Qualitative hydrology: a review of the last quarter century and a glimpse into the future from the perspective of the Division G of the Federal Institute of Hydrology.

With the nationwide introduction of wastewater treatment the overall water quality improved significantly, but challenges remain, including diffuse pollution, historical sediment contamination and the presence of a multitude of anthropogenic chemical species. The implementation of several EU directives in the twenty-first century led to a stronger focus on improving water and sediment quality and the sustainable management of sediments at river basin scale. Hence, in the last 25 years, not only have the regulatory frameworks significantly changed, but also the scientific backbone of our products, delivered to Germany's federal ministries, practitioners from the German Waterways and Shipping Administration, German federal states and the public. In this respect, approaches such as non-target screening, multi-element analysis, effect-based methods, novel approaches in microplastic and nanoparticle analysis and the benefits from the increase in digitalization and automation are key methods and processes to face future challenges, especially those connected to the global climate crisis. [ABSTRACT FROM AUTHOR]