Recent modeling has demonstrated that sediment supply is one of the primary environmental variables that will determine the sustainability of San Francisco Estuary tidal marshes over the next century as sea level rises. Therefore, understanding the environmental controls on sediment flux within the San Francisco Estuary is crucial for optimal planning and management of tidal marsh restoration. Herein, we present suspended-sediment flux estimates from water year (WY) 2009–2016 from the San Francisco Estuary to investigate the environmental controls and impact of the record 2013–2016 California drought. During the recent drought, sediment flux into Lower South Bay, the southernmost subembayment of the San Francisco Estuary, increased by 345% from 114 kt/year from WY 2009 to 2011 to 508 kt/year from WY 2014 to 2016, while local tributary sediment flux declined from 209 to 51 kt/year. Total annual sediment flux from WY 2009 to 2011 and 2014 to 2016 can be predicted by total annual freshwater inflow from the Sacramento-San Joaquin Delta (R² = 0.83, p < 0.01), the primary source of freshwater input into the San Francisco Estuary. The volume of freshwater inflow from the Sacramento-San Joaquin Delta is hypothesized to affect shoal-to-channel density gradients that affect sediment flux from broad, typically more saline and turbid shoals, to the main tidal-channel seaward of Lower South Bay. During the drought, freshwater inflow from the Sacramento-San Joaquin Delta decreased, and replacement of typically more saline shoal water was reduced. As a result, landward-increasing cross-channel density gradients enhanced shoal-to-channel advective flux that increased sediment available for tidal dispersion and drove an increase in net-landward sediment flux into Lower South Bay.

最近的模型表明，沉积物的供应是主要的环境变量之一，随着海平面的上升，它将决定下一世纪旧金山河口潮汐沼泽的可持续性。因此，了解旧金山河口内沉积物通量的环境控制对于优化潮汐沼泽恢复的规划和管理至关重要。本文中，我们提出了旧金山河口2009-2016水年（WY）的悬浮泥沙流量估算，以研究环境控制和创纪录的2013-2016年加州干旱的影响。在最近的干旱期间，进入旧金山河口最南端子湾下南湾的沉积物通量从2009财年的2011克拉/年增加到2011财年的508 kt /年，增长了345 kt，而当地支流的泥沙通量从209 kt /年下降到51 kt /年。从萨克拉曼多-圣华金河三角洲的年度淡水总流入量可以预测2009年至2011年以及2014年至2016年的年度泥沙通量总量（R ² = 0.83，p <0.01），这是旧金山河口输入淡水的主要来源。据推测，萨克拉曼多-圣华金河三角洲的淡水流入量会影响浅滩到河道的密度梯度，从而影响从较宽的（通常是更多的盐水和浑浊的浅滩）到下南湾的主要潮汐河道的沉积物通量。在干旱期间，萨克拉曼多-圣华金河三角洲的淡水流入量减少，通常更换更多含盐浅滩水的数量减少。结果，向陆上增加的跨河道密度梯度增强了浅滩到河道的对流通量，从而增加了可用于潮汐散布的沉积物，并推动了进入下南湾的净陆向沉积物通量的增加。