The potential impact of neo-Castorization on sediment transport by the global network of rivers

Abstract

In this paper, we assess the potential impact of global reservoir construction on sediment transport from the continental land mass. Our study links information on 633 of the world's largest reservoirs (LRs) (>0.5 km3 maximum storage capacity) to a digitized river network at 30-minute spatial resolution. A residence time change (Axft) is used in conjunction with a retention function to predict the proportion of incident sediment flux trapped within each impoundment. The discharge-weighted mean Ax;i for individual LRs distributed across the globe is 0.21 years. We estimate that more than 40% of global river discharge is intercepted by the large impoundments we studied and that a significant proportion («70%) of this discharge maintains a theoretical sediment trapping efficiency in excess of 50%. For regulated drainage basins the global, discharge-weighted residence time change is 0.16 years, representing a 30% potential sediment trapping. For all river systems, we estimate a 16% sediment trapping. From the standpoint of sedi­ ment retention, the most heavily regulated drainage basins are in Europe. North America, Africa, Australia/Oceania are also strongly affected.