长江流域径流趋势变化及突变分析

选取长江流域重要控制站宜昌、汉口和大通站,分别应用1882~2000年、1870~2000年和1950~2000年的月平均流量资料,对年代际、月径流、季节性径流的变化以及径流的变化趋势及突变进行了分析研究，并使用非参数Mann Kendall法来检验径流的趋势变化。趋势分析表明，20世纪90年代长江流域径流呈微弱增加趋势，但不显著且地区分布不均，中上游减少，下游增加；而季节性夏季和冬季径流增加趋势明显，尤其是7月和1月径流增加最突出；更重要的是90年代汛期径流也呈现出增加趋势，汛期径流的增加在一定程度上加大了洪灾发生的可能性，这可能是导致洪灾频繁的原因之一。突变分析指出，宜昌和汉口站从1926年开始径流经历了一个明显减少的变化，这与20世纪20年代初，北半球突然变暖，长江上游地区呈现降温、降水减少趋势一致。

TRENDS AND ABRUPTION ANALYSIS ON THE DISCHARGE IN THE YANGTZE BASIN

Discharge trends and abruption in the Yangtze Basin have been analyzed based on the monthly discharge data, and the Mann-Kendall statistical method was used to test the trend in change of the discharge. The results indicate that slight increase in trend has been detected in annual discharge since 1990s, but the trend is not significant and the distribution is uneven with the decrease in middle and upper reaches, and increase in lower reaches of the Yangtze Basin. According to the seasonal and monthly data, there is significant increase in trend in summer and winter, especially in July and January. The flood season discharge shows slight increase in trend, which may be one of the reasons leading to frequent flood occurence in 1990s. The analysis of the abruption reveals an abrupted change in 1926 on annual scale with the Mann-Kendall rank statistical test in Yichang and Hankou stations, which is somewhat coincident with the change of temperature and precipitation.