Rhine Delta Programme studies

Bifurcations area

Bifurcations area

River-widening measures in the Rhine, Waal, and IJssel bifurcations area can contribute to the substantiation of other taskings in the area, such as those related to nature, recreation, and energy generation. The province of Gelderland has conducted a study to map out opportunities for social added value and the impact of such measures: Effecten en mogelijkheden van rivierverruimende maatregelen in het splitsingspuntengebied van Rijn-Waal-IJssel (in Dutch).

Over the past one and a half years, the Rhine tributaries bifurcations area project team has mapped out potential measures for this area. In a river management study commissioned by the Ministry of Infrastructure and Water Management and Rijkswaterstaat, the effects of such measures have been explored. The study shows how interventions in the bifurcations area can affect the discharge distribution and thus the water levels entailed in different discharge volumes. This study feeds the considerations underpinning the elaboration of Rhine tributary measures, thus generating an overall package of measures that maintains the agreed discharge distribution and is acceptable in terms of side effects.

The results have been set down in the summary report entitled “Rivierkundige studie splitsingspuntengebied” [Bifurcations area river management study].

IJsselkop

In December 2017, the MIRT Consultation Committee decided to launch an MIRT Study to further map out the options for realisation and funding of river-widening measures in the Meinerswijk-Stadsblokken and Huissensche Waarden areas. Such a study will provide more clarity regarding the feasibility and costs of a set of integrated measures for the region around the IJsselkop bifurcation.

This decision follows on from a study conducted earlier, which showed that the implementation of river-widening measures in the IJsselpoort Climate Adaptation Park planning area may necessitate river-widening measures along the Neder-Rijn and/or the Pannerdensch Canal, in order to maintain the IJssel - Neder-Rijn discharge distribution under normative conditions. The study will cover the full scope of the taskings at play in the area; it will provide a more detailed picture of the various measures in terms of costs and risks.

The study focuses on the options for advancing decisions and for determining which decisions need to be taken when in order to not miss out on linkage opportunities. The study is scheduled to be completed by October 2018.

Rijnstrangen

With effect from 2005, The Rijnstrangen area has been reserved as a potential long-term retention area. Together with the other government authorities, the Province of Gelderland has explored how this reservation impacts the spatial development of this area. The research report shows that the reservation does not necessarily limit the development potential. Developments that chime with the zoning plan are permitted in any case: new nature and infrastructure, farm expansions, renovations or new housing developments, and a holiday park. An early dialogue with the municipal authorities is advisable for anyone initiating new developments.

In addition, the Ministry of Infrastructure and Water Management and Rijkswaterstaat have commissioned a study into the effectiveness of the Rijnstrangen retention area. This study has been prompted by the new flood protection standards and the idea that these would cast the effectiveness of using retention areas such as Rijnstrangen in a different light. The study has explored effective scenarios for the use of the retention area, elaborating the costs and benefits of various options. It shows that, from the perspective of the new standards, the use of the Rijnstrangen area could be effective if its inlet volumes are controllable and geared to discharge forecasts. The study feeds the considerations regarding the elaboration of the Preferential Strategy. Het onderzoek voedt de afwegingen rond de uitwerkingen van de Voorkeursstrategie.

The results have been set down in the final report entitled “Effectiviteit Rijnstrangen” [Efffectiveness of the Rijnstrangen area].

In-depth study into river widening

The Preferential Strategy for the Rhine comprises a combination of dyke improvements and river widening. In most cases, if a river is given more room, the water level will fall across a long stretch, including upstream of the river widening. This could save costs with respect to the required dyke improvements. The Ministry of Infrastructure and Water Management has examined the scope of these cost savings.

The “Implementation of Method to Reduce Costs of Dyke Improvements through River Widening of Rhine Tributaries” study shows that the cost savings differ from one tributary to the next: along the IJssel, river-widening measures yield higher cost savings than comparable measures along the Waal. The study will be followed up by mapping out the cost savings for each dyke section. The results, that became available in the autumn of 2016, will be relevant to the update of the Preferential Strategy.

Werkendam/Merwedes

The preferential strategy envisages a dyke relocation near Werkendam (Brakel). However, this measure has failed to garner sufficient support. Further research has generated an alternative that has less of an impact on the area and is considerably cheaper than dyke relocation: secondary channels in the Werkendam floodplains, near Sleeuwijk, and near Avelingen, and flood-proofing the Beatrixhaven port. A final decision on the alternative will be taken at a later date, in the context of updating the Preferential Strategy.

Longitudinal erosion control dams

Rijkswaterstaat is investigating which sections of the Waal and IJssel are suitable for the construction of longitudinal erosion control dams. Constructing such dams, parallel to the river embankment, will reduce dehydration. In addition, it will raise the groundwater levels along the river, which benefits the stability of the flood defences. Furthermore, longitudinal erosion control dams are conducive to the navigability of a river. In the period 2015-2021, Rijkswaterstaat will conduct a practical test involving longitudinal erosion control dams.