A high-resolution life cycle impact assessment model for continental freshwater habitat change due to water consumption

Abstract

Global value chains and climate change have a significant impact on water resources and increasingly threaten freshwater ecosystems. Recent methodological proposals for life cycle impact assessment (LCIA), evaluate water use impacts on freshwater habitats based on river hydraulic parameters alterations. However, they are limited to French rivers due to lack of global data and models. On this basis, this article proposes an approach to compute regionalized characterization factors for modeling river habitat change potential (HCP) induced by water consumption, potentially applicable worldwide. A simplified model is developed for fish guilds and invertebrates. Based on French datasets, it establishes a relationship between HCP and river hydraulic parameters. A methodology to derive discharge and hydraulic geometry at the reach scale is proposed and applied to European and Middle Eastern rivers below 60°N latitude. Regionalized HCPs are calculated at the river reach scale and aggregated at watershed. Then, the impact of agricultural water use in contrasted European and Middle Eastern countries is evaluated comparing the outcomes from the HCP and the Available Water Remaining (AWARE) models at the national scale, considering water supply mix data. The same analysis is carried out on selected river basins. Finally, result consistency, uncertainty and global applicability of the overall approach are discussed. The study demonstrates the reproducibility of the impact model developed for French rivers on any hydrographic network where comparable ecological, hydrological and hydraulic conditions are met. Furthermore, it highlights the need to characterize impacts at a higher spatial resolution in areas where HCP is higher. Large scale quantification of HCP opens the way to the operationalization of mechanistic LCIA models in which the habitat preferences of freshwater species are taken into account to assess the impacts of water consumption on biodiversity.