Ecosystem service mapping study for water safeguard zones in north Somerset

Environment Systems was commissioned by Bristol Water to undertake a prioritised ecosystem service mapping study for water safeguard zones in north Somerset. The project set out to investigate issues around water quality and supporting biodiversity. The work focused on Cheddar Reservoir, Chew Magna Reservoir and Blagdon Lake. These water bodies and their surrounds are designated Drinking Water Protected Areas, which are also Safeguard Zones due to concerns about surface and groundwater. Over recent years significant algal blooms, occasioned by increased nutrient concentrations have become an increasing pressure on the water resource. Safeguard Zones promote voluntary adoption of measures that will prevent further deterioration in water quality through an active and collaborative catchment management approach led by Bristol Water and involving the Wildlife Trusts and Natural England.

Blagdon Lake, a reservoir in north Somerset where blue-green algal blooms have increased since 2006

Using our SENCE (Spatial Evidence for Natural Capital Evaluation) toolkit for mapping and modelling ecosystem services we produced a series of maps which identify where opportunities occur to undertake land interventions that are likely to improve the water quality of the receiving reservoirs as well as slow the flow of runoff. SENCE uses a rule-based approach to map and combine individual environmental variables of the ecosystem service in question. This builds a representation of the whole or part of a complex ecosystem interaction. The rule base is built around a series of key factors such as habitat, soil and geology, location and current management.

We also mapped the eco-connectivity of the semi-natural habitats in the area, to show where establishing habitats might have the greatest effect in terms of enhancing biodiversity resilience. There were three main outputs, a technical report to explain the methodology of the ecosystem approach and map production, a series of ecosystem service and opportunity maps and an advisory guide. The advisory guide is intended for use with the opportunity maps to help those involved in land management improve water quality in drinking water reservoirs, reduce the risk of downstream flooding, enhance biodiversity and improve land and wetland management practices.

You can download the case study here.