大通河跨流域引水和梯级水电站建设对径流的影响分析

Analysis of the Impact of Inter-basin Water Diversion and Cascade Hydropower Stations Construction of Datong River on Runoff

大通河是黄河上游支流—湟水的最大一级支流,流域呈狭长地带,地形西北高,东南低,干流全长560.7 km,天然落差2 793 m,流域面积15 130 km2,占湟水流域总面积的46%。运用1956~2015年60年实测流域长系列水文资料,对黄河流域上游湟水水系的大通河径流量变化特征分析,结果显示,大通河流域近20 a径流量总体呈衰减趋势,天堂~享堂站径流量随河长及集水面积增加而减小,水资源开发利用影响自上游至下游逐渐显著。而梯级电站对对流域洪水过程影响较大,人为蓄放水,使天然的洪水过程由平稳状态转变为剧烈变化状态,对局部河段的冲刷作用加剧,对河床和两岸的稳定性以及下游河段防洪造成一定的影响。水资源密集开发等人类活动使大通河中下游河段生态环境呈现破碎化、片断化发展趋势。研究结果可为最大限度地减轻人类活动对河流特性、自然生态的影响提供基础依据。

The Datong River is the largest tributary of Huangshui which is the upper reaches of the Yellow River. The basin is in the narrow area,the northwest of the terrain is high,while the southeast is low and the total length is 560. 7 km,the natural gap is 2 793 m,the basin area is 15 130 km2,accounting for 46% of the total area of Huangshui. Based on the hydrological data of the 60 years from 1956 to 2015,this paper analyzes the characteristics of the runoff of the Datong River which belongs to the Huangshui water system in the upper reaches of the Yellow River Basin,the results show that the runoff of the Datong River Basin in the upper reaches of the Yellow River Basin has been declining in the past 20 years. The runoff of Tian Tang to Xiang Tang decreases with the increase of river length and catchment area,and the influence of water resources development and utilization is gradually significant from upstream to downstream. The cascade hydropower station has a great influence on the flood process,and artificial saving or discharging water changes a steady state into a violent state,intensifies the erosion of some parts,and causes a certain impact on the stability of the river bed,the two sides and flood control in downstream. Intensive development of water resources and other human activities make the ecological environment of the middle and lower reaches of Datong River show fragmented and fragmented development trend. The results of the study can provide the basis for the maximum reduction of human activities on river characteristics and natural ecology.