The variability of residual flows and saltwater intrusion was evaluated for the duration of a hurricane-related freshwater pulse in a subtropical estuary, the Suwannee River. Increased rainfall affected the river’s watershed when Hurricane Irma skirted the west coast of Florida in September 2017. The river remained short of reaching flood stages, but the increased river discharge was enough to modify the residual circulation and restrict saltwater intrusion. Current velocity profiles and hydrographic variables were collected in five tidal-cycle experiments to study the lower estuary’s response to the peak river discharge and its subsequent relaxation. Data were recorded in three cross-estuary transects. In addition, continuous salinity measurements were recorded for 48 days over the shallow portion of the seaward transect. Results showed that the subtidal water-level slope inside the estuary, between the mouth and a river station at Wilcox, modified the residual circulation and restricted the intrusion of salt water. During high tide, salt water entered the estuary due to tidal pumping even though residual circulation was seaward in the cross-section. Residual seaward flows persisted for the duration of the hurricane-related freshwater pulse. After relaxation of the freshwater pulse, saltwater intrusion was observed in the time series over the shallow portion. This saltwater intrusion responded to changes in wind forcing, with largest intrusions when the wind blew into the estuary, i.e., toward the N and NW.

在亚热带河口Suwannee河中，与飓风有关的淡水脉冲持续时间，评估了剩余流量和盐水入侵的变化性。2017年9月，飓风“艾尔玛”（Irma）席卷佛罗里达州西海岸时，降雨增加影响了河流的分水岭。河流仍未达到洪灾阶段，但河流流量的增加足以改变残留循环并限制盐水的入侵。在五个潮汐实验中收集了当前速度剖面和水文变量，以研究下游河口对洪峰流量及其随后的松弛的响应。数据记录在三个跨河口样带中。此外，在连续海盐样断面的浅水部分记录了连续48天的盐度测量值。结果表明，河口内潮域的水位坡度，位于威尔科克斯河口与河口站之间，改变了残留环流并限制了盐水的入侵。在涨潮期间，即使在横截面上残留环流向海，盐水也会由于潮汐泵送而进入河口。在与飓风有关的淡水脉动期间，残留的海流持续存在。淡水脉冲松弛后，在浅层部分按时间序列观察到盐水入侵。这种咸水入侵对风的变化做出了响应，当风吹入河口时，即向北和向西北吹时，咸水入侵最多。修改了残留循环并限制了盐水的入侵。在涨潮期间，即使在横截面上残留环流向海，盐水也会由于潮汐泵送而进入河口。在与飓风有关的淡水脉动期间，残留的海流持续存在。淡水脉冲松弛后，在浅层部分按时间序列观察到盐水入侵。这种咸水入侵对风的变化做出了响应，当风吹入河口时，即向北和向西北吹时，咸水入侵最多。修改了残留循环并限制了盐水的入侵。在涨潮期间，即使在横截面上残留环流向海，盐水也会由于潮汐泵送而进入河口。在与飓风有关的淡水脉动期间，残留的海流持续存在。淡水脉冲松弛后，在浅层部分按时间序列观察到盐水入侵。这种咸水入侵对风的变化做出了响应，当风吹入河口时，即向北和向西北吹时，咸水入侵最多。淡水脉冲松弛后，在浅层部分按时间序列观察到盐水入侵。这种咸水入侵对风的变化做出了响应，当风吹入河口时，即向北和向西北吹时，咸水入侵最多。淡水脉冲松弛后，在浅层部分按时间序列观察到盐水入侵。这种咸水入侵对风的变化做出了响应，当风吹入河口时，即向北和向西北吹时，咸水入侵最多。