River deltas as Multiplex networks: A framework for studying multi-process multi-scale connectivity via coupled-network theory

Transport of water, nutrients or energy fluxes in many natural or coupled human-natural systems occurs along different pathways that often have a wide range of transport timescales and might exchange fluxes with each other dynamically (e.g., surface-subsurface). Understanding this type of transport is key to predicting how landscapes will change under changing forcing. Here, we present a general framework for studying transport on a multi-scale coupled-connectivity system, via a multilayer network, which conceptualizes the system as a set of interacting networks, each arranged in a separate layer, and with interactions across layers acknowledged by interlayer links. We illustrate this framework by examining transport in river deltas as a dynamic interaction of flow within river channels and overland flow in the islands, when it is controlled by the flooding level. We show the potential of the framework to answer quantitatively questions related to the characteristic timescale of response in the system.

水、营养物质或能量通量在众多自然或人-自然耦合系统中，其传输路径多样，往往涉及广泛的传输时间尺度，并可能动态地相互交换通量（例如地表-地下）。理解此类传输过程对于预测在变化的外部作用下景观如何演变至关重要。本研究提出了一种针对多尺度耦合连通性系统的通用研究框架，通过多层网络模型实现。该模型将系统概念化为一系列相互作用的网络，每个网络独立排列于一个单独的层中，并通过层间链接认可层与层之间的相互作用。我们通过考察河流三角洲的传输过程来阐述这一框架，该过程被视为河流渠道内流动与岛屿地表流动的动态相互作用，受洪水水平控制。我们展示了该框架在定量回答与系统响应特征时间尺度相关的问题方面的潜力。