The global issue 'mega-urbanization': An unsolvable challenge for stakeholders, researchers and residents?

This study aims at discussing the complex, multi-dimensional issue of the global phenomenon of urbanization. Based on a theoretical review and discussion on the situation of cities, the causes, dimensions and consequences of urban growth the idea is to raise the main questions for future activities to meet this challenge. For it a pragmatic and holistic framework is proposed to systematize the manifold approaches and to stimulate discussions on this issue addressing inter- and transdisciplinary thinking

Vulnerability assessment using remote sensing: The earthquake prone megacity Istanbul, Turkey

Hazards like earthquakes are natural, disasters are not. Disasters result from the impact of a hazard on a vulnerable system or society at a specific location. The framework of vulnerability aims at a holistic concept taking physical, environmental, socio-economic and political components into account. This paper focuses on the capabilities of remote sensing to contribute up-to-date spatial information to the physical dimension of vulnerability for the complex urban system of the megacity Istanbul, Turkey. An urban land cover classification based on high resolution satellite data establishes the basis to analyse the spatial distribution of different types of buildings, the carrying capacity of the street network or the identification of open spaces. In addition, a DEM (Digital Elevation Model) enables a localization of potential landslide areas. A methodology to combine these attributes related to the physical dimension of vulnerability is presented. In this process an n-dimensional coordinate system plots the variables describing vulnerability against each other. This enables identification of the degree of vulnerability and the vulnerability-determining factors for a specific location. This assessment of vulnerability provides a broad spatial information basis for decision-makers to develop mitigation strategies

The Vulnerability of a City - Diagnosis from a Bird’s Eye View

When the tsunami in the Indian Ocean on 26 December 2004 hit the city of Banda Aceh on the island of Sumatra, Indonesia, neither the city administration nor its inhabitants, nor national or international organisations were prepared. Approximately 60.000 of the 260.000 inhabitants died, leaving other 30.000 homeless and causing an enormous impact on the local economy. In the aftermath of this event tsunami early warning system were developed and are operated today (e. g. the German Indonesian Tsunami Early Warning System – GITEWS (Lauterjung, 2005)). However, the problem of earthquake or tsunami prediction in a deterministic sense has not been solved yet (Zschau et al, 2002). Thus, an end-to-end tsunami early warning system includes not only the tsunami warning, but also the assessment of vulnerability, perception studies, evacuation modeling, eventually leading to technical requirements for monitoring stations and recommendations for adaptation and mitigation strategies (Taubenböck et al., 2009a). In this study we address several specific questions on the capabilities of one discipline – remote sensing – for diagnosing the multi-faceted and complex vulnerability of a city: • Which remotely sensed data sets are appropriate analyzing vulnerability in highly complex urban landscapes? • What capabilities and limitations does urban remote sensing have regarding mapping, analysis and assessment of risks and vulnerability? • How can interdisciplinary approaches extend the applicability of earth observation

Analysis of urban sprawl at mega city Cairo, Egypt using multisensoral remote sensing data, landscape metrics and gradient analysis

This paper is intended to highlight the capabilities of synergistic usage of remote sensing, landscape metrics and gradient analysis. We aim to improve the understanding of spatial characteristics and effects of urbanization on city level. Multisensoral and multitemporal remotely sensed data sets from the Landsat and TerraSAR-X sensor enable monitoring a long time period with area-wide information on the spatial urban expansion over time. Landscape metrics aim to quantify patterns on urban footprint level complemented by gradient analysis giving insight into the spatial developing of spatial parameters from the urban center to the periphery. The results paint a characteristic picture of the emerging spatial urban patterns at mega city Cairo, Egypt since the 1970s

It’s not big, it’s large: Mapping and characterizing urban landscapes of a different magnitude based on EO-data

The United Nation’s “World Urbanization Prospects” numeralise a migration process of a huge dimension – from rural to urban areas. While in 1975 only 37.7% of the world’s global population were urban dwellers, in 1990 already 43.0% and today little over 50% of all earth-dwellers are living in urban areas. For the year 2050 the expected number is even 67.2% (UN, 2011). This recent and prospective urbanization trend leads to new spatial dimensions of urban landscapes. One new trend is the spatial evolution of once polynuclei urban areas to so-called ‘mega-regions’. Because in literature clear definitions for the term ‘mega-region’ are missing or at least fuzzy and only qualitative we aim to derive quantitative physical spatial characteristics possibly defining mega-regions. For this purpose we use multi-temporal and multi-source satellite data to classify urbanized areas for an exemplary mega-region – the Hong Kong-Shenzhen-Guangzhou mega-region in Southern China – for the years 1975, 1990, 2000 and 2011. Furthermore, we suggest a set of spatial features potentially characteristic for the evolution of mega-regions. In particular we apply a multitude of spatial metrics at a defined spatial unit for the entire mega-region. The result is a novel spatial approach to capture, measure and analyze new dimensions and shapes of urban landscapes

The Analysis of Tsunami Vertical Shelter in Padang City

Padang is a coastal city, which is located opposite to the Indian Ocean. Just across Padang city there are areas of subduction, which can trigger a powerful earthquake and generate tsunami. Geologists have to say that the city of Padang is the area that is highly vulnerable to tsunamis in the near future. Several studies have been conducted to prepare Padang city for tsunamis. Through the research, maps of tsunami inundation area has been successfully designed. So that the tsunami-prone areas, and tsunami safe area can be clearly identified. According to Singh (2008), the time interval between the first powerful earthquake and tsunami to hit the coast of Padang is about 20-30 minutes. While residents have to walk 3-5 km to the safe area. It can be said that the time for tsunami evacuation in Padang city is very short. Therefore the choice of conducting vertical evacuation is urgent for the majority of the population rather than walking along the horizontal evacuation. Padang city government with the aid of the international donors has built buildings for the shelter. Some of them are schools that have a strong structure, three storeys in which the roof are served as a tsunami evacuation. Data from the BPBDs office (Disaster Management Agency), stated that there are 13 tsunami evacuation buildings at this time with a total capacity of 30.550 people and the capacity for each building is varied between 1,000 - 3,000 people (BPBDs, 2013). This amount is very far from enough when compared to the potential loss of life as many as 400,000 people or more, or as only 7.64% of the total amount. And the location of the shelter buildings are not evenly distributed in tsunamis prone areas Places for vertical tsunami evacuation in Padang are called TES (Temporary Evacuation Shelter). There have been 13 shelters established by the Government of Padang and BPBDs, and there is only one TES found in the study area. It really is not enough as it is seen in the range of services. Therefore the existing buildings and multi-storey structure is another alternate places to rescue in which they are expected to withstand earthquakes and tsunamis. This alternative building called Potential TES (PTES)and there are 14 shelters for the study area

Remote sensing contributing to assess earthquake risk: from a literature review towards a roadmap

Remote sensing data and methods are widely deployed in order to contribute to the assessment of numerous components of earthquake risk. While for earthquake hazardrelated investigations, the use of remotely sensed data is an established methodological element with a long research tradition, earthquake vulnerability–centred assessments incorporating remote sensing data are increasing primarily in recent years. This goes along with a changing perspective of the scientific community which considers the assessment of vulnerability and its constituent elements as a pivotal part of a comprehensive risk analysis. Thereby, the availability of new sensors systems enables an appreciable share of remote sensing first. In this manner, a survey of the interdisciplinary conceptual literature dealing with the scientific perception of risk, hazard and vulnerability reveals the demand for a comprehensive description of earthquake hazards as well as an assessment of the present and future conditions of the elements exposed. A review of earthquake-related remote sensing literature, realized both in a qualitative and quantitative manner, shows the already existing and published manifold capabilities of remote sensing contributing to assess earthquake risk. These include earthquake hazard-related analysis such as detection and measurement of lineaments and surface deformations in pre- and post-event applications. Furthermore, pre-event seismic vulnerability–centred assessment of the built and natural environment and damage assessments for post-event applications are presented. Based on the review and the discussion of scientific trends and current research projects, first steps towards a roadmap for remote sensing are drawn, explicitly taking scientific, technical, multi- and transdisciplinary as well as political perspectives into account, which is intended to open possible future research activities

Large Housing Estates – Analysing the Morphologic Similarities and Differences of a Specific Town Planning Concept

Urban Landscapes show different urban structures. The physical face of cities is the result of complex city planning and general principles of spatial planning. And this physical face can be seen as the theater of life influencing life quality, social justice, mobility patterns, etc. In this work we focus on a specific phenomenon in post-war Germany: the town planning concept of large housing estates and their physical realizations. Same principles seem to lead to very similar urban structures and morphologies. However, over time different principles of spatial planning directions were applied for large housing states in the 1950/60s (the principle of the ‘structured and low dense city’) and the 1970/80s (the principle of ‘urbanity by density’) in Western Germany and for the entire time period until 1990 in the German Democratic Republic (the principle of the ‘socialistic city’). In this stuy we analyze whether large housing estates resulted in similar or different urban morphologies. And, whether different urban morphologies developed across variations of the specific town planning concept applied. To do so, we base our work on spatial data capturing the large housing estates in Level of Detail-1 (LoD-1) 3D building models and the street network. These geoinformation are derived from multi-sensoral Earth observation data as well as from Volunteered Geographic Information (VGI) (in our case from OpenStreetMap). For the measurements and analyses of the morphologies of large housing estates we develop and apply spatial features such as building density, floor space index, orientation of buildings, orientations of streets, among others. We reveal that different directions of the same town planning concepts for large housing estates generally create physical variabilities of the urban morphologies within a relatively small range. A closer look, however, reveals that variations do exist and that specific town planning principles had de facto influence on the resulting morphologies

The dynamics of poor urban areas - analyzing morphologic transformations across the globe using Earth observation data

The urban environment is in constant motion, mostly through construction but also through destruction of urban elements. While formal development is a process with long planning periods and thus the built landscape appears static, informal or spontaneous settlements seem to be subject to high dynamics in their ever unfinished urban form. However, the dynamics and morphological characteristics of physical transformation in such settlements of urban poverty have been hardly empirically studied on a global scale or temporal consistent foundation. This paper aims at filling this gap by using Earth observation data to provide a temporal analysis of builtup transformation over a period of ~7 years in 16 documented manifestations of urban poverty. This work applies visual image interpretation using very high resolution optical satellite data in combination with in-situ and Google Street View images to derive 3D city models. We measure physical spatial structures through six spatial morphologic variables - number of buildings, size, height, orientation, heterogeneity and density. Our temporal assessment reveals inter- as well intra-urban differences and we find different, yet generally high morphologic dynamic across study sites. This is expressed in manifold ways: from demolished and reconstructed areas to such where changes appeared within the given structures. Geographically, we find advanced dynamics among our sample specifically in areas of the global south. At the same time, we observe a high spatial variability of morphological transformations within the studied areas. Despite partly high morphologic dynamics, spatial patterns of building alignments, streets and open spaces remain predominantly constant