Spatial and Temporal Patterns of Heavy Rainfall in Different Urbanized Areas of China from 1961 to 2014:Taking Beijing-Tianjin-Hebei,Yangtze River Delta and Pearl River Delta as an Example
We use a variety of statistical methods to compare the temporal and spatial evolution characteristics of heavy rainfall in three major urban areas of Beijing Tianjin Hebei,Yangtze River Delta and Pearl River Delta from 1961 to 2014 years.The results show that Beijing Tianjin Hebei region's annual single station's heavy rainfall amounts,days and intensity presented decreasing trend from 1961 to 2014,while Yangtze River Delta and Pearl River Delta regions' annual single station's heavy rainfall amounts,days and intensity showed increasing trend.And decadal heavy rainfall also had similar change characteristics.Three urban agglomeration's heavy rainfall amounts,days and intensity all had 3,6,15 and 30 year cycle characteristics,but not passed the test of 0.05 significant levels.Beijing Tianjin Hebei region's heavy rainfall amounts and days respectively mutated in 1967 and 1965.The Yangtze River Delta region's heavy rainfall amounts,days and intensity respectively mutated in 1983,1983 and 2013.The rainfall and rainfall intensity in the Pearl River Delta region were mutated in 2011 and 2012 respectively,and all of them passed the test of 0.05 significant levels.The spatial distribution of heavy rainfall amounts,days and intensity mainly showed decreasing trend in Beijing Tianjin Hebei region,while the Yangtze River Delta and Pearl River Delta region showed increasing trends.This research suggests that in city regions need to further establish and improve the comprehensive disaster management system,improve the forecast and early warning system for disaster monitoring,strengthening the overall planning of the city scientific proof,improve ecological service ability,enhance people's awareness of disaster prevention and mitigation,strengthen the ability construction of metropolis to deal with catastrophe.