Urban Encroachment Research Articles

Green spaces in Ghana’s built environment: Analyzing perceptions and urban planning perspectives through the lens of the New Environmental Paradigm

In the busy world of city growth, urban green spaces in Ghana are befallen with destruction due to urbanization. Using a cross-sectional design and case-studying Damongo and Kintampo, this study assessed the perceptions of urban residents and urban planning perspectives about green spaces in enhancing the environmental condition of fast-growing urban areas, and proposed guidelines for the managing green spaces within Ghana’s built environment. The results revealed that underutilization and insufficient funding for greenspace management increase vulnerability to urban encroachment, especially during inward city growth. Again, the exhaustion of the limited resources of the earth could have repercussions for the population of the earth; however, the need for such resources and the level of poverty influences poor environmental decisions. Further, the results showed that planning for urban green and open space ought to be decided at the local level. The study, therefore, recommends a collaborative approach involving city authorities, private sectors, and the public for effective green space management, emphasizing inclusive decision-making and active preservation, and the development of local standards within a national framework, guided by an urban green spaces protection scheme.

Revitalizing Rural Landscapes: Applying Cultural Landscape Gene Theory for Sustainable Spatial Planning in Linpu Village

In the context of rapid urbanization, it is imperative to address the preservation and sustainable development of rural landscapes. This study introduces a novel framework using cultural landscape gene theory to enhance the landscape spatial pattern of Linpu Village, China. Employing a multi-method approach, including data collection and historical data analysis, GIS analysis, and field surveys, we analyze the village’s landscape features and identify a well-preserved “one core, two wings” spatial configuration with diminishing accessibility from the center to the periphery. The study uncovers significant challenges to landscape coherence and legibility, including landscape element discontinuity, inadequate maintenance, and fragmented information. To address these issues, we propose optimization strategies aimed at revitalizing weakened cultural landscape genes, repairing disrupted elements, ensuring corridor integrity, and improving spatial organization. The extraction–construction–analysis–preservation model established in this research not only delivers a comprehensive analysis of Linpu’s cultural landscape but also offers a scalable framework for preserving the ecological and cultural integrity of traditional villages. This study contributes to the practical implementation of sustainable landscape strategies, enhancing the ecological adaptability and resilience of rural environments in the face of urban encroachment.

On-host flea phenology and flea-borne pathogen surveillance among mammalian wildlife of the pineywoods of East Texas.

Flea-borne diseases are endemic in Texas, U.S.A., with an increasing incidence of flea-borne typhus and cat scratch disease. Knowledge of flea natural history could provide information to protect public health, yet many knowledge gaps remain outside of plague-endemic regions. Our objective was to characterize seasonal activity patterns of fleas on common mammalian wildlife species and test fleas and wildlife for Rickettsia and Bartonella pathogens. We performed one year of monthly trapping for rodents and medium-sized mammals in a national forest with high recreational use and urban encroachment in East Texas. From 90 mammal captures representing seven species, 101 fleas were collected representing Polygenis spp., Ctenocephalides felis, and Orchopeas species. Virginia opossums (Didelphis virginianus) hosted 99% of the collected fleas (100 fleas) and a single flea was on an eastern woodrat (Neotoma floridana). Flea infestation prevalence of opossums was 79% (23/29). Mean flea abundance was 4.39 fleas, with intensity peaking in spring. One cat flea removed from an opossum was positive for Bartonella henselae. Furthermore, we identified tissue or blood of four raccoons (Procyon lotor) and one golden mouse (Ochrotomys nuttalli) positive for Rickettsia amblyommatis. These findings provide an ecological basis for the maintenance of vectors and pathogens from sylvatic settings.

The LTAR Grazing Land Common Experiment at Archbold Biological Station-University of Florida.

The Archbold Biological Station-University of Florida (ABS-UF) Long-term Agroecosystem Research (LTAR) site lies in the heart of south-central Florida, representing subtropical humid grazing lands in North America and globally. Beef producers in this region face challenges due to climate variability, limited nutritive value of forages, poor soils, public concerns about water quality and greenhouse gas emissions, management trade-offs, economic uncertainty, and increasing urban encroachment. The ABS-UF Common Experiment, co-designed with stakeholders, will assess innovative management systems in comparison to prevailing management systems on key indicators of sustainability. Innovative management systems being tested are alternative fire (frequency and spatial extent) and grazing practices (stocking rate and system). The common experiment framework was implemented across a management intensity gradient spanning from native rangeland to cultivated pastures, including embedded wetlands. Issues that have arisen to date include difficulties in implementing prescribed fire and reduced productivity in cultivated pastures associated with innovative management, which led to an adjustment of the experimental treatment. A stakeholder advisory council will codesign future alternative treatments and guide experimental changes in this long-term experiment. Stakeholder engagement efforts revealed research priorities centered on financial strength, carbon (C) and greenhouse gas emissions, and water quality. Stakeholders are also interested in testing emerging technology such as the utility of virtual fencing. Results from ABS-UF provide a unique perspective from subtropical humid grazing lands for continental-scale cross-site synthesis on sustainable agroecosystems across LTAR.

The LTAR Cropland Common Experiment at the Texas Gulf.

Texas Gulf is one of the 18 regional sites that is part of the USDA-ARS Long-Term Agroecosystem Research (LTAR) Network and focuses on cropland and integrated grazing land research in Central Texas, addressing challenges posed by soil characteristics, climate variability, and urbanization. This paper provides brief site descriptions of the two Cropland Common Experiments being conducted in the Texas Gulf LTAR region, emphasizing conservation tillage practices and precision agriculture techniques. The plot-scale study is located in Temple, TX, at the USDA-ARS Grassland, Soil and Water Research Laboratory and examines conventional tillage, strip tillage, and no tillage practices. The field-scale study, located in Riesel, TX, at the USDA-ARS Riesel Watersheds, assesses the impact of no tillage, cover crops, fertility management, adaptive management, and precision conservation on crop yield, profitability, and environmental footprint. Key measurements include soil and plant analyses, greenhouse gas fluxes, runoff water quantity and quality, and field operations recorded with precision agriculture equipment. Despite challenges posed by urban encroachment, future research aims to incorporate new technologies, such as unmanned ground vehicles, to enhance sustainability and productivity of the agricultural landscape. These experiments provide valuable insights for stakeholders, contributing to the development of sustainable agricultural practices tailored to the unique challenges within the Texas Gulf LTAR region.

Assessing the Impact of Urban Expansion on Forest Cover using LULC Maps, NDVI, and NDBI: A Case Study of Kathmandu District

Rapid urbanization poses significant challenges to the delicate balance between urban development and environmental conservation. This study investigates the impact of urban expansion on forest cover in the Kathmandu District, employing a comprehensive approach that integrates Land Use/Land Cover (LULC) maps, Normalized Difference Vegetation Index (NDVI), and Normalized Difference Built-Up Index (NDBI). The aim of the study area is to provide insights into the dynamic interplay between urban growth and its consequences on the region's ecological landscape. LULC maps derived from remote sensing data offer a spatially explicit representation of land-use changes over time, enabling the identification of areas where urbanization has encroached upon forest area. The NDVI, a vegetation health indicator, serves as a quantitative measure of changes in the density and health of vegetation cover, aiding in the assessment of ecological impacts. Complementing this, the NDBI highlights intensity of built-up areas, allowing for a nuanced understanding of the urbanization process. This study employs NDBI and NDVI to dynamically assess urban growth and land use cover change, enhancing analytical accuracy. Findings reveal a substantial 89.9 km² increase in built- up areas between 2013 and 2016, coupled with a minor 18.4 km² increase between 2016 and 2021, reflecting continuous urban expansion driven by population growth and development initiatives. Concurrently, forest area marginally increased by 2.3 km² in 2016, suggesting reforestation and conservation efforts, yet a subsequent 23.5 km² decline by 2021, due to deforestation, urban encroachment, and natural disasters such as wildfires. Notably, vacant land decreased by 92.3 km² in 2016, absorbed by built- up areas and forest expansion, underscoring the urgent need for spatial planning to accommodate the growing population and its evolving needs.

Uneven agricultural contraction within fast-urbanizing urban agglomeration decreases the nitrogen use efficiency of crop production.

Diverse development paths among cities within an urban agglomeration can lead to uneven changes in their agricultural production scale, which reshape the inter-city food supply patterns and the spatiotemporal characteristics of nitrogen (N) pollution from the food system. Here, using Guangdong-Hong Kong-Macao Greater Bay Area of China as a case, we found a substantial decrease in N use efficiency of crop production from 45.2% to 29.3% during 1989-2007, along with a growing level of concentration of food N production in less-urbanized cities. From 1989 to 2018, 12.3% to 42.2% of total N pollution in food production became embedded in inter-city trade, leading to aggregation of N pollution in peripheral cities with relatively low levels of economic development. We suggest that protection and intensification of cropland from urban encroachment, as well as enhancing the economic and technical synergies among cities, can serve the sustainable transition of the food system with coordinated N pollution mitigation.

Urban Growth Modeling in Kurunegala, Sri Lanka using Cellular Automata/Markov Chain Multi-criteria Analysis and Markov-Markovian Transition Estimator

With accelerated global urbanization, the expansion of cities has become a pressing concern for urban planners and researchers. The growth and dynamics of urban encroachment are closely tied to changes in land use, especially in urbanized areas. This study seeks to evaluate the accuracy of the CA-Markov (Cellular Automata) model in predicting land use/land cover changes (LULCC) in the Kurunegala district, Sri Lanka as a result of urban expansion. The investigation employs secondary data, including 2007, 2012, 2017, and 2022 Landsat 05, 07, 08, and 09 images respectively. Using software applications such as ArcGIS 10.8, IDRISI 17.0, and MS-Excel 2019, diverse techniques including supervised classification, Markovian transition estimation, and CAMarkov chain analysis, this study attempts to analyze the Urban Growth Modeling for 2027 and 2037 using CA-Markov Chain Multi-criteria Analysis (MCA) under Markov-Markovian Transition Estimator. The study used 32 spatial variables for determining the LULCC. As per the derived results, from 2022 to 2027, urban areas have increased quite markedly. The vegetation cover area has reduced and the areas of water bodies have increased spatially. From 2027 to 2037, the urban area increment is 72.552%. Also, vegetation cover and water body distribution have reduced by 8.051% and 39.91% respectively.

Potential effects of avian predators on the behaviour of the Little Bustard Tetrax tetrax during the display season in a cereal pseudo-steppe

The Little Bustard Tetrax tetrax is an endangered steppe bird whose last remaining breeding populations in Catalonia (NW Spain) are located in the Lleida plains. Although the decline in this population is mainly associated with habitat loss and degradation due to agricultural intensification and urban encroachment, the proliferation of predators, some favoured by hu- mans, may also be having negative effects on this population, either through direct predation or indirect effects on behaviour and survival. Here, we describe the type of behavioural response exhibited by Little Bustards during the display season when they encounter a potential avian predator and discuss the possible indirect effects of these interactions. During counts carried out in the springs of 2010–2022 in three Special Protection Areas in the Lleida plains, 88 encounters between Little Bustards and eight species of avian predators were recorded. Among them, the Western Marsh Harrier Circus aeruginosus, Montagu’s Harrier C. pygargus and the Yellow-legged Gull Larus michahellis were the most frequent species involved in these encounters, although only the Yellow-legged Gull conducted deliberate attacks in a consistent way. Irrespective of the predator or its attitude, most encounters resulted in the Little Bustard being flushed. The number of encounters were higher at the beginning of the mating season, which may prevent Little Bustards from settling in otherwise suitable areas of habitat. The flushing of the bustards may increase the risk of collision with power lines and reduce mating success. Since the number of encounters between Yellow-legged Gulls and Little Bustards seems to have increased in recent years in the study area, we believe that there is a need to conduct further studies to understand how these interactions affect the population dynamics and conservation of this endangered species.

Jewish Cemetery at Gwarna Street (former Claassenstrasse) in Wrocław: Excavation Report from 2017 and Opportunities for Rescue and Commemoration

Excavations in the area of the former Jewish cemetery in Wrocław at Gwarna Street (formerly Claassenstrasse) have been undertaken many times, most recently in 2017. Since the beginning of the 20th century, the cemetery has been subject to urban encroachment which gradually reduced its historic area, forcing two exhumations, followed by devastation in the 1940s under the Nazi regime. The cemetery was formally liquidated in post-war Poland, in the 1950s and 1960s. At that time, the remaining tombstones were removed and part of the area was built over. In order to develop the areas covered by the earlier exhumations, exploration works were carried out to identify the exact area. In 2017, burials from the cemetery were discovered during construction works. Excavations carried out in 2017 revealed seven individual burials, a mass grave with 115 burials in wooden cases, and 5 mass graves from WWII. Within the cases, fragments of pottery from the 18th and 19th centuries were found. The authors discuss the history of the cemetery, details of the 2017 excavation report with analysis, and current efforts to protect and commemorate the area.

Mapeamento de atores para o ordenamento de interfaces urbano-rurais em terras secas

Stakeholder mapping is used as a tool to identify social relations and develop management strategies, but its inclusion in land-use planning has not yet acquired relevance. This article reflects on the usefulness of this technique to express the multi-actor nature that characterizes urban-rural interface territories and to elaborate linkage proposals that facilitate the implementation and sustainability of alternative territorial projects. It is argued that identifying the heterogeneity of actors is fundamental to think of strategies to mitigate the environmental impacts of urban encroachment on rural and natural areas, while an intermunicipal territory of urban-rural interface of the San Juan Metropolitan Area is presented as a case study. The results include the individualization of the general scheme of alliances and coalitions among actors, the clarification of the channels of influence among them and the visibility of the spaces of power in which they participate. The identification of the relational system of actors in interface territories through mapping is useful in the design of public policies aimed at mitigating urbanization processes in rural and natural areas.

Marine mollusk biodiversity in Northeastern islands of Vietnam, impact factors and proposing conservation solutions

A biodiversity and water-quality monitoring campaign was conducted in the Northeastern archipelago of Vietnam, including Quang Ninh province and Hai Phong, in 2017–2018. Mollusks are selected as the critical proxy indicator, and water-quality parameters are tested against National acceptability standards. The study revealed that, despite declining trends over the past two decades, mollusks are still highly diverse, with 647 species belonging to 227 genera, 95 families, and five classes (76% of all the species identified in the Tonkin Gulf). Of these, 253 species of 39 families (39% of the whole stock) are of high economic value, supporting an active trade in the region and thousands of livelihoods. Several species (abalone, blood cockle, green mussel, pearl oysters, Pacific oysters, double-headed clams, Asian hard clams, white clams, and squids) are intensively farmed. However, aquaculture still needs to be derdeveloped as capture from the wild is preferred. Water quality is unexpectedly high despite impacting factors such as urban development, industry, mass tourism, and demographic increase, mainly within the limits of acceptability set by the Government. Salinity, pH, and temperature are compatible with marine life, and a limited impact is represented by dissolved nitrates and suspended hydrocarbons in suspension. Despite favorable conditions of the aquatic environment, biodiversity decline has been a steady trend over the past decade. The causes are the urban encroachment over the coastal tract, the intertidal spawning grounds, breeding grounds, and nurseries, overexploitation, IUU fishing, lack of management, and failed establishment of conservation areas and MPAs. Spawning and breeding grounds identification and demarcation, their participated co-management, investments in environmental protection, technologies, and capacity building, and promotion of aquafarming of marketable species are among the measures recommended to be implemented with priority, to relieve the pressure over the wild stock and promote regeneration. The role of science in monitoring and detecting environmental changes guiding the adoption of proactive measures to prevent depletion and stock collapse, is the pathway to the sustainability of resource use and human well-being.

Vertical accretion rates of mangroves in northeast Brazil: Implications for future responses and management

Northeast (NE) Brazil has a semi-arid climate and low plant diversity mangroves confined to estuaries influenced by a meso-tidal regime (∼2.5 m). Whilst these mangroves are protected by state and federal legislation, large areas have been lost to urban encroachment and shrimp farms, a situation continuing today. This work discusses the potential impacts of sea level rise on mangroves in three estuaries in NE Brazil. The three sites witness decreasing annual precipitation associated with global climate change, which will have the dual effect of increasing water and salinity stress, decreasing productivity, as well as reducing inputs of allochthonous fluvial material. Simultaneously, since the 1990's local sea level rise (3.5 mm/yr) has been greater than the global average (3.2 mm/yr). Average accretion rates, derived from 137Cs and 210Pb dating in fringing mangroves in this study, are likely to be insufficient to maintain surface elevation and keep pace with sea level rise. Notwithstanding, historical data suggest that there has been no recorded mangrove loss as a result of sea level rise and in some areas a recorded gain in the upper estuarine mangrove reaches. At present there are limited inputs from the watershed in all three estuaries, mostly due to decreasing annual rainfall and river damming, limiting the transport capacity and hampering the export of sediments to the fringing mangroves and the sea and limiting the ability of the fringing mangroves to respond to sea level rise. However, this has been suggested to result in the accumulation of soils along river margins further upstream forming new islands and potentially expanding estuarine mangroves upstream. Both the fringing and the estuarine mangroves are surrounded by both licensed and unlicensed settlements, as well as dunes preventing expansion into higher elevation areas as a response to sea level rise. Recent changes to legislation protecting these ecosystems put a further strain on adaptation and resilience capacity, increasing the threat to these important coastal systems and the ecosystem services they provide.

The transition characteristics and driving mechanisms of rural residential land in metropolitan areas-a case study of Tianjin, China.

Rural revitalization is the core decision for eradicating global poverty and achieving shared prosperity, and one of the most important works is to optimize and manage rural land space. A theoretical framework based on urbanization theory was built to reveal the rural residential land transition in the Tianjin metropolitan area, China from 1990 to 2020. The transition features are identified by computing the land-use conversion matrix and the rural residential land expansion index (RRLEI) and the influencing factors and mechanisms through a multiple linear regression model. The spatial distribution of rural residential land shows that it expands from the inner suburbs to the outer suburbs, then diminishes in the outer suburbs, and extends to the Binhai New Area. Low-level conflicts between rural residential land and urban construction land occurred during the rapid urbanization period, resulting in disorganized and wasteful growth. The inner suburbs have edge-expansion, dispersion, and urban encroachment patterns; the outer suburbs have edge-expansion, infilling, and dispersion patterns, with little urban encroachment; and Binhai New Area has just an edge-expansion pattern. During decelerated urbanization stage, a high-level conflict occurred between rural residential land and arable land, forestland, grassland, water, and urban construction land. Dispersion grew as urban encroachment reduced in the inner suburbs; dispersion increased while urban encroachment declined in the outer suburbs; dispersion, infilling expansion, and urban encroachment increased in the Binhai New Area. During the saturation stage of urbanization, rural residential land evolved in tandem with other forms of land use, with more efficient land use and diverse uses. The main pattern of rural residential land in a suburban region is still edge-expansion, dispersion has expanded in the Binhai New Area, and urban encroachment is the way of urban development in the inner suburbs. Economic factors and economic location strongly impact the dispersion pattern. Edge-expansion and infilling patterns are impacted by comparable variables, including geographical location, topography, population resources, and economic location. Furthermore, the amount of economic growth influences the edge-expansion pattern. It might be influenced by land policy, and the eight elements have no substantial relationship with urban occupancy. Based on resource endowment and pattern features, certain optimization techniques are given.

A Historical–Projected Analysis in Land Use/Land Cover in Developing Arid Region Using Spatial Differences and Its Relation to the Climate

Land resources are under relentless pressure from metropolitan regions, pollution, and climate shifts. The urge to monitor Land Use/Land Cover (LULC) and climate changes based on technology and sustainable management are addressed. This study analyzes the historical land cover maps to calculate growth patterns for the years 1985–2022 and uses Logistic Regression (LR) and Artificial Neural Networks (ANN) to project future dynamics forecasts for the years 2030–2040 in the Amman-Zarqa Basin (AZB). The state of the climate and the extreme indices projections of CMIP5 under RCP8.5 are linked to the corrected historical LULC maps and assessed. Given greater dry covering of large surface runoff, little rainfall, and high evapotranspiration rates, the state of the climate across the AZB notably showed instability in key climatic indices and a major exacerbation of warmth and drier soil in the basin. Both climate change and land use are contributing dynamics, but land-use alterations are much more dramatic changes than climate changes. Since the effects of climate alterations are mostly identifiable through land cover forms, land use practices put the phase that may be influenced by climate change. The results revealed that the daily extremes in 1992 are aligned with the corresponding increase of barren lands and diminished the half area of forest, cultivated, rainfed, and pasture lands in 1995. Rainfed regions were converted to agriculture or shrubland with an accuracy of 0.87, and urban encroachment caused the acreage of woodland, cultivated, rainfed, and grazing fields to decrease by almost half. Predicted land cover maps were created using LR in 2030 (Kappa = 0.99) and 2040 (Kappa = 0.90), in contrast to the ANN approach (Kappa = 0.99 for 2030 and 0.90 for 2040). By combining ANN and LR, decreasing bare soil was anticipated between 325 km2 and 344 km2. As a result, 20% of the total area of the major AZB cities’ urban areas will be doubled. More subjective analysis is required to study and predict drought in the future to improve the resilience of various LULC types.

Phenology, floral and reproductive biology of Dichorisandra rhizantha Aona (Commelinaceae), an endemic endangered species in an Atlantic Forest fragment.

Commelinaceae is an important component of the Atlantic Forest and its analysis can provide information on the conservation of that species. This study had the objective of analyzing the phenology and floral and reproductive biology of Dichorisandra rhizantha, growing in an Atlantic Forest fragment, to obtain data related to the form of reproduction and pollination mechanism of this species. We monitored the phenophases and reproductive biology of the D. rhizantha in the area studied using different methodologies and microscopy techniques (LM, SEM and FM). The flowering period occurs during the dry season. The species is andromonoecious and has daytime anthesis (4:30 a.m.-1:30 p.m.). It has purple zygomorphic flowers and rimose but functionally poricidal anthers. The pollen viability was 97.6% and the two floral morphs investigated contained a large quantity of pollen grains. The time of greatest stigma receptivity (anthesis) coincided with the pollen viability. Cross-pollination was the only efficient reproductive system of the species, with observation of gametophytic self-incompatibility and pollen tubes growth only as far as the middle or lower third of the pistil. We observed bee species of the genera Xylocopa and Euglossa visiting the flowers and acting as effective pollinators. The immature fruits were formed after about 3.25 ± 1 days, and the presence was noted of ants of the genus Cephalotes acting as dispersers of the seeds, with aril serving as the reward. Although the natural reproductive system is efficient, D. rhizantha is endangered, mainly due to fragmentation of habitat caused by deforestation and urban encroachment.

Urban encroachment in ecologically sensitive areas: drivers, impediments and consequences

The drivers and consequences of unregulated urban expansion processes in Accra, Ghana, are examined together with the associated encroachment upon ecologically sensitive areas in the city’s rapidly growing periphery. Three sites are considered which attracted settlers from vastly different economic segments of the urban population from the 2000s and onwards. A combination of geographical information system (GIS)-based analysis, evidence from a recent household survey, insights from a range of key informant interviews and field observations provide evidence for the dynamics of urban expansion and settlement consolidation. These dynamics wield significant pressure on ecologically sensitive areas, <em>e.g.</em> wetlands, riparian zones and coastal lagoons, which are transformed into housing development through drainage, landfilling, channelling of streams and construction of barriers. Encroachment upon ecologically sensitive areas is associated with intensifying flood hazards. Key impediments are identified for the preservation of ecologically sensitive areas within the specific urban governance context of Accra. Encroachment is not necessarily driven by poverty or low income; it occurs for several socio-economic situations. Governance and enforcement in planning need improvement. Such insights must inform efforts to promote more sustainable trajectories of urban expansion, allowing cities to accommodate rapidly growing populations while preserving ecologically sensitive areas and benefiting from crucial ecosystem services. <strong><em><br /></em></strong> <strong><em>Policy relevance</em></strong> Critical impediments exist in planning urban expansion. Insights are provided on why ecologically sensitive areas are not sufficiently protected from urban encroachment. These include the intricacies of regulating land transactions in rural and peri-urban areas before incorporation into the built-up area of the city, the ambivalent and overlapping land administration systems, the strong incentives for traditional authorities to commercialise marginal land, the unfeasibility of policing permanent structures, and the lack of cooperation and coordination among local government entities concerning the management of urban watersheds. Within the urban governance context of Accra, encroachment upon ecologically sensitive areas constitutes a ‘wicked’ planning problem that defies rational, technical solutions and which is fraught with multi-causality, multiple perspectives and diverging interests. Insights into these complexities must inform efforts to promote more sustainable trajectories of urban expansion.

Direct and Spillover Effects of Urban Land Expansion on Habitat Quality in Chengdu-Chongqing Urban Agglomeration

Urban land expansion has dramatically changed the spatial distribution patterns and functional structure of habitats. Previous studies on the spatial externality effect of urban land expansion on the habitat quality of urban agglomerations are still insufficient. With the use of remote sensing and statistical data from 2000 to 2018, this study explored the evolutionary relationship between urban land expansion and habitat quality in the Chengdu-Chongqing urban agglomeration (CUA) using the bivariate local autocorrelation method and spatial Durbin model. Partial differential equation decomposition of the local and spatial spillover effects was implemented to investigate the marginal effects of the influencing factors. The highlights of the results are as follows: CUA’s urban land increased by 2890.42 km2 from 2000 to 2018, mainly caused by urban encroachment over farmland and grassland. New urban lands were situated primarily in the main urban districts of Chengdu and Chongqing; urban expansion intensity slowed to 7.64% in 2010–2018, declining by 53.95% from 2000 to 2010. The average habitat quality decreased to 0.905, and two “ring-shaped decline areas” were formed around the main urban areas of Chengdu and Chongqing. “Low-High” and “Low-Low” clusters were the main associations between urban land expansion and habitat quality changes. The impact of urban land expansion on local habitat quality changed from insignificant to negative, while its spatial spillover effects over adjacent areas have increased the negative environmental externalities to habitat quality in adjacent areas through spatial spillovers. Our findings provide evidence for urban agglomerations such as CUA that are still being cultivated to carry out cross-city joint protection strategies of habitat quality, also proving that habitat quality protection should be an integration of urban expansion regulation, natural adaptation and socioeconomic adjustment.

Urbanizing the floodplain: global changes of imperviousness in flood-prone areas

Cities have historically developed close to rivers and coasts, increasing human exposure to flooding. That exposure is exacerbated by changes in climate and population, and by urban encroachment on floodplains. Although the mechanisms of how urbanization affects flooding are relatively well understood, there have been limited efforts to assess the magnitude of floodplain encroachment globally and how it has changed in both space and time. Highly resolved global datasets of both flood hazard and changes in urban area from 1985 to 2015 are now available, enabling the reconstruction of the history of floodplain encroachment at high spatial resolutions. Here we show that the urbanized area in floodplains that have an average probability of flooding of 1/100 years, has almost doubled since 1985. Further, the rate of urban expansion into these floodplains increased by a factor of 1.5 after the year 2000. We also find that urbanization rates were highest in the most hazardous areas of floodplains, with population growth in these urban floodplains suggesting an accompanying increase in population density. These results reveal the scope, trajectory and extent of global floodplain encroachment. With tangible implications for flood risk management, these data could be directly used with integrated models to assess adaptation pathways for urban flooding.

Environmental Impacts of Urbanization Encroachment in the Lowlands of Khyber Pakhtunkhwa, Pakistan

Urban encroachment due to urban sprawl and unchecked expansion in built-up areas is one of the top challenges developing countries such as Pakistan face. The fertile agricultural land is continuously converting into built-up areas reducing the capacity of food production and bringing down the livelihood opportunities associated with agricultural land. Pakistan is an agricultural country with extensive fertile areas. The GDP share of agriculture is more than 20%, and it engages more than half of the country’s total labor force, producing a handsome foreign exchange. However, this fertile and productive land is now altering due to urbanization encroachment. The primary purpose of this study was to assess the level of urbanization encroachment and its temporal dynamics in the lowlands of Khyber Pakhtunkhwa. The sample area of District Peshawar was selected for this purpose. First, the study’s objective was to detect the district’s temporal dynamics in the land-use pattern. Secondly, the quantification of agricultural land converted to built-up in District Peshawar was also considered. The study of urbanization encroachment in temporal dynamics focused on the conversion of agricultural land-use change using high-resolution satellite images (Arc GIS 10.5), a detailed questionnaire survey, and interviews, and focus group discussions were conducted to obtain more profound insight into the study area. SPSS (Statistical Package for Social Sciences), ANOVA, and regression models were applied where needed. For the agricultural land investigation, data from the landowners were also incorporated to learn the size of the lands they currently hold. To claw out the fragmentation of the land, the previous status of the land, its selling, purchasing, and the causes thereof, have also been probed. The results show that 46.35 sq. km of the land area has been built-up since the first census in 1981. In 2019, it increased by 173.3049 sq. km in District Peshawar against the total area of 1257 sq. km. In the sample area, the fertile agricultural land shows a change five times greater than the population increase. The land is continuously reduced and utilized for different purposes. The land values also appeal to the land owners for handsome returns, which is another crucial factor of urban encroachment over the fertile agricultural area. A proper and active regularity authority is recommended, and policies for land transformation from agriculture to built-up coverings should be formed. Decentralization of facilities, subsidies, and incentives to the farmers are recommended to slow down the speed of land conversion.