Significance of Hydromorphological and Sediment Analysis in River Basin Water Quality Management

This conference paper examines hydromorphology and sediment management within integrated water management, aiming to meet EU Water Framework Directive (WFD) objectives in the transboundary Sutla/Sotla river basin (shared by Slovenia and Croatia). Focusing on the Vonarje reservoir (Sutlansko Lake), authors report on sediment and water-quality status from surveillance monitoring. They show that upstream of the reservoir, water status is moderate, while downstream conditions improve to good. Despite infrastructure measures (wastewater treatment, agricultural interventions), nutrient and sediment loads remain significant. The study applies the DPSIR framework and SWAT modelling to evaluate pressures from diffuse and point pollution, assess morphological alteration from the 1980s dam and 2020 reconstruction, and support recommendations for sediment control measures. It contextualises reservoir functionality in achieving ecological targets and managing sediment flux in a rural border catchment.