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148: Water in the Anthropocene (II): Urban Rivers: greening or renaturalization?
2nd Session Chair: Albert Santasusagna Riu
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| Session Abstract | |
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Coming from the successful session set up in the 9th EUGEO congress in Barcelona, in which this topic had more than 30 presentations, we would like to keep this congress as a place of interaction of human and physical geographers to expose, analyse and discuss the effects of the Anthropocene actions in water and, more specifically, in fluvial urban systems. On this occasion, we would like to centre the topic of the session on the recuperation of altered river systems in urban areas. A strong debate between greening or renaturalization of urban rivers is undergoing, and it is highly likely that no clear answer to this debate could be established (Farguell and Santasusagna, 2024). Greening refers to the creation of new green areas in cities for leisure purposes, priorizing the sociability of the river space. These projects usually enjoy great social acceptance as they are seen as a way of using the river space as a healthy environment which provides environmental, educational and leisure values. However, this position often forgets that the river is an active geomorphic agent that changes according to rain events, transports water and sediment, and needs more space than that one provided within an urban area. On the other hand, renaturalization focuses on the restoration of its ecological functioning and structure by improving the water quality of the river, recovering the natural regime, or the hydro-geomorphological processes involved. This approach often limits the accessibility of people to the river because priority to natural fauna and flora development, and river channel shape conservation is given. Despite it, it also increases the quality of the river environment and hence, the quality of the city itself. Under these premises, in this session we would like to draw your attention on the presentation of cases involving greening, renaturalization or other situations that improve somehow the river sections flowing through a city, and how the cities cope with the interaction of river systems flowing through them during extreme events. | |
| Presentations | |
Assessment of nitrogen and phosphorus pollution based on multi-source data and the InVEST model in the Henan section of Yellow River Basin, China Institute of Geographical Sciences, Henan Academy of Sciences, China, People's Republic of In recent years, non-point source pollution (NPSP) has become prominent in the Yellow River Basin (YRB) of China and seriously affects human survival and sustainable development. The Henan section was selected as an example region of the YRB in China, and the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model has been used to quantitatively evaluate nitrogen (N) and phosphorus (P). The results show that (1) the cultivated land (CL), grassland (GL), and unused land (UL) decreased, while forest land (FL), water areas (WAs), and built-up areas (BAs) increased in 2000–2020, and precipitation increased from the northeast to the southwest in 2000–2020; (2) the N export was much more than P export in 2000, 2010, and 2020, and the N and P exports increased in 2000–2020; the spatial distribution of N and P export changes was different in the whole basin in 2000–2010, 2010–2020, and 2000–2020; (3) the N and P exports decreased in Pharmaceutically active compounds in rivers and streams of the Budapest metropolitan area: adsorption in sediments and efficiency of the riverbank filtration 1HUN-REN Research Centre for Astronomy and Earth Sciences, Budapest, Hungary; 2ELTE Eötvös Loránd University, Budapest, Hungary; 3University of Pannonia, Soós Ernő KFK, Nagykaninzsa, Hungary; 4HUN-REN Centre for Ecological Research, Budapest, Hungary; 5MATE Hungarian University of Agriculture and Life Sciences, Gödöllő, Hungary; 6Universidade do Minho, Braga, Portugal A significant part of the world's population lives around rivers. The riparian zone is not only a source of drinking water for urbanised areas; streams and rivers are also sinks for wastewater. As a result of the increased consumption of pharmaceutically active compounds (PhACs) in past decades, wastewater untreated and treated is a continuous load of these compounds (and their metabolites) to fluvial systems. The water supply for these kinds of urbanised areas is partly provided by riverbank filtration plants which can be significantly affected by PhACs loading. Riverbank filtration is effective for most pollutants. However, the filtering efficiency for these molecules is poorly known. This presentation focuses on the spatial and temporal distribution of more than a hundred PhACs in the streams and rivers of the Budapest Metropolitan Area. Our presentation demonstrates that bank filtration can also be effective for the filtration of organic micro-pollutants in highly urbanised areas. Samples were collected during five sampling campaigns. The streams, rivers, and drinking water wells were sampled. The stream sediments were also sampled. Altogether 111 PhACs were measured. In small streams and rivers, eighty-one PhACs were systematically detected, while fifty-three PhACs were detected in the Danube. The quantification of 19 PhACs in the Budapest section of the river was without any precedent, and 10 PhACs were present in >80% of the samples. More PhACswere detectable in the small watercourses, and the concentrations were significantly higher than in the Danube. Sediments always contain fewer PhACs than water. This is mainly due to the high sorption capacity of sediments. The most frequent PhACs showed higher concentrations in winter than in summer. In the drinking water wells 32 PhACs were quantified. For the majority of PhACs, the bank filtration efficiency was higher than 95%. Concentrations of the compounds did not influence the efficiency of filtering. For some PhACs (e.g. carbamazepine lidocaine, tramadol, and lamotrigine), low filtration efficiency was observed. These frequently occurring PhACs in surface waters have a relatively even distribution, and their sporadic appearance in wells is a function of both space and time, which may be caused by the constantly changing environment and micro-biological parameters, the dynamic operating schedule of abstraction wells, and the resulting sudden changes in flow rates. This research was funded by the National Research, Development, and Innovation Office (NKFIH), grant numbers: K-142865, 2020-1.1.2-PIACI-KFI-2021-00309, 2021-1.2.4-TÉT-2021-00029. DANube SEdiment Restoration (DANSER): Towards deployment and upscaling of sustainable sediment management across the Danube River basin (The Upper Danube case) 1University of Vienna, Austria; 2Department of Geology, University of Vienna, Austria; 3BOKU University, Vienna, Austria; 4Paris Lodron University of Salzburg, Austria; 5FLUVIUS, Floodplain Ecology and River Basin Management, Vienna, Austria; 6via donau, Vienna, Austria; 7Donau-Auen National Park, Vienna, Austria; 8Ingenieurbüro Klasz, Vienna, Austria DANSER aims at addressing the urgent need for sustainable sediment management solutions at the river basin scale, focusing on the Danube River-Black Sea system. Foci are demonstration of multidisciplinary innovative and holistic solutions and developing deeper insights into the sediment status and cause-effect relationships (e.g. via spatiotemporal mapping of natural and anthropogenic fluvial processes, sediment transport modelling, sediment dating, 3D historical reconstruction, river processes forecast simulations, sediment budget analysis, connectivity modelling and interventions, stakeholder-engaged sediment parametric evaluation and co-management, interlinkages with biodiversity (patterns), water quality and climate change effects. This EU-funded (HORIZON-MISS-Danube & Black Sea Lighthouse) project seeks to restore sediment balance, improve sediment flow and quality together with EU- and other international stakeholders (existing bodies, digital platforms, events and know-how). In an ample coverage throughout 3 DEMO (incl. 13 pilot) sites, 7 sibling locations, and 6 associated regions (AR), the DANSER approach will develop, validate, and promote key active and passive measures to mitigate human interference in the sediment flow, related biodiversity and ecological aspects and possibly recover the sediment balance and quality in critical stretches of the basin. In this presentation, we aim to provide an overview of the strategies and actions that are foreseen for the Upper Danube region, specifically in DEMO area 1 located in Lower Austria with a specific focus on “urban” river sections. (Dis-)connectivity in urban rivers: the case of Genova (NW Italy) 1University of Genova, Department of Earth, Environment and Life Sciences, Genova, Italy; 2Information System - Technology Office, Genova Municipality, Genova, Italy Urbanization is strictly associated with severe geomorphic changes of fluvial systems. The present work provides a quantitative and qualitative assessment of landscape changes driven by urbanization, which occurred from the mid-19th century to the present day along the lower reaches of the Bisagno and Polcevera rivers and their tributaries in the Mediterranean coastal city of Genova (NW Italy). This study is based on collection and review of historical data, photograph interpretation, GIS analysis, and field surveys. Urbanization essentially occurred between the mid-19th century and the late 1930s. In this period the bankfull channel of the Bisagno and Polcevera rivers experienced large narrowing associated with widespread establishment of channelization structures. The minor hydrographic network essentially disappeared underground. After the 1930s, further minor anthropogenic interventions were implemented to accommodate urban expansion and consolidate channelization works; however, the overall geomorphological setting remained unchanged. Nowadays, the study area is completely urbanized, the fluvial stems flowing through the valley floor are totally disconnected from their adjacent areas, the main rivers show a relevant geomorphological stability induced by anthropogenic pressures, and the accessibility of river margins for people is rather limited. The urban expansion that occurred over the valley floor of the Bisagno and Polcevera rivers, and overall over their catchments, resulted in flood risk increase, river ecosystem degradation and social disconnectivity. Re-establishing the pre-urbanization landscape conditions is impossible as it would need social, political, and economic support far different from what it might have today. Thus, different management measures primarily focused on the reduction of vulnerability by increasing the community resilience to future hazardous events are required. | |