Check dams: Distribution, purposes and effectiveness.

Summary: Check dams are small barriers built across streams to slow down water and catch soil. Lately, more and more of them are being built all over the world to stop erosion. But do they actually work? Researchers looked at 202 studies to find out. They found that most check dams are built to change how water flows or to save soil, but often, there isn't a clear plan for what they should achieve. Also, very few studies look at how much they cost compared to their benefits, especially for the local people. To make check dams better in the future, we need clearer plans and better tracking of how well they work over time.