Expansion Of Urban Areas Research Articles

Assessing the vulnerability of flash floods to climate change in arid zones: Amman–Zarqa Basin, Jordan

Abstract The objective of this study was to evaluate the sensitivity of flash floods to future climate change in the Amman–Zarqa Basin, Jordan. Historical daily rainfall and temperature data from 1970 to 2018 were collected, along with projected daily data derived from general circulation models (GCMs) forecast spanning 2019–2060. The methodology involved analyzing historical and model forecast data, conducting trend analysis, mapping changes in land use, estimating runoff volume, selecting indicators, assigning their weights through the analytical hierarchy process, and generating vulnerability maps. Analysis of precipitation trends revealed a 14.61% decrease in total annual rainfall over the past 48 years; however, future projections indicate a 5.26% increase. Downstream sub-catchments in the arid portion are projected to receive higher rainfall, while upstream sub-catchments are expected to experience a substantial decline, resulting in an overall reduction in runoff. Moreover, our findings demonstrate a rising trend in mean temperature, which is expected to persist. Remote sensing data indicate a 14.76% expansion of urban areas, indicative of rapid population growth. Although no highly vulnerable sub-catchments were identified, downstream sub-catchments 8 and 9 exhibited moderate vulnerability to flash floods, which can be attributed to the increase in rainfall and insufficient stormwater infrastructure.

Spatiotemporal Characteristics and Influencing Factors of Urban Heat Island Based on Geographically Weighted Regression Model: A Case Study of Urumqi City

Rapid urbanization threatens the ecological environment and quality of life by significantly altering land use and land cover (LULC) and heat distribution. One of the most significant environmental consequences of urbanization is the urban heat island effect (UHI). This study investigated the spatiotemporal characteristics of the SUHI and its relationship with land use types from 2000 to 2020 in Urumqi City, located in an arid and semi-arid region of northwestern China. Additionally, the ordinary least squares (OLS) and geographically weighted regression (GWR) models were used to quantify the relationship between the land surface temperature (LST) and influencing factors. The results showed that the area of the lower surface temperature classes has decreased significantly. In comparison, the area of the higher surface temperature classes has experienced a steady rise over the last two decades. From 2000 to 2020, the share of the area occupied by the temperature range <30 °C decreased by 67.09%. In addition, the LST varied significantly from one category of land use to another. The average LST of built-up land and unused land was higher than the average LST of other land use types in all years, while the average LST of grassland, forest land, and water bodies was significantly lower. Finally, the results of the GWR model showed that R2 and adjusted R2 of the GWR were 0.75 and 0.73, obviously larger than the 0.58 of the OLS models. The GWR model’s higher R2 and adjusted R2 compared to the OLS model indicates that the relationship between LST and the influencing factors underlying the model may exhibit spatial non-stationarity, and the GWR model performs better than the OLS model. The results of both OLS and GWR models show that the normalized difference vegetation index (NDVI) and slope were negatively correlated with LST, while the urban index (UI) and normalized difference built-up index (NDBI) were positively correlated with LST. The findings of the study indicate that increasing green spaces and limiting the unplanned expansion of urban areas are effective measures to mitigate the UHIs in the study area. The results of the study may provide valuable insights into the spatiotemporal characteristics of the UHI and its drivers. Understanding the spatiotemporal characteristics of the UHI can help urban planners, policymakers, and scientists develop more effective urban cooling strategies and improve the urban thermal environment.

Ozone Sensitivity Analysis and Ozone Formation Regimes Division in the Beijing–Tianjin–Hebei Region Based on Satellite Remote Sensing Data

In recent years, the concentration of surface ozone (O3) has increased in China. The formation regime of ozone is closely related to the ratio of volatile organic compounds (VOCs) to nitrogen oxides (NOx). To explain this increase in ozone, we determined the sensitivity of ozone generation by determining the regional threshold of the ratio of formaldehyde to nitrogen dioxide (HCHO/NO2) in the satellite troposphere. The different FNR(HCHO/NO2) ratio ranges indicate three formation regimes: VOC limited, transitional, and NOx limited. Polynomial fitting models were used to determine the threshold range for the transitional regime in the BTH region (2.0, 3.1). The ozone formation regime in the BTH (Beijing–Tianjin–Hebei) region mainly exhibited a transitional and NOx-limited regime. VOC-limited regimes are mainly distributed in urban agglomeration areas, transitional regimes are mainly concentrated in urban expansion areas, and non-urban areas are mainly controlled by NOx. The concentrations of HCHO and NO2 in the BTH region showed a trend of urban agglomeration areas > urban expansion areas > non-urban areas in different land types from 2019 to 2022, whereas the FNR showed an opposite trend.

Identification of Urban Heat Island Effect on Land Use Land Cover Changes

The effect of urban heat island (UHI), characterized by higher temperatures in urban areas compared to surrounding rural areas, is a significant consequence of rapid urbanization. As cities continue to grow and attract more people, the UHI effect intensifies due to increased heat-absorbing surfaces and reduced green spaces. This can lead to various environmental and health issues, specifically affecting vulnerable populations. This study investigates the phenomenon of UHIs in the Kalutara district of Sri Lanka and examines the relationship between Land Use Land Cover (LULC) changes, urbanization, and the intensity of UHIs. Landsat satellite images from 1991, 2001, 2011, and 2021 were analyzed using Remote Sensing and Geographic Information System (GIS) techniques to create land Surface Temperature (LST) maps and LULC maps. The results show a significant expansion of urban areas and a reduction in green areas within the Kalutara district over the study period, accompanied by an increase in the intensity of UHIs. Regression analysis indicates a negative correlation between the percentage of green areas and LST, highlighting the cooling effect of vegetation. Conversely, a positive correlation is found between LST and the percentage of urban areas. The research demonstrates the spread of UHIs from limited urban centers in 1991 to larger urban areas and adjacent regions in 2021. The findings emphasize the need for sustainable land management practices, preservation of green areas, and effective urban planning strategies to mitigate the adverse effects of UHIs.

Shine: A deep learning-based accessible parking management system

The ongoing expansion of urban areas facilitated by advancements in science and technology has resulted in a considerable increase in the number of privately owned vehicles worldwide, including in South Korea. However, this gradual increment in the number of vehicles has inevitably led to parking-related issues, including the abuse of disabled parking spaces (hereafter referred to as accessible parking spaces) designated for individuals with disabilities. Traditional license plate recognition (LPR) systems have proven inefficient in addressing such a problem in real-time due to the high frame rate of surveillance cameras, the presence of natural and artificial noise, and variations in lighting and weather conditions that impede detection and recognition by these systems. With the growing concept of parking 4.0, many sensors, IoT and deep learning-based approaches have been applied to automatic LPR and parking management systems. Nonetheless, the studies show a need for a robust and efficient model for managing accessible parking spaces in South Korea. To address this, we have proposed a novel system called, ‘Shine’, which uses the deep learning-based object detection algorithm for detecting the vehicle, license plate, and disability badges (referred to as cards, badges, or access badges hereafter) and verifies the rights of the driver to use accessible parking spaces by coordinating with the central server. Our model, which achieves a mean average precision of 92.16%, is expected to address the issue of accessible parking space abuse and contributes significantly towards efficient and effective parking management in urban environments.

Characterizing land use transition in China by accounting for the conflicts underlying land use structure and function

Human activities and global changes have undergone significant transformations in land systems. It is imperative to comprehend the intricacies of land use transitions (LUT), as they serve as indicators of the evolving dynamics within the complex human-environmental relationship. In this study, we adopt the conflict-coordination theoretical framework to delve into the role of land-use conflicts (LUC) in driving LUT. Our investigation involves the quantification of LUT and the assessment of LUC within China, spanning from 1980 to 2020. Subsequently, we scrutinized the interplay between LUT and LUC using Spearman correlation analysis and the Wilcoxon test. Our findings reveal that greater diversity in land-use structure can be attributed to ecological land fragmentation and the restoration of unused land, while the expansion of urban and cropland areas contributes to a less diverse land-use pattern. Furthermore, there is a discernible upward trend in land use function. Although the overall degree of LUC in China is relatively mild, there is a noticeable upward trajectory over the past four decades. More pronounced conflicts within land-use patterns promote a diversified land-use pattern, while conflicts arising from competing land-use functions elevate the level of land-use functionality. Moreover, a dynamic interplay between land-use transitions and conflicts becomes evident, with intense conflicts within land-use patterns weakening land-use functionality, and imbalances in functionality driving greater diversity in land-use patterns. Our research introduces an innovative analytical framework that elucidates LUT through the lens of LUC, with the potential for broader applicability across different regions. This framework not only enhances our understanding of LUT but also provides valuable scientific guidance for the effective management of conflicts to promote the sustainable development of land resources.

The Use of UAVs to Obtain Necessary Information for Flooding Studies: The Case Study of Somes River, Floresti, Romania

Floods are natural disasters that cause damage, loss of life, and economic problems throughout the world. Part of these losses can be minimized with the help of different methodologies and tools used to prepare simulations, analyses, and data monitoring to predict such phenomena in time. The metropolitan area of Cluj-Napoca, Romania, is the study area of this paper and it is located in Floresti, the largest rural settlement in Romania. In this area, changes in urbanization, land use, and the expansion of urban areas in a chaotic mode represent a problem. This study focuses on an area prone to flooding due to its proximity to the Somes River. Previous events of this type have caused economic losses that must be considered. This approach combines photogrammetric methods for obtaining data from the field with topographical methods for establishing control points and GIS methods for data processing, modeling, and simulation to obtain the necessary data for flood prevention and intervention.

Effects of the urban environment on the developmental stability, size and body condition of dice snakes (Natrix tessellata) living in artificial lakeside habitats

The expansion of urban areas leads to a decrease in natural habitats, resulting some species to live in urban environments. Novel environmental factors might influence their size, body condition and development stability. The environmentally induced developmental instability can be indicated by fluctuating symmetry, which means random deviations from perfect symmetry in bilaterally symmetric creatures.Our research aimed to explore the impact of various urbanization factors on snake populations within urban habitats. To achieve this, we examined how dice snake (Natrix tessellata) populations differ in their asymmetry, body condition and size in a lake characterized by highly modified lakeside habitats, intensive urban land use, and severe human disturbance. The average size, body condition and two asymmetry indices were determined for 25 dice snake populations around Lake Balaton in Hungary. The impacts of the urban environment were characterized by land use and local variables, and the risk of road kill was also estimated.Populations living in areas with a more intensive road network or near a main road showed more asymmetric traits. It is conceivable that pollutants from vehicle traffic lead to developmental disorders that manifest themselves in more asymmetric individuals. In addition, the body condition of snakes was negatively correlated with the area of the harbours, possibly due to the intensive boat traffic and human disturbance. Finally, populations living in more urbanized areas had larger body sizes meaning that despite its negative effects through pollution, anthropized areas can provide a suitable habitat for dice snakes.While urban artificial surroundings can function as suitable habitats, our results confirm that urban environmental factors have negative effects on dice snakes. Our findings indicate that the density of road networks and the proximity of roads have adverse effects on the developmental stability of urban snakes. This underscores the need to implement conservation actions to mitigate the negative effects of roads on biodiversity.

Plastic ingestion in giant tortoises: An example of a novel anthropogenic impact for Galapagos wildlife

The human population of Galapagos has rapidly increased in the last decades accelerating the anthropogenic pressures on the archipelago's natural resources. The growing human footprint, including inadequate management of garbage, may lead to conservation conflicts. Here, we assessed the ingestion of debris by Western Santa Cruz giant tortoises (Chelonoidis porteri) within human-modified and protected areas. Additionally, we characterized environmental debris and quantified tortoise abundance together with tortoise fecal samples. We processed a total of 6629 fecal samples along a gradient of anthropogenic disturbance based on human debris presence. We found 590 pieces of debris in samples within human-modified areas (mean of 3.97 items/kg of feces) and only two pieces in the protected area (mean of 0.08 items/kg of feces). Plastic waste was the predominant category in feces within the anthropic area (86.3%; n = 511), followed by cloth, metal, paper, synthetic rubber, construction materials, and glass. On average, the proportion of plastic was higher in feces (84%) than it was in environmental debris (67%), denoting that plastics are more readily ingested than other types of debris. We also found that green, white, and light blue plastics were consumed more often than their prevalence in the environment, suggesting color discrimination. Tortoise abundance was higher in the protected area when compared to the human-modified area; however, recapture rates were higher in anthropized landscapes which increases tortoise exposure to plastics and other human associated threats. Our results indicate that plastics are frequently consumed by tortoises in the polluted anthropic areas of western Santa Cruz, but scarce in protected areas. More research is needed to understand the negative impacts associated with plastics for Galapagos terrestrial species. We encourage local stakeholders to implement current policies limiting expansion of urban areas, plastic use, and improving waste management systems to minimize threats to human and animal health.

Techno-environmental assessment of outdoor glazing cover of a building with multi-passive solar systems

With the expansion of urban areas and the growth of welfare levels, the energy consumption of buildings will increase in the next decades. Passive solar systems are one of the technologies to reduce energy consumption. In this paper, a building-integrated passive solar energy technology was studied in six different Scenarios including photovoltaic (PV) and Building Integrated Photovoltaic (BIPV) glazing windows, PV glazing façades, PV glazing double-skin façade, and simple double-skin façade. They were compared to the base model, respectively. It has been determined each scenario may be superior in one or more cases compared to other scenarios. Results show in the BIPV model, the inside temperature of the building was decreased by up to 1.3 degrees. The annual energy consumption for heating in the double-skin Scenario was reduced by about 17% compared to the base Scenario. The annual energy consumption for cooling in the building with PV glazing façade compared to the base scenario has decreased by more than 21%. Annually, CO2 emissions by 140%, and the cost of energy have decreased by 3493.4$ in building with PV glazing double skin facade and building with PV glazing facade, respectively. Finally, the shadow effect of the energy of the building is examined.

State of urbanization in Nepal: The official definition and reality

Nepali government's official delineation of several human settlements as new urban areas has been questionable because many important criteria such as urban infrastructure and services, open space, population density, and economic viability are not thoroughly analyzed while defining what is urban. Many settlements in Nepal officially defined as urban, often driven by political considerations, are operating in the rural framework forming ruralopolises. This paper analyzes various criteria needed for defining urbanization that are internationally accepted to assess Nepal's official definition of urban settlements. Urban areas have been expanding in Nepal at the cost of agricultural, forest, and shrubland land uses. We found that using the road as the main variable but keeping agriculture, forest, and shrubland constant, a one percent increase in road length will lead to an increase in the geographical area of urban settlements by 0.47 percent. Spatial visualization of urban expansion and road network clearly indicates that new urban areas that are radiating from the established large urban centers are expanding along the road network on land that is relatively flat with less than 15° slopes to the horizontal plane. In the mountainous region, undulated landscape, low-density population, and lack of road infrastructure, among other factors, have limited the expansion of urban areas. To develop a sustainable urban development plan, this paper detailed land use and land cover analyses of all seven provinces. Using 10 × 10 m sentinel satellite imagery, the paper presents analyses of land use and cover changes from 2017 to 2021. These years were chosen because rapid urbanization started after the promulgation of the new constitution in 2015. However, its implementation and state restructuring began only after 2017. The urban areas, as defined by the government, expanded rapidly in the Tarai and mid-Hills regions from 23 % in 2014 to 66.08 % in 2015.

Model of social sustainability for Dhaka city, Bangladesh

The expansion and development of urban areas require a strategic priority of social sustainability to protect their inhabitants’ quality of life and well-being. However, social sustainability in urban areas, particularly in developing regions, becomes more apparent due to the social problems caused by rapid urbanization. The main objective of this study is to propose a model of social sustainability for socially sustainable cities in developing regions. To accomplish this objective, a quantitative research strategy was used to gather responses from residents of Dhaka city via a structured questionnaire survey; Dhaka served as a representative city from a developing region. This study used a multistage sampling technique to select 564 residents of Dhaka city. The results showed that social sustainability significantly influenced socially sustainable urban development in Dhaka, determining 38 indicators under 11 social sustainability themes using exploratory and confirmatory factor analysis utilizing structural equation modeling. The implication of this model serves as a guiding framework intended to assist governmental bodies, policymakers, and urban planners in navigating the path toward achieving sustainable cities. Likewise, the proposed model provides policy implications for enacting and revising urban sector policies in developing regions, considering the fundamental themes of social sustainability. Eventually, this study contributes to implementing Sustainable Cities and Communities (SDG 11) in the 2030 Agenda for Sustainable Development, bridging the gap between urbanization and sustainable urban societies. Also, this model is a valuable tool for promoting socially sustainable urban development in developing regions.

Atmospheric Transport of Adulticides Used to Control Mosquito Populations across an Urban Metropolitan Area

Pesticides registered with the U.S. EPA for mosquito control are called adulticides and are released directly into the atmosphere as aerosols to target flying mosquitos. This adulticide application approach is different from traditional (agricultural) pesticide applications, yet the fate and transport of adulticides in large metropolitan areas is largely unknown. The Houston Metropolitan Area encompasses eight counties, many of which require county-level mosquito control programs that utilize adulticides. Malathion and permethrin are the primary adulticides used by Harris County (HC) in Houston, TX, USA. Houston, like many other metropolitan areas, has an urban atmosphere supporting the oxidation of both gas and particle phase pollutants. During the summer mosquito season of 2016, we collected atmospheric total suspended particulate matter (PM) samples at Jones Forest (JF), located in Montgomery County (directly north of HC) to investigate the atmospheric transport and oxidation of adulticides in an urban atmosphere. Despite HC alternating the adulticide treatment schedule, we measured permethrin, malathion, and malaoxon (oxidation product of malathion), throughout the sampling campaign. These consistent measurements, in conjunction with 12 h backward trajectories, support the conclusion that JF is influenced by other county-level mosquito-control programs and agricultural pesticide use. This cross-county transport may impact adulticide effectiveness by supporting pesticide resistance in mosquito populations due to repeated exposures to pesticides. This study highlights the need for mosquito control collaborations between counties, especially in areas of urban expansion overlapping with agricultural activities.

Spectral Mixture Analysis (SMA) Model for Extracting Urban Fractions from Landsat and Sentinel-2A Images in the Al-Ahsa Oasis, Eastern Region of Saudi Arabia

The rapid expansion of urban areas is a major driver of deforestation and other associated damage to the local ecosystem and environment in arid and semi-arid oases, especially in the eastern region of Saudi Arabia. It is therefore necessary to accurately map and monitor urban areas to maintain the ecosystem services in these oases. In this study, built-up areas were mapped using a spectral mixture analysis (SMA) model in the Al-Ahsa Oasis in the eastern region of Saudi Arabia by analyzing Landsat images, including Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+), Operational Land Imager (OLI), and Sentinel-2A images, acquired between 1990 and 2020. Principle component analysis (PCA) was used to build and select endmembers, and then SMA was applied to each image to extract urban/built-up fractions. In addition, this study also discusses the possible driving forces of the urban dynamics. SMA classification performance was assessed using fraction error maps and a confusion matrix. The results show that the Al-Ahsa Oasis’ urban area had been rapidly expanding during 2010–2020 with an expansion rate of nearly 9%. The results also indicated that the SMA model provides high precisions (overall accuracy = ~95% to 100%) for an oasis urban mapping in an arid and semi-arid region that is disturbed by the mixed-pixel problem, such as the Al-Ahsa Oasis in eastern Saudi Arabia.

A GIS Approach for Analysis of Traffic Accident Hotspots in Abha and Bisha Cities, Saudi Arabia

Road traffic accidents present substantial global challenges, encompassing a wide range of consequences that have implications for the economy, public health, the environment, and society. The present study is focused on the phenomenon of rapid urbanization in Abha and Bisha, two cities located in the Kingdom of Saudi Arabia. These cities have witnessed a substantial growth in urbanization, with a notable increase of 225% over a span of 40 years. The expansion of urban areas has given rise to significant concerns regarding the density of the road infrastructure, which has been further exacerbated by an increase in the volume of vehicles. Consequently, this has led to a notable escalation in traffic-related issues and accidents. Analysis reveals that traffic accidents are concentrated in specific areas, with hotspots primarily located in the western regions of Abha and Bisha, while cold spots are concentrated in the northern areas. Furthermore, a strong positive correlation (r = 0.93) is observed between the number of traffic accidents and road type, with over half of the accidents occurring on highways. Notably, the highways in Abha and Bisha predominantly follow a direction from southwest to northeast at a 71.1° angle. In conclusion, this research offers significant findings regarding the prevalence and determinants of traffic accidents in Abha and Bisha, emphasizing the need for effective traffic management strategies to enhance road safety and mitigate the associated risks.

Simulating the impact of urban expansion on ecosystem services in Chinese urban agglomerations: A multi-scenario perspective

Urban agglomerations (UAs) are the most active areas of urban land expansion. The encroachment of urban land on large-scale ecological land has caused severe ecological problems and threatens the ecological sustainability of UAs. Understanding the characteristics of multi-scenario urban land expansion and its impacts on ecosystem services (ESs) in UAs can provide guidance for formulating ecologically sustainable management and control policies in UAs. However, few studies have simulated the characteristics of multi-scenario urban expansion and determined its impacts on ESs in Chinese UAs. In this study, we used a patch-generating land use simulation (PLUS) model and the benefit transfer method to conduct a multi-scenario simulation of urban land expansion in Chinese UAs in 2030 and measure its impacts on ESs. The simulation indicates that urban land continued to expand and expanded most severely under an urban development scenario. In the future, under an ecological protection scenario, ESs would be maintained at their highest levels. In general, the global Moran's I indices of the ESs and urban expansion were negative at the 0.001 significance level, indicating that ESs and urban expansion in Chinese UAs were strongly spatially concentrated. The impacts of urban expansion on the ESs varied among the UAs. In national and regional UAs, ESs were affected negatively by patch density (PD) and percentage of like adjacencies (PLADJ), whereas the loss of ESs in local UAs was not only affected by PD and PLADJ, but also by the proportion of urban land. These findings provide effective guidance for improving ESs, urban development planning, and high-quality development in Chinese UAs.

Mussel-inspired antibacterial sponge for highly efficient water purification and sterilization

With the current expansion of urban areas and industrial development, the increasing discharge of wastewater containing bacteria poses a threat to human health. Although substantial advancements have been made in antibacterial materials, there is still a need for an efficient method that can thoroughly remove bacteria through sterilization and adsorption during wastewater treatment. Here, we report a mussel-inspired antibacterial sponge with outstanding antibacterial efficiency exceeding 95% and a high removal ratio of the bacterial corpses for water purification after contacting for 30 min. The high-efficient antibacterial performance is attributed to the stable releasing property of Ag+ and the charge interaction with quaternary amine salts. Combining the key features, including high-efficient, synergistic mechanism, and corpse capture, the antibacterial sponge shows excellent disinfection effects. This study provides a new method for water purification without bacterial residue.

Simulating the dynamics of urban land quantity in China from 2020 to 2070 under the Shared Socioeconomic Pathways

Rapid expansion of urban land areas in the past few decades has exerted great pressure on regional environment, and simulating urban land dynamics is of great significance for sustainable urban development. However, the differences in driving forces of urban land among cities were not fully considered in previous simulations. Here, we adopted a data-driven approach combined with Monte Carlo method to simulate future urban land quantity in China at the city scale under the Shared Socioeconomic Pathways (SSPs). The results show that the total urban land area of China will reach 154,105 to 289,932 km2 by 2070 under different scenarios, 1.8 to 3.4 times that of 2020. Compared with the traditional methods at the national or regional scale, the clustering method used to classify urban land expansion types can better fit the urban land change of each city. Meanwhile, the iterative simuation of future urban land quantity can depict the slowing down trend of urban land expansion. This study provides the amount of urban land from 2020 to 2070 at the city scale, confirming a close relationship between urban development and selection of urbanization pathway. Choosing a more sustainable path of social and economic development is conducive to restraining the rapid expansion of urban land in China. It is particularly important to formulate city-specific sustainable development strategies according to the trend of urban land dynamics over time.

Mechanisms influencing changes in water cycle processes in the changing environment of the Songnen Plain, China

The process of the land-surface water cycle has undergone substantial changes as a result of climate change and human activities. Disclosing the evolution of the water cycle and its mechanisms in a changing environment is a challenging and hot issue in hydrological science research, which is essential for regional ecological protection and sustainable development. Based on the MIKE SHE/MIKE 11 model, multi-source data are used to simulate the water cycle change process in the Songnen Plain from 1980 to 2020. The study indicates that groundwater data inverted by GRACE and GLDAS data is relatively accurate, which effectively reflects the process of groundwater storage change in particular regions. Moreover, the surface-groundwater coupling model employs strongly correlated inverse groundwater data to simulate the water cycle change process in the Songnen Plain, yielding highly accurate simulation results. In terms of the impact of climate change and human activities on the water cycle process, climate change is the primary cause of changes in the regional water cycle, with contributions to actual evapotranspiration, surface runoff, and groundwater level of 77.04 %, 70.88 %, and 67.86 %, respectively. Nonetheless, as human activities intensify, their impact on the water cycle process progressively increases. From the perspective of the mechanism of water cycle change, the decrease in wetland area, the expansion of urban areas, and the increase in urban water demand are the primary causes of regional water cycle change between 1995 and 2010. The establishment of water conservation facilities and the dramatic increase in paddy field area are the primary causes of the water cycle change between 2011 and 2020. This study combines multi-source remote sensing data with hydrological models to simulate medium- and large-scale water cycle processes, providing new concepts and methods for examining water cycle processes in water-scarce areas.

Resetting of soil compositions by irrigation in urban watersheds: Evidence from Sr isotope variations in Austin, TX

Human activities in urban areas disturb the natural landscape upon which they develop, disrupting pedogenic processes and ultimately limiting the ecosystem services urban soils provide. To better understand the impacts on and resiliency of soils in response to urban development, it is essential to understand the processes by which and degree to which soil physical and chemical properties are altered in urban systems. Here, we apply the source-tracing capabilities of Sr isotopes (87Sr/86Sr) to understand the impacts of urban processes on the composition of soils in eight watersheds in Austin, Texas. We evaluate natural and anthropogenic Sr sources in watersheds spanning a wide range of urbanization, comparing soils by variations in their natural (including mineralogy, thickness, soil type, and watershed) and anthropogenic (including irrigation, soil amendments, and fertilization) characteristics. A strong positive correlation between soil thickness and 87Sr/86Sr is observed among unirrigated soils (R2 = 0.83). In contrast, this relationship is not observed among irrigated soils (R2 = 0.004). 95 % of 42 irrigated soil samples have 87Sr/86Sr values approaching or within the range for municipal supply water. These results indicate soil interaction with municipal water through irrigation and/or water infrastructure leakage. Soils irrigated with municipal water have elevated 87Sr/86Sr values relative to unirrigated soils in seven of eight watersheds. We propose that original soil 87Sr/86Sr values are partially to completely reset by irrigation with municipal water via ion exchange processes. Our results demonstrate that in urban systems, Sr isotopes can serve as an environmental tracer to assess the overprint of urbanization on natural soil characteristics. In the Austin region, resetting of natural soil compositions via urban development is extensive, and the continued expansion of urban areas and irrigation systems may affect the ability of soils to retain nutrients, filter contaminants, and provide other ecosystem services that support environmental resilience.