Research focusing on the environmental history of the Lower Danube region is rather scarce compared to the progresses made for the upper and middle sections. Moreover, little is known about the effects of recent climatic fluctuations and increasing anthropogenic pressure on the highly sensitive river systems of the area. In this paper, the information available in various historical sources (charters, narratives and historic maps) was used to carry out cartographic reconstructions of the riverscape in the former borderland of the Romanian Provinces from the fifteenth century to modern times. The results indicate that significant hydrographical disturbances occurred throughout this period and the present day configuration of the drainage network is relatively recent. The diversion of the lower course of river Siret at the beginning of the seventeenth century led to several other hydrological and hydrographical alterations, such as channel planform changes, supplementary channel shifts of the tributaries or increased incision into the floodplain. The origin of the triggering factors is to be found in the interplay between natural conditions and human activities.