A guide for assessing the hydromorphological quality of natural and artificial lakes

This report provides a guide for assessing the hydromorphological quality of natural and artificial lake water bodies in accordance with the requirement of the Water Framework Directive (WFD). First, 60 metrics are described for characterizing the mandatory lake hydromorphological quality elements comprising those that are hydrological (i.e., quantity and dynamics of water flow, residence time, connection to groundwater body) and those that are morphological (i.e., lake depth variation, quantity, structure and substrate of the lake bed, structure of the lake shore). The data required for their calculation, as well as tools and techniques for acquiring them (e.g., field survey, models, remote sensing …), with examples of their application are also provided. Advice is also given on how to define reference conditions and combine metrics to develop a lake hydromorphological index that complies with the WFD. In the final section, a brief review of the literature presents current knowledge on the links between hydromorphology and biology. The document then focuses on recommendations on how to develop WFD-compliant methods addressing hydromorphology in assessing the ecological status of lakes. Some existing methods are described to provide practical examples.