Hydrological connectivity, the capacity of a river network to transport water and associated materials, can be evaluated through structural and functional approaches. Structural connectivity, often assessed using readily available topographic and network data, describes the static arrangement of the river network. Functional connectivity, however, reflects the dynamic flow processes within the network, typically measured through flow data which may be scarce. While numerous structural indicators exist, their ability to represent actual (functional) connectivity remains uncertain.There is still no clear method for accurately evaluating connectivity. Functional connectivity index (FCI) provides a realistic and dynamic representation of connectivity. This study established a research framework that evaluates the consistency between structural connectivity and functional connectivity (considering FCI as actual connectivity). The research framework uses topography and graph model to calculate structural indicators and employs intraclass correlation coefficient (ICC) to evaluate the consistency. Taking the Haihe River basin as an example, the study analyzes the ability of structural indicators to characterize actual connectivity, and proposes new indicator. The results show that Betweenness Centrality (BC) has the highest consistency with FCI, with an ICC of 0.32, while other structural indicators are relatively weak. In multiple scenarios, BC defined by the network and Topographic Connectivity Index (TCI) defined by topography have the potential to characterize connectivity, and there are significant spatial differences between them. The combined index BC&TCI, which considers both network and topography, can better characterize connectivity, with an ICC of 0.40 and reaching an ICC of 0.55 in mountain area. The research framework also reveals the non-consistency between structural connectivity and functional connectivity. And the non-consistency between them can serve as a measure of river network renovation and reconstruction to avoid ecological problems caused by an imbalanced structure and function.

中文翻译：

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数据匮乏流域河流网络连通性评价方法的一致性研究


水文连通性，即河流网络输送水和相关材料的能力，可以通过结构和功能方法进行评估。结构连通性，通常使用现成的地形和网络数据进行评估，描述了河流网络的静态布局。然而，功能连接反映了网络内的动态流过程，通常通过可能稀缺的流数据来测量。虽然存在许多结构指标，但它们表示实际（功能）连通性的能力仍然不确定。目前还没有明确的方法来准确评估连通性。功能连接指数 （FCI） 提供真实和动态的连接表示。本研究建立了一个研究框架，用于评估结构连接和功能连接之间的一致性（将 FCI 视为实际连接）。研究框架使用地形和图形模型来计算结构指标，并采用类内相关系数 （ICC） 来评估一致性。以海河流域为例，分析了结构指标表征实际连通性的能力，并提出了新的指标。结果表明，中介中心性 （BC） 与 FCI 的一致性最高，ICC 为 0.32，而其他结构指标相对较弱。在多个场景中，由网络定义的 BC 和由地形定义的地形连通性指数 （TCI） 有可能表征连通性，并且它们之间存在显著的空间差异。同时考虑网络和地形的组合索引 BC&TCI 可以更好地描述连通性，ICC 为 0。40 分，山区达到 0.55 的 ICC。该研究框架还揭示了结构连接和功能连接之间的不一致。它们之间的不一致可以作为河网改造和重建的措施，以避免因结构和功能失衡而引起的生态问题。