Review of Check Dams as an Erosion Control Practice with a Special Focus on the Loess Plateau, China
Check dams, or gully plugs, are structures built across channels to reduce erosion by lowering water speed and accumulating sediments during floods. Check dams are often introduced in degraded areas, where natural or agricultural vegetation cover was lost or not capable of holding the top soil. They represent one of the most used stabilisation measures worldwide, because of their relative simplicity and easy implementation. Check dams can be grouped into two main categories: temporary and permanent structures. Temporary check dams include structures of small-medium size, designed for use of a maximum of ten years. These structures favour the accumulation of sediments and soil moisture, to establish a permanent vegetative cover. Temporary check dams can be removed when their aim of stabilising the gully with vegetation presence is reached. Reversely, permanent check dams are mediumlarge constructions usually implemented in severely affected sites. They are designed to last many decades and to resist massive flood events and in many cases entire communities benefit from their implementation. Several factors influence the choice of a check dam, such as topography, precipitation intensity, material and financial resources. Advantages of check dams are flexibility, cost efficiency and environmental benefits like groundwater and soil amelioration. However, negative aspects, such as the high risk of failure and the huge maintenance required, must also be considered when deciding to implement a check dam.