Sand Dams for semi-arid Evir

While this local is not in my area of specific interest, I love knowing this knowledge is out there. Sand dam's are such an amazing technology with so many positive effects. Basically a low damn wall is built. As seasons pass sand builds up behind the wall, retaining 20-40% of the water in the sand. That has, "cascading" positive effects on the water quality and the environment. (puns are a negative side effect of my personality)