NL-4 :: Water

The Netherlands are a “water land”, a low delta, partly situated below sea level. Knowledge of the soil-sediment-water system is for centuries an important key for our economy.
The Dutch are known for their hydraulic engineering against floods. Making use of soil-sediment-water system, natural processes and land management can decrease costs for engineering and leads to better environmental quality and prevention of damage. In the Dutch water management this already is implemented in the program ‘Space for the river’ (‘Ruimte voor de rivier’) and the Delta Program ('Delta Programma').
Apart from managing the water in terms of safety (lowlands versus sea level rise), there are many more water management issues. (Ground)water levels are managed in relation to land use functions. For agriculture, water levels are lowered in many locations in the Netherlands, sometimes with detrimental effects such as soil subsidence and degrading peat areas, leading to CO2 emissions, or local water shortage and excess. In urban areas low groundwater levels can cause rot on wooden fundaments of houses, while high groundwater levels cause damage and nuisance.
Groundwater is the most important source for drinking and industry water in the Netherlands. It is microbiological reliable and mostly well protected from outside influences. Sufficient water supply for drinking, irrigation and process water is, now and in the future, recognized as a serious challenge. For that reason strategic groundwater supplies are taken up in the Dutch strategy for subsurface planning “STRONG”. How to make decisions between different uses of groundwater (next to drinking water also functions such as irrigation, ATES) is subject of discussion. The quality and quantity of (ground)water directly are important to support land use functions and they also influence the soil-sediment-water system and its capability to deliver ecosystem services. However, (historical and new) contaminations put the quality of the groundwater under pressure, while climate change and soil sealing in urban areas influence the recharge of groundwater.
(Ground)water is a connecting topic, relevant on different scales and a connection between rural and urban areas. Many stakeholders are involved in different ways and dependant on good water management (policy). Therefore, collaboration and knowledge exchange are crucial. The (ground)water in the Netherlands is very decisive and is managed thoroughly. It is a constant puzzle where soil-sediment-water system, land use and (land and water) management interact closely. This topic has a very strong relation with climate change
A short narrative is given to elaborate the connection between themes and the strong link between policy and practice.

Narrative: soil subsidence and groundwater level management
The main driver for this narrative is the question: How can we use pilots during policy-making to avoid mismatches between policy and practice? As example we take soil subsidence and the management of groundwater levels to support specific land use functions. The province wants in this example function agriculture, which asks for a groundwater level of 60 cm below surface level. Even when the water authority wants to facilitate other, more flexible functions, it is obliged to lower the water level for the agricultural function. This practice is not sustainable, causing soil subsidence and oxidation of peat which causes increased CO2 and methane emissions.
Soil subsidence and salinization by unsustainable land and water management cause continually higher costs to maintain the current land use functions. This situation cannot continue. Costs will become too high or damage will occur because is an end to what the soil-sediment-water system can bear. This tipping point can also become a chance: it asks for an open discussion and adaptive attitude from all stakeholders. This asks for education and awareness, alternative land use functions or land use management and different forms of collaboration. Knowledge from the soil-sediment-water system in relation to land use management practice is essential. Both scientific knowledge as local knowledge from the farmers and water managers should be combined. Stakeholders are water authorities, farmers, municipalities, provinces, NGOs, but also the stakeholders such as the recreational sector, project developers and groundwater dependent industry can be involved. The water authorities can have a leading role in the area process.
Specific research questions:
• How can water tasks, such as drinking water supply at this moment and in the future, be ensured and what does this mean for the soil-sediment-water system and strategic groundwater resources?
Natural capital
• How can the condition of the soil-sediment-water system in total be determined and / or evaluated? And what does this condition mean for the ecosystem services that can be delivered?

Land management
• What opportunities do exist for public and private parties to involve the soil-sediment-water system in their water tasks? And are they aware of these opportunities?
• How can land and water management be designed starting with the balance between the soil-sediment-water system and water tasks (safety, drinking water, agriculture, nature, industry, Water Framework Directive objectives, etc.) and with all stakeholder taking responsibility?
• How can area-based qualitative and quantitative groundwater management be designed?
• Which factors determine in the Netherlands whether active groundwater level management is administratively, technically and financially promising and to what extent?
• How can essential processes and functions of the soil-sediment-water system be implemented to regulate the hydrological cycle?
• Which measures (including eco-engineering) using the soil-sediment-water system are applicable, when and by whom, to optimise the hydrological cycle?
• What is optimal groundwater level management for a location in relation to land use functions and tasks (such as preventing subsidence and rot of wooden piles versus agriculture)?
Net impacts
• To what extent is the local soil condition determining for the influence of water on the soil-sediment-water system? And can this knowledge be translated into generic measures? Which water characteristics influence local soil conditions and to what degree?
• What is the significance of an intervention in the water system for the sustainability balance of the total soil-sediment-water system?
• How do interventions and the resulting changes in the soil-sediment-water system affect other areas such as agriculture and spatial planning?