‘Green’, rammed earth check dams: A proposal to restore gullies under low rainfall erosivity and runoff conditions

Abstract

Gully restoration check dams are usually made with construction materials and have a permanent impact on the landscape. Although earthen dams have not been used to restore gullies, they have been used around the world for water reservoirs and to control flooding. Here, we propose ‘green’, rammed earth check dams as a better environmental solution to restore gullies and integrate check dams in the natural landscape. This new design of earthen dam aimed at achieving a reduction in construction volume, as we propose a straight profile for the earthen wall upstream and an impervious core made of rammed earth wall. Moreover, the sloping, revegetated profile downstream enables integrating the check dam into the landscape, while the rammed earth wall allows the use of traditional materials and construction methods better adapted to the natural environment. We also present the design process, calculating its stability versus overturning, sliding and ground resistance for its weight. In addition, we compare the construction costs and carbon footprint of the rammed earth check dam with those of other frequently used check dams, such as concrete or gabion check dams. It shows that although rammed earth check dams may have a greater cost (>21%), they also have a sink effect of 23,639.36 kg CO2 due to the vegetation cover on the downstream embankment. This work shows their feasibility in gullied areas and ravines of fine textured soils under low runoff and rainfall erosivity conditions.