ABSTRACT
Improving the urban thermal environment and improving the quality of human settlements are important prerequisites for creating ecologically livable cities. The current research on the relationship between urban expansion and the thermal environment is mostly based on remote sensing data, and the application of multi-source data is weak. Here, we selected the Xi'an metropolitan core area, measured the urban expansion and temporal and spatial evolution of the thermal environment based on Landsat remote sensing images in 2010 and 2020, and used multi-source data, such as interest points and the Baidu thermal index, to study the response mechanism of the urban thermal environment through geoscience statistical analysis methods. The results showed that:â the construction land in the study area had expanded by 200.84 km2, and the area and intensity showed that "the center and the periphery are weaker, and the difference between the two" characteristics, and the expansion mode was mainly edge type and infill type. â¡ Between 2010 and 2020, the overall thermal environment in the study area deteriorated, and the area of the heat island area increased by 282.65 km2. The spread of the heat island area was in the same direction as the urban expansion, and the distribution pattern evolved from "southeast-northwest" to "northeast-southwest;" however, the average temperature in the central area of the city decreased 1.09â. ⢠Urban expansion was strongly positively correlated with the deterioration of the urban thermal environment. The expansion of urban space had a contribution rate of 60.40% to the deterioration of the thermal environment, and various socio-economic factors had a weaker effect, with an overall contribution rate of 39.60%. The vegetation water body had an obvious cooling effect; under the influence of multiple factors, the surface temperature increased by 0.241 units. In the process of urban expansion, changes in surface parameters and two-dimensional urban morphology were still the main factors for thermal environment changes, whereas three-dimensional morphology had a small effect on the warming of social and economic activities, and the contribution of water bodies and vegetation to cooling was prominent.
Subject(s)
Environmental Monitoring , Hot Temperature , Cities , Environmental Monitoring/methods , Humans , Temperature , WaterABSTRACT
Wetlands are one of the most productive ecosystems in the world, with functions of water purification, climate regulation, and carbon sinks. Due to the stresses caused by human social development and changes of natural conditions, wetlands have been seriously damaged. We examined the evolutionary law of landscape pattern of wetland along the Yellow River, and acquainted the current situation of wetland resources and dynamic change. Based on satellite images of year 2000, 2009, and 2018 from Landsat, we used landscape indices and geographic detectors to quantitatively analyze the characteristics and driving forces of wetland landscape pattern evolution of the city belt along the Yellow River in Ningxia from 2000 to 2018. The results showed that the wetland area of the city belt along the Yellow River in Ningxia enlarged first and then decreased from 2000 to 2018. The wetland area increased by 52.2 km2 in the early stage of the study with an increasing rate of 8.2%, and decreased by 26.8 km2 with a reduction rate of 3.9% in the later stage. The wetland was mainly transformed to construction land and unused land, with transfer out area being 166.7 and 158.4 km2 respectively. New wetland was mainly transformed from unused land, forest, and grassland, with an area of 543.1 km2. The fragmentation degree of wetland landscape in city belt was increasing, the balanced distribution of all kinds of wetlands was gradually strengthened, the landscape diversity was increasing, and the dominant landscape types were gradually weakening. Natural factors and socio-economic factors jointly affected the evolution of wetland landscape pattern in city belt. Among all socio-economic factors population was the most important one. Among natural factors, precipitation and temperature were important. Other driving factors were relatively weak, but could not be ignored.
