PurposeWhile many examples have shown unsustainable use of freshwater resources, existing LCIA methods for water use do not comprehensively address impacts to natural resources for future generations. This framework aims to (1) define freshwater resource as an item to protect within the Area of Protection (AoP) natural resources, (2) identify relevant impact pathways affecting freshwater resources, and (3) outline methodological choices for impact characterization model development.MethodsConsidering the current scope of the AoP natural resources, the complex nature of freshwater resources and its important dimensions to safeguard safe future supply, a definition of freshwater resource is proposed, including water quality aspects. In order to clearly define what is to be protected, the freshwater resource is put in perspective through the lens of the three main safeguard subjects defined by Dewulf et al. (2015). In addition, an extensive literature review identifies a wide range of possible impact pathways to freshwater resources, establishing the link between different inventory elementary flows (water consumption, emissions, and land use) and their potential to cause long-term freshwater depletion or degradation.Results and discussionFreshwater as a resource has a particular status in LCA resource assessment. First, it exists in the form of three types of resources: flow, fund, or stock. Then, in addition to being a resource for human economic activities (e.g., hydropower), it is above all a non-substitutable support for life that can be affected by both consumption (source function) and pollution (sink function). Therefore, both types of elementary flows (water consumption and emissions) should be linked to a damage indicator for freshwater as a resource. Land use is also identified as a potential stressor to freshwater resources by altering runoff, infiltration, and erosion processes as well as evapotranspiration. It is suggested to use the concept of recovery period to operationalize this framework: when the recovery period lasts longer than a given period of time, impacts are considered to be irreversible and fall into the concern of freshwater resources protection (i.e., affecting future generations), while short-term impacts effect the AoP ecosystem quality and human health directly. It is shown that it is relevant to include this concept in the impact assessment stage in order to discriminate the long-term from the short-term impacts, as some dynamic fate models already do.ConclusionsThis framework provides a solid basis for the consistent development of future LCIA methods for freshwater resources, thereby capturing the potential long-term impacts that could warn decision makers about potential safe water supply issues in the future.

中文翻译：

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将淡水定义为自然资源：将用水与自然资源保护领域联系起来的框架

目的虽然许多例子表明淡水资源的使用是不可持续的，但现有的 LCIA 用水方法并没有全面解决对子孙后代自然资源的影响。该框架旨在 (1) 将淡水资源定义为保护区域 (AoP) 自然资源中需要保护的项目，(2) 确定影响淡水资源的相关影响路径，以及 (3) 概述影响表征模型开发的方法选择。方法考虑到AoP自然资源的当前范围、淡水资源的复杂性及其保障未来安全供应的重要维度，提出了淡水资源的定义，包括水质方面。为了明确界定要保护的内容，我们从 Dewulf 等人定义的三个主要保护主题的角度来看待淡水资源。（2015）。此外，广泛的文献综述确定了对淡水资源的各种可能的影响途径，建立了不同清单基本流量（水消耗、排放和土地利用）及其导致长期淡水枯竭或退化的潜力之间的联系。结果与讨论淡水作为一种资源在生命周期评价资源评估中具有特殊的地位。首先，它以三种资源的形式存在：流量、资金、存量。那么，除了作为人类经济活动的资源（例如水电）之外，它首先是不可替代的生命支持，可能受到消耗（源功能）和污染（汇功能）的影响。因此，两种类型的基本流量（耗水量和排放量）都应与淡水作为资源的损害指标联系起来。土地利用也被认为是淡水资源的潜在压力源，因为它会改变径流、渗透、侵蚀过程以及蒸散。建议使用恢复期的概念来操作该框架：当恢复期持续超过给定时间时，影响被认为是不可逆转的，并纳入淡水资源保护的关注范围（即影响子孙后代） ，而短期影响则直接影响AoP生态系统质量和人类健康。结果表明，有必要将这一概念纳入影响评估阶段，以便区分长期影响和短期影响，就像一些动态命运模型已经做的那样。结论该框架为可持续发展提供了坚实的基础。未来的淡水资源 LCIA 方法，从而捕捉潜在的长期影响，可以警告决策者未来潜在的安全供水问题。