Sand dams in Machakos

I (Doug) took at introductory trip out to Kola in Machakos county to get to know Utooni (UDO) and the work they do with sand dams.  This will be one of the partners I will spend a major amount of my time with.   UDO has worked for years making sand dams and now has over 1000 of them in Machakos, Makueni and Kajiado counties.  Visually it's easy to see impacts of the dams, easy to understand, and I've heard about them for many years, so it was fascinating to see them in person.  UDO, and especially Paul Mutua, graciously hosted me for two days of touring a good selection of the dams.

With Paul (second from left), the UDO field officer (second from right, who works directly with self-help groups in her region, and the group chair (to the right),  Sand during high flows backs up behind the concrete dam and holds water.  A water line here is being used with a pump to irrigate fields near the dam.  Vegetation is much greener near the dam as the water table has been raised due to the dam. 

Sand backs up behind the sand for a considerable distance, up to around a kilometer.  All of that sand can then hold water (about 30% of the volume will be water between the sand particles).  Even more water is stored in the surrounding ground water as it gets recharged.

Some water is used for drinking, usually collected from scoop pits in the sand.  Here kids are filling jerry cans (usually 20 liter cans, so about 40 pounds each).  The boy on the left will use a donkey to carry the cans.  The girls on the right will carry the cans themselves up the hill to their home.  Some homes are a km or more up the hill.  So collecting water is still requires a good deal of labor, but at least there is now water available relatively close by.

Livestock are also watered from scoop holes.  Here a scoop hole is partially surrounded by thorny branches to keep the livestock from stepping directly in the water.  Oxen and a wagon are being used to haul cans of water.

Raising the water table causes a considerable accumulation of water below the dam also.  Here the water is primarily used for watering livestock and cleaning.  In principle, there is some separation of activities (such as getting drinking water upstream) to try and prevent contamination of the water.  They estimated about 1200 people in the valley are served by a series of several of these dams.

Construction of the dams is initially by self-help groups, who often then organize to have other group activities.  Here the group Ngwatanio ("unity", a women's group although a man has also been recruited) is working together on a field to raise vegetables (kale here) which can be sold in market.  Water from the sand dam makes it feasible to do this.  This is particularly helpful in the drier times (such as now) when food stocks are low, and food prices are higher.

This group was in an area with very large gullies that resulted form erosion.  They terraced the gullies, such as this one, and turned the terraces into fields for producing fruit and vegetables.

Another example of vegetable gardening that is made possible by water from the sand dams.  Here water is pumped up with a small gas powered pump.  Cabbage, kale and tomatoes are commonly grown.  The area is fairly high density, with most hillsides terraced as seen here.  The tops of the hills have some forest under government protection, to prevent erosion and provide other ecosystem services.

On a larger stream there is considerable standing water below the dam.  A gas pump is irrigating a large field on the other side, where a farmer intercrops maize, watermelon and kale.  In another area they said a pump was about $500, there are sometimes microfinance loans and some farmers are able to recover the cost in 3 months.

The Makuta Mwea self help group started by making sand dams with UDO/MCC help, grew vegetable crops to raise money, purchased a pump with the money, extended their vegetable production, purchased a plot of land to make bricks and construct a small community building with the funds, and have started a seed saving bank.  They have about 700kg of seeds they hope to sell to raise money to complete an electricity connection.

Another indirect benefit is honey production.  Here traditional African beehives are sited near the sand dam.  Water from the dam means there is food for the bees now all year round, so yearly honey production increases by a large percentage.

In some places, hand pump wells are installed on the banks to make for easier and cleaner access to the water.  Self-help groups control the pumps, it is locked except at certain times of day when they make water available for a small fee (equivalent of 5 cents/20 liters).

Two groups in the Masii area work together to construct a sand dam with UDO water engineers, artisans, and project managers.  James, the UDO field officer for this area, is happy to see the dam going up!

The groups must construct terraces on the edge before construction, so that silt does not wash into the dam area and clog the sand.

A shallow well was installed upstream from the construction site.  This greatly facilitates construction as water for the cement is now close (rather than needing to be carried by donkey from a long distance).  Women and children are generally responsible for the water.  Also, other community members have arrived within hours of operation as they see that a close water source is now available.  In some areas, these natural sand areas could provide water, but it was usually very deep--a 3 meter deep hand-dug well was a risk to children as it could collapse and bury them.

Rock needs to be added to the dam wall.  There is little naturally occurring free rock in most areas, as the bedrock is hard gneiss.  Men are in charge of sledgehammers with chip pieces of rock off the exposed bedrock.

Activities are communal, everybody here is working on the dam.  The dam is for the self-help group that has the Kamba name "hold me, support me".  Another group "Light of the ---[area they are from]" had experience making dams and came to help them.