A very interesting concept. IIRC one of the problems of traditional (water) dams is when they silt up since it reduces the water storage capacity. However, in

A very interesting concept. IIRC one of the problems of traditional (water) dams is when they silt up since it reduces the water storage capacity. However, in this case, the 'silting up' (or sanding up) is the whole intent. So basically they are creating an artificial aquifer. Simple yet effective.