hess-23-2305-2019.pdf (4.13 MB)

Integrating network topology metrics into studies of catchment-level effects on river characteristics

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journal contribution
posted on 13.11.2020, 14:04 by EL Heasley, Nicholas Clifford, JDA Millington
© 2019 Author(s). The spatial arrangement of the river network is a fundamental characteristic of the catchment, acting as a conduit between catchment-level effects and reach morphology and ecology. Yet river network structure is often simplified to reflect an upstream-to-downstream gradient of river characteristics, commonly represented by stream order. The aim of this study is to quantify network topological structure using two network density metrics-one that represents network density over distance and the other over elevation-that can easily be extracted from digital elevation models and so may be applied to any catchment across the globe. These metrics should better account for the multi-dimensional nature of the catchment than stream order and be functionally applicable across geomorphological, hydrological and ecological attributes of the catchment. The functional utility of the metrics is assessed by appropriating monitoring data collected for regulatory compliance to explore patterns of river characteristics in relation to network topology. This method is applied to four comparatively low-energy, anthropogenically modified catchments in the UK using river characteristics derived from England's River Habitat Survey database. The patterns in river characteristics explained by network density metrics are compared to stream order as a standard measure of topology. The results indicate that the network density metrics offer a richer and functionally more relevant description of network topology than stream order, highlighting differences in the density and spatial arrangement of each catchment's internal network structure. Correlations between the network density metrics and river characteristics show that habitat quality score consistently increases with network density in all catchments as hypothesized. For other measures of river character-modification score, flow-type speed and sediment size-there are varying responses in different catchments to the two network density metrics. There are few significant correlations between stream order and the river characteristics, highlighting the limitations of stream order in accounting for network topology. Overall, the results suggest that network density metrics are more powerful measures which conceptually and functionally provide an improved method of accounting for the impacts of network topology on the fluvial system.

Funding

Natural Environmental Research Council (NERC), grant code (NE/L002485/1)

History

School

  • Social Sciences and Humanities

Department

  • Geography and Environment

Published in

Hydrology and Earth System Sciences

Volume

23

Issue

5

Pages

2305 - 2319

Publisher

COPERNICUS GESELLSCHAFT MBH

Version

VoR (Version of Record)

Rights holder

© The authors

Publisher statement

This is an Open Access Article. It is published by Copernicus under the Creative Commons Attribution 4.0 Unported Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/

Acceptance date

15/04/2019

Publication date

2019-05-14

Copyright date

2019

ISSN

1027-5606

eISSN

1607-7938

Language

en

Depositor

Nicholas Clifford. Deposit date: 13 November 2020

Licence

Exports