Floodplains

In order to know how to restore floodplains, knowledge of functioning floodplains is needed. When should they be flooded, how long should this last and at what time of year? Which species benefit, and what are important key factors for success?

We will answer the above questions in a study for the OBN 'knowledge network'. Waardenburg Ecology is working together with Stichting Bargerveen (secretary), Bureau Stroming, Sovon, Kurstjens Ecologisch Adviesbureau, Henk Moller Pillot and Hydrologisch adviesbureau Klink. In a previous desk study, this consortium already identified the most important factors and the most promising areas. Over the next four years we will deepen this knowledge with targeted field research and actual measurements of the life that develops in flooded flood plains.

In the coming years we will study four flood plains along the Waal that flood in a controlled manner every year: Buitenooy and Staartjeswaard (both near Nijmegen), Nieuw Munnikenland (near Loevestein Castle) and the Eijerwaard polder (part of the Noordwaard – Biesbosch). At these locations, water will be retained in various ways, with locks, weirs, valve culverts, etc. This happens after the high water peak in the spring, when the snow from the Alps melts.
We will then monitor whether the water actually remains longer and whether it indeed leads to increased ecological value, including the growth of algae, macrofauna, zooplankton and fish. We look at how much development occurs, which species these are and how the food web is structured. Birds are also included in this study to complete the food web. To determine the control factors, we also measure abiotic conditions such as temperature, transparency and chlorophyll levels.

In addition to this annual monitoring, we will carry out one intensive monitoring campaign in a year in which a extreme spring high water occurs. We will do this in six floodplains along the Rhine and the Meuse that we have selected in advance. In this monitoring campaign, we carry out measurements in several rounds over a longer period to get a good idea of the changes over time. The same parameters are measured as in the annual monitoring, only more often and in more places.

We will use the results to provide targeted advice for the design, management and restoration of floodplains. There are various implementation programmes at Rijkswaterstaat and the provinces where this study perfectly fits when it comes to restoring biodiversity, ecological water quality and climate adaptation.