四川省暴雨洪涝灾情特征及主汛期环流背景分析

Rainstorm and Flood Disaster Characteristics and Analysis of Circulation Background in Main Flood Season in Sichuan

利用1984-2010年四川地区暴雨致灾经济损失调查表以及1981-2010年6-9月四川地区逐日降水资料和NCEP再分析资料,研究了近30年的暴雨洪涝致灾特征,得出了洪涝年主汛期四川地区致灾暴雨的环流背景。结果表明,暴雨洪涝引起的四川受灾人口总体呈现增加趋势,特别是1999年以后,受灾人口上升趋势越来越明显;成都市的暴露度指数高但脆弱性指数低,甘孜/阿坝州的各项暴露度指标都排在全省最末。人口脆弱性和经济脆弱性存在明显的2年震荡周期。四川省暴雨中心的绵阳和巴中受暴雨洪涝灾害的影响将进一步加剧。人口脆弱性和经济脆弱性指标位居全省前列的均是川东地区。洪涝年主汛期的环流背景特征是,南亚高压呈现"西部型",且较常年偏弱;洪涝年7月开始副热带高压有明显的准双周的震荡周期,对流层中高层东亚中高纬大气环流出现20~30天的低频振荡,高原低涡具有22天的震荡周期。低纬度西南气流多次向中高纬输送。

Using the investigation data of heavy rainstorm-induced economic damage in Sichuan province area during 1984-2010,the characteristics of rainstorm-induced flood disaster in the last 30 years were studied. The population exposure and vulnerability index have been derived and used to do potential analysis of flood and economy damage. The disaster associated rainstorm was analyzed with the gauge stations observed daily rainfall data from China Meteorological Agency（ CMA）. Then we analyzed the atmospheric circulation for the heavy rainstorm which has caused flood and economic damage for Sichuan province using National Centers for Environmental Prediction（ NCEP） reanalysis data from June to September（ the main rainfall and rainstorm seasons）during 1981-2010. The results showed that the population affected due to rainstorm and flood disaster was increased during last 30 years. The increasing rate was more significant after the year of 1999. The population and economy potential damage analysis showthat Chengdu city has a high exposure index value,but with a lowvulnerability index. The exposure index of Ganzi/Aba area was the lowest in the province. The big city has a high population intensity influenced by the flood disaster,while the undeveloped area has a lowpopulation disaster intensity. The indices of population vulnerability and economic vulnerability of Sichuan were shown with an oscillation period of 2 years. The impact of heavy rains and flooding on Mianyang and Bazhong city,which was located in the rainstorm center of Sichuan province would be further exacerbated,and the cities,whose indices of population vulnerability and economic vulnerability were among the forefront of the province were mainly located in East Sichuan Area. In addition,circulation background characteristics of heavy rain in main raining seasons was analyzed to showthat： South Asian High was ＂Western-type＂and its intensity was weaker than annual average;Subtropical High was showed with a significantly quasi biweekly oscillation from July; Atmospheric circulation of the middle and upper troposphere in East Asia has a lowfrequency oscillation of 20 ~ 30 days in the mid-high latitude; Plateau vortex was showed with about 22 days of the oscillation cycle and Southwest flowin lowlatitudes was continuously transported to high latitudes. The flood associated heavy rainstorm maybe closely related these atmospheric circulation patterns.