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Inconsistent Regulatory Mapping Quietly Threatens Rivers and Streams
Mathis Loïc Messager1,2, Hervé Pella1, Thibault Datry1
1National Research Institute for Agriculture, Food, and Environment (INRAE), UR RiverLy, Centre Lyon-Grenoble Auvergne-Rhône-Alpes, 5 rue de la Doua, Villeurbanne 69100, France.
Environmental Science & Technology
|September 19, 2024
Summary
Regulatory mapping excludes a quarter of French watercourses from legal protection, disproportionately impacting headwater streams. This exclusion threatens freshwater ecosystems and vital services, highlighting potential issues in global water law implementation.
Area of Science:
- Environmental Law
- Freshwater Ecology
- Conservation Science
Background:
- Environmental laws aim to protect watercourses, but their effectiveness depends on how water bodies are legally defined and mapped.
- Excluding tributaries and headwaters from protection can fragment river networks and compromise ecosystem services.
- Regulatory mapping practices for watercourse protection have been under-examined globally, particularly outside the United States.
Purpose of the Study:
- To analyze the impact of regulatory mapping on the extent of legally protected river networks in France.
- To identify which types of watercourses are disproportionately excluded from legal protection.
- To assess the implications of these exclusions for freshwater biodiversity and ecosystem services.
Main Methods:
- Compilation of the first comprehensive map of protected watercourses in France under the Water Law.
- Comparison of legally protected watercourses with previously mapped hydrographic networks.
- Quantitative analysis of excluded watercourse segments, focusing on headwater and nonperennial streams.
Main Results:
- Approximately 25% of previously mapped hydrographic segments in France were excluded from legal water protection.
- Headwater and nonperennial stream segments were disproportionately excluded (28% exclusion rate) compared to their prevalence (67% of the network).
- Significant geographical variations in the extent of protected freshwater ecosystems were observed across France.
Conclusions:
- Regulatory mapping significantly curtails the reach of water protection laws, leaving substantial portions of river networks vulnerable.
- The disproportionate exclusion of headwater and nonperennial streams poses a considerable threat to freshwater biodiversity and ecosystem services.
- Similar issues with regulatory mapping and legal interpretation are likely prevalent in other countries, necessitating a review of water protection frameworks.
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