28 Aug 2018

A large-scale field study to understand the complex processes in the transition area from the Ems river towards the UNESCO listed Wadden Sea will begin on Tuesday 28 August 2018. This knowledge is very much needed in the assessment of the effectiveness of large measures in reducing the water turbidity. The study is part of the Eems-Dollard 2050 program and will investigate how mud behaves in the transition between fresh river water and salty sea water. The research is led by Rijkswaterstaat and coordinated by Royal HaskoningDHV, in collaboration with German authorities and international research institutions. The turbidity study will take place in the Ems estuary on the border of the Netherlands and Germany.

The research project has attracted attention from academics in the United States of America as well as the United Kingdom. The results of the research, as well as potential intervention, is expected to be shared with other authorities and to contribute to an improved understanding globally of how to keep estuaries and their ecosystems intact and healthy.

Water turbidity as a measure of a healthy ecosystem

Water turbidity is the measure of water clarity; the cloudier the water, the higher the turbidity. The Ems River has large quantities of mud which can cause turbid water, hindering the growth of algae at the bottom of the food chain. This has a knock-on effect on the growth of soil life and fish as their food source is reduced, disrupting the eco-system.

The fine details of the research procedure

At the confluence of the Ems River and the Dollard, ten measuring frames and cables are placed on the bed of the Ems estuary to measure the turbidity and salt and river flow velocity for three weeks at various depths. Tidal cycles last for 13 hours and during this time continuous measurements will be carried out from eight ships.

Water turbulence is also measured as it’s important for the exchange and distribution of mud. The size and fall rate of mud flocs are also measured with a special camera and samples of water and soil are taken to measure the sediment concentration. Measurements will be collated, and calculation models will be created and improved to help find solutions to reduce turbidity.

Dr. Petra Dankers, project leader from Royal HaskoningDHV, a senior consultant on the morphology of coasts, estuaries and rivers, commented: “This is a really important piece of work and we look forward to seeing the results of it. This research contributes to the larger Ems-Dollard 2050 program which aims to improve the ecology and nature, alongside a sustainable economy, of the Ems delta. It is great to see so many parties working together, combining science, practice and policy in order to have this project succeed.”

Two rounds of measurement

During the study two rounds of measurements will take place, one when the river has a high discharge and one when the river has a low discharge to see how the turbidity changes in different situations. The river discharge is the volume of water that passes through the river at any one point of time.

The first round of measurements will be carried out when there is predicted low discharge in the Ems River from 9 August to 7 September 2018, during which the first 13-hour measurement with the ships will take place on 28 August. The second round of measurements will take place when there is predicted high river discharge of the Ems river in January/February 2019. Following this, the first set of results are expected to be announced in the summer of 2019.

Charlotte Schmidt, a spokesperson of Rijkswaterstaat, said; “This is a complex project which has brought together research teams from the Netherlands and further afield to study the ways we can reduce river turbidity to protect estuary ecosystems. We have also collaborated with German parties due our joint need in both Dutch and German water management.

“We also work with specialist technical universities Delft, Twente and Wageningen and research institutes such as Deltares who are involved for advice, scientific interpretation and some field measurements. We would like to extend our thanks to all those involved, particularly in their help in measuring simultaneous aspects in the research.”

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Petra Dankers

Senior Project Leader & Advisor Morphology and Eco-engineering

Nijmegen, NL

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