Semi-arid City Research Articles

INTEGRATING SOCIO-ECOLOGICAL CONNECTIONS INTO URBAN PLANNING

Urban ecology increasingly recognizes urban vacant lots as spaces with untapped aesthetic, social, and environmental potentials. This study focuses on strategies for converting these lots into green areas in Mossoró, a semi-arid city in Brazil, by analyzing urban connectivity patterns. Using a Geographic Information System, the study identifies priority areas for green space conversion based on factors like urban planning, density, land cover, and vacant lots. The analysis revealed 429 hectares of highly suitable land for conversion. A resistance surface was also created, factoring in public amenities and urban infrastructure, which showed varying levels of resistance to human movement. Areas with well-developed infrastructure had lower resistance, encouraging human and ecological movement. Connectivity modeling highlighted a need for more green infrastructure, especially in peripheral regions, to address socio-spatial fragmentation and enhance urban resilience in Mossoró. Keywords: Connectivity, Green Infrastructure, Urban Vacant Lots.

Carbon Sequestration and Storage of Urban Trees in a Polluted Semiarid City

Cities play a critical role in anthropogenic CO2 emissions, which exacerbate climate change and impact urban populations. Urban green infrastructure, such as urban trees, provides essential ecosystem services, including reducing atmospheric CO2 levels. However, there is a significant knowledge gap regarding the impact of urban trees on climate change in semiarid, polluted cities like Tehran, the capital and largest metropolis of the Middle East. This study assesses the carbon sequestration and storage potential of Tehran’s urban infrastructure using the i-Tree Eco model. A randomized cluster sampling method was employed, collecting data on species composition, diameter at breast height (DBH), and total tree height. The results indicate that Tehran’s urban trees sequester approximately 60,102 tons of carbon per year, equivalent to 220,393 tons of CO2. The net carbon storage in urban trees is about 254,579 tons, equivalent to 933,455 tons of CO2. Parks and urban green spaces demonstrate the highest rate of carbon sequestration per hectare, followed by urban services land use. Prioritizing the planting of species with high sequestration rates like Cupressus arizonica (Arizona cypress) and Cupressus sempervirens L. var. horizontalis (Mediterranean cypress) could enhance carbon sequestration efforts in Tehran. These data provide valuable insights into the carbon sequestration potential and environmental impact of different land use types, and may aid in the development of effective environmental policies and land management strategies in semiarid urban areas and other cities in similar settings.

Seasonal dynamics of land surface temperature and urban thermal comfort with land use land cover pattern in semi-arid Indian cities: Insights for sustainable Urban Management

The cities in semi-arid and arid regions generally exhibit distinctive land use land cover (LULC) pattern and seasonal variation in urban thermal comfort (UTC) and land surface temperature (LST). This study examines the seasonal variation in LST and UTC and quantify the importance of LULC pattern in influencing LST in eight Indian semi-arid cities using Landsat 8 datasets. Random forest regression (RFR) model has been applied to quantify the influence of LULC in determining LST. The study shows that bare soil and open spaces in outskirts of selected cities have comparatively high LST than the core of cities. The mean LST varies seasonally from 12.84 °C in Udaipur to 26.18 °C in Jaipur in winter and summer. Analysis of UTC shows that autumn and winter seasons have better UTC than spring and summer seasons. RFR analysis shows a robust correlation (R2 > 0.85) between LULC and LST across all cities. Notably, built-up areas, open land, and vegetation cover exert the greatest influence on LST. Study suggests that targeted LULC planning may effectively address UTC problem in semi-arid cities and enhance sustainability. Study may help in understanding the seasonality thermal environment and assist in mitigating UHI and maintain UTC in these cities.

A multi-objective optimization approach for harnessing rainwater in changing climate

As the world grapples with the profound impacts of climate change, water scarcity has become a pressing issue. However, there is a shortage of in-depth research on the trade-offs between water resource dependence and the economic, ecological, and social needs of arid and semi-arid regions like Lanzhou, China. Flower cultivation in Lanzhou relies heavily on the Yellow River, often overlooking the potential of natural rainfall. Here we first calibrated a water balance model through artificial precipitation experiments in a Soil and Water Conservation Demonstration Park in Lanzhou. We then developed a multi-objective optimization model to balance the cost-benefit considerations of various plausible measures across economic, ecological, and social dimensions in the searching for solutions that are more adaptable to climate change and local development needs. Model simulations show that the solutions we designed can effectively manage water-shortage days, significantly reduce Yellow River water extraction, and improve cost-effectiveness, meeting 66%–80% of water needs for flower cultivation in the studied park. The findings highlight the potential of rainwater collection and utilization solutions to mitigate water scarcity in arid and semi-arid cities, thereby enriching water resource management.

Temperature modification of air pollutants and their synergistic effects on respiratory diseases in a semi-arid city in Northwest China.

Air pollutants and temperature are significant threats to public health, and the complex linkages between the environmental factors and their interactions harm respiratory diseases. This study is aimed to analyze the impact of air pollutants and meteorological factors on respiratory diseases and their synergistic effects in Dingxi, a city in northwestern China, from 2018 to 2020 using a generalized additive model (GAM). Relative risk (RR) was employed to quantitatively evaluate the temperature modification on the short-term effects of PM2.5 and O3 and the synergistic effects of air pollutants (PM2.5 and O3) and meteorological elements (temperature and relative humidity) on respiratory diseases. The results indicated that the RRs per inter-quatile range (IQR) rise in PM2.5 and O3 concentrations were (1.066, 95% CI: 1.009-1.127, lag2) and (1.037, 95% CI: 0.975-1.102, lag4) for respiratory diseases, respectively. Temperature stratification suggests that the influence of PM2.5 on respiratory diseases was significantly enhanced at low and moderate temperatures, and the risk of respiratory diseases caused by O3 was significantly increased at high temperatures. The synergy analysis demonstrated significant a synergistic effect of PM2.5 with low temperature and high relative humidity and an antagonistic effect of high relative humidity and O3 on respiratory diseases. The findings would provide a scientific basis for the impact of pollutants on respiratory diseases in Northwest China.

Study on the sustainable utilisation of water resources in semi-arid megacities of China based on water footprint

ABSTRACT As urbanisation continues to accelerate in China, the contradiction between rapid economic development and water scarcity in semi-arid cities is becoming increasingly evident. Consequently, the study of the relationship between water resources use and economic growth is of particular importance. Lanzhou City was selected as the study area, an evaluation index system was established to comprehensively evaluate the status of water resources utilisation, meanwhile, the water footprint method and Tapio decoupling model were adopted to measure the decoupling status between water utilisation and economic development from 2002 to 2021. The result showed that the total water footprint and per capita water footprint followed an increasing and then decreasing trend. The water footprint varied significantly by industrial sector, with agriculture accounting for 72.87% of total water use. The self-sufficiency rate of water resources was above 96.5%. The economic value increased substantially from 22.25 CNY/m3 in 2002 to 183.99 CNY/m3 in 2021. The water scarcity index and the pressure index were high, with annual mean values of 0.96 and 1, respectively. Water consumption and economic growth are generally decoupled weakly and strongly, with the number of strong decoupling occurrences increasing significantly from 2011 to 2021.

Seasonal quantification of Zn2+, Pb2+ and Cu2+ in urban dusts in a semiarid city in northwest Mexico

Arid and semi-arid cities are of especial interest due to the high amount of dusts that are deposited daily. Dust particles contain heavy metals that are considered potentially toxic elements (PTEs). High concentrations of PTEs in dust particles can result in risks to human health. Few studies have documented accumulation rates of atmospheric deposition and the influence of the North American Monsoon (NAM) in the movement of PTEs. Precipitation and urban runoff derived from the NAM play an important role in the deposition and resuspension of PTEs on urban surfaces. In this work, we quantified spatial and temporal patterns of Zn2+, Pb2+ and Cu2+ in an urban-rural gradient using ion-exchange resin (IER) collectors. Three monitoring periods were chosen and the samplings were carried out during the dry and rainy season in a city influenced by the NAM. Results from the IER collectors during the first monitoring period estimated 4.6 gZn2+ha−1 15 wk−1, 3.3 gPb2+ha-115 wk−1 and 3.7 gCu2+ha-115 wk−1. During the second period, the deposition rates were 5.6 gZn2+ha−1 37 wk−1, 1.1 gPb2+ha−1 37 wk−1 and 1.5 gCu2+ha−1 37 wk−1. Finally, in the third period 7.0 gZn2+ ha-117 wk−1, 0.6 gPb2+ha−1 17 wk−1 and 0.9 gCu2+ha−1 17 wk−1 were found. The central area of the city exhibited the highest deposition rates of PTEs influenced by precipitation and flood areas. Results of this work demonstrate the importance of the NAM in the movement of PTEs caused by precipitation and winds that promote the movement of particles in an urban area.

Sustainability indicators for evaluation of the Water-Energy-Food Nexus in urban agriculture

ABSTRACT Application of the Water-Energy-Food Nexus system is essential for addressing Water-Energy-Food Security and Environmental Protection in urban agricultural areas. However, there is currently no standardized framework for measuring and comparing sustainability indicators in these areas using the WEF Nexus practices. This study proposes sustainability measurement indicators to evaluate the WEF Nexus sustainability. The Analytical Hierarchy Process (AHP) was employed to identify the most crucial indicators for policymakers. The WEF nexus sustainability indicators were selected based on three dimensions of sustainability: social, environmental, and economic. The study focused on Varamin, a semi-arid city in Tehran that serves as a center for urban agriculture. Research results indicate that water-related components are crucial in arid and semi-arid regions. Based on the environmental sustainability indicators, pollution prevention, with a priority of 52.8%, is a critical component of sustainability. Finally, several key indicators are recommended for decision-makers to address sustainability. Allocating national budgets to create environmental policies and increasing public education on environmental issues are two priorities for achieving sustainability goals. However, future studies should utilize the Analytic Network Process (ANP), which enables interdependencies among decision components, as the AHP approach has some limitations.

Enhancing Urban Microclimates: Potential Benefits of Greenery Strategies in a Semi-Arid Environment

The emergence of sustainable development gives greenery an important role in urban planning, namely, by recognizing its environmental potential. However, the rapid urbanization that most cities have experienced in the absence of a sustainable urban policy has led to the establishment of urban realms dominated by manmade constructions. This research aims to evaluate the greening’s effect on the urban climate within the semi-arid city of Djelfa (Algeria) during summertime by assigning the most appropriate greenery strategy to ensure optimal thermal conditions. Using a numerical model built with the ENVI-met tool and validated through measurements in situ, four different scenarios are simulated, starting with the existing area and then changing the greenery strategies. The outputs include meteorological parameters and thermal comfort indices (PET and UTCI). The results show that the green area generates a cool island within the urban fabric, with the peak daytime air temperature being reduced by about 4.75 °C. Vegetation densification in the urban space has a higher cooling performance than greening buildings during the daytime. In the evening, the canopy effect of trees is lower and the wind velocity is reduced, which is the main driver in cooling the city at nighttime.

Use of Spatial Data in the Simulation of Domestic Water Demand in a Semiarid City: The Case of Campina Grande, Brazil

In the face of urban expansion, ensuring sustainable water consumption is paramount. This study aims to develop a domestic water demand forecast model that considers population heterogeneity and the urban area distribution in a city in the Brazilian Semiarid Region. The methodology comprises three main steps: (1) spatial data collection to identify explanatory variables for a future Land Use and Cover (LULC) model; (2) simulation of LULC data for 2030, 2040, and 2050 using the MOLUSCE plugin; and (3) estimation of domestic water demand based on projected urban area expansion and a linear regression model incorporating demographic indicators of household income, residents per household, total population, and gender. The results demonstrated a consistent LULC simulation, indicating an urban expansion of 4 km2 between 2030 and 2050, with reductions of 0.6 km2 in natural formations and 3.4 km2 in farming areas. Using LULC data, the study predicted a 14.21% increase in domestic water consumption in Campina Grande for 2050 compared to 2010, equivalent to an increase of 2,348,424.96 m3. Furthermore, the spatial analysis draws a spatial profile of water consumption among residents, highlighting the areas with the highest per capita consumption. Thus, this research offers a consistent approach to estimating water demand in regions with limited consumption data, providing valuable insights for decision-makers to consider in urban planning.

Source-specific health risks of PM2.5-bound toxic metals in Wuhai, a semi-arid city in northwest China

Quantifying the individual impact of each PM2.5-containing source on increasing health risk is essential for mitigating the harmful effects of atmospheric pollutants to human health. However, there remains a limited understanding of these health risks and their association with sources in semi-arid cities. To address this lack of understanding, 20 PM2.5-bound toxic metals (PTMs) were observed at six sampling sites in Wuhai, a typical semi-arid city in northwest China. The spatiotemporal variations, sources, and health risks of PTMs in Wuhai were investigated. Silicon (Si), Ca, Na, Al, Mg, and Fe were the predominant metals, accounting for 90.2 % of total metals. The contents of anthropogenic metals (Cd, Hg, and Pb) were higher during winter and autumn, whereas those of crustal metals (Si, Fe, Cu, Al, and Co) were higher during spring. The sources of PTMs in Wuhai were identified as soil sources (SS, 57.8 %), fugitive dust (FD, 23.3 %), vehicular emissions (VE, 13.4 %), metal smelting (MS, 3.9 %), and coal combustion (CC, 1.7 %). The hazard quotient of Mn and the hazard index of PTMs for children were >1, suggesting a non-carcinogenic health risk for children. The carcinogenic risk of Cr was >1 × 10−6, suggesting a Cr-associated carcinogenic risk for both adults and children in Wuhai. The main sources of non-carcinogenic risk included VE (62.5 %), SS (18.4 %), MS (11.3 %), CC (4.6 %), and FD (3.2 %). Alternatively, the main sources of carcinogenic risks included MS (53.8 %), VE (15.9 %), SS (13.9 %), CC (8.8 %), and FD (7.6 %). Overall, this study suggests that natural sources (SS and FD) are significant contributors to the health risks of PTMs in semi-arid cities. In conclusion, this study provides a comprehensive understanding of PTMs in semi-arid cities and reveals the contribution of each potential source to corresponding health risks.

The impact of urban tree shade on residential irrigation demand in a semi-arid Western U.S. City

This research examines how shade offsets residential landscape irrigation demand in a semi-arid city in the western United States. Using over 40,000 customer records from Denver Water, the relationship between residential irrigation and quantities of turf, tree canopy, and shade was studied, controlling for other factors related to the vegetation, parcel, and residence. LiDAR and imagery were used to model turf and tree canopy area and daily hours of shade falling on turf. Simultaneous Autoregression determined that each additional hour of daily building and tree shade falling on turf was associated with 18,672 and 11,683 fewer liters of irrigation per growing season, respectively, for the average parcel (turf area = 476 m2), equating to reductions of 39.2 and 24.5 liters per m2 per growing season for a single hour of shade. These numbers, incorporating spatial spillovers, suggest that for landscapes with both trees and turf—the dominant pattern in many Western US cities— mature trees could potentially be arranged to produce enough shade to reduce water demand of underlying turf by an amount equal to, or even greater than, the trees' irrigation demand. This benefit was not found for shorter and younger trees, which have higher irrigation rates per unit area.

Significant roles of aged dust aerosols on rapid nitrate formation under dry conditions in a semi-arid city

Mineral dust can accelerate secondary aerosol formation under humid conditions. However, it is unclear whether it can promote secondary aerosol formation under dry conditions. To investigate this issue, two years of comprehensive observations was conducted at a semi-arid site, near the dust source regions. Three types of episodes were selected: dust, anthropogenic-dominated, and mixed (mixed with dust and anthropogenic aerosols). Compared to anthropogenic-dominated episodes under humid conditions, rapid nitrate formation was still observed in mixed episodes under dry conditions, suggesting that active metallic oxides in dust, such as titanium dioxide, could promote photochemical reactions of nitrogen dioxide. The detailed evolutionary processes are further illustrated by a typical dust-to-mixed episode. After the arrival of the dust, titanium sharply increased ten-fold and rapid nitrate formation was observed, together with a rapid increase in the two most important photochemical pollutants, ozone and peroxyacetyl nitrate. The increased secondary organic carbon further illustrated that the suspended dust particles accelerated the atmospheric oxidative capacity, thereby enhancing secondary aerosol formation and eventually leading to haze pollution. These results differ from those in humid regions and therefore expand the scientific understanding of the impact of dust aerosols on haze pollution under dry conditions.

Spatiotemporal characteristics and driving mechanisms of PM10 in arid and semi-arid cities of northwest China

PM10 pollution is a pressing ecological concern within arid and semi-arid cities, adversely influencing the natural environment and human health. Based on the Geographically and Temporally Weighted Regression (GTWR) model, this study comparatively investigated the spatiotemporal dynamics of PM10 during non-dust and dust periods in five arid cities (Jiuquan, Jiayuguan, Zhangye, Jinchang, and Wuwei) and one semi-arid city (Lanzhou) in northwest China. Further, this study examined the critical mechanisms of PM10 via the GTWR and Geographic Detector model. A comparative analysis illustrated that dust period PM10 concentrations surpassed non-dust period concentrations. The annual average PM10 concentrations during the non-dust period wavily declined from 2015 to 2020, exhibiting significantly higher levels in the semi-arid city as opposed to arid cities. Conversely, during the dust period, PM10 levels rose initially between 2015 and 2017 and diminished from 2018 to 2020, with high concentration clusterings primarily observed in 2015–2016 in western arid cities, Jiuquan and Jiayuguan, in 2017–2019 in eastern cities, Wuwei and Lanzhou, and in 2020 in central arid cities, Jinchang and Zhangye. During the non-dust period from 2015 to 2020, the cumulative effects of single driving factors were ranked in the following order: soil moisture content (MOI), geographical location (LOC), precipitation (PRE), SO2, gross domestic product (GDP), wind speed (WS), and digital elevation (DEM) while during the dust period, the emphasized factors were ranked in the following order: MOI, LOC, PRE, WS, SO2, GDP, and DEM. The interaction between MOI and WS on PM10 was most noticeable in this study (non-dust: 0.787, dust: 0.832). Thus, MOI and WS are critical components in controlling PM10 pollution. The outcomes of this study can furnish theoretical foundations for ecological construction in Northwest China, unlock novel insights for ecological measures in other global arid and semi-arid cities.

Characteristics and sources of carbonaceous aerosols in a semi-arid city: Quantifying anthropogenic and meteorological impacts

Carbonaceous aerosols have great adverse impacts on air quality, human health, and climate. However, there is a limited understanding of carbonaceous aerosols in semi-arid areas. The correlation between carbonaceous aerosols and control measures is still unclear owing to the insufficient information regarding meteorological contribution. To reveal the complex relationship between control measures and carbonaceous aerosols, offline and online observations of carbonaceous aerosols were conducted from October 8, 2019 to October 7, 2020 in Hohhot, a semi-arid city. The characteristics and sources of carbonaceous aerosols and impacts of anthropogenic emissions and meteorological conditions were studied. The annual mean concentrations (± standard deviation) of fine particulate matter (PM2.5), organic carbon (OC), and elemental carbon (EC) were 42.81 (±40.13), 7.57 (±6.43), and 2.25 (±1.39) μg m−3, respectively. The highest PM2.5 and carbonaceous aerosol concentrations were observed in winter, whereas the lowest was observed in summer. The result indicated that coal combustion for heating had a critical role in air quality degradation in Hohhot. A boost regression tree model was applied to quantify the impacts of anthropogenic emissions and meteorological conditions on carbonaceous aerosols. The results suggested that the anthropogenic contributions of PM2.5, OC, and EC during the COVID-19 lockdown period were 53.0, 15.0, and 2.36 μg m−3, respectively, while the meteorological contributions were 5.38, 2.49, and −0.62 μg m−3, respectively. Secondary formation caused by unfavorable meteorological conditions offset the emission reduction during the COVID-19 lockdown period. Coal combustion (46.4% for OC and 35.4% for EC) and vehicular emissions (32.0% for OC and 50.4% for EC) were the predominant contributors of carbonaceous aerosols. The result indicated that Hohhot must regulate coal use and vehicle emissions to reduce carbonaceous aerosol pollution. This study provides new insights and a comprehensive understanding of the complex relationships between control strategies, meteorological conditions, and air quality.

Vegetated roofs as a nature-based solution to mitigate climate change in a semiarid city

• Extensive vegetated roofs (EVRs) sequester c. 0.57 kg C/m2 in semi-arid Córdoba, Argentina. • EVRs reduce energy consumption by c. 40% through the year, especially in summer. • EVRs reduce CO2 emissions and offer a sustainable nature-based solution to climate change. Extensive vegetated roofs (EVRs) are effective in storing carbon and suppressing carbon dioxide emissions to reduce energy consumption in buildings significantly. This study aimed to quantify the carbon sequestration capacity of EVRs and estimate their potential in reducing CO 2 emission in Córdoba city in the semiarid region of central Argentina. For carbon sequestration capacity, we sampled plant and soil materials of three EVRs with similar vegetation but different ages and urban environmental stresses. We measured the carbon storage in the aboveground and belowground biomass and the substrate. To estimate the potential of EVRs in reducing energy consumption and thereby trimming CO2 emission, we simulated the energy consumption reduction by a building with EVRs using the EnergyPlus modeling software. We adjusted the actual data of physical parameters obtained in our study to calculate CO 2 emission reduction compared to a control roof. Our results suggested that EVRs in the semiarid climate could sequester carbon in the order of 2.11 CO2eq/m 2 per year The EVRs achieved a reduction in energy consumption of c. 40%, equivalent to decreasing the emission by 68.38 kg CO 2 /m 2 per year. Since the EVRs can provide an integrative and multifunctional solution to reduce atmospheric CO 2 in urban ecosystems, they offer a promising sustainable nature-based solution with the potential to mitigate climate change effects.

Response of soil moisture and vegetation conditions in seasonal variation of land surface temperature and surface urban heat island intensity in sub-tropical semi-arid cities

Response of soil moisture and vegetation conditions in seasonal variation of land surface temperature and surface urban heat island intensity in sub-tropical semi-arid cities

CO2 flux dynamics of exotic and native species in an extensive green roof simulator with hydric deficit

The rise of urban greenhouse gas emissions creates the need to improve available mitigation strategies. The effectiveness of green roofs depends on their correct design, including vegetation choice. To this aim, we studied the performance of native and exotic plants in hydric deficit conditions of a semi-arid urban area, Bahía Blanca, Argentina, and their ability to sequester CO2. Three native (Poa lanuginosa, Sphaeralcea australis, and Phyla nodiflora) and three exotic (Oscularia deltoides, Sedum ´tokyo sun´, and Sedum nussbaunerianum) species were tested in an extensive green roof simulator with no irrigation. Exotics Oscularia deltoides and Sedum nussbaunerianum did not survive the fall, while Sedum ´tokyo sun´ survived until late spring. All native plants survived, but their growth was affected by the hydric deficit of the warmer months. Seasonal CO2 fluxes were detected, with the most C sequestration in the colder months. Warmer months had the highest CO2 release. Native Poa lanuginosa sequestered 2.2 times more CO2 than exotic Sedum ´tokyo sun´ and native Phyla nodiflora, showing that C sequestration depends on plant type and not hydric-deficit adaptation. Construction of extensive green roofs in semi-arid cities requires the use of native plants that can withstand large hydric deficits.

Groundwater quality assessment by multi-model comparison: a comprehensive study during dry and wet periods in semi-arid regions.

With the impact of human engineering activities, groundwater pollution has seriously threatened the health of human life. Accurate water quality assessment is the basis of controlling groundwater pollution and improving groundwater management, especially in specific regions. A typical semi-arid city in Fuxin Province of China is taken as an example. We use remote sensing and GIS to compile four environmental factors, such as rainfall, temperature, LULC, and NDVI, to analyze and screen the correlation of indicators. The differences among the four algorithms were compared by using hyperparameters and model interpretability, including random forest (RF), support vector machine support vector machine (SVM), decision tree (DT), and K-nearest neighbor (KNN). The groundwater quality of the city during the dry and wet periods was comprehensively evaluated. The results show that the RF model has higher integrated precision (MSE = 0.11, 0.035; RMSE = 0.19,0.188; R2 = 0.829,0.811; ROC = 0.98, 0.98). The quality of shallow groundwater is poor in general, 29%, 38%, 33% of the groundwater quality in low-water period is III, IV, V water. Thirty-three percent and 67% of the groundwater quality in the high-water period were IV and V water. The proportion of poor water quality in high-water period was higher than that in low-water period, which was consistent with the actual investigation. This study provides a kind of machine learning method for the semi-arid area, which cannot only promote the sustainable development of groundwater in this area, but also provide reference for the management policy of related departments.

Exploring the seasonality of surface urban heat islands using enhanced land surface temperature in a semi-arid city

Understanding the seasonal variations in surface urban heat island (SUHI) in different local climate zones (LCZs) is crucial to efforts to reduce the impacts of urban warming on local residents. However, such an understanding is constrained by the lack of land surface temperatures (LSTs) at both high spatial and temporal resolutions. This study created time series LSTs by fusing Landsat 8 satellite data and gap-filled MODIS products to further analyses of the SUHI seasonality in a semi-arid city, Xi'an, China. The results showed that LSTs of the open building types were generally lower than those of the compact building types. The highest SUHI intensity (7.17 °C) was found in ‘compact mid-rise buildings’ (LCZ2), whereas lowest (3.62 °C) was found in ‘open high-rise buildings’ (LCZ4) in July. The SUHI intensity peaked about 17–23 days later than the background LST. The annual SUHI hysteresis cycles exhibited an anti-clockwise concave-up pattern in the monsoon-influenced hot-summer humid continental climate (Dwa per Köppen-Geiger climate scheme). The SUHI intensity in autumn was higher than in spring under the same background LST. These results provide valuable information for developing heat mitigation strategies in different seasons.