Additional information

Drainage systems lower the top level of underground freshwater, increasing the risk of the brackish water underneath rising in dry summers and causing salinisation problems in crops. The Spaarwater project is testing drainage systems where drains are buried deeper to increase soil rainwater storage capacity. The distance between drains are also increased so that more freshwater can infiltrate in the soils and push brackish water down to deeper levels. With this design farmers are able to keep fresh water in the root zone during the growing season.



Another option is to collect drain water during the winter season, and store this water in the underground layers if the salinity is low. The water collected by drains is tested for salinity level; if the salinity is high, the water is discarded by pumping it to ditches. If the salinity is low, the water is infiltrated in the underground, creating a fresh water lens. Due to the fact that the fresh and brackish water don’t mix because of the differences in density, the fresh water will form a bubble. The fresh water which is stored in soils can be used for irrigation. In the case of clay soils, 10 ha can store enough water to irrigate 12 ha of crops and in the case of sandy soils, 10 ha store water for 10 ha of crops, making farms self-sufficient in terms of water resources. In addition, ground water storage kills bacteria that spread through water and could cause diseases in crops.



Furthermore, this drainage system avoids nutrient leaching and pollution of surface waters. Tests proved an increase of productivity between of €4.500,- per hectare in the dry summer of 2018 and on average between €600,- and €1500,- per hectare in the case of seed potatoes and of several thousand Euros in the case of flower bulbs.