Urban Water Buffer Spangen





Spangen, Rotterdam (NL)


Municipality of Rotterdam,
Waterboard Delfland


Completed, in operation


Evides Water Company,
KWR Watercycle Institute,
CODEMA Systems Group

Saving drinking water

Spangen is a neighbourhood located in the west of Rotterdam, which faces nuisances during heavy precipitation events due to lack of retention capacity. At the other hand, the Sparta Stadium in Spangen, uses a significant amount of water for the irrigation of the sport fields.

The aim of the project is to collect, filter, and infiltrate rainwater in the underground to solve the need for retention capacity in Spangen, and to use the stored water to provide the Sparta Stadium with a decentralised source for irrigation.

This project is one of the pilots to implement underground rainwater storage and recovery in urban areas, within the TKI project Urban Waterbuffer. Our role within the project consortium is to design the urban water buffer system and deliver the biofiltration system.


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A feasibility study has been executed to define the technical criteria for the design of the system and to explore the possibilities of integrating the system in its urban environment.

The starting point of the study has been the accommodation and spatial integration of the different functions of the system, including pre-treatment, water storage and reuse of rainwater, without conflicting with the existing spatial functions, such as routing, parking, and greenery. The goal has been to integrate the system in such a way that it improves spatial quality.

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27.000 m2

Disconnected surface

50 mm

Retention capacity

15.000 m3

Supply water


Based on the technical criteria from the feasibility study and in close collaboration with designers of the Municipality of Rotterdam and the consortium team, we designed and dimensioned the components of the system. An underground buffer was added to avoid the area from flooding during extremely heavy weather.



Because this project is the first full scale pilot application of the urban waterbuffer, we first built  and tested a smaller prototype of the bio-filtration system. At The Green Village, an innovation test site in Delft, we have been able to implement and test the performance and mechanical properties of the filter, including water flow, robustness, stability, assembly method and much more! 


Check out the full-scale working prototype


The Urban Water buffer in Spangen is completed and in operation.

TKI: Urban Water Buffer

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Spangen, Rotterdam
Lentsesteeg, Rheden
hNI, Rotterdam
Schilderswijk, The Hague




KWR Watercycle Institute,
Wareco, Codema,
Evides Water Company
Municipality of Rotterdam,
Municipality of Rheden,
Municipality of The Hague,
Waterboard Delfland
Waterboard Schieland and Krimpenerwaard,
Rioned, STOWA

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.


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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.

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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.


NAIAD: insurance value of Nature Based Solutions







Horizon 2020 (EU)




22 EU partners

Deploying ecosystem services in urban water

NAIAD is a Horizon 2020 project which examines how the insurance value of ecosystems for water related risk mitigation can be deployed. This is done by developing and testing concepts, financial instruments and applications on 9 case studies across Europe. In NAIAD, special attention is given to the engagement with relevant stakeholders and end-users, bridging the gap in-between science and practice.

We are responsible for the implementation of an urban demo case in Rotterdam. In the Rotterdam Demo, a NBS nature based solution is being implemented to expand the aboveground rainwater retention capacity. Subsurface storage will be used during intense rainfall. Subsequently, the stored water will be recovered from the infiltration well for reuse. The main objective of this demo is to assess the insurance value of the implemented NBS to reduce the negative effects of pluvial flooding in the area. The results of the Rotterdam Demo will contribute to the development of business models for the upscaling of NBS throughout Europe.


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Identifying hazards, risks and impact. 

The water related risks for the urban area of Spangen are identified by biophysical modelling. Stakeholders mapping and analysis of the exposure of assets have been carried out to define the role of the involved parties. Through workshops with a wide variety of stakeholders the co-benefits of the implemented NBS in the Demo Rotterdam have been identified. The results of the risk assessment, stakeholder analysis and workshops are used as input for the economic assessment of the NBS. 

See workshop on Defining Co-Benefits of NBS  

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We develop a tool to assess the economic impact of both grey infrastructure and NBS interventions under different climate scenarios. The tool enables the assessment of the insurance value of the modelled interventions, through interlinking the risk assessment with the socio-economic impact. 



To support the implementation of NBS in urban areas, new business models and financing schemes are drafted and tested with stakeholders. 


CORE: Level-controlled seedling bed prototype





Siranjganj, Bangladesh

Funded by



In progress


UNESCO-IHE Institute for Water Education,
Bangladesh University of Engineering and Technology

Protecting crops in times of flooding

CORE is a NWO-funded research project focusing on community-based development and implementation of small-scale technical innovations that alleviate immediate flood-related nuisance in  urban Bangladesh. The project is led by UNESCO-IHE Flood Resilience Group, in collaboration with the Bangladesh University of Engineering and Technology.

Field Factors' contribution to the project consists of the development of a flood-proof seedling bed prototype, which will be implemented at the CORE’s experimental learning space in Bangladesh. The prototype demonstrates a scalable system that integrates level-controlled drainage and recirculation of drain water to optimise water usage, while protecting crops from flooding. It provides farmers with a sustainable solution to regulate the irrigation of young crops in an open field in a targeted manner.

The system will be designed adapted to the hydrological, environmental, social and economic conditions of urban Bangladesh. The implementation of the system aims to: 

  • Contribute to a small-scale, community based flood-proof urban environment;

  • Make maximum use of local available materials, resources and manufacturing facilities;

  • Stimulate local adoption, ownership and replication of the solution.


Understanding the users and their needs.

Through field trips and workshops with local stakeholders and end-users, we have gathered insights into the users needs and the local context. For the Bangladeshi, flooded streets or houses do not represent a major problem, but the loss of crops is a major setback due to the scarcity and price hike of new saplings. In the dry season water becomes scarce: salty seawater gets the chance to push back the freshwater in the rivers. This makes the surface water brackish and unsuitable for use, damaging crops. 

These insights provided us with a design brief:

how to create a water regulated environment for farmers to grow young crops all year round.


Based on our knowledge of retention and bio-filtration systems, we designed a flood-proof seedling bed with level-controlled drainage and re-circulation of drain water. The seedling bed is protected from flooding by a closed system in a ring structure. Beneath the seedling bed, a layer of gravel is applied where the drained water can be stored. In this gravel layer, drainage pipes are placed, allowing controlled drainage to discharge the excess of water. 

During the monsoon, the water level within the system may rise, but the appropriate water level can be maintained by raising or lowering the outlet. In the dry season the same drain works the other way around: providing the crops with water stored in the gravel layer.   

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Currently, the design of the system is being tested through a several prototypes.




The implementation of the project is expected to start in December 2018.