For dryland rivers globally, understanding hydro‐ecological function is fundamental to informing trade‐offs between consumptive water use and aquatic ecosystem integrity. The Barwon–Darling is an Australian dryland river system recognised for its hydrological variability, which is considered a primary driver of the riverine ecosystem. Emphasis has been placed on extremes of zero flow and flood but examining low flow hydrology and hydraulics – through historical and modern droughts – demonstrates that under natural conditions, the river system also exhibits persistent and predictable flow characteristics. From 1885 to 1950, prior to flow regulation, the Barwon–Darling flowed 92% of the time, and throughout severe droughts (1895–1903 and 1939–1945) the river system was characterised by: near‐perennial flows (85% of the time), with lotic (flowing water) habitats; and near‐annual, in channel, flow pulses. Furthermore, evidence of lotic biota is found consistently in Aboriginal middens dating over the past 15,000 years, thus indicating the long‐term persistence of lotic conditions. We propose these consistent hydrological and hydrodynamic features have shaped the ecology of aquatic biota in the Barwon–Darling River but are now experiencing unprecedented change. Flow storage and diversion have increased the frequency and duration of zero flows in some reaches, but arguably the most substantial impacts, along the entire river, are on: (i) low flows, which are now frequently below lotic thresholds, and (ii) the magnitude of near‐annual flow pulses, which are reduced by over 90%. Consequently, in modern droughts, the river becomes predominantly lentic (still‐water), an impact that is exacerbated by weirpools which create artificial lentic conditions for approximately 1000 km (40%) of river. The ecological impacts of these changes are increasingly apparent, with the loss of lotic biota and a reduction in biodiversity. An ecohydraulic perspective explains present impacts, provides new directions and some immediate solutions for river management, and clarifies choices for stakeholders.

中文翻译：

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恢复干旱地区河流的生态完整性：为什么必须在Barwon-Darling河中进行低流量

对于全球干旱地区的河流，了解水生态功能对于告知消耗水使用量与水生生态系统完整性之间的折衷至关重要。Barwon–Darling是澳大利亚的旱地河流系统，以其水文变异而闻名，被认为是河流生态系统的主要驱动力。重点放在零流量和洪水的极端情况，但通过历史和现代干旱对低流量水文学和水力学的研究表明，在自然条件下，河流系统还表现出持久且可预测的流量特征。从1885年到1950年，在流量调节之前，Barwon–Darling的流量为92％，在整个严重干旱期间（1895-1903年和1939-1945年），河流系统的特征是：近常年流量（占流域的85％）。时间），充满水的地方 以及通道中的年度流量脉冲。此外，在过去的15,000年中，在土著居民的中部地区一致发现了乳酸菌群的证据，从而表明了长期存在的乳酸菌状况。我们认为这些一致的水文和水动力特征已经塑造了Barwon-Darling河中水生生物的生态，但是现在正经历着前所未有的变化。流量的存储和转移增加了某些河段零流量的频率和持续时间，但是可以说，对整个河流的影响最大：（i）低流量，现在经常低于抽水阈值；（ii）近一年流量脉冲的幅度减少了90％以上。因此，在现代干旱中，河流主要变成lentic（静止水），堰池加剧了这种冲击，堰池为约1000公里（40％）的河流创造了人工透镜状条件。这些变化对生态的影响越来越明显，其中有很多生物群落丧失和生物多样性减少。生态水力的观点解释了当前的影响，为河流管理提供了新的方向和一些立即的解决方案，并为利益相关者阐明了选择。