Sweco supports major hydrological system restoration project in the valley of the Kleine Nete

In the coming years, Sweco will work on an ambitious large‑scale hydrological system restoration project. We are doing this for several clients: ANB, VMM, VLM, the Integrated Water Policy service of the Province of Antwerp, INBO and the Department of Environment. The project involves the complete redevelopment of the Kleine Nete and its valley, including the Olens Broek, De Zegge and the Mosselgoren, in the heart of the Antwerp Kempen. It is based on a framework agreement that enables step‑by‑step progress towards restoring a natural hydrological system. In spring 2026, the first subprojects will start, ranging from conceptual preliminary studies to technical design work and on‑site construction supervision.

The valley of the Kleine Nete is one of the most valuable yet most degraded valley systems in Flanders. Thanks to this framework agreement, we can work together with all partners on a large scale to achieve structural system restoration. This is a thoughtful systems approach that makes the landscape robust and resilient again. The benefits for nature, water quality, climate adaptation and the living environment are enormous.

Jo Lybaert, Project Manager Blue Deal, Sweco

An important link in water management

For centuries, the valley of the Kleine Nete was shaped by water. Naturally, it consisted of extensive, groundwater‑fed peat marshes, with a shallow, meandering river running through them. Over the past hundred years, that landscape changed drastically. The river was straightened and deepened, the valley was reclaimed, and groundwater levels were permanently lowered. As a result, the ecosystem lost its natural resilience, leading to peat degradation, desiccation and flooding with polluted, nutrient‑rich water.

Nature reserves such as De Zegge – one of the most vulnerable ecological gems in Flanders – are now under severe pressure. The European nature objectives for the area, including the development of more than 150 hectares of wetland in the Olens Broek and another 300 hectares in De Zegge–Mosselgoren, risk becoming unattainable without intervention. With this framework agreement, Sweco is tasked with restoring the functioning of the valley and gradually achieving the objectives. This assignment is part of the broader valley and area programme Kleine Nete, coordinated by the governor of the Province of Antwerp.

Spatial context of the Natura 2000 Valley Area of the Kleine Nete – Olens Broek and De Zegge–Mosselgoren © ANB

Maximum ecohydrological restoration

The vast valley of the Kleine Nete requires a phased approach. Several sub‑assignments will therefore be carried out in parallel: from exploratory studies and design‑oriented research to technical design studies with environmental permits, tender documents and construction supervision. Each step is coordinated within a taskforce including ANB, VMM, the Integrated Water Policy service of the Province of Antwerp, VLM, INBO, the Department of Environment and the governor’s office.

An integrated, multidisciplinary approach is essential, considering both current and future boundary conditions. To restore the natural water system, we aim for permanently higher groundwater levels, a readable landscape relief, improved water quality and a balanced flooding dynamic. These goals must always be weighed against current land use (agriculture), local agreements, stakeholder support, and relevant regulations.

The Larumse Loop (a tributary of the Kleine Nete) is straightened, embanked and lacks structure. Its redesign is a key and complex factor for ecological restoration in nearby areas such as De Zegge. © Sweco

Broad integrated expertise in nature and water management

This framework contract mobilises Sweco’s extensive expertise in water and nature management, coordinated by the specialised Blue Deal team within Sweco’s Infrastructure division (Unit Ports and Waterways). These experts work daily on valley restoration, rewetting of vulnerable habitats, peatland recovery, river re‑meandering, natural water purification, flood prevention and climate adaptation.

The Blue Deal team collaborates closely with colleagues from Nature Development and Water & Nature Strategies for landscape analyses, nature permits and ecological assessments. The Integrated Water Management experts contribute knowledge on groundwater and surface water, while Landscape & Public Space ensures landscape and recreational integration. The Urban Management team supports a smooth permit process, including through the Sweco Loket. We also collaborate with Process & Management to ensure efficient project governance and stakeholder engagement.

Together, they form an integrated, multidisciplinary team covering all aspects of a complex hydrological system restoration project.