Hydromorphology is a major component of riverine ecosystems. Therefore, proper assessments of the status quo, as well as the detection of pressures in river basins, are of high relevance. Process-based morphological methods have been developed, relying on a broad data basis and resulting in suitable instruments, such as the Morphological Quality Index (MQI). In this study, the hydromorphological status of the Nanxi river system in Eastern China was assessed by an adapted application of the MQI. Adaptations and amendments in the methodical approach were developed in cycles and carried out to transfer the well-approved method for European river systems to another geographical setting. The strengths of the tested approach are the few data requirements, the applicability for modified river basins, and the decoupling of historical information. The assessment of 161 river kilometers resulted in a hydromorphological status quo with the focus being a relative comparison of different sections ranging from “moderate” to “bad”, with an average classification of a “poor” state. On the one hand, the results build the basis for future restoration and river management planning, specifically, and on the other hand, they create a foundation for the development of an assessment method fitted for modified river systems conditions.

The application of nature-based solutions for climate change adaptation in cities has increased in recent years. To improve microclimatic conditions and to preserve the natural components of related assets, water supply is necessary. As an alternative to drinking water, stream water might serve as a natural source for irrigation. However, due to continuous urbanisation, water courses have often been banned underground in pipes or integrated in the combined sewer network, both making them not directly available for further usage. This article focuses on the perspectives of decoupling captured streams from underground infrastructure to support nature-based urban climate adaptation measures. It introduces a method to identify suitable locations for practical implementation considering the hydrological potential of the stream and the urban microclimatic sensitivity of the concerned area. The approach was applied in a case study in the north-western part of Vienna, including 16 streams with a total length of about 39 km covering an area of approximately 95 km2 with about half a million inhabitants. This work proved the general practicality of the suggested method. It also revealed that about one-third of the investigated stream lengths appears high or medium suitable to support climate adaption measures, leading to notable cost savings for irrigation (for the substitution of drinking water) and wastewater treatment. Concluding, the decoupling of captured streams could contribute to a more sustainable and nature-based urban water management. The introduced method for suitability pre-assessment is applicable with rather easily available input data, which makes it transferable to other cities.

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Introduction: Railway corridors, as linear landscape structures, are highly exposed to natural hazards. In alpine regions intact protective forests form a key basis for safeguarding the route network by complementing technical protection measures through forest-related ecosystem services. From a long-term perspective, these benefits are only generated by resilient and vital forest stands. To maintain sustainable services and benefits under climate change, an understanding of the biological system and its future developments is essential. Difficulties lie in long reaction times of forest stands to management actions and a broad range of species, that need to be considered. Methods: The method used in this study focuses on the extrapolation of potential natural stands based on basic climate parameters by developing a two-dimensional climatic space, describing natural stands for 46 species in all 26 operational units of the Austrian railway corridor. First, we analyzed the current distribution of woody plant species using a climate-envelope modeling approach. Secondly climatic conditions of the Austrian railway network were evaluated and modelled for future climate change scenarios. In the synthesis of steps one and two, potential natural stands were detected, quantified, contextualized and compared to the reference period 1961–2020. Results: Several promising species were detected for future climate scenarios and European wide trends were confirmed on the regional scale. Especially Castanea sativa , Ulmus minor , and Sorbus torminalis can help generating vital stands that can deliver the protective functions we are aiming for. Discussion: The results mark an initial step toward climate-change-adapted protective forest management by detecting changes in natural site conditions and predicting vulnerable areas along the Austrian railway corridor, offering a management tool for infrastructure operators to guide future species selection and assess risks to protective forest functions.

Urban streams are exposed to strong anthropogenic pressures and frequently exhibit extensive morphological modifications, including embankments, channel straightening, and elevated longitudinal slopes. Especially in urban areas hydraulic capacity and requirements on flood control are driving factors for channel geometry and morphology, leaving strongly limited lateral space availability. Despite these pressures, restoration has gained increasing attention also for urban streams. Hydraulic conditions change, roughness is getting higher, slope might be reduced. Such morphological alterations have a direct influence on hydraulic behavior. Frequently, a trade-off exists between riparian vegetation and hydraulic capacity, since flow capacity is generally highest where woody vegetation is absent from banks and adjacent zones. In urban stream systems thermal energy input during low flow situations is mainly connected to short wave radiation and to air temperature. Restoration works slow down the system, increasing hydraulic residence time. In consequence slower systems exhibit a higher energy input, which makes them more sensitive to heat stress. Riparian vegetation can buffer energy input via shading effects. When addressing the trade-off between the services provided by riparian vegetation and hydraulic capacity, linking hydraulic and thermal aspects could provide valuable insights. The research done in the INTERLAYER project dedicates the impact of riparian vegetation on water temperature during low flow conditions at the small to medium size urban river, Liesingbach. Based on a water temperature model the vegetation effects on water temperature through shade during a low flow period with high air temperature values are quantified and compared to a scenario in absence of riparian vegetation. A HEC-RAS water quality model was set up for 8 km along the urban flow path of the river Liesingbach using the full energy budget approach. The model was calibrated and validated by measured water temperature data for two river heat periods in two consecutive years. Vegetation data was collected by hemispherical photographs. The prevailing vegetation was tested against a total absence of vegetation. The results show that effects of shade through riparian vegetation were able to buffer of 0.7 to 1.3°C daily water temperature peaks. An impact on daily minimum values was not detected. Based on our results vegetation effects are not limited to dense riparian forests. Even single tree lines, or shrubby vegetation implemented through soil and water bioengineering techniques have remarkable influence on water temperature. Vegetation can clearly support ecological aspects during low flows. With the prevailing water temperature model, we created a tool to quantify the impacts and predict potential changes. Building on this integration of hydraulic and vegetation modelling will enable us to improve ecological outcomes during low-flow periods.

Climate change adaptation in urban areas often involves the expansion and further development of blue-green infrastructure. In cities where stream systems are routed in the underground, there is potential to adapt public spaces to the growing requirements caused by climate change by daylighting these streams. Usually, urban streams are used as climate change adaptation in terms of PET (physically equivalent temperature) reductions. Beside their usage in cooling public spaces, streams, especially spring-fed streams, also provide potential for thermal utilization as a climate change adaptation measure in the built environment. In case streams originating from thermal springs temperature patterns are inverted. Showing the highest temperatures at the spring and cooling down on their way downstream. Climate change adaptation initiatives include efforts to utilize their thermal potential for geothermal energy. One example is MaDoKli Project, focusing on Mannersdorfergraben in Eastern Austria. The region is characterized through a focus on agriculture and open fields next to the city of Mannersdorf. The initial conditions of the project area show an interesting situation with a constant discharge in a range of 14 – 27 l/s measured with 23° C year-round at the spring. Therefore, the warm stream is intended to be integrated into the municipality’s energy system through heat exchange for thermal energy extraction. The Mannersdorfergraben is monitored over its 6 km long flow path. Water temperature is measured at 300 m intervals using HOBO Bluetooth Onset 1-800-loggers, covering the springs, the flow path in the underground and the open channel. The inverse temperature regime was investigated over a six-month period in 2025 at 15-min interval. The measurements are intended to support a sensitivity analysis assessing how fluctuations of +/- 5° C impact the total water temperature regime of the stream. The data allows the identification of the longitudinal extent affected by thermal stress, manifested as river temperature reduction in heating period and thermal pollution during the summer period. Early results indicate that approximately halfway along the open flow section, the effect of thermal energy extraction diminishes and the water temperature returns to its initial baseline.Additionally, the results are intended to help determine the impact of the thermal intervention in the flow system on the stream and its ecosystem.