Mette Bendixen and colleagues point out that sand extracted from fluvial environments is being consumed faster than it is produced (Nature 571, 29–31; 2019) This has deep implications for managing flood risk in a changing climate.
Extracting sand or restricting its movement (such as through river damming) reduces sediment availability. This means that when large floods occur, insufficient sediment is deposited on the land for it to act as a defence against smaller floods. Fluvial-sediment depletion can also lead to coastal erosion, especially if accompanied by illegal sand mining on the foreshore.
Sea-level rise is projected to accelerate in the second half of this century. According to Bendixen and colleagues, sand prices could be exceptionally high by then. Instead of squandering sand, we need to save it.
Nature 572, 312 (2019)