Surface Water Stream

Source: SRCE — Trame verte et bleue (France) Year: 2013-2015 Category: Transition risks · Sensitive areas · Critical areas · SRCE (France) Coverage: Region (France) Format: Boundary polygons Used in risk analysis: No (contextual layer; not used in materiality scoring)

What it shows

This layer maps the surface water component of France's Green and Blue Network (Trame Verte et Bleue) — the areal aquatic continuities, such as watercourses and associated wetlands, that form the "blue" part of regional ecological connectivity. They matter for nature-related risk because development affecting these aquatic continuities can disrupt freshwater habitat connectivity and is subject to French planning scrutiny.

How it is built

The Green and Blue Network is a French biodiversity-preservation framework that integrates the maintenance and strengthening of functional natural environments into planning and development projects (Allag-Dhuisme et al., 2010). It is delineated at the regional level through the Regional Ecological Coherence Schemes (SRCE). The ecological continuities it defines comprise biodiversity reservoirs and ecological corridors; this layer represents the surface water-stream (areal aquatic) component, mapped as boundaries identified by regional authorities.

How to read it

This is a boundary layer. A site that intersects or lies close to a mapped surface water stream is flagged as potentially affecting regional aquatic ecological continuity, warranting closer review. There is no numeric score — relevance is determined by spatial overlap or proximity.

Class thresholds

This is a categorical / boundary layer, not a physical-flux surface, so it has no numeric thresholds. The mapped features are the surface (areal) aquatic continuities of France's Green and Blue Network (Trame Verte et Bleue), and the "classes" are simply the SRCE Class-1 status of each feature — Functional, Natural or Trame (field CLASSE1). These categories drive the map colours only; they do not rank risk.

There is no risk-flag threshold: this is a contextual layer and is not used in materiality scoring. Relevance is established purely by spatial overlap with, or proximity to, a mapped water-stream polygon — the layer carries no proximity buffer distance in its configuration.

How these thresholds were set. Not applicable. The aquatic-continuity boundaries and their categories come directly from the Regional Ecological Coherence Schemes (SRCE) delineated by French regional authorities (Allag-Dhuisme et al., 2010); Darwin applies no additional classification.

Source

Regional Ecological Coherence Schemes (SRCE), France — Trame Verte et Bleue (Allag-Dhuisme et al., 2010).

Comparison with the WWF Risk Filter Suite

There is no equivalent indicator in the WWF Risk Filter Suite. The SRCE aquatic continuities loosely support the theme of ecological connectivity, but they are a regional French dataset. WWF's connectivity input is the global Brennan (2022) functional-connectivity surface, which Darwin does not yet hold globally, so this layer is a regional extension rather than a WWF-comparable indicator.

Legend

Symbolised field: SRCE Water Stream - Class 1 category

Generated from darwin/layers/layer-surface-water-stream.toml and risk_indicator_pairs.toml (develop).