In medieval times the name Merwede (or "Merwe" in Middle Dutch) was the name of a continuous stretch of river, considered to be the lower part of the river
Waal (a major distributary branch of the
Rhine), and carried on its name all the way to the sea. Later on, the name Merwede was discarded downstream of the town of
Papendrecht and replaced with
Noord river and, even further downstream,
Nieuwe Maas. Only the part of the river between Woudrichem en Papendrecht retained its name. The confusing river names are the result of two major flood events, which both resulted in a significant shift in the course and flow of the lower rivers. The first of these events forced the river
Meuse (Maas) to take a more northerly course and created a direct connection between the Meuse and the Merwede at the town of Woudrichem. The names of several stretches of the lower rivers were then changed to reflect this, for example the
Oude Maas and
Nieuwe Maas. During a second flooding event (the
St. Elizabeth floods) a major breach in the coastal dunes of
Holland created an inlet that would eventually reach the Merwede, thus creating a new, more southerly and shorter path to the sea. Most of the flow of the river
Meuse, and a considerable part of the flow of the
Rhine (by means of the
Waal), were rerouted to this new pathway (the current
Biesbosch,
Hollands Diep and
Haringvliet). From that time on, the Oude Maas and Nieuwe Maas received little water from the Meuse. In recent centuries the influence of the Meuse has decreased even further, to the point that the major stretches of river called
Oude Maas and
Nieuwe Maas have been essentially cut off from the river Meuse completely. Both the current Merwede and all of its lower stretches (now called
Noord river,
Oude Maas and
Nieuwe Maas) are now consequently almost exclusively fed by the Rhine, while the Meuse has been given its own artificial mouth,
Bergse Maas, and the two rivers Rhine and Meuse are now mostly separated to reduce the risk of flooding. This separation of the rivers Rhine and Maas is considered to be the greatest achievement in Dutch hydraulic engineering before the completion of the
Zuiderzee Works and
Delta Works. The
Merovingian dynasty probably derived its name from this river. == Sources ==