Watershed and river managers often face difficult choices between safety issues related to floods and degraded hydraulic structures, requiring urgent works and involving environmental stakes such as biodiversity, landscapes and rare species. These choices require taking precise ecological data and existing knowledge into account. Unfortunately, such databases and pre-existing knowledge are rarely available or they are only fragmentary and exist at the local scale for parts of areas classified as protected, or they are limited to a few species. Obtaining these data is time and money consuming and requires significant means, which is incompatible with the need to take urgent decisions. The aim of our work was to develop a flexible, easy to use and rapid method that does not wholly rely on accurate and comprehensive datasets and knowledge. It was designed to meet the need for fast assessment with limited means, which is a frequent case, particularly when urgent decisions are required or when the human and environmental stakes are circumscribable. The method uses an indicator-based approach to assess the effects of various management scenarios on the systems. Actions leading to the potential mitigation of these effects can be proposed. The method was implemented on the Grand Buech river in La Faurie (French Alps) where works were required to improve the safety of dikes. The impact of three management scenarios was assessed on 8 species and habitats. The results showed that, in the medium term, two scenarios may improve the current situation while the last one could worsen it. The method could be adapted to most watersheds and impact assessment in other environments.

流域和河流管理者通常在与洪水和水力建筑退化有关的安全问题之间面临艰难的选择，需要紧急工作并涉及诸如生物多样性，景观和稀有物种等环境利益。这些选择需要考虑精确的生态数据和现有知识。不幸的是，此类数据库和现有知识很少获得，或者它们只是零碎的，并且在局部范围内被分类为受保护地区的一部分存在，或者它们仅限于少数物种。获得这些数据既费时又费钱，并且需要大量手段，这与采取紧急决定的需求不相容。我们工作的目的是开发一种不完全依赖准确而全面的数据集和知识的灵活，易于使用和快速的方法。它旨在满足使用有限的方法进行快速评估的需求，这是一种经常发生的情况，尤其是在需要紧急决策或可以避免人为和环境利益的情况下。该方法使用基于指标的方法来评估各种管理方案对系统的影响。可以提出可能减轻这些影响的措施。该方法是在拉法里（法国阿尔卑斯山）的大布希河上实施的，那里需要进行工作以提高堤防的安全性。评估了三种管理方案对8个物种和栖息地的影响。结果表明，从中期来看，两种情况可能会改善当前状况，而最后一种情况可能会恶化现状。该方法可适用于其他环境中的大多数流域和影响评估。