Impact of rapid urbanization on temporal and spatial pattern change of heavy rainfall in China during the past 60 years

Abstract

Abstract Through the study of the daily heavy rainfall observation records of 659 meteorological stations in China from 1951 to 2010, we find that rapid urbanization may trigger the significant increase of large-scale heavy rainfall in China. The main conclusions are as follows: Decadal heavy rainfall amounts (HRA), heavy rainfall days (HRD) and heavy rainfall intensity (HRI) in China have increased significantly, with an increase of 68.71%, 60.15% and 11.52% respectively, and the increase of station number is 84.22%, 84.22% and 54.48% respectively, showing a time change process of “rapid slow re rapid increase” and a spatial change from Southeast Coast to Central, Southwest, North and Northeast China. The rapid urbanization factors, including the output value of the second industry (GDP2), the proportion of urban population (UP) and the annual average haze days (HD), are likely to be the main reasons for the increase of heavy rainfall in China. Their variance explanations for the HRA, HRD and HRI in China are 61.54%, 58.48% and 65.54% respectively, of which the variance explanations for the heavy rainfall rainfall, rainy day and rain intensity are respectively high only by haze 25.93%, 22.98% and 26.64% respectively, while the variance interpretation of climate factors, including WPSH, ENSO, AMO and AAO, is only 24.30%, 26.23% and 21.92% respectively. Compared with the forcing factors of rapid urbanization, the impact of these climate factors is only 1/3 of the former. The panel data of the annual mean of the total population and visibility days at the county level in China are significantly related to the HRA, HRD and HRI in China. The spatial correlation coefficient gradually increased from 1950s to 2000s, that is, the total population at the county level increased from 0.35, 0.36 and 0.40 to 0.54, 0.55 and 0.58 respectively, and the annual mean of visibility days increased from 0.36, 0.38 and 0.48 to 0.55, 0.57 and 0.58. It is further indicated that the rapid urbanization triggered the significant increase of heavy rainfall in China.