Modeling water and pollutant connectivity in pristine and human-impacted landscapes

生态水文学家致力于更好地理解、预测和缓解各种具有社会和经济意义的环境问题，包括洪水、干旱和水污染。虽然这些问题是由不同的过程造成的，但都可以通过连通性的透镜来审视。实际上，“连通性”是指给定景观位置“A”传输水和其他物质（例如，污染物或生物群）转移到另一个位置“B”，并且它是陆地和水生生态系统健康的关键指标。由于缺乏科学共识的连接措施，模型被视为实用工具，估计和测试假设的连接。然而，虽然现有的降水径流模型用于连通性估计，很少有明确的设计考虑到这一目标，提出了关于其预测的可靠性的问题。大多数现有的模型依赖于隐式连接模拟方法，其中只有一些景观属性相关的连接被认为是通过空间聚合的代理措施。相反，显式的连接模拟方法是罕见的：他们应该考虑到大量的景观属性，并允许他们的连接的影响，以不同的空间和时间，无论是通过基于方程的建模（EBM）或通过从复杂系统理论，如代理建模（ABM）进口的方法。后者在生态学上比较常见，但在水文学上比较少见。因此，拟议的研究计划的目标有四个方面：1）比较现有的降水径流模型在其隐含的连通性模拟中的性能; 2）使用基于方程的建模原理创建水和水介导的污染物连通性的空间显式模型，这在水文学中是典型的; 3）使用从生态学中借来的基于主体的建模工具创建空间显式的连通性模型;以及4）评估不同空间和时间尺度的混合连通性建模方法的价值。重点将放在加拿大和世界其他地区的森林、农业和城市地区的小集水区到大集水区：这将确保考虑到各种各样的景观，并评估与模型数据要求和计算效率有关的空间可变问题。鉴于其对原始和人类影响景观的数据模型集成的高度重视，拟议的研究计划将为未来的生态水文学家提供独特而重要的培训机会。

Ecohydrologists seek to better understand, predict and mitigate various environmental issues of societal and economic significance, including floods, droughts and water pollution. While those issues are created by different processes, they can all be examined through the lens of connectivity. Indeed, “connectivity” refers to the ability of a given landscape location “A” to transmit water and other materials (e.g., pollutants or biota) to another location “B”, and it is a key indicator of terrestrial and aquatic ecosystem health. Given the lack of scientific consensus on connectivity measures, models are seen as pragmatic tools for estimating and testing hypotheses about connectivity. However, while existing precipitation-runoff models are used for connectivity estimation, few were explicitly designed with this goal in mind, raising questions about the reliability of their predictions. Most existing models rely on implicit connectivity simulation approaches, whereby only some of the landscape properties relevant to connectivity are considered through spatially aggregated proxy measures. Conversely, explicit connectivity simulation approaches are rare: they should account for a large number of landscape properties and allow their influence on connectivity to vary in space and time, either via equation-based modelling (EBM) or through methods imported from complex systems theory, such as agent-based modelling (ABM). The latter are relatively common in ecology but scarce in hydrology. The goal of the proposed research program is, therefore, four-fold: 1) compare the performance of existing precipitation-runoff models in their implicit simulation of connectivity; 2) create spatially explicit models of water and water-mediated pollutant connectivity using equation-based modelling principles, as is typical in hydrology; 3) create spatially explicit models of connectivity using agent-based modelling tools borrowed from ecology; and 4) assess the value of hybrid connectivity modelling approaches at different spatial and temporal scales. The focus will be on sites ranging from small catchments to large watersheds located in forested, agricultural and urban regions of Canada and other parts of the world: this will ensure that a good variety of landscapes is considered and spatially variable issues related to model data requirements and computational efficiency are appraised. Given its strong emphasis on data-model integration in pristine and human-impacted landscapes, the proposed research program will provide unique and vital training opportunities for future ecohydrologists.