Monitoring groundwater-dependent wetlands at a national scale: lessons from England's first strategic network.

Monitoring groundwater-dependent wetlands at a national scale: lessons from England's first strategic network.

¹Elena Armenise, ¹ * Mario Manganaro, Sharon Thomas

*Corresponding author 

¹Environment Agency, Horizon House, Deanery Road, Bristol, BS1 5AH, UK 

 

Abstract:

Recognising the critical role of monitoring in preserving groundwater dependent terrestrial ecosystems (GWDTEs) and the ecosystem services they provide, the Environment Agency is establishing the first national monitoring network for GWDTEs  in England. This work forms part of the government-led Natural Capital and Ecosystem Assessment (NCEA) programme, which aims to place nature at the core of decision-making by embedding natural capital evidence into policy and investment strategies.

The network was designed using advanced statistical methods to ensure unbiased site selection and provide statistically robust data on the condition of GWDTEs in England. Specifically, we adopted the  Generalised Random Tessellation Stratified (GRTS) sampling, a spatially balanced probabilistic design that provides random site selection while ensuring sampling locations are evenly distributed across the study area. This approach minimises clustering of sites and maximises environmental representativeness, making it ideal for large-scale environmental monitoring.

 To validate the design, we conducted a simulation based power analysis to determine the survey effort required to detect ecologically meaningful changes. Results show that the current design achieves ≥70% power to detect medium trends (~3.5% annual change) in groundwater level metrics and wetland quality within 13/15 years, confirming its suitability for long term surveillance. Detecting small changes would require more than 60 sites and over 20 years, which is impractical, but the network is well-suited for detecting meaningful trends within realistic timeframes.

This presentation will outline the GWDTE monitoring network design principles and implementation challenges. We will cover how operational constraints required pragmatic adjustments to maintain spatial coverage while preserving representativeness. The network will provide a foundation for long-term surveillance of wetland condition in England delivering meaningful data to support future national policy. All monitoring data will made openly available in December 2026, supporting research and policy applications.