Chapitre 6 - Techniques géospatiales et de télédétection pour le suivi de l’état et des dynamiques des terres agricoles périurbaines

Ce chapitre est le résultat d’un travail d’équipe incluant tous les auteurs. Il est né des suites d’un atelier franco-australien qui s’est tenu à Sydney en octobre 2013. Introduction Depuis toujours, les sociétés humaines modifient l’environnement dans lequel elles évoluent. Des villes de plus en plus étendues, à l’échelle mondiale, accueillent actuellement plus de 50 % de la population mondiale, et ce pourcentage continue..

Identification of Embodied Environmental Attributes of Construction in Metropolitan and Growth Region of Melbourne, Australia to Support Urban Planning

As growth regions evolve to accommodate the increasing population, they need to develop a wider variety of residential properties to accommodate the varying needs of the residents. As a result, the new accommodation is denser which involves higher embodied water carbon and energy. This research compares the construction differences in metropolitan and growth regions of Melbourne to identify embodied carbon, water, and energy. Representative areas of 25 km2 are selected from both regions. The growth region has 80% of the built area comprised of 2nd generation low-rise residential buildings whereas the prolific construction type in the Metropolitan region is mixed purpose industrial with 30% of the built area comprising of this type. The methodology implies open-source satellite imagery to build a spatial dataset in QGIS. The visual identification of the constructions in the study areas enables to identity the materials used in their construction. The total embodied carbon, water, and energy for the Metropolitan region are 32,895 tonnes, 4192 mL, and 3,694,412 GJ, respectively, whereas in the growth region, the totals are 179,376 tonnes carbon, 2533 mL water, and 2,243,571 GJ. Whilst Metropolitan has a significantly higher overall footprint when this is compared to the population of each region, it is shown that the growth region with its current construction type has a higher embodied carbon, water, and energy per head. The total per head for Metropolitan is 226.7 GJ energy, 257 kL water, and 20 tonnes carbon, whereas in the growth region, the embodied energy, water, and carbon, respectively, per head is 287.4 GJ, 324.6 kL, and 22 tonnes. The current performance per head of the growth region is considerably lower than that of Metropolitan. Using diverse residential construction types and efficient materials can serve the demanding needs of denser populated areas

Les terres agricoles face à l’urbanisation

La perte de terres agricoles liées à l’urbanisation constitue l’une des facettes de la consommation des terres. Commencé dans les années 1970, ce phénomène — essentiellement dû à l’étalement urbain — prend des proportions jusque-là inégalées. Les conséquences de ces processus d’artificialisation sont multiples et portent à la fois sur la production et sur la sécurité alimentaire ainsi que sur la perte de biodiversité. Ces processus interrogent aussi les formes de solidarité territoriale entre les villes et les espaces péri-urbains et ruraux. Issu d’une collaboration scientifique lancée au début des années 2010 entre l’Université de technologie de Sydney (University of Technology Sydney, UTS) et l’Institut national de recherche en sciences et technologies pour l’environnement et l’agriculture (Irstea), cet ouvrage aborde des points clés de la problématique de la consommation des terres en se focalisant sur les terres agricoles en France et en Australie. Plutôt que d’offrir une analyse comparative approfondie de la planification des terres agricoles périurbaines entre les deux pays, il propose une exploration des « boîtes à outils » de l’ingénierie territoriale développées et mobilisées pour faire face à l’enjeu de la perte de terres agricoles liée à l’urbanisation. Il offre également un « arrêt sur image » dans un panorama de champs de recherche en pleine évolution, autant du point de vue théorique que méthodologique

Cities from space : influence of rural to urban gradients on remote sensing of urban heat island

University of Technology Sydney. Faculty of Science.The Urban Heat Island (UHI) effect occurs when urban areas have higher surface/ air temperature differences relative to surrounding rural reference areas. Most of the studies carried out in past are limited to a certain time in a year or a day, and lack a long term analysis. Moreover, the research potential of satellites and its modern tools remain largely untapped. The overall goal of this thesis is to investigate and characterise the UHI in selected Australian cities with satellite data sets, particularly the Moderate Resolution Imaging Spectro-radiometer (MODIS). To achieve these objectives, (1) I, firstly investigated the inter-annual and seasonal characteristics of diurnal land surface temperature (LST) and UHI across urban and rural areas from 2003- to 2017; (2) then I assessed the long-term trends (significant/non-significant) in UHI and LST and their interactions/dependencies with its drivers/indicators (greenness, albedo); (3) furthermore I examined the phenology patterns for greenness and urban greenness deficit in relationship with the diurnal, seasonal, inter-annual characteristics in UHI; (4) lastly, I examined an extreme heat wave event in Sydney and its influence on UHI utilising the geostationary Himawari-8 satellite. The temporal analysis on seasonal and inter-annual variations of UHI revealed maximum intensities in the daytime period for both the cities of Melbourne and Sydney. Melbourne and Sydney experienced the highest daytime UHI in the austral ‘spring’ and austral ‘summer’ season respectively. A nighttime UHI was present in both cities in the ‘summer’ season. Inter-annual trends in UHI revealed a significant increasing trend in daytime UHI (p-value < 0.01) for both selected cities despite no significant trends in daytime urban LST in both cities. The increasing UHI trends were primarily attributed to increasing greenness and declining temperatures in the rural zones surrounding both cities. We found the choice of a rural reference class, whether forest, pasture, or mixed, significantly altered computed UHI values. Greenness and urban green deficit (UGD) showed an inverse relationship with daytime UHI, whereas albedo and delta albedo (urban minus rural albedo) did not show any correlation with UHI. During the extreme heatwave event, the UHI was seen to be more widespread and dominant in the city for a longer time than for an average day, while the intensity remained more or less similar. This thesis highlights the value of remote sensing techniques (e.g. MODIS and Himawari-08 satellites) as essential tools for improved assessments and management of urban landscapes in selected Australian cities

Modelling Coastal Development and Environmental Impacts: A Case Study Across Two Regional Towns in Australia

Globally there has been an increasing trend in urban growth with cities expanding rapidly, indicating a requirement for more sustainable development of cities to minimize human impacts on the environment. In Australia, urban development continues to target areas adjacent to the coastal capital and regional cities such as the Greater Geelong region in Victoria, experiencing the fastest rates of growth in the country in the last decade. This project demonstrates the ability of modelling techniques to model current and future directions in urban development across two adjacent coastal towns, Anglesea and Torquay, in Victoria. The analysis utilized Geographic Information Systems (GIS) and the CommunityViz decision support tool using a variety of assets, environmental and climatic data. The models indicated an increase in greenhouse gas emissions, energy usage and population growth, and the area was found to be highly vulnerable to the impacts of environmental changes including the potential loss of biodiversity, soil erosion, and sea level rise. The modelling approach described here can aid planners and decision makers in the future coastal urban development as well as to mitigate climate change impacts

Article An Estimation of the Anthropogenic Heat Emissions in Darwin City Using Urban Microclimate Simulations

The energy consumption due to urbanization and man-made activities has resulted in production of waste, heat, and pollution in the urban environment. These have further resulted in undesirable environmental issues such as the production of excessive Anthropogenic Heat Emissions (AHE), thus leading to an increased Urban Heat Island (UHI) effect. The aim of this study was to estimate the total AHE based on the contribution of three major sources of waste heat generation in urban environment, i.e., buildings, vehicular traffic, and human metabolism. Furthermore, a comparison of dominating anthropogenic heat factor of Darwin with that of other major international cities was carried out. Field measurements of microclimate (temperatures, humidity, solar radiation, and other factors of climate measures) were conducted along Smith Street, Darwin City. Then, surveys were conducted to collect information regarding the buildings, vehicle traffic and Human population (metabolism) in the study area. Each individual component of AHE was calculated based on conceptual framework of anthropogenic heat model developed within this study. The results showed that AHE from buildings is the dominant factor influencing the total AHE Darwin, contributing about to 87% to 95% of total AHE. This is followed by vehicular traffic (4–13%) and lastly, human metabolism (0.1–0.8%). The study also shows that Darwin gained an average of 990 Wm−2 solar power in a peak day. This study proves that building anthropogenic heat is the major dominating factor influencing the UHI in tropical urban climate

Identification of Embodied Environmental Attributes of Construction in Metropolitan and Growth Region of Melbourne, Australia to Support Urban Planning

As growth regions evolve to accommodate the increasing population, they need to develop a wider variety of residential properties to accommodate the varying needs of the residents. As a result, the new accommodation is denser which involves higher embodied water carbon and energy. This research compares the construction differences in metropolitan and growth regions of Melbourne to identify embodied carbon, water, and energy. Representative areas of 25 km2 are selected from both regions. The growth region has 80% of the built area comprised of 2nd generation low-rise residential buildings whereas the prolific construction type in the Metropolitan region is mixed purpose industrial with 30% of the built area comprising of this type. The methodology implies open-source satellite imagery to build a spatial dataset in QGIS. The visual identification of the constructions in the study areas enables to identity the materials used in their construction. The total embodied carbon, water, and energy for the Metropolitan region are 32,895 tonnes, 4192 mL, and 3,694,412 GJ, respectively, whereas in the growth region, the totals are 179,376 tonnes carbon, 2533 mL water, and 2,243,571 GJ. Whilst Metropolitan has a significantly higher overall footprint when this is compared to the population of each region, it is shown that the growth region with its current construction type has a higher embodied carbon, water, and energy per head. The total per head for Metropolitan is 226.7 GJ energy, 257 kL water, and 20 tonnes carbon, whereas in the growth region, the embodied energy, water, and carbon, respectively, per head is 287.4 GJ, 324.6 kL, and 22 tonnes. The current performance per head of the growth region is considerably lower than that of Metropolitan. Using diverse residential construction types and efficient materials can serve the demanding needs of denser populated areas

Urban Heat Island vulnerability mapping using advanced GIS data and tools

Urban Heat Island (UHI) is a phenomenon that can cause hotspots in city areas due to dense, impervious infrastructure and minimal vegetation cover. UHI hotspots may become worse in extreme heat events that are already affecting many regions across the globe due to increased frequent hot extremes, human-induced warming in cities, and rapidly growing urbanization, as documented by the latest IPCC report 2021. In seeking to support designers, planners, and decision-makers in developing and implementing adaptation strategies and measures to make our cities sustainable and resilient, reliable projections and modelling are required. In this study, we modelled UHI vulnerability using high-resolution spatial data, advanced geospatial tools, and socio-demographic data. This modified vulnerability approach drew upon UHI index maps and 20 select customized indicators of heat exposure, population sensitivity, and mobility/adaptive capacity. The indicators were Delphi evaluated and weighted, and the methodology was applied against the City of Greater Geelong municipality in Australia. The resulting UHI index maps indicated significant hotspots in areas of high building density, commercial/industrial zones, newly constructed sites, and zones with low urban green infrastructure. These UHI maps, in combination with selected indicators, highlighted the areal concentration of heat risk areas and vulnerable locations for the sensitive human population. The highlighted areas were primarily concentrated in high building density and high population density areas, which was seen through correlation curves. However, the building density showed a weak correlation, and population per meshblock indicated a strong correlation with UHI measurements. This study provides a comprehensive analysis of risk mapping and vulnerability assessment using GIS geospatial data for the advancement of a major local government area and concludes that this methodology has replicability incomparable geographical regions