Turning an isolated lake into a thriving ecosystem

The Moerbergse Waard, a disconnected water body in the floodplains of the Lek near Wijk bij Duurstede, has low ecological value in its current state. Research shows that reconnecting it to the Lek River could significantly improve water quality and biodiversity, supporting the Water Framework Directive (KRW) goals. To test this approach, Rijkswaterstaat (RWS) proposed an ecological pilot project, with The Weather Makers leading the design and execution.

Water movement as a driver of ecology

This pilot aims to quantify the impact of water dynamics on ecology and water quality. By modeling flow rate, water exchange time, and velocity, the study identifies optimal conditions for ecosystem productivity. Water exchange time—the key parameter—was set within a target range of 3 to 21 days, with an optimal value of 5 days.

Data-driven design for ecological productivity

Hydraulic models tested one to four culvert designs to determine the ideal eastern connection to the Lek. These models were then linked to custom ecological productivity simulations developed by The Weather Makers. Historical discharge and water level data from the Lek were used to define three representative flow scenarios.

Optimizing flow for biodiversity

Results show that at high discharge, water exchange can drop to 4 days, significantly increasing ecological productivity—up to 60% more than the initial concept. Designs with multiple culverts produced greater flow diversity, enhancing habitat variety and supporting richer aquatic life.

A blueprint for adaptive management

Based on these findings, installing multiple culverts is recommended. The ability to temporarily close specific culverts offers a unique opportunity for long-term ecological monitoring, providing valuable insights into the relationship between water dynamics and ecosystem health.

By designing with nature’s rhythms, water can do more than flow—it can bring life.