Challenges for transboundary river management in Eastern Europe-Three case studies

Matthews G., Baugh C., Barnard C., De Wiart C.C., Colonese J., Decremer D., Grimaldi S., Hansford E., Mazzetti C., O’Regan K., Pappenberger F., Ramos A., Salamon P., Tasev D., Prudhomme C.

Padilha J., Carvalho-Santos C., Cássio F., Pascoal C.

Land cover change scenarios hold far-reaching implications for ecosystem services (ES), highlighting the need for understanding the trade-offs and synergies underlying the provision of multiple ES. The insufficient knowledge of the mechanisms governing the relationships among multiple ES, along with the lack of information on trade-offs among ES under different scenarios, restricts the ability to provide effective information for decision-makers. To fill this gap, we assessed the interplay among six ES: climate regulation, habitat creating and maintaining species diversity, cultivated crops, regulation of the chemical condition of freshwaters by living processes (water quality), water yield, and control of erosion rates, within three river basins in northwest Portugal. We employed the InVEST to map the state of these ES in 2018, along with three projected land cover scenarios for 2050: business-as-usual, farmland return, and afforestation. Our findings indicated the business-as-usual scenario could lead to detrimental impacts on climate regulation, habitat creating and maintaining species diversity, and control of erosion rates. In contrast, the farmland return scenario showed less drastic decreases in habitat-creating and maintaining species diversity and control of erosion rates compared to the business-as-usual scenario. Afforestation emerged as the most favorable scenario, with a 13.6% increase in climate regulation and a 1.3% improvement in habitat-creating and maintaining species diversity. Cluster analysis allowed the identification of six levels of spatial synergies between ES, with regions of high forest cover showing extreme synergy and populated areas exhibiting the lowest levels of synergy, suggesting that a well-planned combination of these practices could yield substantial benefits for future ES provision. These results provide crucial insights for decision-makers to enhance ecosystem management and promote societal well-being. Importantly, our findings underscore the significance of considering multiple ES and their interrelationships in land use planning to achieve sustainable development objectives.

Chalov S., Ivanov V.

This paper presents a comparative study of fluvial sediment budgets for the largest Siberian rivers of Northern Eurasia - Ob', Yenisey and Lena which cover over 14 % of the Eurasia continent. Each component of the sediment budget was assessed using an independent approach. The Revised Universal Soil Loss Equation model (RUSLE) was used to calculate catchment erosion based on the GMTED 2010 DEM with a resolution of 250 m. Channel erosion was quantified through automatic image decoding integrated with riverbank elevation estimated from ArcticDEM and hydromorphological 1D modeling of streamflow depths, whereas sediment yield was assessed based on a combination of long-term suspended sediment load monitoring at the outlet gauging stations and bed load estimates. Large differences between total (catchment and riverbank) erosion (1622 Mt year−1 for the Ob', 898 Mt year−1 for the Yenisey, 1218 Mt year−1 for the Lena) and yearly sediment export (58.2 Mt year−1 for the Ob', 32.5 Mt year−1 for the Yenisey and 38.6 Mt year−1 for the Lena) suggest that catchment, in-channel and overbank sediment sinks and storage dominate the sediment budget. The throughflow from the sources to the sea is less than 4 % of the suspended sediment inflow (total erosion). This data enhances the knowledge of the sediment delivery rates in large river systems. Over ∼96 % decline of sediment transport compared to catchment total erosion is explained by storage in various buffer zones of the catchment and river network including mainly hillslopes, as well as reservoirs and floodplains.

Karthe D., Bogardi J.J., Borchardt D.

Over the past three decades, Integrated Water Resources Management (IWRM) has evolved into one of the leading water management paradigms. Revisiting the starting points and the development of the IWRM concept, this chapter critically analyzes the rationales and the major elements to be considered in the framework of IWRM. IWRM is then related to other recently emerging concepts such as adaptive water management and the Resource Nexus. Even though IWRM has been formally adopted almost worldwide for almost two decades, its implementation remains a challenge for many countries. IWRM also became a major research topic in water sciences and beyond, calling for a reflection of its role and impact. Based on theoretical and empirical analyses of contemporary IWRM research, this chapter provides best practice examples of science based implementation and synthesizes the lessons learnt.

Terskii P., Kuleshov A., Chalov S., Terskaia A., Belyakova P., Karthe D., Pluntke T.

The study provides a new assessment of the water balance components of the catchment (evapotranspiration, surface and lateral flow etc. and its spatial distribution and temporal variability) for the transboundary catchment of Western Dvina river within the poorly gauged Russian part of the catchment.The study focuses on modeling the inland flow generation processes using open source data and the SWAT (Soil Water Assessment Tool) hydrological model. The high interannual variability of river flow and impact of snowmelt processes were especially taken into account when setting up the model and processing the calibration. The database of daily meteorological data for the period 1981 – 2016 was prepared using global atmospheric reanalysis ERA-Interim data and observed station data from the GSOD NCDC/NOAA and ECA&D datasets. The considered datasets were tested on plausibility and regionalized. The catchment model was built on the basis of open land use / land cover (LULC) data sets, topography and soil, so that the entire transboundary catchment area could be easily implemented in the next step. For the daily model calibration, 19 sensitive parameters were chosen manually. The most sensitive are the parameters which consider snow melting processes and flow recession curve number. The highest impact on water balance components has the area and distribution of wetlands. Lakes strongly affect the evapotranspiration rate. The study provides further research with uncertainty analysis and recommendations for model improvement and model limitations. The developed modelling approach can be used to assess water resources, climate change impacts, and water quality issues in comparable regions.