Percent Impervious Surface Research Articles

Spatio-temporal pattern of urban eco-environmental quality of Indian megacities using geo-spatial techniques

Rapid urbanization is often responsible for the degradation of urban eco-environmental quality (UEQ), which is comprised of ecological, environmental and anthropogenic components. Hence, frequently monitoring and tracking UEQ for sustainable cities and communities is recommendable. This study, attempted to compare UEQ of three rapidly growing Indian metros/megacities – Ahmedabad, Hyderabad and Bangalore. A remote sensing-based composite index, namely ‘urban eco-environmental quality index’ (UEQI), was constructed by utilizing Landsat 5 (TM), 8 (OLI-TIRS) satellite imageries and MODIS LST products of 1999/2000–2001 and 2018. Five vegetation indices (i.e. NDVI, SAVI, GVI, NDMI and TcWet) and four urban indices (i.e. BI, NDBI, UI and DTR) were categorized as per pressure-state-response (PSR) framework and integrated through spatial principal component analysis (SPCA) to construct the UEQI. The sensitivity and elasticity of UEQI had been tested with respect to population density (PD) and the percentage of impervious surface (IS). Subsequently, the spatio-temporal pattern (i.e. (non)sequential transition – from excellent to very poor) and spatial heterogeneity of UEQ were investigated using Moran’s I, and local indicator of spatial auto-correlation (LISA). Result indicated overall UEQI value for selected cities during studied periods ranged from 0.20 to 2.20, where lower and higher value referred very poor and excellent UEQ, respectively. The most degraded UEQ was found in Bangalore (average UEQI values were 1.08 and 0.80 in 2001 and 2019, respectively); and the degradation rate was also quite inflated than other cities (i.e. UEQI 1.64 per year). Additionally, the spatio-temporal pattern of UEQI demonstrated that very poor and poor UEQ were primarily clustered in the city’s centre and spilling out towards the outskirts of all cities during the studied periods. Overall, the proportional area under very poor UEQ category was increased i.e., 7.94%, 7.03% and 5.24% for Bangalore, Ahmedabad and Hyderabad, respectively. The non-sequential transition (i.e. excellent to poor or very poor) was prominent in Bangalore, which implied that rapid and abrupt degradation of UEQ. Whereas, Ahmedabad and Hyderabad followed mostly sequential transition. Besides, significant global (Moran’s I = > 0.80) and LISA confirmed the non-randomness pattern of UEQ for three cities. The analysis of sensitivity ensured both PD and IS were strongly influenced poor UEQI (as R 2 ≥ 0.50). Elasticity of UEQI revealed 1% increase of IS would lead to declining of 0.64%, 0.46% and 0.21% of UEQI in Ahmedabad, Hyderabad and Bangalore, respectively. Moreover, the study’s observation and findings could also be used for possible area intervention for ‘area-based development’ (ADB) and ‘greenfield development’ (GFD) plan, as recommended by ‘climate-resilient smart city mission’.

Anthropogenic factors associated with contaminants of emerging concern detected in inland Minnesota lakes (Phase II)

Contaminants of emerging concern (CECs) include a variety of pharmaceuticals, personal care products, and hormones commonly detected in surface waters. Human activities, such as wastewater treatment and discharge, contribute to the distribution of CECs in water, but other sources and pathways are less frequently examined. This study aimed to identify anthropogenic activities and environmental characteristics associated with the presence of CECs, previously determined to be of high priority for further research and mitigation, in rural inland lakes in northeastern Minnesota, United States. The setting for this study consisted of 21 lakes located within both the Grand Portage Indian Reservation and the 1854 Ceded Territory, where subsistence hunting and fishing are important to the cultural heritage of the indigenous community. We used data pertaining to numbers of buildings, healthcare facilities, wastewater treatment plants, impervious surfaces, and wetlands within defined areas surrounding the lakes as potential predictors of the detection of high priority CECs in water, sediment, and fish. Separate models were run for each contaminant detected in each sample media. We used least absolute shrinkage and selection operator (LASSO) models to account for both predictor selection and parameter estimation for CEC detection. Across contaminants and sample media, the percentage of impervious surface was consistently positively associated with CEC detection. Number of buildings in the surrounding area was often negatively associated with CEC detection, though nonsignificant. Surrounding population, presence of wastewater treatment facilities, and percentage of wetlands in surrounding areas were positively, but inconsistently, associated with CECs, while catchment area and healthcare centers were generally not associated. The results of this study highlight human activities and environmental characteristics associated with CEC presence in a rural area, informing future work regarding specific sources and transport pathways. We also demonstrate the utility of LASSO modeling in the identification of these important relationships.

The power of community science to quantify ecological interactions in cities

Studying animals in urban environments is especially challenging because much of the area is private property not easily accessible to professional scientists. In addition, collecting data on animals that are cryptic, secretive, or rare is also challenging due to the time and resources needed to amass an adequate dataset. Here, we show that community science can be a powerful tool to overcome these challenges. We used observations submitted to the community science platform iNaturalist to assess predation and parasitism across urbanization gradients in a secretive, ‘hard-to-study’ species, the Southern Alligator Lizard (Elgaria multicarinata). From photographs, we quantified predation risk by assessing tail injuries and quantified parasitism by counting tick loads on lizards. We found that tail injuries increased with age and with urbanization, suggesting that urban areas are risky habitats. Conversely, parasitism decreased with urbanization likely due to a loss of hosts and anti-tick medications used on human companion animals. This community science approach generated a large dataset on a secretive species rapidly and at an immense spatial scale that facilitated quantitative measures of urbanization (e.g. percent impervious surface cover) as opposed to qualitative measures (e.g. urban vs. rural). We therefore demonstrate that community science can help resolve ecological questions that otherwise would be difficult to address.

Thermal Inequity in Richmond, VA: The Effect of an Unjust Evolution of the Urban Landscape on Urban Heat Islands

The urban heat island (UHI) effect is caused by intensive development practices in cities and the diminished presence of green space that results. The evolution of these phenomena has occurred over many decades. In many cities, historic zoning and redlining practices barred Black and minority groups from moving into predominately white areas and obtaining financial resources, a practice that still affects cities today, and has forced these already disadvantaged groups to live in some of the hottest areas. In this study, we used a new dataset on the spatial distribution of temperature during a heat wave in Richmond, Virginia to investigate potential associations between extreme heat and current and historical demographic, socioeconomic, and land use factors. We assessed these data at the census block level to determine if blocks with large differences in temperature also had significant variation in these covariates. The amount of canopy cover, percent impervious surface, and poverty level were all shown to be strong correlates of UHI when analyzed in conjunction with afternoon temperatures. We also found strong associations of historical policies and planning decisions with temperature using data from the University of Richmond’s Digital Scholarship Lab’s “Mapping Inequality” project. Finally, the Church Hill area of the city provided an interesting case study due to recent data suggesting the area’s gentrification. Differences in demographics, socioeconomic factors, and UHI were observed between north and (more gentrified) south Church Hill. Both in Church Hill and in Richmond overall, our research found that areas occupied by people of low socioeconomic status or minority groups disproportionately experienced extreme heat and corresponding impacts on health and quality of life.

Caterpillar survival in the city: attack rates on model lepidopteran larvae along an urban-rural gradient show no increase in predation with increasing urban intensity

Growing native plants in urban gardens is often promoted as a possible means of increasing lepidopteran populations. However, the efficacy of such efforts has not been well studied. Lepidopterans vary widely in their ability to survive in cities, and the few previous studies of caterpillar abundance or biomass across an urban-rural gradient have yielded mixed results. We placed clay caterpillar models in native plant gardens to assess whether the attack rate on these models varied with degree of urbanization (percent impervious surface within 1 km radius of each garden), and whether responses differed across predator taxa. We also examined how garden characteristics (plant biovolume density, plant species richness) affected probability of attack. Overall, attack rates on these models decreased with increasing impervious surface, although predator taxa varied in their sometimes complex responses. For parasitoid wasps, which accounted for 47% of all attacks, increasing biovolume density increased attack probability at impervious surface levels below 35%, but decreased the probability of attack at higher levels of impervious surface. In contrast, probabilities of attack by both predatory wasps and vertebrates decreased with increasing percent impervious surface, but did not vary with impervious surface for ants and spiders. Predation on caterpillars in urban gardens may be lower than in rural ones; however, this potential increase in survival may be a result of declines in some predator taxa, such as predatory wasps and insectivorous birds. More studies across an urban gradient are needed to measure factors other than predation that influence caterpillar survival in gardens.

URBAN CONFIGURATION AND WATER BALANCE WITH AQUACYCLE MODEL IN THE BELÉM CATCHMENT, SOUTHERN BRAZIL

The influence of anthropogenic activities on drainage basins increases the complexity of hydrological systems in urban watersheds due to the increased amount of impervious surfaces and the interaction between natural and constructed drainage systems. Herein, the aim is to verify how water balance components respond to anthropogenic changes in different configurations of urban space. The study focuses on the Belém catchment, located in Curitiba, Southern Brazil city. Simulations were performed using the Aquacycle model to evaluate the water balance of fourteen Hydrologic Similarity Areas, which were delimited based on the integrated analysis of zoning law, and demographic density data. The results show a direct and linear interaction between an increase in impervious areas with an increase in surface runoff and decreases in infiltration and evapotranspiration, demonstrating the relationship among urban configuration and components of hydrological cycle. Linear regression analysis indicates R² of 0.986 between impervious surfaces and surface runoff, 0.956 for evapotranspiration and 0.934 for groundwater recharge. However, streamflow and baseflow parameters showed no sensitivity to the percentage of impervious surfaces, with R² 0.557 and 0.244, respectively. Finally, the results indicate a significant contribution to the water balance resulting from water-supply system leakage and wastewater discharge into the drainage system.

Estimating Artificial Impervious Surface Percentage in Asia by Fusing Multi-Temporal MODIS and VIIRS Nighttime Light Data

Impervious surfaces have important effects on the natural environment, including promoting hydrological run-off and impeding evapotranspiration, as well as increasing the urban heat island effect. Obtaining accurate and timely information on the spatial distribution and dynamics of urban surfaces is, thus, of paramount importance for socio-economic analysis, urban planning, and environmental modeling and management. Previous studies have indicated that the fusion of multi-source remotely sensed imagery can increase the accuracy of prediction for impervious surface information across large areas. However, the majority of them are limited to the use of specific data sources to construct a few features with which it can be challenging to characterize adequately the variation in impervious surfaces over large areas. Thus, impervious surface maps are often presented with high uncertainty. In response to this problem, we proposed the use of multi-temporal MODIS and Visible Infrared Imaging Radiometer Suite (VIIRS) nighttime light data to construct a more general and robust feature set for large-area artificial impervious surface percentage (AISP) prediction. Three fusion methods were proposed for application to multi-temporal MODIS surface reflectance product (MOD09A1) and Visible Infrared Imaging Radiometer Suite (NPP-VIIRS) Day/Night Band (DNB) data to construct three different types of features: spectral features, index features (band calculations), and fusion features. These features were then used as variables in a random-forest-based AISP prediction model. The model was fitted to China and then applied to predict AISP across Asia. Fifteen typical cities from different regions of Asia were selected to assess the accuracy of the prediction model. The use of multi-temporal MODIS and VIIRS DNB data was found to significantly increase the accuracy of prediction for large-area AISP. The feature set constructed in this research was demonstrated to be suitable for large-area AISP prediction, and the random forest model based on optimization of the selected features achieved the highest accuracy, amongst benchmarks, with testing R2 of 0.690, and testing RMSE of 0.044 in 2018, respectively. In addition, to further test the performance of the proposed method, three existing impervious products (GAIA, HBASE, and NUACI) were used to compare quantitatively. The results showed that the predicted AISP achieved superior performance in comparison with others in some areas (e.g., arid areas and cloudy areas).

气溶胶光学厚度和不透水地表覆盖度对城市热岛强度的影响——以关中地区为例

城市热岛效应（UHI）是人们最为关注的城市生态环境热点问题之一，城市热岛及其影响因子的研究对生态城市建设具有重要意义。利用城市热岛足迹（UHI FP）、局部G^*指数、Pearson相关系数以及气溶胶定量归因分析法研究了气溶胶光学厚度（AOD）和不透水地表覆盖度（ISP）对城市热岛的影响。研究结果表明：在2000-2018年间，关中地区西安及咸阳（西咸）城区的白天/夜晚城市热岛足迹均有显著增加，城市热岛效应逐年增强。西咸白天/夜晚城市热岛足迹范围比宝鸡市大，城市热岛现象更为明显。西咸城区夜晚热岛足迹范围内被地表温度（LST）高值所占据，夜晚城市热岛效应比白天更明显。宝鸡市虽然热岛足迹范围增减幅度不大，但足迹内白天/夜晚LST次热区面积逐渐增大，城市热岛效应日趋增强。西咸、宝鸡市城区的夜晚城市热岛强度（ΔT）与不透水地表覆盖度呈显著正相关关系，与城乡气溶胶光学厚度之差（ΔAOD）呈明显负相关性。西咸城乡ΔAOD为负，对城市热岛强度的平均贡献度为（0.41±0.14）℃；宝鸡市城乡ΔAOD为正，其平均贡献度为（-0.26±0.25）℃。综上所述，城市不透水地表面积的扩张会使城市热岛效应进一步加剧，西咸与宝鸡市城区气溶胶浓度的增加会抑制城市热岛的形成，但综合其他因子的影响作用，西咸与宝鸡市城市热岛强度仍在逐年增加。;The urban heat island effect (UHI) is one of the hot issues of urban ecological environment that people are most concerned about. It is of great significance to explore urban heat island effect and its impact factors for the construction of eco-city development. In this paper, the effect of aerosol optical depth (AOD) and impervious surface percentage (ISP) on urban heat island was investigated via the urban heat island footprint (UHI FP), Getis-Ord G^*, Pearson correlation and AOD quantitative attribution analysis method. The results show that between 2000 and 2018, the day/night UHI FP in the urban area of Xi'an and Xianyang (Xixian) increased significantly and the influence of UHI was enhanced year by year. The day/night UHI FP of Xixian was wider than that of Baoji, and the UHI phenomenon of Xixian was more obvious. The UHI FP of Xixian at night was almost entirely dominated by the high land surface temperature (LST) value, and UHI at night was more obvious than during the day. Although Baoji's UHI FP did not increase or decrease significantly, the day/night LST sub-heat zone area within UHI FP of Baoji increased gradually, and UHI significantly increased. The impervious surface percentage in the urban area of Xixian, Baoji was significantly positively correlated with night urban island intensity (ΔT). The difference between urban and rural aerosol optical depth (ΔAOD) was also significantly negatively correlated with night ΔT. ΔAOD in the Xixian was negative, and the average contribution was (0.41±0.14) ℃. The ΔAOD of urban and rural values in Baoji were positive, and the average contribution was (-0.26±0.25) ℃. In general, the expansion of urban impervious surface will further worsen UHI, and the increase of AOD in the urban area will inhibit UHI formation. However, UHI intensity of Xixian and Baoji is still increasing year over year due to the comprehensive influence of other factors.

Urbanization does not affect green space bird species richness in a mid-sized city

Urbanization is one of the most intensive forms of landscape and habitat transformation, resulting in species loss, and taxonomic and functional homogenization of different communities. Whilst green infrastructure (the network of natural and semi-natural areas in cities) has been studied extensively in terms of specific features that promote biodiversity, there have been no studies that have assessed how species richness in different types of green space (GS) varies with increasing levels of urbanization in the surrounding matrix. We studied the effects of different types of GS and urbanization in the surrounding matrix on bird communities in the mid-sized city of Göttingen, Germany. We used the point-count method for bird observations in allotments and parks. To determine the level of urbanization, we calculated percentage of impervious surfaces around GSs. Increasing levels of urbanization around GSs had no effect on the species richness, functional traits or the community composition of birds. Nevertheless, we found that species richness and functional traits varied according to GS type. Parks had a greater species richness and were found to have more ground nesting and tropical migrant birds compared to allotments. We found more cavity nesting and resident birds in allotments. As different types of GS can contribute to the presence of different species and functional trait variations, their positive effect on bird species richness can be enhanced when they are present together in urban landscapes. Our findings suggest that green spaces with a high variety of local characteristics should be incorporated into urban planning designs in order to ensure diverse bird communities in cities.

Urbanization alters the abundance and composition of predator communities and leads to aphid outbreaks on urban trees

Urbanization can affect arthropod abundance in different ways. While species with narrow habitat range and low dispersal ability often respond negatively to urban environments, many habitat generalist species with good dispersal ability reach high densities in city centers. This filtering effect of urban habitats can strongly influence predator-prey-mutualist interactions and may therefore affect the abundance of predatory and phytophagous species both directly and indirectly. Here, we assessed the effect of urbanization on aphids, predatory arthropods, and ants on field maple (Acer campestre) trees in and around the city of Budapest, Hungary. We used the percentage of impervious surfaces within a 500 m radius of each site as an index of the degree of urbanization. We found that the abundance of aphids increased with increasing level of urbanization. However, abundance of predatory arthropods and occurrence of poorly dispersing species within the predator community were negatively related to urbanization, and we identified these two independent factors as significant predictors of aphid abundances. The abundance of ants decreased with urbanization, and contrary to our expectations, did not affect the abundance pattern of aphids. Our results suggest that urbanization, by altering the abundance and composition of predator communities, can disrupt biological control of aphid populations, and thus may contribute to the aphid outbreaks on urban trees.

Growing in the city: Urban evolutionary ecology of avian growth rates.

IntroductionRapid environmental change driven by urbanization offers a unique insight into the adaptive potential of urban‐dwelling organisms. Urban‐driven phenotypic differentiation is increasingly often demonstrated, but the impact of urbanization (here modelled as the percentage of impervious surface (ISA) around each nestbox) on offspring developmental rates and subsequent survival remains poorly understood. Furthermore, the role of selection on urban‐driven phenotypic divergence was rarely investigated to date.Methods and ResultsData on nestling development and body mass were analysed in a gradient of urbanization set in Warsaw, Poland, in two passerine species: great tits (Parus major) and blue tits (Cyanistes caeruleus). Increasing levels of impervious surface area (ISA) delayed the age of fastest growth in blue tits. Nestling body mass was also negatively affected by increasing ISA 5 and 10 days after hatching in great tits, and 10 and 15 days in blue tits, respectively. High levels of ISA also increased nestling mortality 5 and 10 days after hatching in both species. An analysis of selection differentials performed for two levels of urbanization (low and high ISA) revealed a positive association between mass at day 2 and survival at fledging.DiscussionThis study confirms the considerable negative impact of imperviousness—a proxy for urbanization level—on offspring development, body mass and survival, and highlights increased selection on avian mass at hatching in a high ISA environment.

Using Landsat 8 data to compare percent impervious surface area and normalized difference vegetation index as indicators of urban heat island effects in Connecticut, USA

This empirical research examines the normalized difference vegetation index (NDVI) and the percent impervious surface area (%ISA) as indicators of urban heat island (UHI) effects, using the relationships between land surface temperature (LST), %ISA, and NDVI. Landsat 8 Operational Land Imager and Thermal Infrared Sensor data were used to estimate the LST in Connecticut at different times. A map of the percent impervious surface was generated using the Impervious Surface Analysis Tool developed by the Center for Land Use Education and Research and distributed through the National Oceanic and Atmospheric Administration. Strong linear relationships between LST and %ISA exist, as stated in previous studies, whereas the relationship between LST and NDVI is evidently affected by the seasons. As the patterns of LST in urban areas are influenced by the UHI, the results demonstrate that %ISA is a more reliable indicator of UHI effects than NDVI. Thus, %ISA could be a promising alternative for use in the quantitative analysis of LST when studying UHI effects.

Impacts of the remnant sizes, forest types, and landscape patterns of surrounding areas on woody plant diversity of urban remnant forest patches

Remnant forests in urban areas are hotspots of urban biodiversity. However, the survival and integrity of many remnant forests are currently at risk. Better knowledge of the interactions between remnant forests and urban environments is urgently needed for guiding the conservation effort. In this study, we intend to answer the question: how do patch attributes and landscape patterns of surrounding environments affect the taxonomic diversity of woody plants in urban forest remnants? We surveyed the woody plant species in 240 sample plots in 54 remnant forest patches in Guiyang City, China. We analyzed the taxonomic diversity of woody plants and the effects of influencing factors using multi-level taxonomic diversity indicators and the generalized dissimilarity modeling. The results showed that shrubs had higher within-patch α-diversity than that of trees. However, adult trees had higher among-group β-diversity than those of shrubs and saplings/seedlings. The vegetation type of the patch had more influence than other factors on the compositional dissimilarity of adult trees and sapling/seedling among patches. The patch size had the highest impact on the compositional dissimilarity of shrubs. Besides, small patches had a higher rate of compositional turnover in all woody plants. The percentage of impervious surfaces in surrounding areas and the spatial distance from each other were the main influencing factors for adult trees and saplings/seedlings, respectively. Based on our results, we recommend that more attention should be paid to preserve the small remnant forest patches and protect sampling/seedlings to maintain the taxonomic diversity of urban remnant forests.

Remote sensing monitoring of impervious surface percentage in Hangzhou during 1990—2017

Remote sensing monitoring of impervious surface percentage in Hangzhou during 1990—2017

The Influences of Landcover structure on surface urban heat islands: A case study of Ho Chi Minh, Vietnam

Urbanization is taking place at an unprecedented rate around the world, particularly in Vietnam. One of the key impacts of rapid urbanization on the environment is the effect of urban heat island (UHI). Understanding the effects of landscape pattern on UHI is crucial for improving the ecology and sustainability of cities. This study investigated how landscape composition and configuration would affect UHI in the District 7, Ho Chi Minh City of Vietnam, based on the analysis of land surface temperature (LST) in relation to the percentage of vegetation, impervious, and water surface. Landsat 8 OLI satellite images acquired on February 14th, 2017 was used to estimate the LST from the thermal channel, while the percentage of vegetation, impervious, and water surface were extracted from multi-spectral channels. Our results indicate that there is a significant difference in LST among the wards in the study area. Impervious surfaces contribute the most to UHI, followed by bare soil, vegetative cover, and water. The research results also show that the structure of urban coverings should reach: 50% of impermeable surfaces and bare land, the remaining 50% are water and vegetation. These results are useful for understanding urban ecology as well as land use planning to minimize the potential environmental impacts of urbanization.

More than a View: School Landscape Features Are Associated with Improved Student Adjustment.

Research indicates that natural features surrounding schools are associated with better academic achievement, enhanced focus, and reduced stress in students. However, few studies have examined the associations between school landscape elements and anxiety, depression, and behavioral concerns in students. The purpose of this study was to determine whether greenery and impervious surfaces surrounding schools are associated with student internalizing and externalizing problems. Fifth-grade students (n = 21,378) reported internalizing and externalizing behaviors on the 2016 Minnesota Student Survey, an anonymous school-based survey administered statewide. Geographic information system landscape data were available for 268 schools in metropolitan areas. We calculated the percentages of tree canopy, grass and shrub cover, and impervious surfaces within 300- and 500-m radius areas around each school building. Multilevel regression models evaluated the associations between student-level internalizing and externalizing behaviors and school-level landscape percentages, controlling for sex, race, and free/reduced-price lunch. Students attending metropolitan schools with a higher percentage of impervious surfaces were more likely to report externalizing behaviors and marginally more internalizing symptoms than students in schools with a lower percentage of impervious surfaces. Higher percentages of tree canopy and grass and shrub cover surrounding schools were not associated with internalizing or externalizing behaviors. Increased impervious surfaces around schools in metropolitan areas were related to increased student externalizing behaviors. Further studies are necessary to understand the significance of the built environment, types of greenery, impact of greenery on student adjustment in nonmetropolitan settings, and varying areas surrounding schools. These results could inform initiatives to improve school landscapes.

Quantitative analysis of the interannual variation in the seasonal water cooling island (WCI) effect for urban areas

Water body, as water cool islands (WCIs), is an effective factor of mitigating the urban heat island (UHI) effects through the evaporation and absorption of solar shortwave radiance. In this study, a combination of the range, amplitude, efficiency and capacity of the WCI effect (WCI_R, WCI_A, WCI_E and WCI_C as descriptors) within water buffers, is proposed to evaluate the interannual variation of the seasonal WCI effects within the fifth loop of Beijing from 2000 to 2018, further construct optimal regression models by seven impact factors with the four WCI descriptors through all-subset regression, as well as calculate the independent contribution rate (CR) of these factors by hierarchical partitioning (HP) analysis. The results indicate that (1) In terms of the interannual variation of WCI effects, the most significant trends that rise over fall produced by four descriptors generate in summer after 2009, while relatively stable states exist in spring and winter. (2) As for the impact factors, the water temperature (WT) and the percentage of vegetation (PV) contribute most for WCI_R, WCI_A and WCI_E in reaction to the interannual average, while the water temperature capacity (WTC) maintains significant impact on WCI_C from spring to autumn over 18 years but shares power with water temperature (WA) and WT in winter. (3) Considering the factor changes yearly, the dominance relationships of external ones, mainly the percentage of impervious surface (PI) and PV, gradually surpass that of WA and WTC in four seasons especially after 2009. On this basis, urban designers could propose suitable plans to better exert the cooling effect of water bodies, thereby reducing the UHI effect.

Predicting Urban Waterlogging Risks by Regression Models and Internet Open-Data Sources

In the context of climate change and rapid urbanization, urban waterlogging risks due to rainstorms are becoming more frequent and serious in developing countries. One of the most important means of solving this problem lies in elucidating the roles played by the spatial factors of urban surfaces that cause urban waterlogging, as well as in predicting urban waterlogging risks. We applied a regression model in ArcGIS with internet open-data sources to predict the probabilities of urban waterlogging risks in Hanoi, Vietnam, during the period 2012–2018 by considering six spatial factors of urban surfaces: population density (POP-Dens), road density (Road-Dens), distances from water bodies (DW-Dist), impervious surface percentage (ISP), normalized difference vegetation index (NDVI), and digital elevation model (DEM). The results show that the frequency of urban waterlogging occurrences is positively related to the first four factors but negatively related to NDVI, and DEM is not an important explanatory factor in the study area. The model achieved a good modeling effect and was able to explain the urban waterlogging risk with a confidence level of 67.6%. These results represent an important analytic step for urban development strategic planners in optimizing the spatial factors of urban surfaces to prevent and control urban waterlogging.

Bee community response to local and landscape factors along an urban-rural gradient

Over a third of the world’s crops require insect pollination, and reliance on pollination services for food continues to rise as human populations increase. Furthermore, as interest in urban agriculture has grown, so has a need for studies of urban pollinator ecology and pollination. Analyzing pollinator assemblages along a rural-urban gradient provides powerful mechanistic insight into how urbanization impacts pollinators. Yet, studies examining pollinators along urban-rural gradients are limited and results vary. Since pollinators vary tremendously in life history characteristics and respond to urbanization differently, studies from different regions would improve our understanding of pollinator response to urbanization. This study documents different bee assemblages along a high-plains semi-arid urban-rural gradient in Denver, Colorado, USA. Percent impervious surface was used to define the extent of urbanization at 12 sites and local and landscape characteristics were estimated using field assessments and geospatial analysis. Wild bees were collected and the relationships between urbanization and bee communities were explored using linear modeling. Overall, bee abundance and diversity decreased with increasing urbanization, suggesting that urban areas negatively impact bee communities. However, all bee guilds responded positively to local floral richness and negatively to the degree of landscape urbanization, suggesting that different types of bees responded similarly to urbanization. These findings suggest that providing a greater diversity of floral resources is key to mitigating the negative impacts of urbanization on pollinator communities.

Extracting Impervious Surface from Aerial Imagery Using Semi-Automatic Sampling and Spectral Stability

The quantification of impervious surface through remote sensing provides critical information for urban planning and environmental management. The acquisition of quality reference data and the selection of effective predictor variables are two factors that contribute to the low accuracies of impervious surface in urban remote sensing. A hybrid method was developed to improve the extraction of impervious surface from high-resolution aerial imagery. This method integrates ancillary datasets from OpenStreetMap, National Wetland Inventory, and National Cropland Data to generate training and validation samples in a semi-automatic manner, significantly reducing the effort of visual interpretation and manual labeling. Satellite-derived surface reflectance stability is incorporated to improve the separation of impervious surface from other land cover classes. This method was applied to 1-m National Agriculture Imagery Program (NAIP) imagery of three sites with different levels of land development and data availability. Results indicate improved extractions of impervious surface with user’s accuracies ranging from 69% to 90% and producer’s accuracies from 88% to 95%. The results were compared to the 30-m percent impervious surface data of the National Land Cover Database, demonstrating the potential of this method to validate and complement satellite-derived medium-resolution datasets of urban land cover and land use.