Rapid changes to global river suspended sediment flux by humans

Abstract

Rivers support indispensable ecological functions and human health and infrastructure. Yet limited river sampling hinders our understanding of consequential changes to river systems. Satellite-based estimates of suspended sediment concentration and flux for 414 major rivers reveal widespread global change that is directly attributable to human activity in the past half-century. Sediment trapping by dams in the global hydrologic north has contributed to global sediment flux declines to 49% of pre-dam conditions. Recently, intensive land-use change in the global hydrologic south has increased erosion, with river suspended sediment concentration on average 41 ± 7% greater than in the 1980s. This north-south divergence has rapidly reconfigured global patterns in sediment flux to the oceans, with the dominant sources of suspended sediment shifting from Asia to South America.

MOdern River archivEs of Particulate Organic Carbon: MOREPOC

“…In the last decade, sediment delivery in fluvial systems has increased by 215 %, whereas the net export of riverine sediment to the ocean has simultaneously decreased by 49 % (Syvitski et al, 2022), indicating the changing amount of eroded POC mobilized to fluvial systems and the final exported POC mass to the ocean (Stallard, 1998). While land-use change (e.g., soil erosion by agricultural practices) can lead to increasing terrestrial POC input (Syvitski et al, 2022;Dethier et al, 2022;Montgomery, 2007;Quinton et al, 2010), massive sequestration of POC upstream of dams significantly alters the nature and flux of downstream POC (Syvistski et al, 2022;Maavara et al, 2017;Best, 2019;Battin et al, 2009).…”

Sediment sources and transport dynamics in large, regulated river systems with multiple lakes and reservoirs in the subarctic region of Canada

“…For example, Syvitski et al (2022) estimated that, on average, large dams and their associated reservoirs on 34 major rivers are responsible for a reduction of ~74% in the sediment loads in those rivers. Dethier et al (2022) determined that sediment loads for major rivers in the global North (i.e., above 20°N) had declined by an average of 49% compared to pre‐dam conditions. Lake Winnipeg, the third largest hydroelectric reservoir in the world, is also among the most effective reservoirs in retaining sediments; in that it sequesters ~97% of upstream riverine sediment loads.…”

“…(a) a large quantity of the seven-fold increase in the BR suspended sediment load is intercepted by Split Lake; (b) riverbank and lake shore erosion associated with diversion of the Churchill River does not measurably add to the sediment load transported from the BR into the LNR; (c) the UNR is currently the primary sediment source for both Split Lake and the LNR; and (d) the LNR sediment transport dynamics is more sensitive to the variability of sources and fluxes of sediment in the UNR due to environmental changes.5.5 | Comparison between the sediment loads in the BR and UNR and selected large riversA number of studies have considered to compare the influence of dams on the sediment loads in the BR and the UNR with other large rivers in the world. For example,Syvitski et al (2022) estimated that, on average, large dams and their associated reservoirs on 34 major rivers are responsible for a reduction of $74% in the sediment loads in those rivers Dethier et al (2022). determined that sediment loads for major rivers in the global North (i.e., above 20 N) had declined by…”

Long-term variations in water discharge and sediment load of the Pearl River Estuary: Implications for sustainable development of the Greater Bay Area

“…The water discharge and sediment load delivered to the sea are dominant factors affecting the geomorphologic and ecosystem evolution of the estuaries and coast (Syvitski et al, 2009;Meiggs and Taillefert, 2011;Liu et al, 2020;Liu et al, 2021b). For over half a century, the water discharge and sediment load in large river systems have been increasingly altered by climate change and human activities, such as reservoir or dam construction, land use changes, soil conservation measures, and water extraction (Dai et al, 2016;Best, 2018;Khan, 2018;Dethier et al, 2022). Changes of water discharge and sediment load can cause various effects on coastal ecosystems and the geomorphological evolution of river channels (Dai et al, 2016;Liu et al, 2021b).…”