2 dec 2014
© Royal HaskoningDHV

The innovation concept 'Water-storing Greenhouse Roofs' of Royal HaskoningDHV has won the Water Innovation Award 2014 in the category 'Enough Water', an annual award organised by the Dutch Water Boards. By placing partitions between the sections of existing greenhouse roofs in greenhouse horticultural areas, water is captured and stored temporarily. According to the jury, this application reduces the risk of flooding in areas used for greenhouse horticulture in an effective manner and contributes to a good use of rainwater in times of drought.

A small discharge opening in the partition at a lower part of the greenhouse roof slows down the flow of water to the water system, which can be discharged at a later stage. This reduces the risk of flooding during severe rainfall. From 135 entries, 13 projects were nominated.

Background

Rainwater is drained very quickly in greenhouse horticultural areas, resulting in flooding and damage during heavy precipitation. The idea to capture rainwater for several hours on greenhouse roofs helps the water board in ensuring dry feet and enough water. It generates cost savings, less risk of flooding and saves on space, whereby more horticultural land becomes available. Discharging rainwater results in the loss of good quality irrigation water and prevents a greater use of less sustainable irrigation water sources, namely the pumping and desalination of brackish groundwater with a residue of 'brine'. The partitions are easy and cheap to install, making this a robust and simple concept.

Field test

The effects were assessed in the Oude Lierpolder in Greenport Westland. If the concept is applied to all greenhouses, which could be the case in 15 to 20 years, it will lead to a reduction of water level rise by 7 centimetres during extreme precipitation. That is equivalent to an open water storage capacity of 10,000 cubic metres. If the water storage were to be built in this low-lying land, it would cost 2.2 hectares of scarce and expensive land. The concept for the water-bearing greenhouse roofs was invented by Royal HaskoningDHV. Further development was carried out in cooperation with Frank van der Burg B.V, Rabobank Westland, the Province of Zuid-Holland, the Municipalities of Westland and Langsingerland, and TNO (Netherlands Organisation for Applied Scientific Research) and Delfland Water Board. As the winner, Royal HaskoningDHV received a glass art object from master glass-blower Gert Bullée during the award ceremony, and a guidance process worth 15,000 euros for an innovation agent to assist in the further development of this innovation.