长江中游不同典型年水情因子分析
Factor Analysis of Water Conditions in the Middle Reaches of the Yangtze River in Different Typical Years

水情因子分析是研究后汛期判别的基础，本文通过分析历史长系列数据得到不同典型年下长江中游水情因子的变化规律：① 当发生流域型洪水时，沙市站水位在1954年和1998年7月上旬已超过警戒水位，持续到9月上旬水位才开始逐渐降低到警戒水位以下，1998年8月上旬和中旬水位超保证水位；2020年中下游发生大洪水时，上游来水属于一般洪水，且长江上游梯级水库施行联合调度，荆江河段洪水位较低，沙市站水位仅在7月下旬和8月下旬超过警戒水位；莲花塘水位自6月下旬开始一直超过警戒水位，持续到9月上旬水位才开始逐渐降低到警戒水位以下；四水合成流量有多个洪峰过程，洪峰大，汛期流量变化较大；② 发生区域型洪水时，莲花塘发生超警戒水位洪水的时间主要集中于7月中旬和7月下旬，最晚洪峰出现时间为9月上旬；四水合成基本为多峰且波动较大，直至8月底9月初降低至20,000 m³/s以下；③ 发生流域型枯水时，莲花塘站各典型年最高水位均在7月下旬前出现，四水合成流量变化主要集中在6月份，在7月中下旬流量降低至15,000 m³/s以下。研究成果可为长江中游后汛期动态判别指标构建提供支撑，为实时调度中滚动快速研判当前情汛情及演变趋势、及时优化调整水库动态运行方案提供决策依据。
Water condition factor analysis is the basis of the study of the late flood season discernment, this paper gets different typical years under the middle reaches of the Yangtze River water condition factor change rule through data analysis of historical long series: 1) When basin-type floods occurred, Shashi station water level in 1954 and 1998 in early July exceeded the warning level, continued to the water level in early September and began to gradually reduce to below the warning level. The water level of the first half of August and the mid-August water level exceeded the guaranteed water level in 1998; When big floods occurred in the middle and lower reaches of the river in 2020, water from the upper reaches belonged to the general flood, and the upper reaches of the Yangtze River cascade reservoirs carried out joint scheduling, and the flood level of the Jingjiang River section was low, and the water level at Shashi station only exceeded the warning level in late July and late August; the water level at Lianhuatang exceeded the alert level since late June, and lasted until early September before the water level began to gradually reduce to below the alert level; the four water synthetic flow had multiple flood processes, large flood peaks, and large changes in the flood season flow; 2) When regional-type flood occurred, Lianhuatang floods occurred mainly in middle and late July, the latest flood peaks occurred in early September; the four-water synthesis was basically multi-peak and fluctuations till the end of August and early September, reduced to less than 20,000 m³/s; 3) When basin-type floods occurred, the highest water level at Lianhuatang station of the typical year was in late July, the four-water synthesis of the changes in flow mainly concentrated in June, and the four-water synthesis flow in