Get an overview about the project outputs and related knowledge

A2) Ecology of the training dams

Start: 09/2014
End: 09/2018
Status: Active

Contact details

Frank Collas

Radboud University Nijmegen

Download here the summary poster and the PhD thesis related to this project.

The constructed longitudinal training dam in the river Waal near the village of Tiel (Source: F.C Collas)

Project output

Assessment of the ecological value of novel river training measures and a tool to design restoration measures based on habitat requirements of fish, macroinvertebrates and aquatic macrophytes.


Freshwater ecosystems are among the most endangered ecosystems in the world. Especially lowland rivers have been substantially modified to increase flood safety and to facilitate commercial navigation, resulting in low biodiversity and dominance of invasive alien species. To mitigate navigation-induced disturbance and to improve discharge capacity, longitudinal training dams (LTDs) were built in the river Waal in the Netherlands. LTDs are river training structures aligned parallel to the river shore (see figure). Thereby, these dams protect the river banks from navigation-induced impacts and possibly allow the development of sheltered lotic habitats and gentle slopes. Knowledge on the relation between multiple physical factors and habitat requirements of riverine species is required to evaluate and optimize the design of LTDs and other future river restoration measures.

Key goals: Innovative monitoring Integrated management

Overview of our approach to get insights and support the ecological design of river training interventions.

Innovative components

River restoration measures are often built without a detailed assessment of potential ecological effects. By combining field observations of riverine species with local conditions ecological models were developed that enable such a detailed assessment. Further innovation has been achieved by using state of the art abiotic measuring techniques (unmanned aerial vehicle, side scan sonar) to measure abiotic conditions in restoration measures. For the evaluation of the ecological effect of the build longitudinal training dams (LTDs) in the river Waal a similar approach has been applied. Innovative abiotic measurements were performed regarding water dynamics, water level fluctuation, flow velocity and underwater sound levels. The used method was found to accurately assess impacts of navigation on abiotic conditions in the littoral zone of the river Rhine. Abiotic conditions in the shore channel of the LTD were found to improve compared to traditional groyne fields. Subsequently, fish and macroinvertebrate monitoring was performed with traditional techniques combined with the previously mentioned method to determine abiotic conditions during sampling. Through combining species occurrence with simultaneous abiotic conditions measurements insights are gained on habitat preferences of riverine species.

For whom and where?

  • River managers that want to optimize the ecological potential of river restoration measures.
  • River restoration projects across Europe that are interested in constructing LTDs or other river restoration measures.

Data-collection methods: Field survey measurements Physical and laboratory experiments Remote sensing Systematic review

Temporal scale: Monthly series Seasonal measurements Yearly measurements

Application development and findings

  • The constructed longitudinal training dams (LTDs) reduce the impacts of navigation on abiotic conditions in the littoral zone of the river Waal.
  • The stability of dynamics is increased in the shore channel behind the LTD.
  • As a result juvenile fish densities increased two to threefold compared to nearby reference locations.
  • Macoinvertebrate densities also increased in the shore channel behind the LTD.
  • Rare and endangered species are more abundant (e.g. River Lamprey, River clubtail, native unionid mussels).
  • Based on known occurrences of riverine freshwater species habitat requirements have been assessed.
  • A multitude of ecological models (species sensitivity distributions, SSDs) has been developed.

SSDs are a valuable tool for improving the design and monitoring of riverine restoration measures.

Status for day-to-day practice

Consultants and river managers need to consider mitigation of navigation effects in river restoration measures. Additionally, SSDs are an important tool to improve the design of river restoration measures.

Location along the 10 km stretch of the river Waal (between Tiel and Ophelmert) in which the longitudinal dam pilot was implemented.

Spatial scale: River section

Key locations: Rhine River (NL) Waal River (NL)

Next steps

The coming years additional monitoring will be performed near the LTD and new technologies will be applied to spatially measure abiotic conditions as an input for the SSD models.

Last updated: 10/02/2020

Explore the contact details to get to know more about the researchers, the supervisory team and the organizations that contribute to this project.

Main researcher

Frank Collas

Radboud University Nijmegen

Supervisory team

prof. dr. Rob Leuven

Radboud University Nijmegen

dr. Tom Buijse


Prof. dr. Aalbert Hendriks

Radboud University Nijmegen

Contributing partners

As soon as available, explore the storyline to get to know more about the main methods or prototype tools that were developed within this project.

Ecological benefits of a sheltered channel parallel to the main river

The longitudinal dams minimize the effects of commercial navigation to protect the habitat of fish and macroinvertebrates.

Frank Collas

Radboud University Nijmegen

View storyline

Explore the output details for available publications to get a glance of the innovative components and implications to practice as well as the links to supporting datasets.

Project outputs

Absence of freshwater mussels in Europe in relation to climate-related environmental factors

A unique database was constructed on the sensitivities of all European freshwater bivalves in relation to environmental factors that are affected by global change.

23/05/2018 by Frank Collas et al.

View details View publication

Contains: Dataset upon request

Longitudinal training dams decrease effects of navigation and increase the density of juvenile fish species in the littoral zones of the river Rhine.

The construction of this novel intervention in a highly navigated river like the Waal quickly allowed for ecological restoration while continuing with commercial navigation.

01/04/2018 by Frank Collas et al.

View details View publication

Contains: Dataset upon request

Also applicable to this project

Predicting effects of ship-induced changes in flow velocity on native and alien molluscs in the littoral zone of lowland rivers

Shipping increases local flow velocities thereby potentially decreasing species richness of freshwater mussels and snails which in turn affects ecosystem functioning and services.

12/11/2018 by Remon Koopman et al.


View details View publication

Contains: Publication open access

Take a look to the dissemination efforts and application experiences which are available in the news items and blogs.



Sharing knowledge with HKV, one of the project partners.

For RiverCare, it is very important to have face to face meetings to exchange the knowledge, and make sure to discuss with interested parties the results of the researchers.

View event

All events


Collaborative monitoring or longitudinal training dam effects in the Waal River

15/07/2018 by Prof. dr. S.J.M.H. Hulscher

RiverCare is part of 'WaalSamen', a collaborative group to measure and compare the effects of the longitudinal dams as an alternative to river groynes.

View details

Dutch serie “Vroege Vogels” (Early birds) about nature and ecology in the Netherlands

07/11/2017 by Remon Koopman

During the 2017 summer and autumn a fish monitoring campaign was performed by RiverCare  and experts from Bureau Waardenburg.

View details

All news


Brochures about the longitudinal training dams

19/03/2018 by Laura Verbrugge

Communication of project results is important to enable the exchange of knowledge between the different stakeholders affected by the river intervention in the case...

View newsletter

Citizen Science newsletter editions of a participatory monitoring project

01/12/2017 by Laura Verbrugge

Monthly newsletters during the fishing season and a Facebook page update participants of the ongoing activities and results.

View newsletter

All newsletters


WaalSamen videos


View video

Rivercare floodplain


View video

All videos

Anything to ask or share?

About us

We would like to learn from your experiences and questions to take our knowledge further into practice in the Netherlands and abroad. Your feedback will help us to find out about your interests and how useful the information provided was to you.