基于变异性范围法（RVA）的河流生态流量估算

河流生态系统的生物组成、结构和功能依赖于河流水流的天然动态变化特征,即河流水文情势。变异性范围法（Range of Variability Approach,RAV）被广泛应用于评估河流生态系统是否得到维护。将RVA法的思路扩展到生态流量的计算,提出了一种简便、立足整体河流水文情势的生态流量估算方法。该方法使用均值与RVA阈值差计算了生态流量值,为维持河流健康生态系统提供支持。将该方法应用于南水北调西线一期工程中泥曲河的生态流量估算,得到引水坝址仁达处年可调径流量为6.44亿m3,与其他生态需水估算方法的结论基本一致。另提出了可支配系数反映河流流量可调用状况。南水北调西线一期工程计划从泥曲调水8亿m3·a-1,从RVA法的理念来看,该方案对仁达至朱巴河段的生态系统将构成威胁,需谨慎实施。

Estimation of instream ecological flow based on RVA

The biotic composition,structure,and function of river ecosystems rely heavily on the characteristics of river flow’s natural dynamic variation,i.e.,river hydrological regime.The Range of Variability Approach（RVA）is a method widely used to estimate river hydrological regime for maintaining river ecological system integrity.In the past,researches focused on assessing anthropogenic effect on river flow regimes.The estimation method is put forward in this paper,which uses the mean value and the difference values of RVA targets to calculate ecological flow.Since this method is based on the integrated river hydrological regime,in spite of its simplicity,it is applied for estimating ecological flow in Niqu River.The results show that annual deliverable runoff at Renda diversion dam-site in Niqu river is estimated to be 6.44×10 8 m 3 ,which is in agreement with other study results.Based on annual transferable water,the results indicate that this method is feasible.Moreover,allocating coefficient is efficient in reflecting the dominating state of river flow.The scheme of transferable water quantity via the South-North Water Transfer Project from this site is 8×10 8 m 3 /a.This shows that the diversion would threaten ecological system of the reach between Renda and Zhuba based on RVA Therefore,the diversion scheme implementation needs to be considered with more cautions.These results provide valuable scientific reference for water resources management and ecological protection in Niqu river.