During the past decades, the São Francisco River basin encountered substantial changes due to intensive human activities such as river regularization and damming, and more recently, climate change. As a result, a decrease of streamflow in the lower São Francisco River sector has received considerable attention due to its drastic geomorphological and hydrodynamic changes. This study presents a detailed investigation on the changes of streamflow and its effect on spatiotemporal migration of estuarine plume along the São Francisco coastal zone from 1994 to 2017 based on salinity and water temperature extracted from HYCOM numerical modeling.The progressive saltwater intrusion from in situ observation for 2005 and 2017, is analyzed. The results show two distinct periods with substantial inter-annual variability of streamflow during the period from 1994 to 2011 and accentuated decreasing trends from the second semester of 2012 onwards, and discontinuous periodicities from later 2012 due to the extreme hydrological events of droughts. The spatiotemporal variability in salinity and water temperature on the coastal zone revealed a severe retraction of the estuarine plume due to the low streamflow rates, which started after the second semester of 2012, and the presence of Tropical Surface Waters (TSW, S $>$ 35.9 g/kg) closer to the river mouth, shifting the previous estuarine mixing zone from the coastal region to inward areas of the estuary. The continuous penetration of saltwater towards inner areas of the São Francisco estuary ($\sim$10 km upstream from estuary mouth) is attributed to the decline of water flow supply from the river upper reaches due to the extreme drought events and water conservation measures. These changes may lead to potential ecological and human problems due to persistent high salinity above the limit for human consumption (S $>$ 0.5 g/kg) from the estuary mouth to the limits of local cities along the river.

在过去的几十年中，圣弗朗西斯科河流域由于人类密集的活动而发生了重大变化，例如河道调整和筑坝，以及最近的气候变化。结果，由于其剧烈的地貌和水动力变化，圣弗朗西斯科河下游河段的水流减少受到了相当大的关注。这项研究提出对径流的变化和河口基于从HYCOM数值modeling.The逐步海水入侵摘自盐度和水温沿圣弗朗西斯科海岸带羽1994年至2017年其对时空迁移的影响进行详细的调查原位分析了2005年和2017年的观测结果。结果表明，1994年至2011年期间，河水流量有两个明显的年际变化趋势，并且从2012年下半年开始呈下降趋势，而由于干旱的极端水文事件，从2012年下半年开始出现不连续的周期性。沿岸地区盐度和水温的时空变化表明，由于低流速（从2012年下半年开始）和热带地表水（TSW，S）的存在，河口羽流严重退缩。$>$35.9 g / kg）越靠近河口，将先前的河口混合区从沿海地区转移到河口向内地区。盐水不断渗入圣弗朗西斯科河口的内部区域（$〜$河口上游10公里处）是由于极端干旱事件和节水措施导致河流上游的水供应减少。由于持续的高盐度超过了人类消费的极限，这些变化可能导致潜在的生态和人类问题。$>$ 从河口到沿河当地城市的界限为0.5 g / kg）。