Minimum Data Requirements For Integrating Urban Development And Urban Water Infrastructure Models

Data quality and availability is a common problem in many modelling studies dealing with regional, spatially distributed case studies. This is true for both, urban development models and urban water management models. As current research in urban water management more and more tries to benefit from an integrated view of the performance of water networks in the context of dynamically growing and shrinking cities, this problem of data scarcity increases. Having different applications with different levels of details available, the question arises which data (and which temporal and spatial resolution) is really necessary to be collected in a modeling study with a certain modeling aim. This work tackles this question by running an integrated urban development and urban water model with different detail levels of input data. The approach uses variations in quality (temporal and spatial) of input data for simulating urban development (population data & projections) and given data on existing city structures (e.g. buildings, road network). Permutations of the given information propagated through the urban development model represent several scenarios to calculate parameters for the urban water models (effective impervious area (EIA), dry weather flow (DWF) and water supply demand (WSD)) As urban water models in this study SWMM (storm water management model) for drainage systems and EPAnet for water supply systems is used. Consequently the impact of the input data variation on the results of the hydraulic and hydrodynamic simulations is statistically analyzed using different performance indicators: EIA in relation to ponded volume, DWF to flow velocities and WSD to system pressure clustered by input data. For comparison reasons simulation runs with a well-established urban development model are conducted

Reduktion von Hitzestress und Überflutungen im urbanen Raum durch Nutzung von Synergien bei Anpassungsmaßnahmen an den Klimawandel

Klimaschutz und KlimaanpassungUnsere Städte sind kontinuierlichen Veränderungen unterworfen. Das Bevölkerungswachstum führt zu einem steigenden Bedarf an Wohn-, Gewerbe- und Verkehrsflächen und damit zu voranschreitender Versiegelung von natürlichen Flächen. Durch den Klimawandel sind unter anderem vermehrt auftretende Starkniederschläge, aber auch längere Trockenperioden und Hitzewellen zu erwarten (z.B. IPCC, 2014). Somit sehen sich Städte in naher Zukunft großen Herausforderungen ausgesetzt. Gleichzeitig sind Ressourcen für Anpassungsmaßnahmen begrenzt, und Flächen, die für Anpassungsmaßnahmen benötigt würden, stehen unter hoher Nutzungskonkurrenz. Vor diesem Hintergrund rücken Anpassungsmaßnahmen in den Vordergrund, die einen mehrfachen Nutzen aufweisen, wie dezentrale Entwässerungsmaßnahmen. Durch die Behandlung von Niederschlagswasser direkt vor Ort können gleichzeitig Grünflächen und Schattenplätze geschaffen, sowie Infiltration, Evapotranspiration und die Speicherung von Wasser gesteigert werden. Neben einer Entlastung des städtischen Abwassersystems kommt es damit auch zu einer Verbesserung des urbanen Mikroklimas und zu einer Minderung von Hitzeinseln. Die Auswirkung dezentraler Entwässerungssysteme auf das urbane Mikroklima wurde hier am Beispiel der Stadt Innsbruck näher untersucht. Zukünftige Klimaänderungen wurden anhand von Beobachtungsdaten und regionalen Klimaprojektionen aus EURO-CORDEX/ReKliEs unter Berücksichtigung verschiedener RCP-Szenarien (Abb. 1, 2) abgeschätzt. Indikatoren wie der Universal Thermal Climate Index wurden mittels eines vereinfachten Ansatzes in Abhängigkeit von lokalen Standorteigenschaften in einem GIS (Geoinformationssystem) simuliert (Back et al., 2020). Dieser Ansatz dient der Analyse urbaner Hitze auf mehreren Maßstabsebenen und kann unter Berücksichtigung verschiedener RCP-Szenarien durchgeführt werden (Abb. 3). Eine Koppelung dieses Ansatzes mit einem Ansatz nach Simperler et al. (2018), zur Differenzierung städtischer Strukturtypen und ihrer Potenziale und Einschränkungen für die dezentrale Niederschlagswasserbehandlung, soll prioritäre Gebiete zur Einbettung optimierter Anpassungsmaßnahmen lokalisieren und dadurch Synergieeffekte fördern. Diese Arbeit ist Teil der Projekte CONQUAD (Projekt Nr. KR16AC0K13143) und cool-INN (Projekt Nr. KR19SC0F14953), welche vom Österreichischen Klima- und Energiefonds gefördert werden

Modeling the Effects of Introducing Low Impact Development in a Tropical City: a Case Study from Joinville, Brazil

In tropical countries like Brazil, fast and uncontrolled urbanization, together with high rainfall intensities, makes flooding a frequent event. The implementation of decentralized stormwater controls is a promising strategy aiming to reduce surface runoff and pollution through retention, infiltration, filtration, and evapotranspiration of stormwater. Although the application of such controls has increased in the past years in developed countries, they are still not a common approach in developing countries, such as Brazil. In this paper we evaluate to what extend different low impact development (LID) techniques are able to reduce the flood risk in an area of high rainfall intensities in a coastal region of South Brazil. Feasible scenarios of placing LID units throughout the catchment were developed, analyzed with a hydrodynamic solver, and compared against the baseline scenario to evaluate the potential of flood mitigation. Results show that the performance improvements of different LID scenarios are highly dependent on the rainfall events. On average, a total flood volume reduction between 30% and 75% could be achieved for seven LID scenarios. For this case study the best results were obtained when using a combination of central and decentral LID units, namely detention ponds, infiltration trenches, and rain gardens.(VLID)2512613Version of recor

Greenhouse gas emissions from integrated urban drainage systems: where do we stand?

Integrated urban drainage systems (IUDS) (i.e., sewer systems, wastewater treatment plants and receiving water bodies) contribute to climate change being sources of greenhouse gas emissions (GHG). This paper, produced by the International Working Group on Data and Models, which works under the IWA/IAHR Joint Committee on Urban Drainage, reviews the state-of-the-art and the recently developed modelling tools used to understand and manage GHG emissions from IUDS. Further, open problems and research gaps are discussed, while proposing a framework for handling GHG from IUDS. The literature review reveals that there is a need to strengthen and partially adequate already available mathematical models for IUDS to take GHG into account

Comparison of Multi-Criteria Decision Support Methods for Integrated Rehabilitation Prioritization

The decisions taken in rehabilitation planning for the urban water networks will have a long lasting impact on the functionality and quality of future services provided by urban infrastructure. These decisions can be assisted by different approaches ranging from linear depreciation for estimating the economic value of the network over using a deterioration model to assess the probability of failure or the technical service life to sophisticated multi-criteria decision support systems. Subsequently, the aim of this paper is to compare five available multi-criteria decision-making (MCDM) methods (ELECTRE, AHP, WSM, TOPSIS, and PROMETHEE) for the application in an integrated rehabilitation management scheme for a real world case study and analyze them with respect to their suitability to be used in integrated asset management of water systems. The results of the different methods are not equal. This occurs because the chosen score scales, weights and the resulting distributions of the scores within the criteria do not have the same impact on all the methods. Independently of the method used, the decision maker must be familiar with its strengths but also weaknesses. Therefore, in some cases, it would be rational to use one of the simplest methods. However, to check for consistency and increase the reliability of the results, the application of several methods is encouraged.(VLID)2519672Version of recor

Green Infrastructures for Urban Water System: Balance between Cities and Nature

Urban water systems face severe challenges such as urbanisation, population growth and climate change. Traditional technical solutions, i.e., pipe-based, grey infrastructure, have a single purpose and are proven to be unsustainable compared to multi-purpose nature-based solutions. Green Infrastructure encompasses on-site stormwater management practices, which, in contrast to the centralised grey infrastructure, are often decentralised. Technologies such as green roofs, walls, trees, infiltration trenches, wetlands, rainwater harvesting and permeable pavements exhibit multi-functionality. They are capable of reducing stormwater runoff, retaining stormwater in the landscape, preserving the natural water balance, enhancing local climate resilience and also delivering ecological, social and community services. Creating multi-functional, multiple-benefit systems, however, also warrants multidisciplinary approaches involving landscape architects, urban planners, engineers and more to successfully create a balance between cities and nature. This Special Issue aims to bridge this multidisciplinary research gap by collecting recent challenges and opportunities from on-site systems up to the watershed scale.ISSN:2073-444

Integrating CFD-GIS modelling to refine urban heat and thermal comfort assessment

Constant urban growth exacerbates the demand for residential, commercial and traffic areas, leading to progressive surface sealing and urban densification. With climate change altering precipitation and temperature patterns worldwide, cities are exposed to multiple risks, demanding holistic and anticipatory urban planning strategies and adaptive measures that are multi-beneficial. Sustainable urban planning requires comprehensive tools that account for different aspects and boundary conditions and are capable of mapping and assessing crucial processes of land-atmosphere interactions and the impacts of adaptation measures on the urban climate system. Here, we combine Computational Fluid Dynamics (CFD) and Geographic Information System (GIS) capabilities to refine an existing 2D urban micro- and bioclimatic modelling approach. In particular, we account for the vertical and horizontal variability in wind speed and air temperature patterns in the urban canopy layer. Our results highlight the importance of variability of these patterns in analysing urban heat development, intensity and thermal comfort at multiple heights from the ground surface. Neglecting vertical and horizontal variability, non-integrated CFD modelling underestimates mean land surface temperature by 7.8 °C and the Universal Thermal Climate Index by 6.9 °C compared to CFD-integrated modelling. Due to the strong implications of wind and air temperature patterns on the relationship between surface temperature and human thermal comfort, we urge caution when relying on studies solely based on surface temperatures for urban heat assessment and hot spot analysis as this could lead to misinterpretations of hot and cool spots in cities and, thus, mask the anticipated effects of adaptation measures. The integrated CFD-GIS modelling approach, which we demonstrate, improves urban climate studies and supports more comprehensive assessments of urban heat and human thermal comfort to sustainably develop resilient cities.ISSN:0048-9697ISSN:1879-102

A rapid fine-scale approach to modelling urban bioclimatic conditions

Surface characteristics play a vital role in simulations for urban bioclimatic conditions. Changing relationships and distribution patterns of sealed and vegetated surfaces as well as building geometry across different scales in urban environments influence surface temperatures. Cities comprise different urban forms, which, depending on their surface characteristics, enhance the heating process, increasing the emergence of urban heat islands (UHIs). Detecting priority areas to introduce multi-beneficial climate change adaptation measures is set to be a key task for the cities long-term strategies to improve climatic conditions across different urban structures and scales. We introduce a simple and fast spatial modelling approach to carry out fine-scale simulations for land surface temperature (LST), mean radiant temperature (MRT) and Universal Thermal Climate Index (UTCI) in a 2D environment. Capabilities of our modelling approach are demonstrated in evaluating urban thermal comfort in the alpine city of Innsbruck, the capital of Tyrol in western Austria. Results show a major contrast between sealed and vegetated surfaces reflected in the distributional patterns and values of LST, MRT and UTCI, correlating with the appearance and frequency of specific surface classes. We found the Sky View Factor to have a substantial impact on calculations for bioclimatic conditions and see high-albedo surfaces decrease LST but increase the apparent temperature (MRT and UTCI values) effecting human thermal comfort. Furthermore, MRT and UTCI are more sensitive to changes in emissivity values, whereas LST is more sensitive to changes in Bowen Ratio values. Application of our modelling approach can be used to identify priority areas and maximise multi-functionality of climate change adaptation measures, to support urban planning processes for heat mitigation and the implementation of policy suggestions to achieve sustainable development goals and other political objectives.ISSN:0048-9697ISSN:1879-102