近50a江西省旱、涝变化趋势及驱动因素研究

基于江西省5个气象站(赣县、吉安、南城、南昌、景德镇)近50 a(1961~2010年)平均气温、最高、最低平均气温、相对湿度、风速、日照时数、降雨量等逐月平均资料,计算江西省干旱侦测指数(Reconnaissance drought index,RDI),分析旱情、涝情变化趋势。同时,运用多元回归法分析主要驱动因素。研究结果表明,1961~2010年江西省年及四个季节的降雨量、平均相对湿度与RDIst值均呈现极显著的正相关关系(p0.01),而日照时数则与RDIst值呈现极显著的负相关关系(p0.01)。降雨量对江西省旱、涝变化的贡献率最大,为42%~58%;其次是平均气温和相对湿度,分别为11%~19%和7%~19%;平均风速和日照时数对江西省旱、涝变化的贡献率较小。降雨量、相对湿度的增加,日照时数的减少共同导致了1961~2010年江西省年际尺度和春季RDIst值的增加,表明江西省总体从偏旱向偏涝转变。1961~2010年江西省夏季、秋季和冬季RDIst没有明显的增长或降低趋势。

STUDIES ON THE SHIFTING TRENDS IN DROUGHTS AND FLOODS OF JIANGXI PROVINCE IN RECENT FIFTY YEARS AND MAIN DRIVING FACTORS

Droughts and floods are the most severe disasters in China, featuring wide spread, high occurrence and tremendous economic damage. Based on the analysis of documentation and observation data, the inter-decadal changes of drought-and-flood in south China indicated that the yearly and inter-decadal changes of d-and-f disaster have been becoming more and more obvious corresponding to the process of global warming. Jiangxi province is located in the central area of southern red soil region. In recent decades, Jiangxi suffered from the harm of frequent droughts and floods. Moreover, Jiangxi is one of the provinces famous for its farming production. Therefore, frequent droughts and floods have resulted in enormous economic losses in this region. Hence, studies about the inter-annual variation of droughts and floods in Jiangxi province are helpful for the early warming of droughts and floods. In this study, the monthly mean meteorological data during 1961-2010 including monthly mean temperature, maximum temperature, minimum temperature, relative humidity, wind speed and sunshine data in five meteorological stations such as Ganxian, Ji'an, Nancheng, Nanchang and Jingdezhen in Jiangxi province were collected from China Meteorological Data Center (CMDC). Based on these data, reconnaissance drought index (RDI) was adopted and calculated and the changes of droughts and floods in Jiangxi in recent fifty years (1961~2010) were looked into with the help of the Mann-Kendall test. Moreover, main driving factors for such changes in droughts and floods have been investigated with the help of multiple regression analysis method. The results suggested that an increase break point of the inter-annual scale RDI_st value of Jiangxi province occurred in 1969 years during 1961-2010, suggesting that the drought level increased but flood level declined during this period. It was indicated that an increase break point of the RDI_st value in spring occurred in 1967 years, indicating that the drought level gradually increased but flood level gradually decreased in spring in Jiangxi province since 1967 years. It was suggested that an increase break point of the RDI_st value in fall occurred in 1971 years, indicating that the drought level gradually increased but flood level gradually decreased in fall in Jiangxi province since 1971 years. No break points existed in the RDI_st value of Jiangxi province in summer and winter during 1961-2010 as indicated by the Mann-Kendall test, which suggested that drought level or flood level in summer and winter during 1961-2010 showed no increasing or decreasing trends. The inter-annual scale or seasonal-time scale of RDI was significantly positive correlated with rainfall and relative humidity, but negative correlated with sunshine (p < 0.01). The contribution rates of rainfall to the changes in droughts and floods were highest, accounting for 42%~58%, followed by mean temperature and relative humidity accounting for 11%~19% and 7%~19%, respectively. The contribution rates of mean wind speed and sunshine to the changes in droughts and floods were small. Inter-annual scale and spring standardized RDI displayed an increasing trend during 1961~2010, caused by increases in rainfall and relative humidity and decrease in sunshine. However, summer, fall and winter standardized RDI showed no increasing or decreasing trends during 1961~2010.