WATERUN - Sustainable urban water management

Urbanization brings both opportunities and challenges. As cities expand, so does the strain on water systems. For the past 10 years Aarhus Vand has operated and maintained blue/green infrastructure for storm water runoff at the city of Aarhus in Denmark. Rainwater basins and rain wadis have been established as a means of managing storm water. The green infrastructure has been instrumental in creating recreative areas in the city. In some instances, it has even been used to slow down traffic.

Sustainable management of urban surface water

To become wiser on the cleansing effect of these green infrastructures and improve the knowledge on stormwater quality in the city, Aarhus Vand has joined the WATERUN project. Supported by Horizon Europe, this project aims to develop an innovative methodology to contribute to the implementation of urban water runoff management plans in cities based on the Water-Sensitive Urban Design concept. Specifically, the focus is on preventing and mitigating diffuse pollution from surface water in cities. Three case cities—Santiago, Aarhus, and Amman—serve as cases from which data will be collected and used as test sites to develop, execute, and validate proposals that will be part of WATERUN. These case studies have been selected according to different climate conditions, land use and level of implementation of measures for diffuse pollution, in order to validate the tools in different scenarios. 

Four test sites in Aarhus

As a part of the Waterun Project, Aarhus Vand provides access to four case sites, consisting of Green Infrastructure solutions in and around Aarhus. The four case sites are chosen in different types of urban areas, such as a newer residential area, a more densely build area and an area with light industry, in order to assess the stormwater quality from these types of urban areas. The four case sites consist of traditional and innovative stormwater mitigation solutions, i.e. two wet detention ponds and two infiltration ponds/beds, which has been prioritized in order to assess the performance of different mitigation solutions.

Assessing roadside infiltration beds at Risvangen

At Risvangen, Aarhus University samples and assesses the performance of a roadside infiltration bed, which collects stormwater runoff from both roofs and streets from a well-defined, minor catchment area. The performance of the infiltration bed is assessed through collected stormwater samples at both inlet and outlet, while the stormwater flow in and out of the system is monitored as well.

Two local case sites at the Tulip Ground

The Tulip ground offers two perspectives of a newer development, with regards to stormwater solutions.

In the eastern part of the developed area, stormwater is transported in a traditional stormwater sewer system and collected in a wet detention pond, in which Aarhus University is sampling stormwater quality at both inlet and outlet. Inlet and outlet flow of the wet detention pond is estimated using hydraulic models along with measurements of the water level and rainfall data.  

In the western part of the area, stormwater is transported on terrain in swales and ditches, and collected in internally connected infiltration ponds. In one of these dry ponds, Aarhus University has developed an experimental setup where both the accumulation of pollutants in the soil as well as the efficiency of purification through the soil is assessed

Wet detention pond in Lystrup

In Lystrup, Aarhus University monitors the performance of a wet detention pond. The specific detention pond is the most downstream detention pond, through a larger stormwater collecting system. Stormwater is sampled at both inlet and outlet, while inlet and outlet flow are estimated using hydraulic models along with measurements of the water level and rainfall data.

An opportunity to share knowledge

In addition to the test sites, Aarhus Vand also contributes on a broader scale to WATERUN with communication, stakeholder involvement as well as assisting in qualifying and discussing results in the project. A motivation to join WATERUN is on the one hand to become wiser on the cleansing effect of Green Infrastructure. Thus, Aarhus Vand is very keen on results from other project partners that will be measuring substances at the inlet and outlet of the test sites. On the other hand, participation is also driven by the possibility to offer knowledge on open storm water solutions.