Impact of urbanization on variability of annual and flood season precipitation in a typical city of North China

摘要

Urbanization plays an important role in a global change,but there are few studies that combine land use with topography and precipitation. The urbanization in Jinan,a typical city of North China,between the 1980s and 2005 was analyzed by transition matrix analysis,and the topographic effects on land use changes were explored considering altitude,slope,and aspect. The temporal trends and abrupt changes of annual and flood season precipitation for the last 60 years were detected by multiple nonparametric detection methods,and the precipitation indices were adopted to characterize the frequency and intensity of precipitation. The relationship between urbanization and precipitation was finally investigated by grey correlation analysis. The results showed that land use structure in Jinan experienced a dramatic change during recent decades due to the urbanization process,the conversion of cropland to forest,and the protection of spring in Jinan. The land use types that closely related to mankind's activities and living behaviors were more concentrated in areas with lower altitude and slope,and detected more significant changes. The significant abrupt changes of precipitation generally occurred in 1989 and concentrated in urban areas and southern mountainous areas with high increment. The increase of flood season precipitation was more significant in the central urban region with a maximum increasing rate of 39.52%,and the increase in the number of storm and precipitation days was also obvious. The precipitation indices in the flood season were more closely related to changes in farmland and settlements affected by urbanization with a maximum correlation coefficient of 0.75. These findings illustrate the impact of urbanization on the variability of precipitation and support that the changes in the urban underlying surface have a certain effect on the surface energy balance.