Understanding Open Spaces in an Arid City

abstract: This doctoral dissertation research aims to develop a comprehensive definition of urban open spaces and to determine the extent of environmental, social and economic impacts of open spaces on cities and the people living there. The approach I take to define urban open space is to apply fuzzy set theory to conceptualize the physical characteristics of open spaces. In addition, a 'W-green index' is developed to quantify the scope of greenness in urban open spaces. Finally, I characterize the environmental impact of open spaces' greenness on the surface temperature, explore the social benefits through observing recreation and relaxation, and identify the relationship between housing price and open space be creating a hedonic model on nearby housing to quantify the economic impact. Fuzzy open space mapping helps to investigate the landscape characteristics of existing-recognized open spaces as well as other areas that can serve as open spaces. Research findings indicated that two fuzzy open space values are effective to the variability in different land-use types and between arid and humid cities. W-Green index quantifies the greenness for various types of open spaces. Most parks in Tempe, Arizona are grass-dominant with higher W-Green index, while natural landscapes are shrub-dominant with lower index. W-Green index has the advantage to explain vegetation composition and structural characteristics in open spaces. The outputs of comprehensive analyses show that the different qualities and types of open spaces, including size, greenness, equipment (facility), and surrounding areas, have different patterns in the reduction of surface temperature and the number of physical activities. The variance in housing prices through the distance to park was, however, not clear in this research. This dissertation project provides better insight into how to describe, plan, and prioritize the functions and types of urban open spaces need for sustainable living. This project builds a comprehensive framework for analyzing urban open spaces in an arid city. This dissertation helps expand the view for urban environment and play a key role in establishing a strategy and finding decision-makings.Dissertation/ThesisPh.D. Geography 201

A spatially explicit approach for analysing the landscape pattern of urban vegetation using remotely sensed data and its impacts on urban surface temperature.

Doctoral Degree. University of KwaZulu-Natal, Pietermaritzburg.The landscape pattern of urban green spaces and vegetation plays a significant role in supplying essential benefits and ecological services including sequestering and storing carbon, purification of air and water, regulating climate and providing recreational opportunities. However, due to the negative impacts of land cover change and rapid rates of urbanization, vegetation in an urban landscape typically becomes isolated and highly heterogeneous in space and time, relative to non-urban landscapes or natural areas. This research aimed to develop a spatially explicit approach based on remotely sensed data to quantify and monitor vegetation fragmentation and landscape structure of urban vegetation over time and its related impacts on the urban thermal environment using Harare metropolitan city in Zimbabwe as a case study. Specifically, multi-temporal Sentinel 2, Landsat 8 and Aster data were used in achieving the above objectives. Results based on the forest fragmentation model showed that the patch vegetation conditions, which represents the highest and severe vegetation fragmentation level, were dominant across the landscape, followed by edge, transition and perforated, whilst the core vegetation covered a small portion of the city. The decrease of large, connected and contiguous vegetation to a more scattered and fragmented vegetated patches was common across the city but more dominant in the heavily built-up areas of western, eastern and the southern parts of the city, indicating the significant impact of urban development. The small, isolated and scattered vegetation patches were associated with low positive and negative spatial autocorrelation of Local Indicators of Spatial Association (LISA) indices. On the other hand, the more homogeneous (clustered) vegetation was associated with high positive spatial autocorrelation in the northern part of Harare metropolitan city. Furthermore, the study showed that clustered, highly connected vegetation produces stronger cooling effects than dispersed, isolated and smaller patches of vegetation. Overall, spatial explicit approach and tools including the forest fragmentation model and LISA indices could play a significant role in landscape ecology with significant implications for conservation and restoration efforts based on the delineation of spatially explicit clusters of high or low vegetation cover, core or patch or edge vegetation conditions

True colours of urban green spaces : identifying and assessing the qualities of green spaces in Kuala Lumpur, Malaysia

This thesis starts from the proposition that the ingrained perception of urban green space as being synonymous only with fairly well maintained amenity parkland is too narrow and generally overlooks the many environmental and social benefits that other types of green space and their natural habitats bestow on urban residents and wildlife. A critical review of the literature on the benefits which different kinds of green space confer on urban residents in environmental, social, health and well being and economic terms confirms the need for a more holistic approach to the study of green spaces in cities and also highlights the need to develop and realise a more comprehensive "ontology" of urban green space in tropical countries, a fundamental task which is a main concern of the present thesis. From reviewing the classification schemes or typologies used in different countries to formally recognise and to distinguish different types of green space, the author develops a new, expanded typology for urban green space adapted to Malaysian conditions, aiming to use this as far as possible as a framework to categorise the green spaces of Kuala Lumpur (KL). KL provides a particularly interesting case study as a rapidly growing city in a developing country with a tropical climate, a context where there has been relatively little research on urban green space, despite shade being particularly appreciated in very hot climates. Also KL has experienced much loss of green space in recent decades: on its periphery from urban expansion; and around the city centre from the drive, fuelled by economic growth, to use central land more intensively. The main empirical analysis in the thesis uses data obtained from remotely sensed satellite images of high resolution (from the IKONOS satellite) to try to identify all vegetated forms of land cover in KL and to discern their nature, primarily whether trees, shrubs or grass, regardless of their location, using object oriented software to process the IKONOS data. The degree to which the different types and functions of green space can be identified from IKONOS imagery using both semi-automated and manual methods of visual interpretation is then compared. The results show that, using high resolution IKONOS imagery, it is not possible to identify unambiguously all the types of green land use or green land cover that are found in the proposed, new typology of green space, either by using semi-automatic classification or by visual interpretation, although the latter enables more types of green space to be distinguished with confidence. A key result of the preceding analysis, nevertheless, is to produce maps of green space showing the foregoing 3 classes of vegetation (plus water, bare ground and built up areas) for the entire city in very fine detail using first a semi-automated classification followed by selective manual revision. This produces a more complete picture of the geography of these 3 basic types of green space across the whole city than the typical picture purely or mainly of public parks generated from the typologies used by city governments in developing countries, including KL, simply reflecting their traditional concerns being largely restricted to the latter kinds of green space. These finely detailed maps showing the complex mosaic of green space are, in some respects, the most important result of the thesis. These maps of green space produced from satellite data are linked in a geographic information system (GIS) with data on land use for small land parcels and, using dasymetric methods, with data on population from the census to produce a range of alternative, illuminating perspectives on the nature and extent of green space across the whole city, often at a very fine geographical scale, and including an analysis of the relative provision (or lack thereof) of green space over the whole city; this also yields insight into the role of particular green spaces in the wider urban system. Subsequently, the use of GIS operations enables officially recognised green spaces and the even more extensive and diverse areas of green space not officially recognised to be mapped and examined separately, possibly for the first time in KL. A social survey designed mainly for urban planners and landscape architects in KL was carried out mainly to learn and study their views on the nature, roles and benefits of urban green space, on the new expanded typology, on the problems of protecting urban green space in KL and on what attributes of green spaces they considered should be seen as most important when considering how much priority a particular green space should be given for preservation. From some 38 environmental and social criteria the 41 respondents considered very important, 31 criteria (13 environmental and 18 social) were chosen as attributes to use in evaluating 17 different green spaces of various types in different parts of the city through assessment on site by a small team of trained assessors. A smaller subset of 4 environmental and 3 "social" (actually all accessibility) criteria, selected from the foregoing 31 criteria, was identified which could be estimated "remotely" by "desk based" methods i.e. by using the satellite data and the population data held in our GIS, as well as by direct field survey. It was then possible to compare the 3 sets of evaluations for the 17 green areas in the form of overall rankings in turn on the environmental and then accessibility criteria: firstly the ranks of the sites on all 13 environmental criteria, then on the subset of 4 environmental criteria (both of the latter from field assessment) and finally on the same subset of 4 criteria estimated "remotely". The equivalent overall rankings for the 18 social amenity criteria, then the subset of 3 accessibility indicators from field observation and lastly the same subset of 3 but estimated remotely were then compared. The results showed clear similarities and strong correlations between the three sets of evaluations for the 4 environmental criteria measuring aspects of vegetative cover and "green connectivity" but less consistent similarity for the social and accessibility measures, with only weak correlations between rankings on the field and remote estimates for the 3 accessibility indices. The main conclusion is therefore that "remote" evaluation could potentially have a useful role, complementary to ground surveys, in monitoring and assessing green spaces as regards some key environmental criteria and, more debatably, may also be able to provide useful measures of accessibility, which are difficult to estimate from field visits. However, observation on site is necessary for assessment of nearly all the social criteria relevant to evaluating urban green spaces

Using the urban landscape mosaic to develop and validate methods for assessing the spatial distribution of urban ecosystem service potential

The benefits that humans receive from nature are not fully understood. The ecosystem service framework has been developed to improve understanding of the benefits, or ecosystem services, that humans receive from the natural environment. Although the ecosystem service framework is designed to provide insights into the state of ecosystem services, it has been criticised for its neglect of spatial analysis. This thesis contains a critical discussion on the spatial relationships between ecosystem services and the urban landscape in Salford, Greater Manchester. An innovative approach has been devised for creating a landscape mosaic, which uses remotely-sensed spectral indices and land cover measurements. Five ecosystem services are considered: carbon storage, water flow mitigation, climate stress mitigation, aesthetics, and recreation. Analysis of ecosystem service generation uses the landscape mosaic, hotspot identification and measurements of spatial association. Ecosystem service consumption is evaluated via original perspectives of physical accessibility through a transport network, and greenspace visibility over a 3D surface. Results suggest that the landscape mosaic accuracy compares favourably to a map created using traditional classification methods. Ecosystem service patterns are unevenly distributed across Salford. The regulating services draw from similar natural resource locations, while cultural services have more diverse sources. The accessibility and visibility analysis provides evidence for the importance of urban trees as mitigators of ‘grey’ views, and urban parks as accessible producers of multiple services. Comprehensive ecosystem service analysis requires integration of quantitative and qualitative approaches. Evaluation of spatial relationships between ecosystem services and the physical landscapes in this thesis provides a practical method for improved measurement and management of the natural environment in urban areas. These findings can be used by urban planners and decision makers to integrate ecological considerations into proposed development schemes

Land Surface Monitoring Based on Satellite Imagery

This book focuses attention on significant novel approaches developed to monitor land surface by exploiting satellite data in the infrared and visible ranges. Unlike in situ measurements, satellite data provide global coverage and higher temporal resolution, with very accurate retrievals of land parameters. This is fundamental in the study of climate change and global warming. The authors offer an overview of different methodologies to retrieve land surface parameters— evapotranspiration, emissivity contrast and water deficit indices, land subsidence, leaf area index, vegetation height, and crop coefficient—all of which play a significant role in the study of land cover, land use, monitoring of vegetation and soil water stress, as well as early warning and detection of forest fires and drought