INRAE, UR RiverLy, centre de Lyon-Villeurbanne, 5 rue de la Doua CS 20244, 69625 Villeurbanne, France; EA 6293 GéoHydrosystèmes COntinentaux, Université François-Rabelais de Tours, Parc de Grandmont, 37200 Tours, France.
INRAE, UR RiverLy, centre de Lyon-Villeurbanne, 5 rue de la Doua CS 20244, 69625 Villeurbanne, France.
Sci Total Environ. 2021 Apr 20;766:142667. doi: 10.1016/j.scitotenv.2020.142667. Epub 2020 Oct 5.
Anthropogenic impoundments (e.g. large dams, small reservoirs, and ponds) are expanding in number globally, influencing downstream temperature regimes in a diversity of ways that depend on their structure and position along the river continuum. Because of the manifold downstream thermal responses, there has been a paucity of studies characterizing cumulative effect sizes at the catchment scale. Here, we introduce five thermal indicators based on the stream-air temperature relationship that together can identify the altered thermal signatures of dams and ponds. We used this thermal signature approach to evaluate a regional dataset of 330 daily stream temperature time series from stations throughout the Loire River basin, France, from 2008 to 2018. This basin (10 km) is one of the largest European catchments with contrasting natural and anthropogenic characteristics. The derived thermal signatures were cross-validated with several known catchment characteristics, which strongly supported separation into dam-like, pond-like and natural-like signatures. We characterize the thermal regime of each thermal signature and contextualize it using a set of ecologically relevant thermal metrics. Results indicate that large dams decreased summer stream temperature by 2 °C and delayed the annual stream temperature peak by 23 days relative to the natural regimes. In contrast, the cumulative effects of upstream ponds increased summer stream temperature by 2.3 °C and increased synchrony with air temperature regimes. These thermal signatures thus allow for identifying and quantifying downstream thermal and ecological influences of different types of anthropogenic infrastructures without prior information on the source of modification and upstream water temperature conditions.
人为蓄水设施（例如大坝、小水库和池塘）在全球范围内不断增加，通过其结构和在河流连续体中的位置以多种方式影响下游温度格局。由于下游存在多种热响应，因此在集水区尺度上对累积效应大小进行特征描述的研究很少。在这里，我们引入了基于河流-空气温度关系的五个热指标，这些指标共同可以识别大坝和池塘的改变的热特征。我们使用这种热特征方法评估了 2008 年至 2018 年法国卢瓦尔河流域 330 个每日河流温度时间序列的区域数据集，该流域（10km）是具有不同自然和人为特征的最大欧洲集水区之一。所得的热特征与多个已知的流域特征进行了交叉验证，强烈支持将其分为类似于大坝、类似于池塘和类似于自然的特征。我们对每个热特征的热状况进行了特征描述，并使用一组与生态相关的热指标对其进行了背景化。结果表明，与自然状态相比，大型水坝使夏季河流水温降低了 2°C，并使年河流温度峰值推迟了 23 天。相比之下，上游池塘的累积效应使夏季河流水温升高了 2.3°C，并增加了与空气温度的同步性。因此，这些热特征可用于识别和量化不同类型人为基础设施的下游热和生态影响，而无需有关修改源和上游水温条件的先验信息。
