Analysis

Water Net Gain is a new £1.1 million initiative led by South West Water and the Westcountry Rivers Trust. It is funded under the OFWAT Water Breakthrough Challenge, a pioneering £200 million programme to unleash a wave of innovation in the water sector and tackle some of the major challenges of our time – delivering transformative benefits for consumers, society and the environment.

The overarching objective of the Fund is for the sector to better meet the needs of, and create long-term value for, customers, society and the environment through innovation. To meet this objective, South West Water teamed up with the Westcountry Rivers Trust and other partners, building on the award-winning drinking water programme Upstream Thinking,¹ to encompass water resource management in future water company asset management plans.

Nationally, projections show that per capita future water resources are expected to reduce due to population growth, climate change-driven reductions of summer rainfall, and increased environmental stress. The Environment Agency’s National Framework for Water Resources² estimates that an additional 3,434 Mega-litres per day nationally will be needed by 2050. Additionally, the National Infrastructure Commission report³ highlights that under current plans, there is about a one-in-four chance over the next 30 years that large numbers of households will have water supplies cut off for extended periods because of drought, highlighting that an extra 1,300Ml/day supply will be needed.

With water resources across the country predicted to be in deficit by 2050 – albeit variable across the country – the ability to hold water efficiently through a distributed network of storage sites depends on rainfall, topography and soil or geology type in each region. The expectation is that water companies in the South will need to hold greater volumes to manage direct deficits, whereas water companies in the North West may wish to hold surplus water for shunting. This forecast requires urgent action. However, building new reservoirs is expensive and lengthy, and an urgent plan is needed to increase water storage across the landscape to ensure sufficient supply through these extreme droughts.

To help alleviate the above pressure, Water Net Gain was formed, and is a catchment-scale concept whereby farmers would be paid to store water on their land. Restoring natural sponges, like healthy soils, woodlands and wetlands, can passively contribute water to summer base flows, but the creation of additional ecologically connected smart ponds and lakes can be used for farm demand management or actively releasing flows during droughts. The impact of this distributive ecologically connected water bank, released to the river during droughts – especially when fish are in distress – adds much-needed flow to the system and dilutes residual pollution not managed through current agricultural water quality incentivisation schemes. Alongside water purification, water retention solutions are designed to provide additional flood protection and aquatic biodiversity benefits.

The scheme would form a Smart Water Grid (see Figure 1) where rainfall and surface water generation that would have been lost in the system is slowly transmitted using nature-based solutions to storage ponds and lakes. These features are telemetrically monitored and controlled to show the total capacity within a system and are recharged during the winter months and heavy rainfall events. They can then be used to offset farm demand, especially on high drinking water consumptive businesses such as dairy (e.g. for drinking, washing and cooling plates), or if not needed sold into the river to recharge flows at peak times. This Smart Water Grid is analogous to the Smart Energy System of transmitting solar energy through panels to charge batteries where electricity can either be consumed locally or sold into the grid.

Due to the way these nature-based solutions would be designed, the protection and enhancement of the environment would be felt not only during these low flow conditions, where the lack of dilution exacerbates summer pollution, but also during high rainfall events, as smart ponds can be drawn down before flood events are forecast. These solutions also deliver towards water quality and aquatic biodiversity goals and deliver an Integrated Catchment Management approach, rather than the siloed engineered technical solutions approach (see Figure 2). Additionally, this work adapts to climate change by building catchment resilience using nature-based solutions that also contribute to net-zero carbon. By creating this mix of a distributed network of passive and active water storage features across the landscape, this increases the long-term operational resilience within both surface water and groundwater systems, and tests new ways of trading water storage and deployment at a drinking water catchment network level.

The benefit of supplying a Mega-litre of water during peak drought starts to address the National Infrastructure Commission’s need for more deployable water, but at a fraction of the cost of reservoirs. However, there are considerable barriers to implementing this system in a similar way to the barriers for incentivising and installing solar and batteries within the Smart Energy Grid.

Water Net Gain will explore and break down these barriers through exploring governance issues, uniting technical components, understanding the willingness to accept by farmers, and embedding the approach in future Asset Management Plans. Therefore, the project’s long-term outcomes are:

• To slow and store water at a catchment scale to ensure sufficient flows during the summer months for both drinking water abstraction but also maintenance of aquatic biodiversity (both water quantity and quality);
• To generate secondary benefits such as retention of flood waters, sequestration of carbon and creation of habitat connectivity; and
• To communicate the benefit of catchment-scale use of nature-based solutions to create a distributive deployable and tradable water bank.

These longer-term objectives will be broken down into seven short-term project outcomes that centre around how the Natural Water System overlaps with the Social Water System (see Figure 3). These shorter-term outcomes are:

1. To understand and manage the multi-sector, multi-stakeholder risks associated with creating a distributive network of ponds and lakes.
2. To create the components of a water trading system that allows the creation, monitoring and deployment of a distributive water bank based on both passive and actively releasable nature-based solutions.
3. To allow farmers and their buyers to deliver a Water Net Gain from their business by firstly reducing their own pollutant loading, but secondly diluting summer pollution loads by releasing water during droughts and low flow periods.
4. To create a living laboratory catchment that allows for the governance to be researched, tested and demonstrated.
5. To explore, elucidate and address any barriers and enablers needed to embed this approach across the wider water sector.
6. To embed the findings within water company 2030 business plans.
7. To help fill evidence/knowledge gaps in the use of nature-based solutions for water resource management.

By pulling together partners from across the country and the South West, the longer-term impacts of Water Net Gain can be realised – benefits to water companies and to wider society and bill payers.

The biggest impacts on water companies are:

• reducing demand for potable water through rainwater and effluent harvesting and reuse/water use reductions;
• supply-side benefits such as increasing the water available for use at key times, reducing reliance on other supply-side options (e.g., pumping); and
• increasing non-household customer resilience during periods of water shortage (e.g. agriculture).

Typical solutions to increasing water storage have centred on reservoirs (estimated at £3-5 million per Ml/d of deployable water – OFWAT 2020-25 minimum supply-demand balance unit costs £1.2 million per Ml/d) whereas the savings for smart ponds and lakes are expected to be around 10% of this figure to create deployable flow in times of peak drought.

On top of the above direct benefits, the impacts to bill payers and the wider society and environment are multiple, and include:

• improved catchment resilience;
• dilution of summer pollutants during extreme low flows;
• reduced flooding of homes due to attenuation capacity in the winter;
• reduced sediment loss due to reduced run off and soil protection;
• improved river corridor habitat and connectivity; and
• increased aquatic species diversity.

These broad benefits deliver Integrated Catchment Management based on our need for food and energy, but delivered in a way where water is released slowly and cleanly rather than the release being quick and dirty (see Figure 4).

By investing in the governance and innovation needed to create a smart water grid, the partnership aims to not only build water resource resilience both within the water sector and the farming sector, but also reduce flooding and increase ecological connectivity in our rivers and wetlands. Additionally, these nature-based solutions improve water quality by buffering and reducing mobility of pollutants, but also diluting in river loading, especially during droughts, therefore having a Water Net Gain.

References

1. Upstream Thinking (2020). https://wrt.org.uk/project/upstream-thinking/ ↩︎
2. Meeting our Future Water Needs: a National Framework for Water Resources (2020). https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/873100/National_Framework_for_water_resources_summary.pdf ↩︎
3. Preparing for a drier future: England’s water infrastructure needs (2018). https://nic.org.uk/app/uploads/NIC-Preparing-for-a-Drier-Future-26-April-2018.pdf ↩︎