Author(s): Fabrice Zaoui; Quentin Royer; Diane Von Gunten; Yann Le Coarer; Nicolas Lamouroux; Herve Capra; Pierre Sagnes

Linked Author(s): Fabrice Zaoui, Yann Le Coarer, Nicolas Lamouroux, Hervé Capra, Pierre Sagnes

Keywords: Fish Habitat; Hydraulic Models; Substrat; GIS

Abstract: The availability of freshwater is crucial for the maintenance of biodiversity and human society. For the latter, rivers and streams provide a wide range of ecosystem services such as irrigation, drinking water supply or power generation. Anthropogenic use of freshwater is therefore intensive: most of the world's largest rivers are negatively affected by human activities, which threatens aquatic biodiversity worldwide. One of the main stresses on freshwater biodiversity is the degradation of fish habitat resulting from major changes in flows and river systems due to, among other things, flow regulation by dams, land use changes and water abstraction. Freshwater biological communities depend on the interaction of biological, physical, and chemical characteristics of rivers and streams. These characteristics are strongly influenced by changes in flow rates, which represent a significant risk to fish habitat and the river ecosystem as a whole. It is therefore necessary to determine the flow rate and its variability for a more acceptable and efficient management of the water resource. To determine these environmental flows, a range of methods are currently used, such as look-up tables, holistic methodologies, habitat simulation method or hydraulic rating. The habitat method is one of the most widely used methods. It is based on modelling the hydraulic conditions of the river or stream under analysis. It estimates environmental flows on the basis of hydraulic conditions that meet biological requirements. In most cases, this method uses hydraulic model outputs (water depths and mean velocities), substrate data in GIS representation and biological models to estimate the minimum flow and its required variability This paper presents a new tool that overcomes some of the limitations of the usual software implementing the habitat method. Hence, it proposes: •To process a variety of world-renowned 1D and 2D model results for shallow waters, as it is crucial to adapt the choice of hydraulic model to the characteristics of the water system •A variety of univariate and bivariate biological models including the possibility for each user to define their own •Open-source license allowing users to modify the program for their research needs or to obtain full information on how the modelling was done.

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221378

Year: 2022