WHAT IS A WEIR?
A weir is a barrier built across a stream or river. It can be made out of wood, concrete, or a mixture of rocks, gravel, boulders and soil. Water pools behind a weir, spreading the water from the river or stream. This means that the water from the river covers a greater area of land, which can help farmers. Weirs slow down the flow of the river, but do not stop it completely.
WHAT ARE THE DISADVANTAGES OF A WEIR?
Weirs can create issues with fish migration, as the fish cannot swim over the weir. However, it is possible to build the weir so that fish are able to get over it. Weirs can also be dangerous for people travelling on or in the river. This is because they can get stuck in the current created by the weir.
WHAT IS A SAIL GEDAIM WEIR?
The Sail Gedaim weir was built over the Wadi El Ku river between 2013 and 2017, in North Darfur, Sudan. The river is seasonal and so only flows at times of greater rainfall. The Sail Gedaim weir is 7 metres high and is made of soil.
HOW IS THE SAIL GEDAIM WEIRD HELPING THE LOCAL COMMUNITY?
Climate change in Africa has caused local temperatures to rise. This has led to changing rainfall patterns. In addition to this, the Sahara is spreading. This has led to difficulties with farming in the region. Weirs allow people to adapt to the changing rainfall, because they help bring water to land in drought. This helps with farming, so people in the area can stay rather than having to leave.
Building the Sail Gedaim weir has slowed the flow of the river during seasonal downpours. As it helps spread the water, the space that the water from the downpour reaches has increased. This increases the area suitable for farming, as more land has enough water to be farmed on. Additionally, the slower flow allows water to seep into the ground. This makes the soil better for farming. The improved soil quality resulting from the weir allows watermelon, sorghum, tomato and sesame to be grown. Previously, only millet and sorghum could be grown on this land. Building the weir has also brought together local communities that were previously in conflict. This is because these communities are now sharing the farming land the weir has provided, which has helped increase cooperation. 34 village councils have come together to use the land, and the number of farmers using the land has increased from 150 to 4000.
THE FUTURE OF THE WEIR?
The second phase of the Sail Gedaim weir project was launched in 2018. There are plans to expand the weir, so that water is spread at more points in the river. This will further increase the amount of land available for farming around the river.