Hydromorphological investigations of different approaches to improve the ecological state of the lower Ems river

IIn this project four alternative solutions are analyzed with respect to their potential to sustainably reduce the sediment import into the river Ems and to improve the water quality in the lower river. A three dimensional hydrodynamic numerical model is applied to conduct hydromorphological simulations. The results are used in conjunction with an verified set of indicators to evaluate the proposed solutions against the actual situation.

Depth averaged velocity in some of the retention areas of the alternative “Retention areas along the lower Ems river”
Figure: Depth averaged velocity in some of the retention areas of the alternative “Retention areas along the lower Ems river”.

Duration: 2010 – 2014

Background of this investigation is the persisting critical ecological status of the Ems Estuary. It is characterised by strongly increased suspended sediment concentrations in the lower Ems river, which derogate the lighting and oxygen conditions in the water and hereby the overall ecological function of the estuarine habitat. Moreover, high sediment concentrations and upstream sediment transport increase the necessity for dredging  in the lower Ems. 

The causes for the unfavorable development in the Ems river are changes in the tidal dynamics and sediment transport dynamics which are attributed to anthropogenic interference into the morphology and geometry of the system (Talke and de Swart 2006; de Jonge 1983).

The alternative solutions being investigated in this project aim to weaken the tidal asymmetry with flood dominance to lead to a long-term reduction of the import of suspended sediment in the lower Ems. The considered solutions are:

  • Polder at the mouth
  • Retention areas along the lower Ems river
  • Extention of the upstream tidal limit to Bollingerfähr in combination of a polder upstream of the weir Herbrum
  • Groundsill in the vicinity of the Ems storm surge barrier.

 

Research division:

Coordination:

  • Prof. Dr. R. Mayerle

Staff

  • MSc. Katharina R. Niederndorfer
  • Dr. Gerd Bruss
  • MSc. José M. Fernandez Jaramillo
  • Dr. Talal Etri

Partners:

  • Projektgruppe Ems der Regierungsvertretung Oldenburg
    Website
  • Dano Roelvink, Unesco IHE Delf
    Website