Urban Intensity Index Research Articles

Intra-annual variability of urban effects on streamwater quality: An examination of watersheds in the Atlanta, Georgia USA region

There has been considerable research on urban impacts on streamwater quality, but studies have mostly ignored intra-annual variations in water-quality variables and thus seasonally-varying impacts. Therefore, this study uses daily water-quality data over eight years for 38 streams in the Atlanta, Georgia USA region and watershed-level, urbanization variables to assess month-specific impacts of urbanization on water quality. The water-quality variables were mean specific conductance, mean temperature, mean dissolved oxygen, median pH, and median turbidity. The watershed-level variables were population density, housing density, proportion of watershed that is high-intensity developed land, imperviousness, proportion of watershed that is urban land use, an urban-intensity index, and change in developed land. Both differences in water quality between urban, suburban, and exurban streams and correlations between water quality and the watershed-level variables were examined. During all months, urban streams had significantly higher specific conductance than suburban and exurban streams, and the urban intensity of a watershed was significantly positively correlated with specific conductance. Differences and correlations were intensified during winter and spring. For temperature and dissolved oxygen, only during non-winter months did urban streams have significantly higher temperatures and significantly lower dissolved oxygen as well as significant positive correlations between urban intensity and temperature and significant negative correlations between urban intensity and dissolved oxygen. Urban streams had the highest pH during all months, but none of the differences were significant. Significant correlations between pH and urban intensity were restricted generally to winter and spring months. Turbidity was highest for exurban watersheds and thus was not significantly positively correlated with urban intensity. Seasonal and stream-group differences in the weathering of concrete, use of road salts, solar heating of streams, urban surface temperatures, baseflow, and land-disturbance activities explain the water-quality findings. Most of the findings should be applicable to urban areas in humid subtropical climates within the Piedmont physiographic region.

Risk assessment of city site landscapes in the central plains of China

Scientific cognition and assessment of threats to cultural heritage and surrounding landscapes are prerequisites for targeted management and protection of cultural heritage. This study took 530 city sites in the Central Plains of China as the research object. Based on the survey information of city sites in the third national cultural heritage survey in China, a combination of high resolution google images and land use/land cover data products and city sites survey data enables a comprehensive evaluation of landscape elements impacts on city sites. With spatial statistical method, we divided city site landscape types, and constructed a landscape element risk assessment model and an urbanization intensity index to analyze the threats of each landscape element to city site protection. The results indicated that 40.64% of the sites are in farmland landscapes, where agricultural cultivation, irrigation, and other production activities may affect the surface and subsurface remains of the sites. The sites (16.82%) in urban landscapes are affected by activities such as building houses and roads. Only six sites belong to the water landscape area, which may be affected by water erosion. Other sites (2.84%) are mainly affected by plant root growth in forest landscapes. The city sites distributed in urban areas such as Zhengzhou or the urban–rural junction were significantly affected by urban expansion and got the greatest protection pressure. City sites in agricultural landscapes have the second highest conservation risk. Plant erosion and flooding mainly affected the city sites in the northwest-southwest mountainous areas or near the water area of the study area, and the risks were relatively small. It can be seen that landscape types such as urban and farmland, which are closely related to human activities, bring the most pressure to the protection of city sites, and it is necessary to focus on the impact of human activities such as urban construction on city sites and the surrounding environment in the future, while paying attention to the protection and rational use of city sites with high assessment risk in urban planning and management for the protection of the city site proper and landscape scenery.

Associations of Urban and Green Land Covers and Heat Waves in 49 U.S. Cities between 1992 and 2019.

The study aimed to examine how changing land use conditions are related to the occurrence of heat waves. The employed methods were (1) the Urban Expansion Intensity Index (UEII) and the Green Expansion Intensity (GEII) for 49 cities in the U.S. between 1992 and 2019; (2) Spearman correlation analyses of heat wave indicators including frequency, season, duration, and intensity for UEII, and GEII, respectively. Major findings include the following: (1) urban areas have increased rapidly with an average UEII value of 1.5; (2) green Areas have increased at a slow pace, which have a GEII average value of 0.017, where the median value is −0.1, meaning the green area is declining in most U.S. cities; (3) The UEII and heat wave duration show a negative relationship with a significant correlation ( = −0.296 and = 0.04); (4) UEII and heat wave intensity show a positive relationship with a significant correlation ( = 0.32 and = 0.027). It was found that heat wave intensity can be a public health issue in high urban expansion intensity areas. The results imply that cities would be better in a more compact pattern with more expanded green areas to mitigate the negative health impacts of heat waves on citizens in urban areas. It is noticeable that there are some patterns to be investigated further in the context of urban developments and heat wave characteristics.

High-Speed Rail Network Expansion and Its Impact on Regional Economic Sustainability in the Yangtze River Delta, China, 2009–2018

The rapid expansion of high-speed rail (HSR) has significantly improved spatial accessibility and connectivity efficiency, and affected the reallocation of spatial resources and regional economic sustainability. This study examined 40 prefecture-level (or above) cities in the Yangtze River Delta (YRD) region, and explored the evolution process of the HSR service network and its impact on the sustainability of economic development. The research results show that: (1) From the perspective of intercity travel time and service connections from 2009 to 2018, the rapid development of HSR has increased the city’s rail accessibility by about 50%, leading to closer intercity connections. (2) There are obvious regional differences in the effect of HSR on urban functional levels and the intensity of inter-city connections. Compared with 2009, the central cities play a greater role as transportation hubs in 2018, creating a significant Matthew effect of accumulated advantage. (3) The distribution pattern of regional urban intensity index is uneven, and the difference in urban intensity index in 2018 is significantly greater than that in 2009. (4) The evolution of the HSR network has significantly affected regional economic development, especially the development of tertiary industry, and increased the polarization of economic development in the YRD. This research can provide a certain reference for regional sustainable development.

Urbanization impact on landscape patterns in cultural heritage preservation sites: a case study of the complex of Huế Monuments, Vietnam

The late 20th and early twenty-first centuries saw massive urbanizations across the world, leading considerate changes in land-cover/land-use, and posing significant threats to UNESCO recognized heritage. The Complex of Huế Monuments, one of World Heritage Site in the centre of Vietnam, is now facing such challenges. This paper conducts a systematic spatial and temporal analysis for a better insight into the contemporary conflict between preserving the historical landscape and developing the urban areas. The analysis involves: (1) classification of land-cover/land-use between 1995 and 2016 using SPOT data; (2) investigation of the urbanization intensity index; (3) identification of key metrics of landscape, spatial index, and natural hazard indicators to build a risk map of the heritage sites; and (4) a final assessment of the risks, as results of urban expansion, on the Outstanding Universal Values (OUV) of these selected samples. The results show that monuments are under threat as risks increased from 1995 to 2016 with a considerable correlation between urbanization intensity index and the risks to OUV. In particular, the area with high risk to OUV increased from 19.78% in 1995 to 23.74% in 2016, and the increasing percentage for the area with very high risk was from 1.26% to 6.67%, respectively. The study area is an example of many similar worldwide cultural heritages that might be threatened by socio-economic development. The successful implementation of the approach for assessing heritage risk presented in this study can be used for other areas with similar characteristics.

An urbanization monitoring dataset for world cultural heritage in the Belt and Road region

ABSTRACT World cultural heritage refers to properties recognized as having historical, social, and anthropological value. Global urbanization has changed the land cover, land use, transportation, landscape, and local environment in cities, and thus exposed World Heritage sites to risks induced by direct or indirect damaging factors. In this paper, an urbanization intensity index (UII) was developed to quantitatively measure urban dynamics in the vicinity of World Heritage sites. This index is based on three global Earth observation datasets, including a global human settlement layer, a global population grid product, and a global nighttime light imagery. Large UII values represent high urbanization levels and intensive human activities in the study area and vice versa. The assessment results show that the mean UII value at 79 world cultural heritage sites in the Belt and Road region increased from 0.26 in 2000 to 0.29 in 2015. The heritage sites were then classified into four types based on the change rates of UIIs. A total of seven heritage sites were identified as exposed to risks due to urban sprawl and infrastructure expansion. The UII dataset can be combined with UNESCO’s periodic reports and site-specific data to provide valuable information for international communities to develop heritage preservation policies. The dataset is available at http://www.dx.doi.org/10.11922/sciencedb.980.

Urbanization monitoring using big Earth Observation data for world heritage sites of China

World heritage is a precious treasure left to mankind by history. It is a treasure of all human civilization and has very important historical, artistic and scientific value. Protecting world cultural heritage is a prerequisite for protecting the inheritance of human culture, safeguarding the diversity and creativity of the world’s culture, and promoting the development of mankind. However, the rapid urbanization process globally has changed the land cover/land use, transportation and environmental conditions in cities, and has caused some impacts and damages to the world heritage sites. Based on three global Earth Observation datasets including Global Human Settlement Layer (GHSL), global population grid products (Worldpop) and the global night-time light images (DMSP/OLS), this paper proposed an urbanization intensity index (UII) to dynamically monitor and quantitatively assess the intensity of urbanization around the world heritage sites. Large UII values represent high urbanization degrees in the study area, and vice versa. The rapid increase of UII indicated that great impacts might be caused by the urban development process on corresponding heritage sites. The assessment results showed that the mean value of UII at 10 world cultural heritage sites in China’s urban areas increased from 0.35 in 2000 to 0.42 in 2015. The urbanization intensity index of the world cultural heritage sites can provide valuable datasets and scientific basis for the protection and development of world cultural heritage sites.

Landscape Transformations in Rapidly Developing Peri-urban Areas of Accra, Ghana: Results of 30 years

Abstract Beyond the loss of peri-urban agricultural and forested land as a result of built-up expansion, not much information exists on the changes in the structure of the peri-urban landscape in Ghana. The aim of this paper is to examine the extent to which urban expansion is driving changes in landscape structure of the peri-urban fringes of Accra. We submit that rapid peri-urbanisation will fragment the existing agricultural and forested landscape with consequent ecological, socio-economic and urban governance implications. Using Landsat satellite images for the years 1985, 1991, 2002 and 2015 the study area was classified into four land cover classes. The study adopted the use of Urban Intensity Index (UII) and the Annual Rate of Urbanization (R) as measures of urbanization. Edge density (ED), largest patch index (LPI) and Aggregation index (AI) were used as proxies to measure landscape structural transformations. The study reveals substantial reductions and fragmentation in agricultural lands, riverine and open forests, while there has been over 200 percent increase in built-up areas. Beyond these revelations in spatiotemporal changes in landscape structure, the paper points to the ecological implications of the changes, and three key socio-economic and urban governance implications.

Analysis of the Dynamic Urban Expansion Based on Multi-Sourced Data from 1998 to 2013: A Case Study of Jiangsu Province

Recently, with the fast speed of urban expansion, research concerning the regulation of urban built-up area expansion is a significant topic, especially in Eastern China with its high urbanization level. The Defense Meteorological Satellite Program’s Operational Linescan System (DMSP/OLS) nighttime light data has a high association with the urban-rural distribution, which provides a new method to study urban expansion effectively and with relatively high accuracy. Between 1998 and 2013, China experienced a rapid economic development period, making it crucial to learn the patterns and driving forces to better manage urban master planning and sustainable development. The urban built-up area for the research years are mapped, and the annual urban expansion speed, urbanization intensity index, and built-up area gravity center are analyzed in this paper. The results will show that the amount of the urban built-up area grows continuously from 1998 to 2008, with the development focus in southern Jiangsu, while from 2008 to 2013, the development center moves to northern Jiangsu. The main driving forces behind this urban built-up area expansion are population growth and economic development.

Impacts of Urban Sprawl on Soil Resources in the Changchun⁻Jilin Economic Zone, China, 2000⁻2015.

The Changchun–Jilin Economic Zone (CJEZ) is one of the most rapidly developing areas in Northeast China, as well as one of the famous golden maize belts in the world. This is a case study to assess the impacts of urban sprawl on soil resources using remote sensing imagery and geographic spatial analysis methods. The common urbanization intensity index (CUII), soil quality index, and soil landscape metrics were calculated to reflect urbanization and the response of soil resource. Results showed that the area of soil sealing changed from 112,460 ha in 2000 to 139,233 ha in 2015, and in the rural region, the area occupied by urbanization nearly kept balance with the area of rural residential expansion. Urban land increased by 26,767 ha at an annual rate of 3.23% from 2000 to 2015. All seven soil types were occupied during the urbanization process, among which black soil ranked the highest (18,560 ha) and accounted for 69.34% of the total occupied area. Soils of Grades I (3927 ha) and II (15,016 ha) were 64.75% of the total occupied soil areas. Urban land expanded in an irregular shape and a disordered way, which led to an increasing large patch index (LPI) and aggregation index (AI), and a decreasing edge density (ED) and Shannon’s diversity index (SHDI) of the soil landscape in the study area during 2000–2015. According to the geographically weighted regression (GWR) model analysis, the R2 between the CUII and soil landscape metrics decreased from the LPI and ED to SHDI and in turn to AI. The local R2 between SHDI, ED, and CUII showed a gradient structure from the inner city to peri-urban areas, in which larger values appeared with strongly intensive urbanization in urban fringes. Soil sealing induced by urbanization has become a significant factor threatening soil, the environment, and food security. How to coordinate regional development and ensure the sustainability of the multiple functions of soil is a problem that needs to be taken into account in the future development of the region.

Health Dynamics in the Built Environment: An Urban Intensity Perspective - An Exploratory Study in Trinidad and Tobago.

The built environment encompasses the physical components of the environment, inclusive of infrastructure, households, buildings, streets, and open spaces, within which individuals reside and carry out their daily activities. It affects both indirectly and directly on the outdoor and indoor physical environment as well as the socio-economic environment. The elements which comprise the built environment and those of the physical and socio-economic environments, which are affected by it, are recognised as key determinants of health. In this study, health dynamics in the built environment are explored along the urban-rural gradient in Trinidad and Tobago. The gradient is measured by a statistically validated Urban Intensity Index developed previously, using physical data from the built environment. Published physical health data from National Surveys as well as data collected on perceptions of health care access and environmental quality are utilised in conjunction with the Urban Intensity Index values to model chronic illness. Multivariate statistical analysis and maps are used to explore and illustrate these dynamics. Ultimately, the outputs of this study can potentially support efforts to diminish the gap between rhetoric and reality, through provision of critical information for policy and decision making, as the global development agenda moves towards evidence-based policy making.

Development of an urban intensity index to facilitate urban ecosystem studies in Trinidad and Tobago

ABSTRACTUrban ecosystems, considered centres of economic, social and cultural development, face a multitude of environmental and socio-economic challenges, which impact on quality of life. Effective management of the urbanization process is believed critical to improving quality of life and realizing sustainable development. The ecosystem perspective provides a holistic approach, needed to address the complexly interconnected issues, which arise from urban development. Central to the mapping and characterization of urban ecosystems is the delineation of their boundaries, which are made less transparent by growing urbanization. This exposes the limitations of a dichotomous approach. An urban intensity index is a critical tool which supports urban ecosystem studies by facilitating analysis of effects along the urban–rural gradient. In this study, Urban Intensity is estimated and ranked from most to least intense for communities across Trinidad and Tobago, using multivariate statistical analysis of physical data from the built environment. This statistically validated index, designed for Trinidad and Tobago, should have wider applicability to other disciplines and countries.

Wetland Transitions and Protection under Rapid Urban Expansion: A Case Study of Pearl River Estuary, China

Understanding wetland changes under urbanization is important for wetland management. In this study, net transition intensity (NTI) and total transition intensity (TTI) are presented to characterize wetland transitions based on spatial data obtained from Landsat satellite images of Pearl River estuary in South China. NTI is commonly used to represent changes in absolute amounts for each class of wetland, while TTI reflects the internal transition activities and amounts. The third index, the urbanization intensity index (UII), is used to investigate the intensity and velocity of urban land expansion at the same time periods. The results show that one-third of the total wetland area was lost from 1979 to 2009 in the study area and seven types of estuarine wetlands were degraded. The basic pattern of wetland transition is from natural wetlands to constructed wetlands and then to urban lands. Intertidal mud and sand and paddy fields were the major natural and constructed wetlands, respectively, transferred to urban lands. The TTI value was generally greater than the NTI value for these wetlands. TTI >> NTI is an important indicator for wetland transitions under rapid urban expansion in the Pearl River estuary. Based on the integration of the two indices (NTI and TTI), a protection and management plan framework for the Pearl River estuary wetlands is proposed. This plan emphasizes the key and important zones and their different features, and includes actions that can be implemented in and around natural and constructed wetlands.

Effects of urbanization expansion on landscape pattern and region ecological risk in Chinese coastal city: a case study of Yantai city.

Applied with remote sensing, GIS, and mathematical statistics, the spatial-temporal evolution characteristics of urbanization expansion of Yantai city from 1974 to 2009 was studied. Based on landscape pattern metrics and ecological risk index, the landscape ecological risk from the landscape pattern dynamics was evaluated. The results showed that the area of urban land increased by 189.77 km2 with average expansion area of 5.42 km2 y−1 from 1974 to 2009. The urbanization intensity index during 2004–2009 was 3.92 times of that during 1974–1990. The land use types of urban land and farmland changed greatly. The changes of landscape pattern metrics for land use patterns indicated that the intensity of human activities had strengthened gradually in study period. The landscape ecological risk pattern of Yantai city shaped half-round rings along the coastline. The ecological risk index decreased with increase of the distance to the coastline. The ratio of high ecological risk to subhigh ecological risk zones in 2009 was 2.23 times of that in 1990. The significant linear relationship of urbanization intensity index and regional ecological risk indicated that the anthropological economic activities were decisive factors for sustainable development of costal ecological environment.

Local spatial modeling of paddy soil landscape patterns in response to urbanization across the urban agglomeration around Hangzhou Bay, China

This study employed geographically weighted regression (GWR), a local spatial modeling approach, to characterize the local varying response of paddy soils to urbanization at the landscape scale in the urban agglomeration around Hangzhou Bay, China. Spatial non-stationary and scale-dependent relationships between three geographical urbanization indices (the common urbanization intensity index, distance to road corridors and distance to urban centers) and four spatial metrics depicting paddy soil landscape patterns (total area, edge density, aggregation index, and perimeter area ratio distribution) were captured at two block scales (4 km × 4 km and 7 km × 7 km) because the predictive ability of GWR and the nature and strength of the identified relationships all varied significantly in space and scale. Moreover, GWR models have achieved better performance than their corresponding global ordinary least squares (OLS) models given their greater ability to (1) describe data (higher adjusted R2 and lower Akaike Information Criterion values) and (2) address spatial autocorrelation in model residuals. This study highlighted scale effects when applying GWR. Both bandwidth and block size can impact the predictive ability of GWR as well as estimated parameters for GWR analysis. This study demonstrates a novel joint application of GWR and associated metrics in applied geography.

Spatiotemporal Dynamics and Urban Land-Use Transformation in the Rapid Urbanization of the Shanghai Metropolitan Area in the 1980s–2000s

As one of the world's largest cities, Shanghai has undergone rapid urbanization over the past two decades. This process has been characterized by high intensity and extreme heterogeneity in its spatiotemporal dynamics, and it has been driven by various transformation processes of nonurban to urban land use. However, the spatiotemporal dynamics of this unique, rapid urbanization has not been adequately addressed, and the contribution of the urban transformation process to regional urbanization has likewise not been targeted. The present study aimed to examine the urbanization dynamics in Shanghai by measuring the magnitude and spatiotemporal heterogeneity of two major forms of urban land uses — high- and low-density constructed areas. The complexity in the urban transformation process and its contribution to regional urbanization were also investigated. Four time-successive Landsat Thematic Mapper (TM) image datasets were used, and a GIS-based gridding system combined with the urbanization intensity index was employed to measure and analyze the spatiotemporal characteristics of urbanization in the Shanghai metropolitan area from 1987 to 2000. We identified 34 types of urban land-use transformation and compared their effects on urbanization based on area contribution and transformation frequency. A neighboring index was introduced to measure the spatial interactions among those types of urban land-use transformation and reveal the formation and evolution of urban land use in urbanization. We expect that our research can make a contribution in the monitoring and detection of urbanization using remote sensing and GIS approaches.

Multi-scale analysis of spatially varying relationships between agricultural landscape patterns and urbanization using geographically weighted regression

Scientific interpretation of the relationships between agricultural landscape patterns and urbanization is important for ecological planning and management. Ordinary least squares (OLS) regression is the primary statistical method in previous studies. However, this global regression lacks the ability to uncover some local-specific relationships and spatial autocorrelation in model residuals. This study employed geographically weighted regression (GWR) to examine the spatially varying relationships between several urbanization indicators (urbanization intensity index, distance to urban centers and distance to road) and changes in metrics describing agricultural landscape patterns (total area, patch density, perimeter area ratio distribution and aggregation index) at two block scales (5 km and 10 km). Results denoted that GWR was more powerful than OLS in interpreting relationships between agricultural landscape patterns and urbanization, since GWR was characterized by higher adjust R 2, lower Akaike Information Criterion values and reduced spatial autocorrelations in model residuals. Character and strength of the relationships identified by GWR varied spatially. In addition, GWR results were scale-dependent and scale effects were particularly significant in three aspects: kernel bandwidth of weight determination, block scale of pattern analysis, and window size of local variance analysis. Homogeneity and heterogeneity in the relationships between agricultural landscape patterns and urbanization were subject to the coupled influences of the three scale effects. We argue that the spatially varying relationships between agricultural landscape patterns and urbanization are not accidental but nearly universal. This study demonstrated that GWR has the potential to provide references for ecological planners and managers to address agricultural landscapes issues at all scales.

Judging a Brook by Its Cover: The Relation between Ecological Condition of a Stream and Urban Land Cover in New England

The US Geological Survey conducted an urban land-use study in the New England Coastal Basins (NECB) area during 2001 to determine how urbanization relates to changes in the ecological condition of streams. Thirty sites were selected that differed in their level of watershed development (low to high). An urban intensity value was calculated for each site from 24 landscape variables. Together, these 30 values reppresented a gradient of urban intensity. Among various biological, chemical, and physical factors surveyed at each site, benthic invertebrate assemblages were sampled from stream riffles and also from multiple habitats along the length of the sampling reach. We use some of the NECB data to derive a four-variable urbanintensity index (NECB-UII), where each variable represents a distinct component of urbanization: increasing human presence, expanding infrastructure, landscape development, and riparian vegetation loss. Using the NECB-UII as a characterization of urbanization, we describe how landscape fragmentation occurs with urbanization and how changes in the invertebrate assemblages, represented by metrics of ecological condition, are related to urbanization. Metrics with a strong linear response included EPT taxa richness, percentage richness of non-insect taxa, and pollution-tolerance values. Additionally, we describe how these relations can help in estimating the expected condition of a stream for its level of urbanization, thereby establishing a baseline for evaluating possible affects from specific point-source stressors.

Assessment Tools for Urban Catchments: Defining Observable Biological Potential1

Abstract: Urbanization represents a strong and increasingly more prevalent impact on stream quality worldwide. One of the characteristic effects of increased urbanization is a consistent decline in biological stream condition. The characterization of this biological degradation with increasing urbanization presents a number of advantages for the study and management of urban streams and catchments. In this paper, the limitation of biological condition with urbanization, called observed biological potential, is characterized. Using an urban intensity index and a biological index developed specifically for urban systems in the Baltimore, Maryland; Cleveland, Ohio; and San Jose, California regions, two principal techniques were compared (quantile regression and bin regression) to define observed biological potential along urban gradients. Quantile regression was selected as the preferable tool for describing observed biological potential given the consistency with which it can be applied and its statistical efficiency, however, bin quantile regression performed similarly. Having identified a numeric approximation of observed biological potential, two methods for identifying factors related to distance from potential as a way of identifying critical environmental factors affecting biological condition in urban areas were explored. The results of this work can be used for identifying benchmarks for urban stream biological condition, identifying limiting catchment characteristics, and prioritizing urban stream management efforts.