Two Centuries Room for the River

Abstract

The Room for the River program is generally regarded as successful in freeing up room to the river and seen as an exemplary alternative to conventional river flood protection measures. However, over the course of the last two centuries large amounts of room have been taken from the river. Therefore, the amount of room the program has returned to the river should be related to the room that has been taken away in the period prior to the implementation of the Room for the River program. The aim of this study is to produce a timeline of volume available to the Rhine and its branches over the past 200 years, which has changed drastically as a result of human interventions both predating 1995 in the form of dike placement, normalization operations and other forms of river management and following 1995, in the form measures taken in the Room for the River program. Historic maps are used to reconstruct the winter river extent for each year within the scope of the study. Terrain rasters for each target year are constructed through both spatial and temporal interpolation. The extents per year are then used to clip the corresponding terrain rasters. The normative discharge of 16,000m3/s set by Rijkswaterstaat is used as a ’roof’ for the volume calculations. For each year within the temporal scope of the study, an area and volume is calculated for the whole of the research area as well as per defined sections. Furthermore, the contribution of terrain for the summer bed and the winter bed are separately calculated. Due to parts of the data used for this study being prone to errors as a result of its historic nature, an uncertainty analysis over the volume calculations is performed. Results show a major drop in volume available to the Rhine in the period before the implementation of the Room for the River program due to reduction in available area. From 1995 onward, the volume shows major increase which can be mostly attributed to floodplain excava- tion operations performed as part of the Room for the River project. Ultimately, the constructed volume timeline shows the Room for the River program was successful in returning the amount of room to the river that was taken from 1940 onward.