水保所知识产出(1956---)知识库

日流量能更细致地刻画和表征河流径流量的变化，其变化特征对流域生态治理以及水资源的开发利用都具有重要的指导
作用。按照频率分布定义了极端日流量及其计算方法，并以延河甘谷驿水文站 1953—2010 年实测逐日流量为基础数据，选取日流
量大于或等于第 95 百分位的日流量的发生天数及其平均流量作为极大日流量指标，小于或等于第 5 百分位的日流量的发生天数
及其平均流量作为极小日流量指标，采用 Mann－Kendall 趋势检验法、累计距平法和小波分析法，分析了近 60 a 来延河极端日流量
的趋势性、阶段性和周期性变化特征。结果表明:延河极大和极小日流量发生天数及其平均流量均呈显著减小趋势;在季节变化
中，极大日流量主要发生在汛期，占全年的 93．03%，且代际间变化稳定，而极小日流量的发生集中在 12 月—次年 2 月和 5—7 月，其
中 5—7 月占全年的 45．2%，且 12 月—次年 2 月的代际间波动较 5—7 月的大;极大日流量发生天数的突变年份为 1971 年、1996 年，
其平均流量的突变年份为 1971 年、1986 年、1996 年，且较极大日流量发生天数的变化大，而极小日流量发生天数及其平均流量开始
减小的突变年份较极大日流量突变年份稍有延迟，且极小日流量发生天数较其平均流量不稳定，极小日流量发生天数的突变年份
为 1976 年、1991 年，其平均流量的突变年份为 1976 年;极大和极小日流量发生天数及其平均流量均存在 5、15、30 a 的周期，且以
30 a为第一主周期，各指标近年来均呈减小趋势。

 The daily flow can describe and characterize the change of river runoff more finely． Its changing characteristics play an important
role in ecological management of river basin and water resources development and utilization． The paper proposed to define the extreme daily
flow and its calculation method according to the frequency distribution． Based on the measured daily flow of Ganguyi Station in Yanhe Ｒiver
from 1953 to 2010，the daily flow was greater than or equal to the number of days and the average flow of the 95th percentile as the maximum
daily flow indexes，less than or equal to the fifth percentile as the minimum daily flow indexes． Its trend，stage and periodicity of extreme dai-
ly flow were analyzed by Mann-Kendall trend test，cumulative anomaly and wavelet analysis． The results show that the number of days and av-
erage flow of extreme daily flow in the Yanhe Ｒiver are significantly decreased． In the seasonal variation，the maximum daily flow mainly oc-
currs in the flood season accounting for 93．03%，and the intergenerational variation is stable; the minimum daily flow occurres from Decem-
ber to next February and May to July，of which the time from May to July accounts for 45．2%，and the time from December to next February
fluctuated greatly in the time from May to July． The mutation years of the number of days about the maximum daily flow are the beginning of
soil and water conservation work (1971) and the late period of returning farmland to forest and grassland policy implementation period
(1996) in Yanhe Ｒiver basin，and the mutation years of average flow are 1971，1986 and 1996． The mutation year of the number of days a-
bout the minimum daily flow is 1976 and 1991，slightly delays compared with the maximum daily flow． The number of days and its average
flow of the maximum and minimum daily flow have the main period of 5 a，15 a and 30 a，and the stability is about 30 a． Extreme daily flow
indexes have been decreasing in recent years．