Water supply is of crucial importance for greenhouse horticulture. An adequate supply of fresh (irrigation) water has to be available – during dry periods as well – and the water needs to be clean and not contain too many salts. Commitments have moreover been made to significantly decrease discharges of plant protection products from greenhouse horticulture in the years ahead and, ultimately, to eliminate them altogether.
This project is part of a coherent programme which should result in an integrated and sustainable (irrigation) water provision: the securing of ‘good irrigation water’, reduction of the use of disinfectants, and zero emissions of nutrients and environmentally-alien substances. The cluster research programme, ‘Circular Water Provision for (Greenhouse) Horticulture’, consists of four projects:
- Water to the greenhouse: freshwater provision and well technology
- Water in the greenhouse: microbially ‘healthy’ irrigation water
- Water from the greenhouse: water treatment and reuse
- Operate: operating circular irrigation water systems
Within these four projects the supply, discharge and use of water on a scale beyond that of the individual horticulturalist are studied. In this way, a sharper focus can be placed on closing the watercycle, increasing the sector’s self-sufficiency, assuring efficient water use, matching (regional) water surpluses and shortages in time and place, and reusing water.
The Operate project involves the development of systems for the efficient and remote control of collective irrigation water supply.
To achieve a robust and sustainable water provision, ASR (aquifer storage & recovery) systems are increasingly being installed in collective water systems (e.g., Nieuw Prinsenland, Glasparel+). Besides supply security, these systems contribute to other objectives, such as emission reduction and sometimes also flood prevention. The horticulturalists also want the peace of mind of having their water provision carried out through cooperatives or contracted out to utility companies.
The recurring question among greenhouse horticulturalists is how such a collective ASR should be designed and managed, particularly in view of the variety of objectives, for instance: irrigation water supply security – including during drought peaks and after relatively dry winters; the prevention of flooding/overflow into the surrounding area; and cost effectiveness.
Up until now, no suitable model existed to calculate the water balance for such a water provision.
A calculation tool (‘ASR Balance) has been developed in this project that automatically conducts time-dependent calculations of the water balance in greenhouse horticulture clusters. The tool takes account of the actual and future water demand of horticulturalists, water streams within the greenhouse complex, and the actual availability of water in the surface basins and the subsurface freshwater lens.
The tool can be used in the design phase to define the correct initial assumptions (e.g., for licenses), and supply input to the automatic and optimal operational management of the collective ASR systems. The measurement and control system consists of operational decision-making rules for short-term control. In addition, prediction model calculations will be regularly conducted on the ASR system to determine whether the freshwater volumes are sufficient over the long term. The latter requires a separate groundwater model that is very site-specific and is therefore not yet a component of the calculation tool. (HydroBusiness, Brabant Water).