Urban Model Research Articles

How water circularity can help to reduce and regulate water waste in urban districts

Abstract Global water consumption has increased sixfold in the past 100 years and is growing at about 1% per year due to population growth, economic development, and changing consumption patterns; therefore, climate change, combined with urbanization and population growth, is causing water availability problems in cities around the world. Rethinking circular cities that put water at the centre of their priorities and that manage it cyclically and keep it within the urban environment as much as possible to maximize its value must become the fundamental goal. However, to date, cities are not even close to maximizing the use of water that reaches their buildings. As a result, two main issues have emerged as crucial in the international debate: the scarcity of water resources due to its wastefulness and overuse, and extreme weather events, such as heavy rains alternating with periods of prolonged drought, a consequence of global warming. In response to these issues, this research aims to investigate the potential of a design approach that takes into account the two phenomena of water excess and shortage, integrating water from the earliest decision-making stages of building design. Starting from the definition of architectural strategies, replicable solutions are defined and evaluated against specific KPIs to develop a resilient and climate-neutral architectural and urban design model.

Urban geoheritage and degradation risk assessment of the Sokograd fortress (Sokobanja, Eastern Serbia)

Abstract Sokobanja is a well-known spa centre in East Serbia, whose popularity is mostly based on its natural heritage (thermo-mineral springs, waterfalls, canyons, caves, and pits). However, built heritage also offers significant potential for developing geotourism. This article aims to assess the geoheritage values of the geocultural site Sokograd fortress to support geotourism development in this area. For the assessment of geotourism potentials, the urban geoheritage assessment model (UGAM) was applied. To support the criteria of UGAM (e.g. variety of geodiversity and educational potentials), a macroscopic mineralogical–petrographical observation of the building stone was performed. The results revealed significant educational potentials, especially concerning petrodiversity, with sedimentary rocks (limestone, sandstone, tufa, and conglomerates). By comparing the obtained results with the local geology, it is recognized that the building stone was mainly of local provenance. The UGAM parameters, such as geocultural and ecological values, as well as a variety of geodiversity, confirmed that Sokograd has great potential for urban geotourism development. After all, the assessment of degradation risk was performed and revealed that tourism development cannot cause serious threats to the site, but tourism has to be adequately regulated and managed in a sustainable way. The results of this study can provide information to policymakers, local governments, and other interested stakeholders on whether and how to develop urban geotourism at the Sokograd fortress in the upcoming period.

Structural Uncertainty in the Sensitivity of Urban Temperatures to Anthropogenic Heat Flux

AbstractOne key source of uncertainty for weather and climate models is structural uncertainty arising from the fact that these models must simplify or approximate complex physical, chemical, and biological processes that occur in the real world. However, structural uncertainty is rarely examined in the context of simulated effects of anthropogenic heat flux in cities. Using the Weather Research and Forecasting (WRF) model coupled with a single‐layer urban canopy model, it is found that the sensitivity of urban canopy air temperature to anthropogenic heat flux can differ by an order of magnitude depending on how anthropogenic heat flux is released to the urban environment. Moreover, varying model structures through changing the treatment of roof‐air interaction and the parameterization of convective heat transfer between the canopy air and the atmosphere can affect the sensitivity of urban canopy air temperature by a factor of 4. Urban surface temperature and 2‐m air temperature are less sensitive to the methods of anthropogenic heat flux release and the examined model structural variants than urban canopy air temperature, but their sensitivities to anthropogenic heat flux can still vary by as much as a factor of 4 for surface temperature and 2 for 2‐m air temperature. Our study recommends using temperature sensitivity instead of temperature response to understand how various physical processes (and their representations in numerical models) modulate the simulated effects of anthropogenic heat flux.

Research on data processing of 3D modeling by images based on helicopter oblique photogrammetry

Abstract The use of tilting photogrammetry technology to build a refined urban 3D model has become the industry research hotspot with the rapid development of China’s “digital city.” To investigate and analyze the methodology of 3D data modeling using helicopter oblique photogrammetry, a 3D model was generated for a study area covering approximately 34 km2. This paper delves into the technical process of 3D modeling data processing utilizing helicopter oblique photogrammetry, and it examines the precision of the model results alongside a comprehensive technical analysis. The results show that the results of the process are consistent with the relevant specifications of the first-order 3D model landscape. Compared with the traditional 3D model, the method has obvious progress in efficiency and has a very wide application prospect.

Dynamic vulnerability assessment framework for urban flood disasters considering real-time population changes

ABSTRACT Flood vulnerability assessment is an important means to cope with urban flood disasters. However, urban population mobility and land-use changes bring significant uncertainty to vulnerability assessments. In order to respond to the refined and dynamic needs of urban flood disaster prevention and control, a multi-scale and multi-categorized urban flood dynamic vulnerability assessment framework that considers real-time population changes was proposed in this study. The framework used the comprehensive function of exposure, sensitivity, and coping ability under population dynamic changes to characterize urban flood dynamic vulnerability, and constructed urban flood disaster vulnerability assessment models at both grid and regional scales. The results show that population mobility has a significant impact on the vulnerability of urban flood disasters. The vulnerability of flood disasters in Zhengzhou City is highest at 8:00 and 18:00, and high-vulnerability areas are mainly concentrated in residential areas in the central part of the city and main transportation channels. From 10:00 to 15:00, the high-vulnerability areas migrate to public service areas in the eastern part of Zhengzhou City. In the evening, the vulnerability degree of flood disasters is relatively low. The research results can provide a theoretical basis for urban flood managers to prevent and control flood disasters.

An Integrated Framework for Estimating Origins and Destinations of Multimodal Multi-Commodity Import and Export Flows Using Multisource Data

Estimating origin-destination (OD) demand is integral to urban, regional, and national freight transportation planning and modeling systems. However, in developing countries, existing studies reveal significant inconsistencies between OD estimates for domestic and import/export commodities derived from interregional input-output (IO) tables and those from regional IO tables. These discrepancies create a significant challenge for properly forecasting the freight demand of regional/interregional multimodal transportation networks. To this end, this study proposes a novel integrated framework for estimating regional and international (import/export) OD freight flows for a set of key commodities that dominate long-distance transportation. The framework leverages multisource data and follows a three-step process. First, a spatial economic model, PECAS activity allocation, is developed to estimate freight OD demand within a specific region. Second, the international (import and export) freight OD is estimated from different zones to foreign countries, including major import and export nodes such as international seaports, using a gravity model with the zone-pair friction obtained from a multimodal transportation model. Third, the OD matrices are converted from monetary value to tonnage and assigned to the multimodal transportation super network using the incremental freight assignment method. The model is calibrated using traffic counts of the highways, railways, and port throughput data. The proposed framework is tested through a case study of the Province of Jiangxi, which is crucial for forecasting freight demand before the planning, design, and operation of the Ganyue Canal. The predictive analytics of the proposed framework demonstrated high validity, where the goodness-of-fit (R2) between the observed and estimated freight flows on specific links for each of the three transport modes was higher than 0.9. This indirectly confirms the efficacy of the model in predicting freight OD demands. The proposed framework is adaptable to other regions and aids practitioners in providing a comprehensive tool for informed decision-making in freight demand modeling.

Assessing the impact of maker services in Barcelona and Milan towards the 15-minute city model through their accessibility

Re-organizing cities with proximity-based urban planning models such as the 15-Minute City model is an emerging and promising direction of policy, practice and research for sustainable cities. The planning of new urban spaces, infrastructures and mobilities requires planning and designing services that support citizens in their proximities. Along this direction, the emergence of the Maker Movement and its maker laboratories (Fab Labs, Makerspaces, Hackerspaces, DIYbio Labs, and so on) contributes to building the infrastructure for distributed design and manufacturing services in cities. How can we adopt the impact assessment of maker services in terms of potential accessibility for designing services towards the 15-Minute City model? We explore this issue within the context of the metropolitan areas of Barcelona and Milan by analysing 1) the 15-minute walking distance catchment areas of their maker service; 2) how to adopt this method for service design and impact assessment in the 15-Minute City model.

THE URBAN EVOLUTION OUAD EL HAD: FROM A MINOR URBAN EXTENSION TO AN INFAMOUS AND ILLICIT NEIGHBORHOOD

Informal housing represents a complex phenomenon with far-reaching implications for urban development and social equity, it is characterized by its spontaneous and unauthorized nature, it has emerged as a significant phenomenon in urban areas worldwide and usually arises a multitude of socio-economic challenges such as rapid urbanization, poverty, and as in our case, rural migration, Therefore, understanding the spatial evolution of informal settlements is crucial for designing more equitable and sustainable living environments. That was the case of “Ouad El Had”, a neighborhood that may be considered as one of the focal points in metropolis of Constantine, informal housing started as an extension, an illicit urbanization due to rural-to-urban migration led to the perpetuation of informal settlements on what was in that time the outskirts of city, Nowadays, housing shortages caused the proliferation of informal settlements, those settlements presented a chance to obtain a house in the social housing program given by the government leading it to get repopulated every time and after several attempts to evacuate the entire zone starting from 2012 to this actual day. Our paper offers an in-depth analysis of the spatial and temporal evolution to the informal housing situated in the neighborhood “Cité des Fréres Abbas” (Ouad El Had) and its evolution within urban and social contexts with the objective of understanding the complex case of this neighborhood that led to its repopulation after every evacuation or displacement and identifying the urban model generated of during this process.

Instant infrared: Estimating urban surface temperatures from street view imagery

As the impact of climate change on cities intensifies, the analysis and modeling of the urban microclimate are becoming increasingly important. A key parameter to this end is the estimation of urban surface temperatures. Traditional approaches for such estimates, that use urban micrometeorology models, are based on simulations that require heavy computations and complex inputs — including urban geometry, radiative parameters, and meteorological conditions. As a result, they cannot be applied extensively in all cities, where some of the input parameters might be missing and computational power might not be available. In this paper, we propose an alternative approach founded upon a deep learning framework, requiring markedly simplified inputs: street view imagery and meteorological conditions. We use our model to estimate building facade surface temperatures in the city of London (Ontario, Canada) and compare results both with simulated values obtained from an established simulation software TUF-3D and ground truth data collected through an onsite campaign with a FLIR thermal imager. Results substantiate the superiority of our proposed approach over TUF-3D, concurrently emphasizing its advantages in terms of input simplicity and computational resource efficiency. As street view imagery is becoming ubiquitous across the world – for instance, through platforms such as Google Street View – our approach lays the foundation for a new paradigm of fast, cost-effective, and highly scalable models, empowering urban designers and local authorities to better understand a changing urban climate.

Optimal representation of tree foliage for local urban climate modeling

Trees impact the local urban climate, notably at street level by intercepting solar radiation and providing shading. Evapotranspiration in foliage may reduce the air temperature although it may increase relative humidity and leaf drag may reduce wind speed, affecting thermal comfort. To document and quantify this impact, microclimate modeling with Computational Fluid Dynamics (CFD) simulations requires explicit information of the urban configuration, including trees. However, trees are complex individuals with a variety of shapes and a variety of foliage distribution. This study aims to investigate the sensibility to the tree modeling of the urban climate simulations. Starting with terrestrial LiDAR data from trees of different species, ages, and forms, we propose a systematic evaluation of the optimal representation of arboreal configurations in terms of local urban comfort. One way to represent the foliage of trees accurately is to apply Delaunay triangulation on the LiDAR data, which yields a convex envelope model. The resulting foliage shape is very close to the actual tree, but includes a high number of facets leading to complex objects to model numerically. Comparing four species and three maturity level of trees with this method, the paper shows that the size of the zone shadowed by a tree is the parameter with the largest impact on thermal comfort, as the ability of trees to absorb solar radiation is the main asset to improve thermal comfort. The UTCI could be up to 2.1°C lower for a mature ACPL than for a sapling, mainly because the zone covered by the tree is larger. In addition, polyhedron shape rhombicuboctahedron (RBC) produces accurate shadowed zones. Mostly, in literature, tree canopies are modeled with cubic representations while we see that they overestimate the size of the shadowed zone. To have reliable compromise between accuracy and time for conception and computational time, this paper shows that the RBC is the best alternative to common tree models. Despite requiring a good knowledge of the canopy geometry, RBC provides a strong capacity for accurately modelling complex canopy shapes of most tree species and offers large benefits in reduced complexity. We show that the RBC shape, thanks to its simple but flexible geometry, is an efficient and accurate methodological approach to model trees and allows savings in computational time (up to 15% faster than the convex envelope) and costs; and we expect that this method will improve the modeling of further parametric studies on vegetation impact on thermal urban comfort.

Empirical Analysis on the Mechanism of Industrial Park Driving Urban Expansion: A Case Study of Xining City

Taking Xining City as an example, this article analyzes the mechanism by which industrial park construction drives the expansion of urban population size and built-up area, based on a review of the process of industrial park development and urban population growth. It also discusses future urban governance models in light of urban development trends. The research finds: (1) In the process of urban development, industrial park construction is often the initial factor in the cumulative and cyclical development of a city; (2) As the level of development improves and the mode of economic growth changes, the government should timely adjust its strategies, shifting from the expansion of industrial park construction towards structural optimization and quality improvement. The most significant difference from previous research is that this paper emphasizes the importance of government planning. This study can not only demonstrate the general process of industrial parks promoting urban expansion, but more importantly, it explains the fundamental reasons for the transition of urban expansion to adjustment from a mechanism perspective, thereby eliminating the drawbacks of simply predicting urban scale evolution through data models.

Analysis of Low-Carbon, Energy-Saving, and Emission Reduction Models Based on Rail Transit

It is difficult to define scientific applicability conditions when dealing with different evaluation objects and scope. This article is based on multi-source big data such as the Automatic Fare Collection System (AFC) of urban rail transit, comprehensively considering the multidimensional impact of urban rail transit on the urban transportation system, and conducting a quantitative analysis of the energy-saving and emission reduction effects of urban rail transit. This study adopts a traffic emission model based on specific driving forces and a traffic demand prediction model, coupling the model and data to establish an urban rail transit energy conservation and emission reduction evaluation model suitable for different urban rail transit setting scenarios. Finally, this study selected six districts in Beijing as model application cases and used a combination of RP (display preference) survey and SP (state preference) survey to complete model parameter calibration for application cases.

Stakeholder-Based Optimal Indicators for Urban Sustainability Assessment in Sub-Saharan Africa: A Case Study from the City of Moundou in Chad

Over the last two decades, scientific studies have increasingly highlighted the vulnerability of cities to global changes, especially in sub-Saharan Africa, where climate phenomena and urbanization are intensifying. These realities necessitate a reassessment of current urban management models in order to reaffirm the central role of cities in promoting sustainability. In this context, establishing a robust scientific foundation for evaluating the transition processes of cities towards sustainability is essential. This article presents a methodology developed to select and validate indicators, taking into account local issues and the needs expressed by stakeholders. The research was conducted using a mixed-methods approach, which included a literature review, consultations with populations from five study districts, analysis of the indicator needs of development stakeholders, adoption of two methods, and validation of the indicators by a group of experts. The outcome of this research is a set of 20 indicators organized into five dimensions: environmental, social, economic, built environment, and cultural. The analysis of the proportional distribution of these indicators across dimensions reveals a notable predominance of the social dimension, which accounts for 35% of the indicators, including key indicators such as access to potable water, electricity, education, and healthcare services, inter alia. The environmental and built environment dimensions each comprise 20% of the indicators, encompassing indicators such as the preservation of natural resources, waste management, land use management, and flood management, among others. The economic and cultural dimensions represent 15% and 10% of the selected indicators, respectively. These data indicate that achieving sustainable urban development within the context of this study requires a focused effort on enhancing the performance of these indicators, with substantial efforts needed in the social domain. It is of paramount importance to incorporate these indicators into the decision-making processes related to urban development planning in Moundou and other cities in the region, as they provide valuable scientific insights crucial to the pursuit of sustainability.

An Urban Flood Model Development Coupling the 1D and 2D Model with Fixed-Time Synchronization

Due to climate change, the frequency and intensity of torrential rainfall in urban areas are increasing, leading to more frequent flood damage. Consequently, there is a need for a rapid and accurate analysis of urban flood response capabilities. The dual-drainage model has been widely used for accurate flood analysis, with minimum time step synchronization being commonly adopted. However, this method has limitations in terms of speed. This study applied the hyper-connected solution for an urban flood (HC-SURF) model with fixed-time step flow synchronization, validated its accuracy using laboratory observation data, and tested its effectiveness in real urban watersheds with various synchronization times. Excellent performance was achieved in simulating real phenomena. In actual urban watersheds, as the synchronization time increased, the errors in surcharge and discharge also increased due to the inability to accurately reflect water level changes within the synchronization time; however, overall, they remained minimal. Therefore, the HC-SURF model is demonstrated as a useful tool for urban flood management that can be used to advantage in real-time flood forecasting and decision-making.

Developing a Chained Simulation Method for Quantifying Cooling Energy in Buildings Affected by the Microclimate of Avenue Trees

This paper introduces a methodology aimed at bridging the gap between building energy simulation and urban climate modeling. A coupling method was developed through the Building Control Virtual Test Bed (BCVTB) and applied to a case study in Taipei City, Taiwan, to address the microclimate factors of street trees crucial to cooling energy consumption. The use of the Urban Weather Generator for weather file modification revealed a 0.63 °C average air temperature disparity. The coupling method emphasized the importance of accurate wind speed and convective heat transfer coefficients (CHTCs) on building surfaces in determining cooling energy. The results indicated that elevated CHTC values amplify heat exchange, with higher wind velocities playing a crucial role in heat dissipation. The presence of street trees was found to significantly reduce heat flux penetration, leading to a reduction in building surface temperatures by as much as 9.5% during hot months. The cooling energy was lowered by 16.7% in the BCVTB simulations that included trees compared to those without trees. The EnergyPlus-only simulations underestimated the cooling energy needs by approximately 9.3% during summer months. This research offers valuable insights into the complex interactions between buildings and their environments. The results highlight the importance of trees and shading in mitigating the heat island effect and improving energy-efficient urban planning.

Development of an Urban Growth Model Using Geographical Information System in Malaysia: A Review

Urbanization is one of the major problems faced by various countries over time. The process by which rural regions transform into cities and people move from rural to urban areas is known as urbanization. Urban land use development is influenced by a variety of factors, including physical, socioeconomic, and environmental issues. While urbanization benefits many stakeholders by enhancing social, economic, and infrastructure aspects, it also poses risks to people's safety and harms the physical, social, and cultural landscape as more buildings are constructed. Consequently, spatial models for urban growth are often used in planning to develop strategies for controlling land use actions, such as GIS, GIS-based remote sensing, CA-Markov, AHP, and MCE. GIS and CA-Markov are among the models widely employed by researchers to simulate land use change. Malaysia also tends to utilize urban growth models as part of its efforts to plan for sustainable cities in the future. Therefore, this study was conducted to assess and review the use of GIS in developing an urban growth model in the Malaysian context. The results indicate that GIS and other models or techniques can serve as a strategic framework for urban development policy.

Трехмерное моделирование городов: исторические реконструкции и альтернативная реальность

The paper considers the technology of creating 3D models of cities, photogrammetric and other ways of their construction. The author shows projects created on the basis of this technology - 3D models of Yaroslavl, Moscow and St. Petersburg. The paper also describes the essence and results of the research performed on the basis of the constructed three-dimensional urban planning models. The paper presents historical recreation projects of cities for different time periods: Yaroslavl at the beginning of the XX century and Moscow at the XIX-beginning of the XX century. The author presents a list of monuments lost in reality, but recreated in a virtual three-dimensional environment and inscribed in the 3D model of the city. The paper presents a project involving the modelling of unrealised projects of avant-garde architects, as well as projects of the 1930s-1970s on the basis of a Moscow 3D model. The author concludes about the growing popularity of such digital models and the penetration of augmented and virtual reality technologies into our daily life.

A Coupled River–Overland (1D-2D) Model for Fluvial Flooding Assessment with Cellular Automata

To provide accurate and efficient forecasting of fluvial flooding assessment in the river basin, the present study links the well-known CA-based urban inundation modeling (2D-OFM-CA) with a one-dimensional river flow model (1D-RFM) as a coupled 1D-2D river–overland modeling. Rules to delineate the geometric linking between the 1D-RFM and 2D-OFM-CA along embankments are developed. The corresponding exchanged water volume across an embankment is then computed by using the free and submerged weir flow formulas. The applicability of the proposed coupled model on fluvial flooding assessment is then assessed and compared with a well-recognized commercial software (HEC-RAS model) through an idealized fluvial case and an extensively studied real-scale fluvial case in the Severn River Basin. Based on the simulated results concerning the numerical accuracy, the coupled model is found to give similar results in the aspects of the river flow and overland flow modeling in both two study cases, which demonstrates the effectiveness of the linking methodology between the 1D-RFM and 2D-OFM-CA. From the viewpoint of numerical efficiency, the coupled model is 47% and 41% faster than the HEC-RAS model in the two cases, respectively. The above results indicate that the coupled model can reach almost the same accuracy as the HEC-RAS model with an obvious reduction in its computational time. Hence, it is concluded that the coupled model has considerable potential to be an effective alternative for fluvial flooding assessment in the river basin.

DEM-based pluvial flood inundation modeling at a metropolitan scale

The global increase in urban flooding presents a substantial challenge that affects communities across the globe. This study introduces a post-flood inundation modeling framework tailored to pluvial floods on a metropolitan scale. We employ a dual drainage modeling approach for enhanced accuracy. The framework comprises two primary components: a Storm Water Management Model (SWMM) for simulating water movement within the storm drain system, and an advanced DEM-based flood inundation module that leverages SWMM results to predict flood inundation areas. Compared to the conventional flood spreading models commonly used in dual drainage modeling, this module incorporates high-resolution DEM cells into the surface flow routing processes, allowing to capture intricate surface terrain complexities. Additionally, the proposed module considers direct rainfall impacts on pluvial flood inundation mapping, resulting in enhanced accuracy. To evaluate the proposed model's accuracy, a two-step validation approach has been implemented. This includes comparing the proposed model results with both the high water marks measured in the aftermath of Hurricane Harvey and the flood depth map generated by a hydrodynamic model. The findings affirm the effectiveness of our proposed framework for post-flood inundation mapping within metropolitan settings. This method provides a dependable approach to urban flood modeling and represents an advancement in addressing the challenges associated with urban flooding.

Urban community security system model from the perspective of resilience: a study on Chinese cities

To enhance urban governance and bolster community disaster resilience, it is urgent to innovate and develop an urban community security system to cope with the complex and volatile social security situation. From the perspective of resilience, the concept, layout, and structure of the security system are organized. Considering the current situation and development trend of the social security system, and based on the constructed cost-capability model, the cost and benefit of the two modes are analyzed and compared. Subsequently, from the perspective of multi-agent participation, a game model between governments and enterprises is constructed. The evolutionary stability strategies of enterprises are analyzed, and simulation analysis is conducted on the factors influencing enterprises. Finally, to propose targeted improvement measures based on the community security capabilities of different communities, a grey fuzzy comprehensive evaluation method is employed. The community security comprehensive capabilities of the top 10 cities in China are quantitatively analyzed and evaluated. The results indicate that the urban community security system from a resilience perspective is more comprehensive compared to the traditional security system. Adopting mode 2 is relatively effective to improving government emergency management capability. In a certain range, reducing C, increasing F, reducing R2, and increasing h can achieve the effect of promoting enterprise to participate in construction. The urban community security capability is within the upper-medium level in general, close to the level of good. The urban community security system constructed in this paper can provide a theoretical basis for the government to formulate policies of the urban community security system and serve as a reference for strengthening the comprehensive capability of the urban community security.