A hydrogeomorphic river network model predicts where and why hyporheic exchange is important in large basins

Geophysical Research Letters
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Abstract

Hyporheic exchange has been hypothesized to have basin-scale consequences; however, predictions throughout river networks are limited by available geomorphic and hydrogeologic data and by models that can analyze and aggregate hyporheic exchange flows across large spatial scales. We developed a parsimonious but physically based model of hyporheic flow for application in large river basins: Networks with EXchange and Subsurface Storage (NEXSS). We applied NEXSS across a broad range of geomorphic diversity in river reaches and synthetic river networks. NEXSS demonstrates that vertical exchange beneath submerged bed forms rather than lateral exchange through meanders dominates hyporheic fluxes and turnover rates along river corridors. Per kilometer, low-order streams have a biogeochemical potential at least 2 orders of magnitude larger than higher-order streams. However, when biogeochemical potential is examined per average length of each stream order, low- and high-order streams were often found to be comparable. As a result, the hyporheic zone's intrinsic potential for biogeochemical transformations is comparable across different stream orders, but the greater river miles and larger total streambed area of lower order streams result in the highest cumulative impact from low-order streams. Lateral exchange through meander banks may be important in some cases but generally only in large rivers.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title A hydrogeomorphic river network model predicts where and why hyporheic exchange is important in large basins
Series title Geophysical Research Letters
DOI 10.1002/2014GL061099
Volume 41
Issue 18
Year Published 2014
Language English
Publisher AGU Publications
Contributing office(s) National Research Program - Eastern Branch
Description 10 p.
First page 6403
Last page 6412