Improved flood control and water quality with a smart water solution

The geographic characteristics of the city of Vejle in Denmark make it naturally prone to flooding. Vejle Municipality and Vejle Waste Water Utility needed a smarter solution to operate the city’s existing flood control structures. A real-time control system based on rainfall radar nowcasts, hydrological and hydraulic model forecasts, as well as operational rules was implemented. The result? Improved flood protection and better water quality of the river.

Challenge

Vejle, nestled at the confluence of two rivers before they meet the fjord, faces significant flood risks due to its geographical location. Historical data reveals frequent flooding triggered by intense rainfall in the city or upstream river catchments, compounded by high water levels from fjord storm surges.

Furthermore, the impact of climate change has increased the frequency and severity of flooding as rainfall events get more intense, sea level continue to rise and storms surges become more frequent.

To prevent floods, Vejle has installed a flood gate where the Omløbsåen River meets Vejle Å. This gate prevents fjord water from surging into Omløbsåen during high tides, a measure complemented by three motor-driven sluice gates further upstream for automated and remote flood control.

A primary challenge has been to define operational rules for these flood structures. The dilemma lies in safeguarding one part of the city from flooding, which could inadvertently expose others to risk. Moreover, prolonged closure of flood gates could compromise the water quality of Omløbsåen River, underscoring the need for a balanced approach to flood management.

Solution

In collaboration with Vejle Municipality, Vejle Waste Water Utility and Aalborg University, DHI implemented the SMART Water Vejle Solution. Solution highlights:

• Real-time data from rainfall radar to provide nowcast of rainfall for the next two hours (implemented by Aalborg University)
• Integration of real-time data and forecasts from various sources into a single platform
• Real-time forecasting with MIKE Powered by DHI’s models for ground water, rivers and storm water drainage
• Real-time control of flood control structures using rainfall nowcasts, sensor data and flow and water level forecasts