Deltas are a particular type of estuarine system in which the dependence on river flow (water, sediments and nutrients) is very strong, especially in river-dominated deltas such as the Mediterranean ones, but environmental flow (e-flow) proposals for deltaic systems are scarce. The Ebro Delta is one of the largest wetland areas in the western Mediterranean and one of the most important estuarine systems in Europe. The aim of this paper is to review the state of the art regarding e-flows and to carry out a critical analysis of the proposals for the lower Ebro River and Delta, in order to highlight the possible environmental and socioeconomic impacts arising from the e-flow regime currently approved. Additionally, based on existing scientific information, methods to establish an e-flow regime that allows the maintenance of the main socio-ecological functions and values are discussed; including those functions and values for which not enough information is available. The study concludes that the currently approved e-flows are not suitable for maintaining most functions and values, as they would not prevent the proliferation of alien fish species and macrophytes in the river, the intrusion of the salt wedge in the estuary, the deficit of sediment/nutrient transport and the degradation of riparian habitats or the decline of coastal fisheries. Socioeconomic consequences on coastal fisheries, river navigation, salt water intrusion, sediment deficit, biodiversity, water quality, aquaculture and hydropower are also considered. Other e-flow proposals such as the proposed by the Catalan government would be more suitable to maintain the main socioecological functions and values of the lower Ebro River and Delta. Nevertheless, additional studies are needed to validate e-flows in some relevant aspects such as the capacity of the river to transport sediments to the delta to avoid coastal regression and mitigate the effects of sea level rise and subsidence, as well as the capacity of floods to control the spread of macrophytes. The lower Ebro River and delta is among the case studies where more quantitative and qualitative criteria to set e-flows with a holistic approach have been established.

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埃布罗河下游和三角洲的环境流量：整体方法的现状和指南

三角洲是一种特殊类型的河口系统，其中对河流流量（水、沉积物和营养物）的依赖性非常强，尤其是在以河流为主的三角洲，如地中海三角洲，但三角洲系统的环境流量（e-flow）建议稀缺。埃布罗三角洲是地中海西部最大的湿地之一，也是欧洲最重要的河口系统之一。本文的目的是回顾电子流的最新技术，并对埃布罗河下游和三角洲的提案进行批判性分析，以强调电子流可能产生的环境和社会经济影响。目前已批准的流态。此外，根据现有的科学资料，讨论了建立允许维护主要社会生态功能和价值的电子流动制度的方法；包括那些没有足够信息可用的功能和值。研究得出的结论是，目前批准的电子流不适合维持大部分功能和价值，因为它们不能阻止外来鱼类和大型植物在河流中的增殖、河口盐楔的侵入、河口的缺乏。沉积物/养分运输和河岸栖息地退化或沿海渔业衰退。还考虑了对沿海渔业、河流航行、咸水入侵、沉积物缺乏、生物多样性、水质、水产养殖和水电的社会经济影响。其他e-flow提案，如加泰罗尼亚政府提出的，将更适合维持埃布罗河下游和三角洲的主要社会生态功能和价值。然而，需要额外的研究来验证一些相关方面的电子流，例如河流将沉积物输送到三角洲以避免沿海回归和减轻海平面上升和沉降的影响的能力，以及洪水的能力以控制大型植物的传播。埃布罗河下游和三角洲是案例研究之一，已经建立了更多的定量和定性标准，以采用整体方法设置电子流。需要更多的研究来验证一些相关方面的电子流，例如河流将沉积物输送到三角洲以避免沿海回归和减轻海平面上升和沉降的影响的能力，以及控制洪水的能力大型植物的传播。埃布罗河下游和三角洲是案例研究之一，已经建立了更多的定量和定性标准，以采用整体方法设置电子流。需要更多的研究来验证一些相关方面的电子流，例如河流将沉积物输送到三角洲以避免沿海回归和减轻海平面上升和沉降的影响的能力，以及控制洪水的能力大型植物的传播。埃布罗河下游和三角洲是案例研究之一，已经建立了更多的定量和定性标准，以采用整体方法设置电子流。