Environmental flows (e-flows) management is a basic task in reservoir operation. A simple approach for managing e-flows is to maintain a fixed minimum flow, which releases at least a constant amount of water to sustain daily streamflow. Then e-flows management becomes increasingly more sophisticated. Newer approaches include multicomponent e-flow management, which provides different flows during different periods. This management approach produces a better flow regime than the fixed minimum flows because it more closely resembles the natural flow regime. However, in addition to e-flow management strategies, flow regimes are also influenced by reservoir capacity, reservoir inflow, and water supply. The effects of these three variables on flow regime alteration have been rarely studied. To compare the effects of different reservoir capacities, reservoir inflows, and water supply quantities on flow regime alteration, we developed a hypothetical reservoir system for use in numerical experiments. In addition to the fixed minimum flows, we tested the effects of three other widely used e-flow management strategies on flow regime alteration: the fraction of inflow, flow components, and four-period release approaches. The range of variability approach is adopted to evaluate the flow regime alteration. The results show that the flow regime alteration decreases with increasing reservoir inflows and increases with increasing water supply quantity for all of the four e-flow management strategies. We found that for certain values of reservoir capacity, reservoir inflow sequence, or water supply, the simple fixed minimum flows approach may produce the same results as the more sophisticated approaches.

中文翻译：

---

多组分环境流量管理是否总是优于河流生态系统的固定最小流量？

环境流量（e-flows）管理是水库运营中的一项基本任务。管理电子流量的一种简单方法是保持固定的最小流量，这至少会释放恒定量的水以维持日常流量。然后电子流管理变得越来越复杂。较新的方法包括多组件电子流管理，它在不同时期提供不同的流。这种管理方法产生比固定最小流量更好的流动状态，因为它更接近于自然流动状态。然而，除了电子流管理策略之外，水库容量、水库入流和供水也会影响流态。很少研究这三个变量对流态改变的影响。为了比较不同水库容量的影响，水库流入量和流态改变的供水量，我们开发了一个用于数值实验的假设水库系统。除了固定的最小流量外，我们还测试了其他三种广泛使用的电子流量管理策略对流态改变的影响：流入比例、流量分量和四期释放方法。采用可变范围方法来评估流态变化。结果表明，对于所有四种 e-flow 管理策略，流态改变随着水库流入量的增加而减少，并随着供水量的增加而增加。我们发现，对于水库容量、水库入流顺序或供水的某些值，