Abstract
Reducing the degree of flow regime alteration is a basic principle for biodiversity conservation in rivers. The range of variability approach (RVA) is the most widely used method to assess flow regime alteration. Generally, researchers tend to put all of the available pre-impact and post-impact flow records into the RVA. However, no research has tested whether it is optimal to use the entirety of the available flow records from the perspective of calculation accuracy for the degree of flow regime alteration. In this research, a series of numerical simulations is conducted, demonstrating that the greatest accuracy for flow regime alteration degree assessed by the RVA is achieved when the length of both the pre- and post-impact flow time series is set equal to multiples of periodicity length, and that, when attempting to put the whole available flow record into the RVA, calculation accuracy may be reduced. On the basis of these findings, we further propose revising the traditional RVA procedure by assessing the periodicity of the pre- and post-impact flow time series in advance. If the periodicity of the pre- or post-impact flows is detected, the length of the time series should be set equal to its periodicity.
Highlights
The natural flow regime plays a crucial role in preserving the structures and functions of riverine ecosystems [1,2]
Maintaining the natural flow regime is a foundational principle for biodiversity conservation in rivers [1,6], but human activities and climate change have seriously altered the natural flow regimes of rivers worldwide, leading to degradation of riverine ecosystems [8,9,10]
Assessing the degree of flow regime alteration in rivers is a basic principle for sustainable water resources management
Summary
The natural flow regime plays a crucial role in preserving the structures and functions of riverine ecosystems [1,2] It can be defined by five major ecologically relevant characteristics, i.e., magnitude, frequency, duration, timing, and rate of change [3,4]. The range of variation approach (RVA) proposed by Richter et al [11,12,13] is the most widely used approach and represented a milestone in efforts to assess the degree of hydrologic alteration. It has been cited more than 2400 times in scientific publications by 2020 according to Google Scholar.
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