A check dam is a small, sometimes temporary, dam constructed across a swale, drainage ditch, or waterway to counteract erosion by reducing water flow velocity. Check dams themselves are not a type of new technology; rather, they are an ancient technique dating from the second century AD. Check dams are typically, though not always, implemented in a system of several dams situated at regular intervals across the area of interest.

The Graliwdo is a river of the Nile basin. Rising in the mountains of Dogu’a Tembien in northern Ethiopia, it flows northward to empty finally in the Weri’i and Tekezé River.