Historically, delta areas solely rely on freshwater cycles-of-use, i.e. intake – treatment – use – treatment – discharge. Saltwater intrusion is countered by flushing freshwater through canals and rivers, a well-known practice in the Netherlands. But this approach is no longer sufficient to secure water supply essential for domestic, industrial and agricultural use.
Water Nexus is a high impact paradigm shift in water supply: saline water is not treated as a threat but as an opportunity. The end goals of the Water Nexus programme are:
- Make (agro) industrialised regions water self-sufficient using green infrastructure
- Fresh water when needed, saline water when possible
- Used & salt (including brackish) water as an indispensable resource
- Regional Integration; industrial demonstration
The program consists of three interdependent research lines:
- Resource management and control: the focus of this research line is to obtain (and maintain) an optimal spatial distribution of saline and freshwater (saline water where possible, freshwater where essential) by developing models and control tools for strategic and operational water management. Instead of using scarce freshwater to reach such a distribution, saline water is used to push freshwater to critical areas. Special attention will be given to salt concentrations at root zone levels, essential for food production and nature development. Here especially monovalent salts can be detrimental.
- Treatment technologies: the focus of this research line is to develop treatment technologies enabling the use of saline water as an alternative to freshwater use. Sources can be either natural saline water, or water from industrial production such as from oil and gas production. Technologies are sustainable and cost efficient, removing only those substances that hinder use of saline water (e.g. monovalent salts and pesticides) and maintaining those that are beneficial to the end use (e.g. nutrients).
- Technology + natural system integration and governance: this research line focuses on developing integral solutions, combining the new technologies from Water Nexus, for optimal use of freshwater and saline water quantities and qualities. Integral solutions and underlying models will be validated and tested in simulated and practical cases.