基于RVA法的河流生态基流过程研究

针对我国目前生态需水量研究难以反映河流水文情势自然涨落变化的问题,从河流水文情势的整体角度出发,采用IHA法分析了金沙江上游岗托至巴塘河段的天然水文情势特征,得到了该河段各指标的RVA阈值范围。在总结前人研究的基础上,对计算河流生态基流量的RVA法进行了改进,提出非汛期、汛前期和汛后期采用RVA目标差值的75%推荐河流生态基流量,主汛期采用RVA目标差值的50%推荐河流生态基流量。采用改进的RVA法计算了金沙江上游巴塘断面的生态基流过程,得到巴塘断面各月的生态基流量分别为39.5 m~3/s、42.5 m~3/s、33.0 m~3/s、74.2 m~3/s、124.4m~3/s、259.3 m~3/s、394.0 m~3/s、581.0 m~3/s、493.5 m~3/s、259.7 m~3/s、131.1 m~3/s、71.0 m~3/s,占相应多年月均流量的比例范围为14.0%~32.9%,并与Tennant法的结果进行了对比分析。结果表明,该方法能够更好地反映金沙江上游天然河流水文情势的动态变化特征,可为金沙江上游水电开发生态保护提供技术参考。

RVA method-based study on river ecological baseflow hydrograph

Aiming at the problem that the natural fluctuation of river hydrological regime is difficult to be reflected by the study made on water demand in China at present， the characteristics of the hydrological regime of the river reach from Gangtuo to Batang of the Upper Jinshajiang River is analyzed herein with IHA （indicators of hydrologic alteration） method from the overall aspect of the river hydrological regime therein， and then the RVA （range of variability approach） threshold ranges of all the indexes of the river reach are obtained. On the basis of summarizing the previous studies concerned， the RVA method for calculating river ecological flow is improved; from which it is proposed to take 75% of the RVA target difference for recommending the river ecological base flow during non-floodseason， pre-floodseason and post-flood season， while 50% of the RVA target difference is taken for recommending the river ecological base flow during the main flood season. The improved RVA method is adopted to calculate the ecological base flow hydrograph at Batang Section of the Upper Jinshajiang River and all the monthly ecological base flows at the river section are obtained， i.e. 39.5 m3/s， 42.5 m3/s， 33.0 m3/s， 74.2 m3/s， 124.4 m3/s， 259.3 m3/s， 394.0 m3/s， 581.0 m3/s， 493.5 m3/s， 259.7 m3/s， 131.1 m3/s and 71.0 m3/s respectively， which are 14.0%~32.9% within the proportional range of the relevant yearly mean monthly flow and compared with the results got from the Tennant method. The result shows that the calculation result from the method given herein can better reflect the dynamic changing characteristics of the natural river hydrological regime of the Upper Jinshajiang River， thus can provide technical reference for the ecological protection made for the hydropower development along the Upper Jinshajiang River.