Abstract
Urbanization significantly impacts regional precipitation. In this study, using the city of Xi’an in China as a study area, we analyze the variation in land use and the characteristics of the variation in extreme precipitation events and discuss the response of urbanization to extreme precipitation. The main conclusions drawn are as follows. (1) The construction land area of the study area rapidly expanded in size from 80.76 km2 in 1984 to 400.3 km2 in 2018. The transfer of land use mainly occurred as the transfer from farmland to other types of land use. The urban land use intensity continues to increase. (2) The intensities and different frequency indices of extreme precipitations both show an increasing trend. In addition, the former exhibits periodic alternation with a dominant frequency of 21 years during the flood season, and both the fluctuation amplitude and maximum value of the periodic variation increase with time. (3) The urbanization in the study area has a significant impact on Rx1h and Rx2h precipitations, but little impact on the intensity of long-duration precipitation. Hence, urbanization significantly increases the intensity of extreme precipitation. After the 2000s, the urban building area, rainfall frequency, and rainfall intensity growth trends are highly consistent.
Highlights
Urbanization is rapidly occurring across the world, and the global urban population is predicted to increase by 2.5 billion by 2050 [1]
9,750 Miles greater than 0.8. e land use within the study area is categorized into five types, namely, farmland, vegetation, bare land, water body, and construction land. e spatiotemporal evolution of the urban sprawl in the study is mainly analyzed in terms of the speed, direction, and intensity of the changes in urban land use
E results show that the farmland area in the central urban area of the study area varies the most significantly
Summary
Urbanization is rapidly occurring across the world, and the global urban population is predicted to increase by 2.5 billion by 2050 [1]. Increasing urban population can directly lead to enlarged urban construction areas and changes in land use types, which can further alter the physical properties of the underlying urban surface and greatly affect the characteristics of regional hydrological circulation [2, 3]. Given the clustering trends of population and industry, different artificial heat sources, carbon sources, and pollutant emissions directly affect the chemical and physical properties of the atmosphere, which can lead to changes in the movement state of near-surface matter and energy in local urban areas and over an even larger range and have complex effects on a series of meteorological and hydrological elements, including wind fields, temperature, precipitation, evapotranspiration, and runoff. E mechanisms of the impact of urbanization on precipitation mainly include the urban heat island effect, underlying surface changes, and aerosol emissions.
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