This study evaluates long-term (2014–2023) and seasonal water quality in the Jerma River, a transboundary watershed between Serbia and Bulgaria, using annual mean physicochemical and microbiological parameters at two monitoring sites as well as Water Pollution Index (WPI) classifications. Seasonal datasets (spring, summer, autumn and winter) were applied to assess intra-annual variability. The water quality reflects the influence of geomorphology, hydrological seasonality, and anthropogenic pressures. The river reflects the influence of geomorphology, hydrological seasonality, and anthropogenic pressures typical of mountain catchments. Upstream conditions were favorable, characterized by stable oxygen regimes, low suspended solids, and low nutrient levels, with occasional phosphorus enrichment. Downstream sections showed stronger deviations, including elevated nutrients, departures from reference conditions, and variability in microbiological indicators. Seasonal analyses indicated stable oxygen conditions at both sites, while nutrient and microbial parameters varied during specific periods. Dissolved metals remained within Class I thresholds throughout the study. WPI values confirmed spatial and seasonal differences. Upstream water quality mainly corresponded to Class II, with occasional shifts toward Class III, whereas downstream values fluctuated between Classes II and IV, with short-term deterioration during seasons. Higher variability occurred in spring and summer, while winter conditions were more stable. Overall, the results indicate better upstream status and increased nutrient and microbial pressures downstream, highlighting the need for continued monitoring and management.

The assessment of the hydromorphological condition of river corridors represents an established approach for evaluating the quality of fluvial systems. However, the potential to utilize existing hydromorphological assessment protocols and their indicators for the evaluation of ecosystem services remains largely unexplored. This study examines the applicability and robustness of such an indicator – transfer approach using two hydromorphological assessment protocols developed in Czechia (HEM and HYMOS), linked to the CICES 5.1 classification framework. The approach was tested across eight morphologically distinct reaches of the Bečva River, encompassing channelized, renaturalized, and restored segments. Relevant hydromorphological indicators were successfully identified and assigned to eight selected ecosystem services, including regulating, cultural, and provisioning categories. The comparison of HEM and HYMOS, including their respective indicator sets and the resulting ecosystem service assessments, showed that the HYMOS-based transfer generally yielded estimates reflecting a higher ecosystem service capacity. The results also indicate substantially higher ecosystem service capacity in renaturalized and restored reaches, a pattern that is particularly pronounced in the process-oriented HYMOS protocol. At the same time, the study highlights notable uncertainties in the assessment of cultural ecosystem services based solely on hydromorphological indicators. These services are strongly influenced by human perception, suggesting that their robust evaluation requires the integration of sociological data, including stakeholder surveys and participatory research. Overall, the findings demonstrate that hydromorphological assessment protocols can serve as a practical and conceptually consistent basis for the at least a preliminary evaluation of ecosystem service capacity associated with habitat quality, hydrological functioning, and channel-floodplain structure in river corridors.

Torrential flows are hazardous hydro-geomorphological phenomena characterized by sudden water discharge and intense sediment transport. They occur in mountainous areas where hydrometeorological monitoring is often limited or absent. The lack of such data hinders the identification of flow types and sediment transport conditions, reducing the effectiveness of mitigation measures. To address this issue, the current study focuses on geomorphic characteristics of torrential watersheds and identifies indirect indicators of torrential activity. The sedimentological and geomorphic signatures of torrential flows in the lower Damdere River catchment (Eastern Rhodopes Mountains, southern Bulgaria) were characterized. To capture inter-annual variability in torrential activity and differences between the Damdere and its tributary the Duandere, we sampled riverbed deposits. We also sampled areas upstream and downstream of the check dam to assess its influence. Samples were analyzed for grain size distribution, petrography, and mineralogy (X-ray diffraction). Results show contrasting controls on sediment supply and transport: the Duandere delivers relatively coarse material, whereas the Damdere attains higher transport capacity during torrential events. The check dam is largely infilled and exerts only local effects by trapping finer sediments upstream. Downstream, the channel retains its torrential character. Inter-annual comparison upstream of the structure shows sediment fining linked to lower flows. Petrographic and XRD data point to mechanically driven erosion and rapid sediment transfer. The results underline the importance of geological–geomorphological indicators in the lack of long-term monitoring in similar mountain catchments and can support flood risk management.