1. The water square as central area in a unit | 2. Rotterdam as a collection of water storage units
  
  
 1. Schematic functioning sewerage system | When rain continued: 2. Buffering in the system | 3. Overflow - level fluctuation canal | 4. Overflow street gully - overflow canal
  
 1. Uncoupling of rainwater storage: from conventional mixed system through an improved system to decoupling and local collection of clean water | 2. Proposal for other investments
  
 Samples water squares: 1. Buoyed square | 2. Playground | 3. Purification square | 4. Canal | 5. Canyon | 6. Cork mat | 7. Sponge square | 8. Purification gravel
  
 Reference costs per cubic metre water storage: 1. Digging a pond (350 euro/m3) | 2. Digging a canal(500 euro/m3) | 3. Underground basin (1000 euro/m3) | 4. Restructure with water (1000 euro/m3) | 5. Water square
  
 Three basic principles: 1. Buffering regardless of the system with a permeable basin | 2. Buffering for the system with an open basin | 3. Additional buffer in the sewer system with a closed basin
  
 Example open basin | 1. Several sports facilities with the rainwater storage capacity | 2. The open basin as sporting landscape with a water storage capacity of 5.000m3
  
 Important factors for rainwater collection
  
 Urban strategies for Rotterdam with three principles and six typologies
  
 The positioning of the six example types of water squares in four districts of the city
  
 Centre (district Cool): a shallow square on Het Landje
  
 District Oude Noorden: a system of dams
  
 Centre (district Oude Westen): a series of recessed squares
  
 Crooswijk: water balloon on the Mariniersweg
  
LOCATION
Rotterdam
YEAR
2006
COLLABORATORS
VHP, City of Rotterdam ( Municipal Public Works, Urban Planning and Public Housing Department, Development Corporation), Higher water board from Schieland and Krimpenerwaard, Urban Affairs
PROGRAMM
Rainwater storage
SURFACE
411000 m2
CLIENT
Initiative Urban Affairs, financed by the Netherlands Architecture Fund

PUBLICATIONS
WATERPLAN 2 ROTTERDAM
LAY-OUT 02
ROTTERDAM WATERSTAD 2035

PRESS
WONDERBAAR-LIJKE WATER-WERELD OP KOMST

NEWS
SHAPE OUR COUNTRY: WATER
SMV TAKES PART IN THE NAI/AA VISITING SCHOOL IN BRAZIL
WATERSQUARE INTRODUCED AT WORDLEXPO SHANGHAI
WATERSQUARES IN BOSATLAS
FIRST WATERSQUARE OF ROTTERDAM OPENED

WATER SQUARES

Introduction to a type

The Netherlands has a tradition of discharging rainwater underground via an extensive sewerage system. Despite having a number of visually-prominent canals, the Dutch city has relatively little surface water where the rain can be retained. And the sewerage system already has difficulty coping with the rainwater when it rains heavily. In the coming decades it will not only rain more frequently, the downpours will also be more intense. These peak downpours create problems in the densely-populated urban area: the rainwater cannot drain away because of all the surfaced space. When the sewerage system becomes overloaded the streets become flooded. This flooding leads to difficulties and damage. These large puddles and pools of water are a nuisance, pedestrians cannot keep their feet dry when walking about the city. The flooding causes damage to cellars and houses, shops and catering basements. This is why we are introducing a new type of rainwater storage: the water square.

In order to be able to collect peak downpours (temporarily), areas in the public space are laid out in such a way that the flooding can be regulated. We call these areas water squares. Not a square in the traditional sense of the word, but a square as a central space in a water management collection unit, a collecting basin. Rainwater is collected and retained in this basin. From this basin it can either be gradually infiltrated into the groundwater or finally, at a later point in time, discharged via the existing sewerage system. The water square is dry for the great majority of the time and then it is used like any other public space in the city. After a heavy downpour the form and the use of the water square are transformed. This means that, when designing a water square, the main focus is on its use and recreational value in a dry state. The elements that are necessary for the water storage are, wherever possible, deployed to create an attractive recreational area.
RELATED PROJECTS

ROTTERDAM WATER CITY 2035
2004, ROTTERDAM
WATER SQUARE PROTOTYPE
2007, SITE LESS
POOL BOAT
2004, DUTCH DELTA
BATH STEAD
2000, AMSTERDAM, JOSEF ISRAELKADE
ROTTERDAM SUBZERO
2002, ROTTERDAM CENTER

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