The concept, approach, and future research of hydrological connectivity and its assessment at multiscales

Abstract

In this review, we explore the concept, approach, and future research of hydrological connectivity and its assessment at multiscales, because according to the literature, an integrated review upon hydrological connectivity is lack. Systematic studies illustrate the effects of (i) human activities (i.e., dam construction, groundwater extraction, water flow regulation and diversion, and land management) and (ii) natural factors (i.e., climate, soil characteristics, vegetation, and topography) on hydrological connectivity. Approaches (i.e., soil water content patterns, runoff patterns and processes, numerical models, and index of hydrological connectivity) applied to evaluate hydrological connectivity are examined in detail. Lastly, hydrological connectivity at multiscales is indicated. This review concludes with a discussion of potential research trends that can improve understanding of hydrological connectivity. Reported records showed that few studies were published on hydrological connectivity from 1980 to 2003, whereas the evolution of these studies is temporally promising since 2003. We cannot define a standard concept of hydrological connectivity that works in all environments. We desire to show different concepts of hydrological connectivity in different environments. The degree and nature of hydrological connectivity are not static due to the influences of human activities and changes of natural factors. The index of hydrological connectivity and numerical models are the most significant approaches to assess the changes in hydrological connectivity. This study showed that considering hydrological connectivity in social-economical-ecological-hydrological frameworks can prevent its negative effects on surface or subsurface water quantity and quality and is beneficial for sound water sources management.

Effects of roots systems on hydrological connectivity below the soil surface in the Yellow River Delta wetland

“…Recently, the term ‘hydrological connectivity’ provides a new perspective to indicate the changes of hydrological responses and to define its correlations with ecological functions (Liu et al, 2019; Zhang et al, 2021). Hydrological connectivity defines the water‐mediated transfer of mass, energy and organisms from one part of the landscape to another at larger scales (Bracken & Croke, 2007; Xie et al, 2021).…”

Recent advancement in water quality indicators for eutrophication in global freshwater lakes

“…Natural geomorphological processes such as sedimentation also fragment the rivers and alter system connectivity (Doretto et al 2020). The lateral (to floodplain) and longitudinal (fragmentation) river connectivity in a basin are important in understanding spatiotemporal responses of rivers to external disturbances and nutrient retention mechanisms (Tockner et al 1999, Wohl 2017, Zhang et al 2021b causing algal blooms in lakes. Lakes are connected to rivers in three ways: (i) permanently; or (ii) pulsing; or (iii) isolated and there are three nutrient exchange pathways in these ecosystems: (i) floodplain to rivers, (ii) rivers to floodplain, and (iii) rivers to lakes.…”

A new framework combining hydrological connectivity metrics and morphological spatial pattern analysis for the hydrological connectivity evaluation of wetlands

“…Dynamic functional connectivity and static structural connectivity, as two related and complementary concepts, have been applied to measure the degrees of interconnection and interaction among different landscape units (Jahanishakib et al, 2021; Y. Li, Tan, et al, 2021; Y. Li, Zhang, et al, 2021; Y. Liu, Cui, et al, 2020; Zhang et al, 2021; Zhao et al, 2020). To date, much has been learned about quantitative evaluation methods from the perspectives of functional connectivity and structural connectivity.…”

“…Commonly used methods include field monitoring (Brooks et al, 2018; Tian et al, 2021), hydrological models (Tan et al, 2019), and an index‐based approach (e.g., hydrological connectivity metrics and ecological connectivity indicators; Gülçin, 2021). Hydrological connectivity metrics have been recommended as an effective strategy because they are easily characterized by GIS and remote sensing imagery (Zhang et al, 2021). But the difficulty lies in the selection of reasonable indexes.…”