Sand mining far outpaces natural supply in a large alluvial river

Abstract. The world's large rivers are facing reduced sediment loads due to anthropogenic activities such as hydropower development and extraction. Globally, estimates of sand extraction from river systems lacking, in part the pervasive distributed nature processes. For Mekong River, widely assumed estimate basin-wide is 50 Mt per year. This figure based on 2013 likely be outdated. Here, we demonstrate ability high-resolution satellite imagery map, monitor, volumes Lower River Cambodia. We use monthly composite images PlanetScope (5 m resolution) over period 2016–2020 through tracking barges. show that rates have increased a yearly basis 24 (17 32 Mt) 2016 59 (41 75 2020 at rate ∼8 yr−1 (6 10 yr−1), where values parentheses relate lower upper error bounds, respectively. Our revised for (59 nearly 2 times greater than previous best Cambodia (32 current entire Basin (50 Mt). 5-year period, only months seen positive (supply exceeds extraction) budgets under mean scenarios with greatest natural supply). this net negative budget driving major reach-wide bed incision median −0.26 a−1 2019. monitor mining provides low-cost means generate up-to-date, robust needed underpin sustainable management plans global commons.