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Hydrologic response to valley-scale structure in alpine headwaters

Hydrological Processes

By:
, , , , and
DOI: 10.1002/hyp.10141

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Abstract

Few systematic studies of valley-scale geomorphic drivers of streamflow regimes in complex alpine headwaters have compared response between catchments. As a result, little guidance is available for regional-scale hydrological research and monitoring efforts that include assessments of ecosystem function. Physical parameters such as slope, elevation range, drainage area and bedrock geology are often used to stratify differences in streamflow response between sampling sites within an ecoregion. However, these metrics do not take into account geomorphic controls on streamflow specific to glaciated mountain headwaters. The coarse-grained nature of depositional features in alpine catchments suggests that these landforms have little water storage capacity because hillslope runoff moves rapidly just beneath the rock mantle before emerging in fluvial networks. However, recent studies show that a range of depositional features, including talus slopes, protalus ramparts and 'rock-ice' features may have more storage capacity than previously thought.

To better evaluate potential differences in streamflow response among basins with extensive coarse depositional features and those without, we examined the relationships between streamflow discharge, stable isotopes, water temperature and the amplitude of the diurnal signal at five basin outlets. We also quantified the percentages of colluvial channel length measured along the stepped longitudinal profile. Colluvial channels, characterized by the presence of surficial, coarse-grained depositional features, presented sediment-rich, transport-limited morphologies that appeared to have a cumulative effect on the timing and volume of flow downstream. Measurements taken from colluvial channels flowing through depositional landforms showed median recession constants (Kr) of 0.9-0.95, δ18O values of ≥−14.5 and summer diurnal amplitudes ≤0.8 as compared with more typical surface water recession constant values of 0.7, δ18O ≤ −13.5 and diurnal amplitudes >2.0. Our results demonstrated strong associations between the percentage of colluvial channel length within a catchment and moderated streamflow regimes, water temperatures, diurnal signals and depleted δ18O related to groundwater influx.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Hydrologic response to valley-scale structure in alpine headwaters
Series title:
Hydrological Processes
DOI:
10.1002/hyp.10141
Volume
29
Issue:
3
Year Published:
2015
Language:
English
Publisher:
Wiley
Publisher location:
Chichester, Sussex, England
Description:
17 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Hydrological Processes
First page:
356
Last page:
372
Number of Pages:
17
Country:
United States
State:
Washington
Online Only (Y/N):
N
Additional Online Files(Y/N):
N