Schilderswijk, The Hague
KWR Watercycle Institute,
Evides Water Company
Municipality of Rotterdam,
Municipality of Rheden,
Municipality of The Hague,
Waterboard Schieland and Krimpenerwaard,
Underground storage and recovery of rainwater in urban areas
Cities are increasingly facing flooding due to intense rainfall, as well as water shortages resulting from longer periods of drought. The current solutions are based on centralised discharge and supply, which are often expensive and unsustainable. How can we retain rainwater of urban areas longer and more effectively? And can we then subsequently make use of this water?
However, the necessary space for retention and infiltration in urban areas is usually scarce, leading to conflicts with other spatial functions. Therefore the Urban Water Buffer (UWB) project strives to retain rainwater in the deeper aquifer: via wells the rainwater is infiltrated, stored and can be extracted for further use. The goal of the project is to investigate whether the Urban Water Buffer can make a significant, positive contribution to the prevention of flooding in urban areas, while enabling decentralised water supply . The project consists of four case studies in Rotterdam, Rheden and The Hague. In Rotterdam and Rheden two pilots will be built and monitored.
Within this project, Field Factors is responsible for the spatial integration of the UWB in the urban context, the design and realisation of the bio-filtration system and the communication of the lessons from the pilot applications through the elaboration of a design guide.
In the first phase of the TKI- UWB project, the location, the water balance, the preliminary design and the estimated costs of actually installing a UWB system has been identified for four cases: Spangen- Rotterdam, hNI- Rotterdam, Rheden and Schilderswijk- The Hague. The results show that, particularly in the case of the targeted locations in Rotterdam and Rheden, a UWB could make a positive contribution in the short term to the discharge of surplus rainwater and thus to flood prevention. The aspects requiring particular attention are the speed with which the peak precipitation loads can be infiltrated into the subsurface, and the pre-treatment of the rainwater with a view to preventing clogging of the system.
Case Schilderswijk, The Hague
The Schilderswijk is a neighbourhood with a high percentage of impervious pavement and therefore a need for rainwater discharge. Due to the discontinuation water extraction by DSM and the changing climate, groundwater levels are rising. The area has little surface water and in fact no other drainage option than a mixed sewer system.This situation provides a clear water assignment: the district needs an extra option for rainwater discharge. In view of the large distances to surface water, controlled drainage in the subsoil might be a solution. It is still unclear how the phreatic layer may be used for this purpose and whether there are opportunities regarding reuse of the water in dry periods.
Case het Nieuwe Instituut, Rotterdam
In the coming years the area around Museumpark in Rotterdam will become greener. One of the current blue-green features is a large, shallow pond of about 3,000 m2 located at het Nieuwe Instituut building. In summer, the pond colours green because of algae growth, since the water body is not connected to the water system. In addition, the pond must be regularly refilled with drinking water. Furthermore, this part of Rotterdam needs more water storage capacity to prevent flooding. The intention is to use the pond as temporary collection of rainwater and to maintain it at the desired level through the Urban Water Buffer.
To collect the rainwater Bluebloqs can be implemented, improving the water quality and adding greenery to the area.
Pilot Lentesteeg, Rheden
Because of the large height differences in the Arnhemsestraatweg in Rheden, rainwater runoff flows quickly from the Veluwe to an intersection. At the junction, the sewer cannot cope with such a quantity of runoff. Due to the limited space in the area, shallow infiltration of rainwater is not an option. Infiltration in the deeper aquifer offers an alternative. To make aquifer storage possible, additional measures has been taken, such as the capture of sludge upstream and the implementation of wadi’s near the infiltration well.
Pilot Spangen, Rotterdam
Learn more about the details of the Urban Water Buffer Spangen
The pilot systems in Rotterdam and Rheden will be executed in spring 2018. The operation and effectiveness of the systems will be monitored within the TKI project. The results will be presented at the end of 2018.