Water Matchmaker: guiding the water transition from a systemic perspective

Freshwater resources management involves a complicated puzzle, as households, agriculture, industry and nature all rely on the same, scarce resources. Climate change and population growth are intensifying this competition. The water sector therefore faces the need to transition towards fundamental changes in freshwater management. To support the sector in these transformations, it is necessary to develop a long-term vision of a future-proof supply chain that continues to provide sufficient water of good quality to all users and functions.

Mismatch
At the heart of current and future freshwater distribution challenges lies a triple mismatch between supply and demand: in space, time and quality. Where one region may struggle with abundance, another faces shortages. It can be too wet in winter and too dry in summer, just when the demand for water increases. Moreover, the required water quality is not the same for all functions (e.g. drinking water vs. agriculture or industry), and there are spatial and temporal variations in the available quality.

These imbalances will have to be addressed on a regional or national scale. Local options to match surpluses and shortages are often limited, cumbersome and expensive. Between regions, more affordable options or solutions that benefit nature at larger scale may be conceivable. To visualize and discuss such questions, we developed the Water Matchmaker within Waterwijs, the Dutch drinking water industry's collective research programme. In this article, we present the method and demonstrate its value using a hypothetical case study.

Transcending boundaries
The Water Matchmaker is a model-based framework that can be used to design a balanced allocation of water in a transboundary context. After all, freshwater resources are not partitioned to match political borders. Therefore, organisations, sectors and provinces need to look beyond their boundaries. Interregional system analyses increase the number of possible solutions, but also the number of stakeholders involved and their specific interests. This makes the consequences of potential measures more difficult to oversee.

The Water Matchmaker consists of a framework and mathematical model, integrating knowledge of water infrastructure, water treatment, water systems and nature. A broad and flexible assessment of the consequences of design choices forms the core of the framework, to assist stakeholders in studying and resolving (future) water resources conflicts. As this involves the water system of a region, country or river catchment area, this type of decision-making cannot draw from experimentation in the real world. Therefore, scenarios are used to compare different possible situations.

Explicit objectives
A supra-regional approach to freshwater distribution requires coordination between water authorities, utilities and provinces. The Water Matchmaker aims to assist these organizations in formulating and aligning their (often abstract) objectives explicitly. This clarifies the economic, environmental and social consequences associated with each objective.

The method brings implicit assumptions to the surface. For example, what exactly is meant by an 'appropriate water quality for sustainable use'? What should be considered 'appropriate', and what does 'sustainable' mean? This may be different for an engineer than for an ecologist, or a director. Placing design choices in a quantitative systems perspective provides a basis for well-informed discussions between parties.

The Water Matchmaker is inspired by mathematical techniques for pipeline network design (numerical optimization), which utilities are using more and more often. This approach has several advantages. For example, it forces assumptions to be formulated unambiguously and enables automation, allowing a range of scenarios to be explored. This creates solutions that might have been otherwise overlooked, and unfolds a well-informed dialogue toward well-reasoned water allocations.

Water Matchmaker is a conceptual framework combined with a mathematical model. Using an automated systems approach, this method helps to address dilemmas such as:

• Where should new data centres be located if their location is chosen based on spatial freshwater distribution?
• When an area suffers from water shortage, would it be better to extract additional water from a nearby nature reserve or to use residual water from a factory?
• What costs are acceptable when transporting water from a neighbouring province over a long distance? And how much will it cost the country as a whole if provinces decide not to collaborate?

Set-up
The Water Matchmaker is set up as follows:

1. In a software programme, users load a map of, for example, a province, constructed from information layers such as soil conditions and infrastructure. In it, they place elements such as cities and natural areas. With the input of data such as population numbers and groundwater availability, a model is built that represents the existing freshwater distribution, at a level that is manageable but sufficiently detailed with regard to for example:
   - sources (for example: groundwater, surface water, rainwater or residual water);
   - users (for example: households, agriculture, industry or nature);
   - the link between these two (for example: drinking water mains, a canal, or soil);
   - infrastructure for storage and sanitation.
2. A functionality is then added to assess the construction and functioning of this system, via self-defined (or default) objectives. These design objectives determine what the tool will define as an optimal water distribution. By setting explicit objectives for diverse interests, each design can be assessed on its merits. Design objectives can be for example:
   - minimising drought stress in the local natural environment due to groundwater extractions;
   - minimising the energy required to operate transport and sanitation infrastructure; 
   - or minimising the number of users with water shortages when there is a seasonal deficit.
3. The software will then analyse and redesign the freshwater distribution of the area. The latter is done with an algorithm that calculates the 'best solution'. This refers to the optimal freshwater distribution and matching infrastructure. To this end, the programme uses numerical optimization to automatically find the best design for the specified set of design objectives. When these conflict with each other, this can also mean a range of solutions (for example: ‘to minimise drought damage to nature, without bringing the economy to a halt, the following investments are needed in transport and extraction...’).
4. Finally, an iterative process follows in which users can fine-tune the design through changing the previously introduced assumptions.

Case study
Figure 1 demonstrates the output of the model in an example. In a fictitious and simplified system, we investigated what the optimal design would look like for different objectives, being in this example the minimization of (a) infrastructure costs, (b) infrastructure costs and CO₂-emissions or (c) infrastructure costs, CO₂ emissions and natural damage. This way, the Water Matchmaker showcases the options available for infrastructure design and water distribution.

Figure 1. Sample case study showing output from the Water Matchmaker. The numbers indicate how much water of quality A (WQ_A) and B (WQ_B) a source can supply, how much water of WQ_A and WQ_B a user needs and how much water of quality B becomes quality A at a water treatment plant. The arrows indicate how much water is transported between sources and users.

Design group
The best designs emerge when working with a diverse design group consisting of delegates from, for example, water companies, water boards and provinces. The Water Matchmaker asks questions that encourage joint reflection on design objectives, and enables the design group to formulate ideas, preconditions and interests clearly and conveniently. Objectives and data are then combined into concrete designs, sometimes resulting in unexpected possible solutions. These form the basis for further continuation of the dialogue.

Without offering a ready-made outcome, the Water Matchmaker materializes the consequences of design choices and supports conversations between stakeholders. In 2026, the Water Matchmaker will be applied to a real case study and further refined in cooperation with drinking water companies and water boards.

Challenges
The strength of the Water Matchmaker – the holistic approach – also presents a challenge. Quantifying all societal aspects of a balanced freshwater distribution is a complicated task. Health-based, natural and financial-economic values have to be weighed against each other, while being expressed in different currencies. Bringing sufficient water to the right place is one thing, but at what cost? In short, it is often a question of what we consider important. Filling the tool with the right data, such as properly quantified impacts of groundwater extractions on nature, present another challenge.

Finally, the systems perspective calls for cooperation on an unusually large scale. For utilities for example, depending on sources beyond their control is a sensitive matter, and administrators may feel reluctant to share water resources across provincial boundaries. However, for a balanced freshwater distribution, we must face the bigger picture and learn to speak each other's language. That is why we want to further develop and refine these challenges to provide valuable support in the water transition.

To support water authorities and (drinking) water companies in balancing water demand and availability, KWR developed a systemic, model-based framework: the Water Matchmaker. Through numerical optimization of quantitative and qualitative data on the water flows in a specific area, the framework aims to design optimal water allocations based on the objectives of various stakeholders. The Water Matchmaker provides concrete solutions for a fair freshwater distribution and aims to support decisionmakers in studying and resolving (future) water resources conflicts.