used along with drought-resistant crops, rather than the standard maize.