ABOUT US

We cherish, protect, and develop over 70,000 hectares of nature reserves, forests, and parks in Flanders. We want as many people as possible to be able to enjoy them.

From European top nature in untouched places to modest nature gems right at your doorstep: the more than 300 nature reserves managed by Natuur en Bos are there for everyone!

www.natuurenbos.be

www.beheercommissienatuurlinkerscheldeoever.be

COMPETENCIES

• You have a strong background in ecohydrology and enjoy working with data.
• You possess analytical and synthesizing skills to handle data and generate policy-relevant output.
• You are capable of independently setting up and conducting research.
• You have excellent communication skills and can effectively network with various stakeholders.
• You are motivated to contribute to research on nature restoration and the conservation of biodiversity in Flanders.

What will you do?

• Analyze a local problem and investigate possible solutions based on existing studies and site visits.
• Actively search for new research ideas and implementation possibilities.
• Conduct a review of an existing management plan to map out the effects of the area and propose improvements and adjustments.

RESEARCH QUESTION

Background

De Haasop was created during the construction of the harbor area on the Left Bank of the Scheldt. The then polder area was reclaimed in the 1970s into a sand plain 500 m wide and 4 km long. In the subsequent years, nature reshaped the area, creating a pattern of valuable reed beds, woodlands, and poor grasslands. The soil composition is anthropogenic and characteristic of reclaimed sites, consisting of (subterranean) pressure dikes and heterogeneous infill with silt and calcareous sandy spoil.

In the context of drafting a nature management plan for the Haasop nature reserve, a design plan was developed with the aim of optimizing the area for several nature objectives. Target species for this management include Marsh Harrier, Bluethroat, Spotted Crake, Fen Orchid, Natterjack Toad, and Pond Bat.

The management of this area aims to provide a sufficiently large and high-quality habitat for the habitat-typical breeding bird species.

In Haasop, several habitat patches are present that are comparable to the habitat type ‘Humid dune slacks (EU code: 2190)’ with key species such as Fen Orchid, Bitterling, and Marsh Helleborine. Management should focus on strengthening the most important Fen Orchid population in Flanders.

The hydrology of the Fen Orchid sites needs to be optimized. In dry years, the water drains away faster than optimal, while in very wet years, the water remains high for too long. Possible measures to consider are:

• Sealing possible leaks in the historical pressure dikes by means of a ground screen, similar to the works that MLSO carried out in the winter of 2021-2022.
• Supplementing groundwater by allowing external rainwater to infiltrate outside the relevant management unit.
• Creating the possibility to drain excess water in very wet years.
• Maintaining pioneer situations on artificial soil comparable to humid dune slacks.
• Counteracting natural succession towards willow and birch thickets.

The design plan provides for a set of measures including bank slopes along existing ditches, surface lowering to create additional habitat for Fen Orchid and Natterjack Toad, and installation of adjustable weirs to better control groundwater and surface water levels. Elevations are also planned to improve habitat for Natterjack Toad and buffer the area for its surroundings.

Online information sources regarding Haasop:

https://natuurenbos.be/natuurgebieden/haasop

https://beheercommissienatuurlinkerscheldeoever.be/deelgebieden/haasop

https://www.ecopedia.be/planten/groenknolorchis

https://www.ecopedia.be/dieren/rugstreeppad

Documentation (this will be provided to researchers via SharePoint)

• Nature management plan in preparation for Haasop, in pdf and dwg (for uploading in autocad etc.)
• Access to dataloggers and data archives
• IMDC study
• Species protection plan Fen Orchid and Natterjack Toad
• INBO reports
• …

Problem statement

a/ Due to the surface lowering proposed in the design plan with the intention of creating additional habitat for Fen Orchid, more open water will be created and there are concerns that increased evapotranspiration could lead to further drying out of the area, potentially degrading the quality of current Fen Orchid sites. Therefore, we would like to have an ecohydrological calculation to better estimate the difference between the current and planned situation and, if necessary, make adjustments.

b/ In case the proposed surface lowering would lead to a significant deterioration of the current Fen Orchid sites, we would like to have substantiated reference values to adjust the design plan.

More generally, we are looking for measures to optimize the hydrology of the sites as much as possible. Are there additional measures that could contribute to this? Are there aspects of the design plan that should be adjusted to ensure optimal control of the water level?

Objective of the assignment

With this ROK we aim to hire the expertise of a hydrologist or an engineer to:

• Analyze the design plan and review it in light of the research question;
• Provide regular feedback to the client regarding reporting and conclusions;
• Formulate proposals to optimize the design plan.

PRACTICAL

• The proposed rate cannot be indexed nor revised during the duration of the assignment and/or extension, unless explicitly approved by the client.
• This assignment can be extended by 3 x 1 year.
• An all-in rate must be offered. No additional kilometer allowance will be provided.
• This job is hybrid and spread over a period of 40 days within 4 months. The working days are to be mutually agreed upon based on the feedback meetings.
• Interview moments (Teams) for this role are scheduled on 8/4/2026.