Holistic water management is essential to ensure efficient and long-lasting mechanisms are put in place. One example is the management of chalk rivers and streams, recognised as a priory habitat under the UK Biodiversity Action Plan. While England’s chalk rivers are ecologically important, they also have very high cultural and economic value leading them to have many demands placed on them from abstraction, irrigation, fisheries management, energy provision and navigation.
In Cambridgeshire, the Council, water companies, the Environment Agency and communities are seeking ways to best manage the cumulative impacts of groundwater abstractions on flows in chalk streams under low flow stress, to supply a growing Greater Cambridge area with drinking water.
Management is complex because natural groundwater levels vary significantly from year to year, and are susceptible to dry periods and drought. Over abstraction can cause ecological impacts, but large scale reduction in abstraction from current levels could also lead to an increase in local groundwater flooding, as well as increasing environmental impacts from development of alternative sources for public water supplies. One major project underway to tackling these issues.
Why are Chalk Streams Important?
Chalk streams are exceptionally rare habitats, with only around 200 in the world and they are predominantly located in southern England. They are fed by groundwater from the underlying chalk aquifers, making them characteristic of exceptionally clear, clean water. This makes them a key habitat for species such as otters, water voles, kingfisher and salmon, and their underlying aquifers provide a valuable source for drinking water.
Despite the environmental importance of chalk streams, less than 1/5 of English chalk streams are considered to be healthy. They often suffer low flows in the summer months, and are sensitive to pollution from industry and agriculture. It is therefore essential that we maintain our chalk stream habitats to protect and enhance the biodiversity that they support and the ecosystem services they provide.
Granta Catchment Resilience Programme (GCRP)
This is a collaborative Programme between Cambridgeshire County Council, Water Resources East, Cambridge Water and farmers and land managers within the Granta Catchment in South Cambridgeshire. The programme aims to develop an integrated approach to managing water resources, flood risk and natural capital in the Granta Catchment.
The River Granta and its connecting rivers and watercourses, like many other chalk streams, are classed as unhealthy due to low summer flows and pollution, with significant barriers to fish passage. On the other hand, many parts of the catchment are at high risk to surface water flooding and flooding from rivers and watercourses.
Benefits of the programme:
- Groundwater recharge: The programme will introduce natural measures such as wetlands, basins and wet woodlands to encourage cleaned surface water to soak into the ground and recharge groundwaters.
- Habitat creation and enhancement: River channel restoration and enhancement to improve and generate habitats for chalk stream biodiversity. Habitats will also be created or improved outside of the river within the wider catchment.
- Natural Flood Management (NFM): NFM measures will be introduced to slow the flow of water throughout the catchment to provide flood risk management for downstream villages.
- Climate change mitigation and adaptation: The programme will provide catchment resilience to climate change related rainfall and drought. The establishment of wetlands and woodlands will also provide climate change mitigation benefits by capturing carbon dioxide.