The São Francisco River is the fourth longest river in South America and one of the most regulated. Severe coastal erosion has affected the delta shoreline since 1985, leading to the complete destruction of Cabeço village between 1997 and 1999. In this study, we mapped and radiocarbon dated the beach ridge sets occurring on the delta plain and performed a detailed analysis of the delta shoreline changes since 1960. During the Holocene, the delta plain construction was punctuated and took place during episodes of higher river discharges coincident with Bond events 4, 2 and 1 and periods of higher precipitation in the river basin, as reconstructed by δ¹⁸O measurements in cave speleothems. The last major episode of delta construction apparently ended at approximately 1.0 ka cal. BP. Since that time, riverine sediment input has been just sufficient to maintain the shoreline. A comparison of historical maps and aerial photographs showed that from 1853 to 1960, the shoreline at the river mouth remained in approximately the same position. A decrease in rainfall in combination with river regulation, particularly after 1985, triggered extensive erosion at the delta shoreline. This erosion was not caused by sediment retention behind the major dams but instead resulted from changes in the backwater/drawdown effects deriving from river regulation. Shoreline erosion mostly affected the river mouth. The mobilized sediments caused progradation of the downdrift shoreline. Updrift of the river mouth, the shoreline remained stable, as it had already reached an equilibrium orientation in which the net longshore transport was zero.

圣弗朗西斯科河是南美第四长的河流，也是监管最严格的河流之一。自1985年以来，严重的海岸侵蚀已影响三角洲海岸线，导致Cabeço村庄在1997年至1999年之间被完全破坏。在这项研究中，我们对三角洲平原上发生的海滩山脊组进行了测绘并用放射性碳标明了日期，并对三角洲进行了详细的分析。海岸线变化自1960年以来的全新世期间，三角洲平原建设被穿插和更高的河流的发作期间发生的放电重合邦德事件4，2和1，并在流域更高沉淀的时期，由δ作为重建¹⁸洞穴洞穴中的O值。三角洲建设的最后一个主要阶段显然结束于大约1.0 ka cal。BP。从那时起，河流沉积物的输入就足以维持海岸线。历史地图和航拍照片的比较表明，从1853年到1960年，河口的海岸线保持在大致相同的位置。降雨的减少和河流的管制相结合，尤其是在1985年以后，在三角洲海岸线引发了广泛的侵蚀。这种侵蚀不是由大坝后面的沉积物滞留引起的，而是由河流调节产生的回水/排水效应变化引起的。海岸线侵蚀主要影响河口。动员的沉积物导致了下漂海岸线的发展。河口向上漂流，