Mozambique Diary - Day 18

Sand dams! Usually we think of dams filled with water but in Tete Province of Mozambique we are building dams with the express purpose of having them fill with sand. So what about that?

Given the very hot climate and limited water most rivers are intermittent in nature and water tables very low. Crops can often not be grown and women and children have to walk many kilometres for water - one community could find water only 20 kilometers away from their home.

One very unique approach has been to build dams that over time fill up with sand. During the annual rainy season, as the water is slowed by the dam, the suspended sand quickly drops filling up the area behind the concrete barrier. Within 1-3 seasons, depending on the rainfall and the particular geologic formation the sand will accumulate up to 800 metres behind the dam.  This sand now holds the water and instead of rushing off or evaporating, it sinks into the soil and repletes the water table. Once established the dam will provide most communities with water year round instead of only 2-3 months.

Cattle are a big reason the farmers initially seek water sources. Cattle have been their primary food source and water is critical to their well being. Once they see that water is available the idea of gardening and crop production also becomes an option. Our engineers and agriculturalists together with our partners staff work closely with communities to define appropriate sites that meet both engineering and community expectations. The community then engages in the building of the dam by providing labor and local resources.

MCC supplies cement and other essential components of the project as well as supporting the salaries and training of local staff. The goal is to establish a national capacity that will enable our partners to resource communities throughout the country.                                                           

You will notice in the picture on the right that upstream from the dam there are garden plots. Farmers are now able to plant vegetables and fruit trees to supplement their diets and provide additional income when sold at local markets. Watering holes can be dug for cattle and on the sides of the sand wells can be dug for potable water.

It is indeed exciting to see seedlings push forth from the ground where before this was not a possibility. Agricultural best practices are introduced as part of the overall program.

The work is transforming communities. Men do now not have to leave to find work. Women and children do not have to carry water great distances. Children are freed up to go to school.