Extract of the Rhine map of Wilhelm Besserer from the year 1595. Mechtersheim (above) is protected by a dike against the Rhine.
Land unter? – Floods and flood prevention at the upper Rhine during early and high middle ages
The aim of the interdisciplinary project “Land unter“, which is funded by the Thyssen foundation, is to develop a regional history of floods and flood prevention measures based on archaeological and geomorphological studies on the upper Rhine between Straßburg/ Kehl and Mannheim/ Ludwigshafen. The results will be compared with other regions, particularly in Western Europe. The main focus is on trying to identify potential early dike lines and to locate them in the area. In a multi-methodological approach, the team would like to clarify not only construction and dating of dikes, but also reconstruct contexts of origin and functions related to flood sediments
Meanwhile in Speyer the team was searching for dikes in the areas of “Eselsdamm” and “Domgarten”, which were supposed to be created in the late 11th century. But the “Eselsdamm” dated in modern times, probably around 1700. Within the Domgarten no evidence of the “huge masses of stone” which Benno of Osnabrück should have heaped up to protect the dome against the Rhine could be found so far (fig. 1).
But the combined analysis of historical, geomorphological and topographic maps has shown suspected lines, which are now being studied with geoarchaeological and historical methods. In this context the oldest map of the upper Rhine from the year 1595 shows a dike line near Mechtersheim (fig. title). It is to determine where this dike is located in the area today. The topographic map of 1878 (fig. 2) shows three or more lines that are to be considered. The combination of LiDAR-data, archival sources and soil samples should help to date these dikes and understand their connection with flood and river dynamics.
Fig. 2:The topographic map of 1878 shows south of Mechtersheim two dikes and a path that might correspond to the dike on the view of the map from 1595.
While it appears to us today that floods have always been perceived as a problem because of great damages and risks – but it is doubtful whether this was really the case. After all flood protection in the form of dikes in Western Europe has been proven not much before the 11th century. These first dikes have not protected the settlements, but the respective business areas on the Loire, on the Rhône and the dutch Rhine.
Therefore it is questionable whether rivers had floods before the middle ages. Since frequency and magnitude of floods are dependent from the regional climate and the intensity of agricultural use, we cannot assume from present environmental conditions.
But the cultural perception may have changed: possibly floods have become a problem/ disaster, as more and more capital (e.g. cornfields, houses and facilites) were accumulated in the floodplains. In addition it is important to consider from which period of time it allowed the changing understanding of nature, to accept disasters no longer as an expression of the divine will, but rather as a challenge to shape and control nature.