黄河上游主要支流径流时空分布规律及演变趋势分析

Runoff Space-time Distribution Rule and Evolution Tendency of Yellow River Upstream and Main Tributaries

基于有关水文站径流观测资料,对黄河上游兰州以上干流与主要支流流域径流的补给来源、时空分布规律及演变趋势进行了分析。结果表明,研究区域内径流的补给来源主要是大气降水汛期(5～10月)水量占年总量的52.4%～68.0%,非汛期地下水补给量占年总量的35.1%～43.1%,冰雪融水量占年总量的2.5﹪～5.0﹪;从空间分布看,由于流域下垫面条件不同,其产流模数在空间的分布差异性很大,产水量较大的区域模数为7.874～8.500L/s.km2;产水量中等区域模数为5.047～6.536L/s.km2;产流量较小区模数为3.416～3.812L/s.km2;从时间上看,自有观测资料至2008年,以1986年为分界点,径流的多年变化过程总体上先表现出具有长持续性的波动上涨、后表现出跌宕中下落的趋势过程;各月径流量的长期变化趋势主要表现为汛期径流量减少的幅度较大,非汛期减少的幅度相对较小。鉴于源区各区间径流持续减少的原因,导致兰州站自1986年以来径流变化过程有显著减少的趋势,且这种变化趋势还在持续。黄河上游径流的持续减少给流域各省的经济与社会、生态与环境的和谐发展带来不利影响,应当引起高度重视。

Based on the observed runoff data of the related hydrometry stations,we analyzed the supply source,space-time distribution rule and evolution tendency of the runoff in the area above the Lanzhou station of the Yellow River upstream and main tributaries.The results show that the runoff is mainly from precipitation.The supplied runoff in the flood season（from May to October） amounts to 52.4%~68.0% of the total in a year,the supplied runoff from groundwater in the non-flood season accounts for 35.1%~43.1% of the total,and the runoff from snow and ice melt accounts for 2.5%~5.0% of the total.In the space distribution,because of different underlying surface conditions,difference of the runoff yield modulus is very big in spatial distribution,with the modulus being 7.874~8.500 L/s·km2 in the great-sized contributing area,being 5.047~6.536 L/s·km2 in medium-sized contributing area,and being 3.416~3.812 L/s·km2 in small-sized contributing area.In the time distribution,from start observation to 2008,the year of 1986 is a set apart.The runoff multi-annual variation process firstly displays long continuous fluctuation rise,then displays decline tendency process.The variation tendency of monthly runoff shows that runoff has a great decrease in flood season and has a smaller decrease in non-flood season.In view of the fact that the runoff reduces continually in the various reaches of the source area,there is decline tendency process of the runoff at the Lanzhou station since 1986,and this kind of change tendency is continuing.