Zusammenfassung
Im Rahmen des EU-finanzierten Netzwerkprojekts COST Action Circular City wurde die Anwendung von naturbasierten Lösungen (NBS) im Kontext der Kreislaufwirtschaft in Städten ...untersucht. Dabei steht die Minimierung des Inputs von notwendigen Ressourcen wie Wasser, Nährstoffen, Biomasse, lebenden Organismen und Energie im Vordergrund. Die Hauptergebnisse sind das Circular-City-Rahmenwerk (Framework) und dessen grafische Umsetzung als Online-Toolbox. Das Rahmenwerk beschreibt einen Technologie-Katalog mit NBS-Einheiten und -Interventionen, mit denen die Bewältigung der urbanen Herausforderungen der Kreislaufwirtschaft möglich ist, sowie eine Methodik zur Definition von Input- und Output-Ressourcenströmen. Das Online-Tool besteht aus einer Toolbox sowie einem Tool zur Quantifizierung der Ressourcenströme. Meist wird bei der Implementierung von NBS deren Potenzial zur Förderung der Multifunktionalität in der Regel nicht voll ausgeschöpft. Eine sektorübergreifende Zusammenarbeit ist dafür im Planungsprozess unerlässlich. Zirkuläres Denken unterstützt dabei eine bessere und multifunktionale Planung mehrerer städtischer Herausforderungen.
Sustainable agriculture should be based on management practices that improve resource usage efficiency and minimize harmful impacts on the environment while maintaining and stabilizing crop ...production. Both tillage and irrigation can have an influence on water resource usage and thus on hydrological processes within agroecosystems. However, it remains difficult to directly assess the effect of practices on water fluxes. Therefore, the objective of the study was to use oxygen and hydrogen isotopes (δ18O, δ2H) in the pore water of soil profiles as well as moisture contents for quantifying the soil water balance and fluxes. Covering all combinations, water content and isotope analysis in soil profiles were performed for 16 plots planted with winter wheat and managed with different tillage (conventional tillage (CT), reduced tillage (RT), minimal tillage (MT), and no-tillage (NT)) and irrigation systems (hose reel boom irrigation with nozzles (BI), sprinkler irrigation (SI), drip irrigation (DI) and no irrigation (NI)). The results indicated that the more intense the tillage, the lower the water content. Among the irrigation systems, DI had the highest average water content. Tracing the isotope minimum of winter precipitation in pore water of soil profiles showed deeper percolation of water in the CT plots, which indicates higher water flow velocity for CT compared to other tillage variants. Considering both water content and water flow velocities resulted in average water fluxes ranging from 23 to 46 mm for six months (end of November to May). For the same time period, between 80% and 91% of the water contributed to evapotranspiration. The resulting evapotranspiration within tillage and irrigation variants decreased in the order CT>RT>MT>NT and SI>BI>DI>NI. Thus, the method revealed that the lower water content in CT fields is a consequence of both deeper water infiltration and higher evapotranspiration. Moreover, irrigation water contributed mostly to evapotranspiration, and drip irrigation showed the lowest evapotranspiration among irrigation systems. This study demonstrated that water stable isotopes can be used as indicators and are a promising method to quantify average water fluxes in agricultural fields with great potential for evaluating management practices.
•The method allows direct quantification of average water flux in a given period in agricultural soils.•The influence of management practices on hydrological processes could be compared.•Deuterium profiles show higher flow velocity in more intensively tilled soils.•The more intensive the tillage, the higher the evapotranspiration.•Mobile soil water was greater in untilled plots and plots using drip irrigation.
Climate change poses challenges to agricultural water resources, both in terms of quantity and quality. As an adaptation measure, the new European Regulation (EU) 2020/741 establishes different water ...quality classes for the use of reclaimed water in agricultural irrigation. Italy is also working on the definition of a new regulation on reclaimed water reuse for agricultural irrigation (in substitution of the current one) that will also include the specific requirements imposed by the European one. Nature-based Solutions (NBS) can be a cost-effective and environmentally friendly way to facilitate water reclamation and reuse. The present study reports the outcomes of a long-term monitoring campaign of two NBS (e.g., a constructed wetland (CW) and a lagoon system (LS)) comparing influent and effluent concentrations of different contaminants (e.g., E. coli, BOD5, TSS, TN and TP) with the threshold values imposed by the new regulations. The results showed that in both the case studies, E. coli (about 100 CFU 100 mL-1) and BOD5 (lower than 25 mg L-1) mean effluent concentration need to be further reduced in reclaimed water to be suitable for unlimited reuse. As a negative aspect, in both the monitored NBS, an increase in TSS mean concentration in the effluent was observed, up to 40 mg L-1 in the case of the LS, making reclaimed water unsuitable for agricultural reuse. The CW has proven to be more effective in nitrogen removal (the effluent mean concentration was 3.4 mg L-1), whereas the LS was better at phosphorus removal (with an effluent mean concentration of 0.4 mg L-1). Based on the results, recommendations were made to further improve the performance of both systems in order to have adequate water quality, even for class A. Furthermore, the capacity of reclaimed water to meet crop water and nutrient needs was analyzed, and total nitrogen removal rate coefficients were calculated for the design of future LSs.
In Austria, single-stage vertical flow (VF) wetlands with intermittent loading are a state-of-the-art technology for treating domestic wastewater. They are designed according to the Austrian design ...standard with a specific surface area of 4 m
per person (i.e. 20 g COD/(m
·d)) and thus demand a bigger amount of land to treat the same amount of wastewater compared to intensified technical treatment systems. In order to reduce the amount of land needed, a modified design for VF wetlands has been proposed. The modified design has a specific surface area of 2.5 m
per person (i.e. 32 g COD/(m
·d)) and it has been shown to be able to meet the Austrian effluent requirements. To allow higher organic loading, more loadings per day but lower volume of a single loading, a constant loading interval, and increased number of openings per m
are applied. A simulation study using the HYDRUS Wetland Module was carried out to compare the treatment efficiencies of single-stage VF wetlands with classical and modified design. Data from a classical Austrian single-stage VF wetland was used for calibration of the model using the standard parameter set for the CW2D biokinetic model. The influent COD fractionation was calibrated to adapt to the wastewater. The simulations showed a good performance of the modified design compared to a classical VF wetland for COD removal with COD effluent concentrations in winter (effluent water temperature of 4.5 °C) of 35 and 29 mg/L, respectively. The simulation study showed that during high-loading events the VF wetland with modified design has lower maximum NH
-N effluent concentrations. Single-stage VF wetlands with modified design seem to be very effective and allow application of higher organic loads compared to single-stage VF wetlands with classical design.
Urban agriculture (UA) plays a key role in the circular metabolism of cities, as it can use water resources, nutrients, and other materials recovered from streams that currently leave the city as ...solid waste or as wastewater to produce new food and biomass. The ecosystem services of urban green spaces and infrastructures and the productivity of specific urban agricultural technologies have been discussed in literature. However, the understanding of input and output (I/O) streams of different nature-based solutions (NBS) is not yet sufficient to identify the challenges and opportunities they offer for strengthening circularity in UA. We propose a series of agriculture NBS, which, implemented in cities, would address circularity challenges in different urban spaces. To identify the challenges, gaps, and opportunities related to the enhancement of resources management of agriculture NBS, we evaluated NBS units, interventions, and supporting units, and analyzed I/O streams as links of urban circularity. A broader understanding of the food-related urban streams is important to recover resources and adapt the distribution system accordingly. As a result, we pinpointed the gaps that hinder the development of UA as a potential opportunity within the framework of the Circular City.
A framework developed by the COST Action Circular City (an EU-funded network of 500+ scientists from 40+ countries; COST = Cooperation in Science and Technology) for addressing Urban Circularity ...Challenges (UCCs) with nature-based solutions (NBSs) was analyzed by various urban sectors which refer to different fields of activities for circular management of resources in cities (i.e., reducing use of resources and production of waste). The urban sectors comprise the built environment, urban water management, resource recovery, and urban farming. We present main findings from sector analyses, discuss different sector perspectives, and show ways to overcome these differences. The results reveal the potential of NBSs to address multiple sectors, as well as multiple UCCs. While water has been identified as a key element when using NBSs in the urban environment, most NBSs are interconnected and also present secondary benefits for other resources. Using representative examples, we discuss how a holistic and systemic approach could facilitate the circular use of resources in cities. Currently, there is often a disciplinary focus on one resource when applying NBSs. The full potential of NBSs to address multifunctionality is, thus, usually not fully accounted for. On the basis of our results, we conclude that experts from various disciplines can engage in a cross-sectoral exchange and identify the full potential of NBSs to recover resources in circular cities and provide secondary benefits to improve the livelihood for locals. This is an important first step toward the full multifunctionality potential enabling of NBSs.
River systems have undergone a massive transformation since the Anthropocene. The natural properties of river systems have been drastically altered and reshaped, limiting the use of management ...frameworks, their scientific knowledge base and their ability to provide adequate solutions for current problems and those of the future, such as climate change, biodiversity crisis and increased demands for water resources. To address these challenges, a socioecologically driven research agenda for river systems that complements current approaches is needed and proposed. The implementation of the concepts of social metabolism and the colonisation of natural systems into existing concepts can provide a new basis to analyse the coevolutionary coupling of social systems with ecological and hydrological (i.e., ‘socio-ecohydrological’) systems within rivers. To operationalize this research agenda, we highlight four initial core topics defined as research clusters (RCs) to address specific system properties in an integrative manner. The colonisation of natural systems by social systems is seen as a significant driver of the transformation processes in river systems. These transformation processes are influenced by connectivity (RC 1), which primarily addresses biophysical aspects and governance (RC 2), which focuses on the changes in social systems. The metabolism (RC 3) and vulnerability (RC 4) of the social and natural systems are significant aspects of the coupling of social systems and ecohydrological systems with investments, energy, resources, services and associated risks and impacts. This socio-ecohydrological research agenda complements other recent approaches, such as ‘socio-ecological’, ‘socio-hydrological’ or ‘socio-geomorphological’ systems, by focusing on the coupling of social systems with natural systems in rivers and thus, by viewing the socioeconomic features of river systems as being just as important as their natural characteristics. The proposed research agenda builds on interdisciplinarity and transdisciplinarity and requires the implementation of such programmes into the education of a new generation of river system scientists, managers and engineers who are aware of the transformation processes and the coupling between systems.
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•River systems have been massively transformed and are socio-ecohydrological systems.•A socio-ecohydrologically driven approach provides insights into coevolutionary processes.•Social metabolism and the colonisation of natural systems are underlying concepts.•Four research clusters analyse the transformation and coupling of society and nature.•Interdisciplinary and transdisciplinary approaches support the operationalization of the research agenda.
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