Infrastructure Engineering, Melbourne School of Engineering, The University of Melbourne Parkville, Parkville, VIC, 3010, Australia.
Environ Manage. 2018 Mar;61(3):390-397. doi: 10.1007/s00267-017-0955-8. Epub 2017 Nov 13.
This paper evaluates an experimental environmental flow manipulation by modeling the counterfactual case that no environmental flow was applied. This is an alternate approach to evaluating the effect of an environmental flow intervention when a before-after or control-impact comparison is not possible. In this case, the flow manipulation is a minimum flow designed to prevent hypoxia in a weir on the low-gradient Broken Creek in south-eastern Australia. At low flows, low reaeration rates and high respiration rates associated with elevated organic matter loading in the weir pool can lead to a decline in dissolved oxygen concentrations with adverse consequences both for water chemistry and aquatic biota. Using a one dimensional oxygen balance model fitted to field measurements, this paper demonstrates that increased flow leads to increases in reaeration rates, presumably because of enhanced turbulence and hence mixing in the surface layers. By comparing the observed dissolved oxygen levels with the modeled counterfactual case, we show that the environmental flow was effective in preventing hypoxia.
本文通过模拟未施加环境流量的反事实情况来评估实验性环境流量管理。当无法进行前后对比或控制影响对比时，这是评估环境流量干预效果的一种替代方法。在这种情况下，流量管理是一种最小流量设计，旨在防止澳大利亚东南部低梯度破碎溪堰中的缺氧。在低流量下，低再曝气率和与堰池中有机物质负荷增加相关的高呼吸率会导致溶解氧浓度下降，对水化学和水生生物群都有不利影响。本文使用拟合现场测量的一维氧平衡模型，证明增加流量会导致再曝气率增加，这可能是因为表面层的紊流增强和混合增强。通过将观测到的溶解氧水平与模拟的反事实情况进行比较，我们表明环境流量有效地防止了缺氧。
