Impacts of Urbanization on the Precipitation Characteristics in Guangdong Province, China

With the development of urbanization,whether precipitation characteristics in Guangdong Province,China,from 1981 to 2015 have changed are investigated using rain gauge data from 76 stations.These characteristics include annual precipitation,rainfall frequency,intense rainfall(defined as hourly precipitation≥20 mm),light precipitation(defined as hourly precipitation≤2.5 mm),and extreme rainfall(defined as hourly rainfall exceeding the 99.9 th percentile of the hourly rainfall distribution).During these 35 years,the annual precipitation shows an increasing trend in the urban areas.While rainfall frequency and light precipitation have a decreasing trend,intense rainfall frequency shows an increasing trend.The heavy and extreme rainfall frequency both exhibit an increasing trend in the Pearl River Delta region,where urbanization is the most significant.These trends in both the warm seasons(May-October)and during the pre-flood season(April-June)appear to be more significant.On the contrary,the annual precipitation amount in rural areas has a decreasing trend.Although the heavy and extreme precipitation also show an increasing trend,it is not as strong and significant as that in the urban areas.During periods in which a tropical cyclone makes landfall along the South China Coast,the rainfall in urban areas has been consistently more than that in surrounding areas.The precipitation in the urban areas and to their west is higher after 1995,when the urbanization accelerated.These results suggest that urbanization has a significant impact on the precipitation characteristics of Guangdong Province.