The Delta Program Freshwater Plan includes initiatives and measures aimed at making the freshwater provision in the Netherlands more robust against the future impact of climate change. On 8 November, the programme held a third knowledge day, in which questions like the fresh/saline water theme and the effect of soil improvement measures on the freshwater provision were addressed. I talked about measures to improve the self-provision in free-draining parts of the Netherlands, with a special focus on the moisture provision for agricultural crops (unfortunately, thanks to the vicissitudes of the national railway service, I had to do it without co-presenter Bas Worm from the Vechtstromen Waterboard).
Lengthy drought periods, alternating with heavy downpours, are an increasingly common occurrence in the Netherlands. Agricultural yields depend on the moisture conditions in the root range; drought, but certainly also excess water in this range curtail crop yields. For agriculture and water management it is becoming more and more important to be able to anticipate this growing dynamic and such drought and wet extremes in soil moisture conditions. This can be done using Climate Adaptive Drainage (CAD): through the dynamic and adaptive management of the drainage level, water can be stocked when possible and discharged when necessary. CAD can also be used to actively introduce/infiltrate water to improve the moisture provision. We discussed the use of alternative sources to better meet the regional water supply needs. Despite the water shortages faced by agriculture, industries and WWTPs actually discharge treated wastewater into surface water every day. By not directly discharging this residual water into open waters, and instead using it to diminish the moisture deficit for agricultural crops, drought damage in the sector could be reduced. WWTP effluent contains, among other things, pharmaceuticals, pesticides, viruses and bacteria. What risks the reuse of this type of residual water might entail regarding the contamination of crops and deeper groundwater is therefore an important question. Working together with the Delta Program, we should be able to effectively tackle the task of extensively developing our knowledge in this area.
Besides (technical) measures to improve the freshwater provision in the high sandy ground regions, a great deal of attention was paid to the fresh/saline water theme. The Province of Zeeland made a pointed presentation on the scaling-up possibilities and limitations of the Freshmaker. My colleague Klaasjan Raat presented COASTAR: a framework for action for a robust freshwater provision in low-lying areas of the Netherlands through the large-scale use of the subsurface storage capacity. That brackish water can be used for our drinking water supply was news to many participants. COASTER is an initiative of the Salutions Collab of Allied Waters.
In his concluding remarks, Egon Ariëns, programme manager of the Freshwater subprogramme, pointed to the responsible reuse of residual water and COASTER as important initiatives. Clearly our messages got through.