They explain in their videos that the dams are there to prevent the sand from running off, which then acts as a sponge/filter to retain water. Having such a hu

They explain in their videos that the dams are there to prevent the sand from running off, which then acts as a sponge/filter to retain water. Having such a huge water supply also helps vegetation, which prevents erosion and helps the soil absorb water, so I guess it's a virtuous circle, at least in theory. Very interesting concept.