Climate Stress, Infrastructure Limits, and Urban Landslide Risk

The 3D-Navier-Stokes Equations (3D-NSE) describe the flow of fluids. Due to advanced numerical techniques and increased computer capacities, numerical solutions are available for many applications, but require expensive computations. In river hydraulics the Shallow Water Equations (SWE) are applied successfully to model the flow of water. They are derived from 3D-NSE via depth integration under the assumption that the vertical velocity components are negligible.Calculations for the flow of water in urban areas show differences between 3D-NSE and SWE. In particular when water is pressing out of a manhole or is flowing against or over a curb, vertical velocity components are not negligible.To give reliable forecasts for flood risks in urban areas with reduced computational efforts, SWE need to be modified appropriately.

With the intensification of climate change and increasingly frequent rainstorms, rainfall-induced shallow landslides have become a widespread geohazard. However, the influence of rainfall patterns on rainfall-induced landslides is often overlooked compared to other factors like rainfall intensity and accumulative rainfall. This study addresses this gap by using rainfall-induced landslides occurred in Futian Town, Chongqing City in 2014 as a case study to examine how different rainfall patterns (uniform, advanced, delayed, intermediate) affect the occurrence of shallow landslides. The TRIGRS model was applied to calculate the hourly factor of safety (FS) for each pattern, with adjacent FS ≤ 1 indicating potential landslides. Their volumes and occurrence times were estimated based on the failure areas, thickness, and specific hours when FS ≤ 1, and probability density curves were used to quantify differences with rainfall patterns. The results show that advanced rainfall induces the greatest number of shallow landslides but with the smallest volumes, whereas intermediate rainfall induces the largest volumes. Temporally, advanced rainfall leads to the shortest occurrence times, indicating the fastest response to rainfall, whereas delayed rainfall corresponds to the slowest response. These insights are valuable for developing early warning models for rainfall-induced landslides.

Addressing land use planning: A methodology for assessing pre- and post-landslide event urban configurations

Flood risk management, since long based on the hazard control, is increasingly orientated towards an attempt to reduce the vulnerability of territories. In fact, the dangers of flood risk on the territory of Casablanca have been the subject of numerous analyzes, whereas studies on the vulnerability of Morocco’s first economic city are very rare. This work aims to contribute to the development of methods for assessing the vulnerability of the urbanized watershed area of Oued Bouskoura facing the overflow of the latter in case of storm floods. The methodology of this study is the use of a geographic information system coupled with the hierarchical multi-criteria analysis developed by T. Saaty (Saaty 1980) for the identification and quantification of urban elements lying in the natural course of Oued Bouskoura and are at risk of flooding.

The extent to which the high suicide rate in urban areas is influenced by exposures to risk factors for suicide other than urbanicity remains unknown. This population-based study aims to investigate suicide risk in relation to the level of urbanicity in the context of other factors, and to study the risk variation in a sex, age, and calendar year perspective. The study is a nested case-control study comprising 21 169 suicides and 423 128 population controls matched for age and sex. Personal data on place of residence, socioeconomic status and psychiatric history were retrieved from various Danish longitudinal registers. Data were analysed with conditional logistic regression. This study confirms that people living in more urbanized areas are at a higher risk of suicide than their counterparts in less urbanized areas. However, this excess risk is largely eliminated when adjusted for personal marital, income, and ethnic differences; it is even reversed when further adjusted for psychiatric status. Moreover, the impact of urbanicity on suicide risk differs significantly by sex and across age. Urban living reduces suicide risk significantly among men, especially young men, but increases the risk among women, especially women aged 24-35 or >65 years. In addition, during 1981-1997, the suicide risk associated with urbanicity remained rather constant among women, whereas it dropped significantly among men, a trend that seemingly gained strength during the last part of this period. Suicide risk associated with urbanicity varies significantly by sex and age groups and recent years have seen a decline in the urban-rural disparities among men. The increased risk in urban areas can largely be explained by the effects of marital status, ethnics, income, and psychiatric status.

Urbanization and climate change have negative effects on the changes of natural precipitation and runoff regime, which results with more frequent floods and landslides. Besides of the increased quantity of the stormwater that drainage channels have to collect, neg- ative consequences of urbanization are also evident through increased pollution of runoff stormwater. Stormwater has immense impacts on urban flooding and water quality, leaving the marginalized and the impoverished disproportionately impacted by and vulnerable to stormwater hazards. However, the environmental health concerns of socially and econom- ically marginalized individuals are largely underestimated. Therefore stormwater manage- ment should be adapted to these changes so that the negative effects of new hydrological conditions of precipitation and runoff and stormwater pollution in the urban areas are mitigated. By 2050 the world population will grow to about 9 billion contributing to deep changes in urban areas structure. This would increase the effect of water deficiency and along with projected climate changes the impact of urban flooding, urban heat islands or drought. Stormwater threats can be mitigated with the application of stormwater management meth- ods named differently such as ‘Sustainable (Urban) Drainage Systems’ (SUDS), ‘Low Impact Development’ (LID) or ‘Best Management Practices’ (BMPs). This method includes differ- ent techniques such as Green roof, Rain barrels and cisterns, Infiltration basin, Detention Ponds, Retention Ponds, Green walls, Porous pavements, Bioretention basins, Bioswales. The aim of the research includes a study of the effectiveness of urban stormwater manage- ment techniques for the case study area. The concept of urban stormwater management techniques refers to the ability to provide and manage this primary resource in quantitative and qualitative terms in order to satisfy the future needs of population. The storm wa- ter management techniques provides several benefits: mitigation of the urban heat island effects, reduction of air pollution, additionally, It induces important hydraulic advantages acting as an effective tool for reducing flood risk in urban area with runoff reduction, attenuation and delay of the peak flow. The results confirm that bioretention basin, Permeable pavement, Grassed swale, Infiltration basin are effective techniques for the reduction of total runoff volume of rainwater falling on their area.

A time-based model and GIS framework for assessing hazardous materials transportation risk in urban areas

The life space of populations is materialized by the habitat. This habitat spreads with the population increase. In the urban area, the transformation of the habitat is sometimes accompanied by problems like, segregation, risks.., rais- ing the problem of the zone planning. The case of fire risk in the city of Yaounde is mentioned here and calls for an analy- sis, in a context that clarifies on decision making for problems of zone planning. The strategy of approach here is to determine steps of phenomenon analysis, to describe the fire risk in its evolution while unveiling the derived information, which can characterize the urban area; an application is made to the city of Yaounde. At the end of this survey, the elements of definition and characterisation of the fire risk in urban area follow by character- istics of the city zones of Yaounde, taking account fire risk and measures to remedy them have been done. The urban area ensures to populations several functions including sanitary, social, administrative, etc.. Difficulties of management increase with the expansion of the city. Those of developing countries are the main concerned. These man- agement difficulties become more pronounced with the ap- pearance of several problems (poverty, segregation, risk, etc.). Thinking about solutions, it would firstly be necessary, to provide knowledge concerning them. It is the case of fire risks in the city of Yaounde of which we propose to study the complexity of existence in order to provide information of decision-making for problems of urban planning. There is a relationship between fire risk and the elements of habitat; what strategy of risk analysis is necessary so as, to provide information of solution to the problem of zone plan- ning? For that, we have counted all elements of existence of fire risk in their space while following its setting up since the appearance until the occurrence of the fire catastrophe (1). We also propose to the relations and properties between these elements. This numbering leads to the determination of natures, and possible types of entities. This description of existence of fire risk in its environment permits to discover factors of risk (2), including mainly elements of habitat, and to characterize zones and constructions concerned. Looking forward to eliminate these factors, we have proposed solu- tions to the planning of zones.

<p>This research attempts to monetize drought risk in 97 cities around the globe, using multiple climate and socioeconomic scenarios. Subsequently, it identifies possible adaptation actions to mitigate drought risk in these cities. This study is essential because whilst much effort has been put into modelling drought on all spatial scales in recent decades, urban areas are often not explicitly included in these analyses, even though we live in a rapidly urbanizing world. Two types of drought risks for cities are identified and investigated: (1) drought induced food shortages and increased food prices (agricultural drought), and (2) municipal surface water supply shortages (hydrological drought). To assess agricultural drought risk, we represent the hazard using the Standardized Soil Moisture Index, and exposure using physical agricultural areas. For hydrological drought risk, we represent the hazard by linking discharge data from climate models to water withdrawals per city, with exposure data on the total population of a city. The risks are monetized by estimating the replacement costs of freshwater by means of alternative water sources like desalination. Vulnerability is qualitatively included by spatially overlapping the monetized values with vulnerability indicators and primarily gives context to the risk estimates. Finally, an inventory of reactive, preventive and transformative adaptation actions is developed to provide cities with a perspective for action. Cities may use this inventory to identify a mix of adaptation measures, where a combination of the three approaches would be an adequate way to address both short- and long-term risks and opportunities. The overall goal of this research is to provide an order of magnitude of potential drought risk, as well as to identify possible next steps in drought risk research in urban areas.</p>

Global warming and anthropogenic activities have imposed noticeable impacts on rainfall pattern changes at both spatial and temporal scales in recent decades. Systematic diagnosis of rainfall pattern changes is urgently needed at spatiotemporal scales for a deeper understanding of how climate change produces variations in rainfall patterns. The objective of this study was to identify rainfall pattern changes systematically under climate change at a subcontinental scale along a rainfall gradient ranging from 1800 to 200 mm yr−1 by analyzing centennial rainfall data covering 230 sites from 1910 to 2017 in the Northern Territory of Australia. Rainfall pattern changes were characterized by considering aspects of trends and periodicity of annual rainfall, abrupt changes, rainfall distribution, and extreme rainfall events. Our results illustrated that rainfall patterns in northern Australia have changed significantly compared with the early period of the twentieth century. Specifically, 1) a significant increasing trend in annual precipitation associated with greater variation in recent decades was observed over the entire study area, 2) temporal variations represented a mean rainfall periodicity of 27 years over wet to dry regions, 3) an abrupt change of annual rainfall amount occurred consistently in both humid and arid regions during the 1966–75 period, and 4) partitioned long-term time series of rainfall demonstrated a wetter rainfall distribution trend across coastal to inland areas that was associated with more frequent extreme rainfall events in recent decades. The findings of this study could facilitate further studies on the mechanisms of climate change that influence rainfall pattern changes. Significance Statement Characterizing long-term rainfall pattern changes under different rainfall conditions is important to understand the impacts of climate change. We conducted diagnosis of centennial rainfall pattern changes across wet to dry regions in northern Australia and found that rainfall patterns have noticeably changed in recent decades. The entire region has a consistent increasing trend of annual rainfall with higher variation. Meanwhile, the main shifting period of rainfall pattern was during 1966–75. Although annual rainfall seems to become wetter with an increasing trend, more frequent extreme rainfall events should also be noticed for assessing the impacts of climate changes. The findings support further study to understand long-term rainfall pattern changes under climate change.

Mapping commuter cycling risk in urban areas

The Urban Heat Island (UHI) effect, driven by anthropogenic environmental modifications, heightens heat risks in urban areas. Climate change is already accelerating global temperatures. This effect is being further exacerbated with rapid urbanization with the effects of UHI posing critical challenges to human health and urban infrastructure. Urban planners and decision-makers require robust tools to quantify UHI effects under diverse climate and socioeconomic scenarios to address this. Currently, urban canopy models (UCMs) are implemented in numerical weather prediction models. They generate temperatures in urban areas at comparatively high resolutions that cannot be achieved with Regional Climate Models (RCMs). However, using UCMs coupled to atmospheric models is computationally expensive and requires users to acquire detailed urban canopy parameters (UCPs), which is arduous, especially for rapid future urban planning focussed scenario modelling.This study introduces an innovative geospatial framework consisting of a GPU-based UCM implementation coupled with an in-canyon vegetation model. This framework streamlines the modelling process through a built-in geospatial toolkit capable of pre-processing UCPs from either openly available urban datasets or user-supplied high-quality data. The GPU-based implementation significantly enhances computational efficiency, enabling UHI simulations with a standalone UCM at high spatial resolutions. This framework empowers planners to simulate UHI under various future climate and urban development scenarios by integrating climate projections and socioeconomic data. The resulting UHI predictions can identify high-risk areas, prioritize adaptation strategies, and inform climate adaptation planning for rapidly expanding cities. This research provides a transformative yet practical approach to UHI modelling, equipping urban decision-makers with an accessible, high-performance tool to confront the challenges of climate-driven urban heat risks.

Driven by urban growth in hazard prone areas such as along coasts or rivers as well as by climate change induced sea-level rise and increase in extreme rainfall, flood risk in urban areas is increasing. Better understanding of risks, risk drivers and its consequences in urban areas have revealed shortcomings in the existing flood risk management approaches. This has led to a paradigm shift in dealing with floods from managing the risk to reduce damages, to making urban communities resilient to flooding. Often described as a complex and at times confusing concept, this systematic review identifies and summarises the different dimensions and approaches of urban flood resilience and how they are applied in practice. Our analysis shows that urban flood resilience as a concept has evolved over the last two decades. From an engineering concept with a strong focus on ensuring that the built environment can withstand a flood to a more recent definition as a transformative process with the aim to enable all parts of the urban system to live with floods and learn from previous shocks. This evolved understanding is also reflected in the increasing number of dimensions considered in urban flood resilience assessments and decision support tools. A thematic analysis of the challenges in conceptualising and applying urban flood resilience reported in the literature has revealed a number of issues including around fairness and equity of the applied approaches, a lack of data and widely accepted methods as well as uncertainty around changing risks as a result of climate change. Based on these findings we propose a new research agenda, focusing on meta studies to identify the key dimensions and criteria for urban flood resilience, supporting a transparent and evidence-led operationalization.

In this study, we evaluated the risk to urban areas due to the hydraulic and water quality availability of water supply facilities caused by medium- and large-scale earthquakes, applied the results to City A in Korea, and compared and analyzed them. The analysis confirmed that the damage to hydraulic availability increased rapidly as the earthquake magnitude increased, but the water quality did not deteriorate compared to hydraulic availability. This suggests that the water quality supply risk is low except for extreme interruption in the water supply route. However, if an earthquake of a certain magnitude or greater occurs, the building risk, evacuation risk, fire risk, and water outage risk are at a certain level or higher. When considering the water quality supply risk, the overall comprehensive earthquake risk in urban areas increased. Thus, uniformly applying the weights of all factors in the earthquake risk assessment does not correctly reflect the characteristics and environment of the region, and a process of realistically calculating the weights of each factor through various methods is necessary.

Hydro-meteorological or climate-related hazards, such as storms, droughts, floods and landslides, transform into natural disasters when they hit vulnerable areas. In the last decades, climate-related disasters alone accounted for between 70-90 percent of the natural disasters around the globe (Hoyois and Guha-Sapir, 2012). On the other hand, the rapid rate of urbanization leads to an increase the exposure to risk in urban areas. It is sufficient to highlight that around half of the world’s population lives in urban areas at present; by 2050, this ratio is estimated to rise up to around 70% (UN-HABITAT, 2010). There is increasing evidence in the favor of a correlation between the climate change and extreme weatherrelated phenomena (Khan and Kelman, 2011). In this regard, assessment and prediction of the adverse effects of climate change scenarios on the frequency and/or intensity of extreme weather-related events and delineation of the potentially vulnerable areas are important steps in an integrated climate change adaptation strategy.