长江2006年汛期特枯径流分析

A Study on the Exceptionally Low Flow of Yangtze River in the Flood Season of 2006

2006年汛期长江出现了历史罕见的特枯径流，汛期长江寸滩站、嘉陵江北碚站出现了有记录以来历史同期最低水位，乌江武隆站出现了历史同期第4低水位。这一现象引起了各方面的关注。论文根据2006年长江干支流主要水文站实测数据以及长江流域33个气象站气温数据和降水量数据，对2006年汛期长江流域特枯径流进行了分析。研究发现，宜昌、汉口、大通三站的汛期月平均流量均降至有历史记录以来的最小值，部分月份不足正常年份的1／3，总体径流量偏少30％～60％。全线水位快速退落，重庆、宜昌、沙市、汉口水位为100多年来同期最低，几近常年长江枯水季节水位。研究认为降水减少是造成长江2006年汛期枯水的主要原因。2006年气温较多年平均明显偏高0．5～2℃，副高和大陆高压的异常，使汛期长江流域降水量大大减少，尤其在7～10月份，几大支流流域降水量减少幅度达到20％～80％。在全球气候变暖的背景下，对2006年汛期长江流域特枯径流进行研究具有非常重要的理论和现实意义。

An exceptionally low flow happened in flood season in the Yangtze River in 2006. It was observed lowest water level at Cuntan and Beibei station since 1892. Based on the hydrology data from the major hydrologic gauging stations and the meteorological data （ temperature and precipitation ） recorded at 33 meteorological stations in the Yangtze River basin, this paper analyzes the phenomenon in detail. It is found that the monthly average water discharge in the flood season of Yichang, Hankou and Datong reached the lowest water level in their gauging history. The water level of Chongqing, Yichang, Shashi and Hankou. reached the lowest in the past 100 years, some even close to their low flow level in the dry season. It is concluded that the main cause of the exceptionally low flow in flood season in 2006 is the sharp decreasing in precipitation in the river basin. The temperature was 0.5 - 2℃ higher in 2006 than the mean annual temperature. The abnormal of the Subtropical High Pressure and continental high pressure induced the sharp decreasing of precipitation in the flood reason of 2006, especially in July and October. The precipitation in the major tributaries river decreased 20% - 80%. The study on the exceptionally low flow of Yangtze River in flood season in 2006 is of great significance in the context of global warning.