Physical assessment of groundwater dependent wetland ESs

Description

Wetlands that live on groundwater are the most direct expression of the link between an aquifer and the services people obtain from it. This tool assesses what a groundwater-dependent wetland ecosystem provides — water regulation, habitat, water quality attenuation, and the cultural and amenity values attached to a functioning wetland — and how those services respond when the water table moves.

The assessment is built from the physical characterisation of the wetland and its connection to the aquifer rather than from land-cover proxies alone, because the service depends on the depth and variability of the water table rather than on the presence of the wetland. It identifies the threshold conditions beyond which a service degrades, and the timescale over which it recovers.

It was developed at the Medina del Campo demonstration site, where the groundwater body supports wetland ecosystems that have been affected by decades of abstraction and where restoration is one of the candidate measures.

Applications to decision making in the insurance sector

Groundwater-dependent ecosystems respond slowly and recover slowly, which makes them poor candidates for a short-horizon appraisal and good candidates for a risk-transfer discussion. The assessment supplies the physical basis for asking whether abstraction management should be treated as a prevention measure, since a maintained water table removes a drought exposure that would otherwise be carried.

Added value of this modelling approach

It connects the state of the aquifer to the services that depend on it, so that a change in abstraction policy can be read as a change in service delivery — which is the form the decision is actually taken in.

What decision can be improved with this modelling approach

Setting abstraction limits that protect dependent ecosystems; choosing between wetland restoration and other recharge measures; and establishing the baseline against which the effectiveness of a restoration measure is judged.