Influence of lakes on catchment hydrology and stream temperature

气候变化、森林干扰和城市化正在对河流及其水生生态系统的健康产生深远影响。了解这些环境变化是如何影响水流和水质的，这对有效管理水资源至关重要。在我们对集水区如何响应环境变化的理解中，一个明显的知识缺口是湖泊对下游水文和水质的作用。实证研究强调了湖泊在景观尺度上对溪流水质的重要影响，即使湖泊只占景观面积的一小部分。然而，只有少数研究集中在支撑这些景观格局的水文和热过程上。此外，大多数研究都集中在大型湖泊及其进出口河流上；然而，小湖泊在冰川景观中普遍存在，但对其对流域水文的影响知之甚少。关于湖流网络的重要问题包括：湖泊如何影响下游的水流状况和水质？这些湖泊的影响会持续到下游多远？湖水网结构如何影响集水区尺度上的流量和水质？有湖泊的集水区比没有湖泊的集水区更能适应环境变化吗？拟议的研究将使用现场和建模方法的结合来解决这些问题。实地研究将在不列颠哥伦比亚省南部海岸山脉雨雪区包含湖流网络的研究集水区进行。实地工作的目的是描述控制这些集水区及其湖流网络的水文和热状况的物理过程。水流和水温都是影响鱼类生长、发育、生存和分布的重要因素。从实地研究中获得的过程知识将用于建立和测试计算机模型，以提高我们预测气候变化和森林干扰的影响以及湖泊对河流和水温的作用的能力。这种模型构建和测试框架将推动流域水文理解的快速发展，这对于开发有效管理这些系统的工具至关重要。

Climate change, forest disturbance, and urbanization are having a profound impact on the health of streams and their aquatic ecosystems. Developing a process understanding of how these environmental changes are impacting streamflow regimes and water quality is critical for effective management of our water resources. A glaring knowledge gap in our understanding of how catchments respond to environmental change is the role of lakes on downstream hydrology and water quality. Empirical studies have highlighted the important influence of lakes on stream water quality at landscape scales, even when lakes comprise just a small fraction of the landscape area. However, only a few studies have focused on the hydrologic and thermal processes underpinning these landscape patterns. In addition, most research has focused on large lakes and their inlet and outlet streams; however, small lakes are prevalent in glaciated landscapes but little is know about their influence on catchment hydrology. Important questions about lake-stream networks include: How do lakes influence downstream flow regimes and water quality? How far downstream do these lake effects persist? How does the lake-stream network structure impact streamflow and water quality at catchment scales? Are catchments with lakes more resilient to environmental change than catchments without lakes? The proposed research will address these questions using a combination of field and modelling approaches. Field research will be conducted at research catchments containing lake-stream networks in the rain-on-snow zone of the southern Coast Mountains in British Columbia. The field work will aim at characterizing the physical processes controlling the hydrology and thermal regimes of these catchments and their lake-stream networks. Both streamflow and water temperature are critical influences on fish growth, development, survival and distribution. The process knowledge gained from the field studies will be used to build and test computer models to improve our ability to predict effects of climate change and forest disturbance, and the role of lakes, on streamflow and water temperature. This model building and testing framework will drive rapid advances in catchment hydrology understanding, which will be critical for developing tools to effectively manage these systems.