Challenges of mapping, modelling and quantifying sediment connectivity

Hooke, Janet ORCID: 0000-0002-8367-3010 and Souza, Jonas
(2021) Challenges of mapping, modelling and quantifying sediment connectivity. EARTH-SCIENCE REVIEWS, 223. p. 103847.

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Major advances continue to be made in development and application of the connectivity concept as a framework for analysis of runoff and sediment fluxes in catchments and landscapes and it is becoming a major paradigm in geomorphology and hydrology. It involves the identification of the locations and patterns of pathways of water and sediment movement and extent of their linkage. However, significant issues and challenges remain. Various approaches to identification and quantification of connectivity in a landscape are taken, involving mapping and modelling of various types. It is important in applying techniques that the purpose and basis is clear. A differentiation is made here between direct mapping of known situations, which elucidates patterns and can then be the basis for quantification, and that of modelling, which is predictive and often explanatory but requires validation. Thus, there is a synergy between the two. Various aspects of the spatial arrangements may be of interest, such as sources of sediment to a point in a catchment, pathway position, hotspots of erosion and deposition, controls on the connectivity, positions of disconnectors, influence of human activities, and natural variability with rainfall, seasons and other factors. The approach and styles of mapping usually entail recording all links at a particular time, possibly with differentiation of type of link, and commonly based on field surveys, but developments are taking place to test the effectiveness of drones for this purpose. Much modelling has used Connectivity Indices to generate patterns, with varying weighting of factors, and additional factors are now being introduced to indices to add functionality to the modelling. The other major approach to modelling is that of graph theory, based on network analysis, which is particularly applied to larger river systems. Both types of modelling have benefitted from availability of open-access software. Deficiencies and problems in use of modelling and indices persist, including: need for validation; ability to recognise disconnections; variability of connectivity over time; distinguishing sediment from flow connectivity; and clarity of representation. Challenges remain of spatial scale, particularly in validation/ field surveys but also base data for modelling; in identifying link status and functioning or dynamics at various timescales, and incorporation of feedback arising from those dynamics; in incorporating processes as a step to this functionality, and in testing indices. Methods and approaches to addressing these challenges are discussed and evaluated here.

Item Type: Article
Uncontrolled Keywords: Connectivity index, Sediment, Runoff, Disconnectivity, Catchment, Landscape dynamics
Depositing User: Symplectic Admin
Date Deposited: 25 Nov 2022 12:51
Last Modified: 18 Jan 2023 19:43
DOI: 10.1016/j.earscirev.2021.103847
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