Snowpack Influences on Geomorphic Processes in Green Lakes Valley, Colorado Front Range

Caine, Nel

doi:10.2307/3059928

Cited by 36 publications

(22 citation statements)

References 32 publications

(33 reference statements)

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“…An adjacent tower (10 m away) is equipped with a suite of meteorological instruments. Snow cover at the Soddie site generally lasts from late October into June, and ∼ 80 % of the annual precipitation of ∼ 1000 mm falls as snow (Caine, 1995). During the sampling period, the snowpack thickness at the Soddie site varied from 138 cm to 184 cm.…”

Section: Study Sitementioning

confidence: 99%

“…Among natural Hg reservoirs, the role of the cryosphere (i.e., snow-and ice-covered surfaces) is important as it represents a highly dynamic system situated between the atmosphere and the subniveal (covered by the snowpack) ecosystems (Dominé and Shepson, 2002). A recent review from Durnford and Dastoor (2011) concluded that no study has yet simulated the behavior of Hg in the cryosphere near its full complexity, and that it is crucial to develop models based on physical and chemical processes to simulate revolatilization processes from the cryosphere, particularly in regards to future changes in climate.…”

Section: Introductionmentioning

confidence: 99%

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Mercury dynamics in the Rocky Mountain, Colorado, snowpack

et al. 2013

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Abstract. Gaseous elemental mercury (GEM) was monitored at the Niwot Ridge (NWT) Long-Term Ecological Research (LTER) site (Colorado, USA, 40° N) from interstitial air extracted from the snowpack at depths ranging from the snow surface to 10 cm above the soil. A highly dynamic cycling of mercury (Hg) in this mid-latitude snowpack was observed. Patterns were driven by both GEM production in surface snow and GEM destruction in the deeper snowpack layers. Thorough mixing and vertical transport processes were observed through the snowpack. GEM was photochemically produced near the snow-air interface throughout the entire winter, leading to enhanced GEM levels in interstitial air of surface snow of up to 8 ng m−3. During low-wind periods, GEM in surface snow layers remained significantly above ambient air levels at night as well, which may indicate a potential weak GEM production overnight. Analyses of vertical GEM gradients in the snowpack show that surface GEM enhancements efficiently propagated down the snowpack, with a temporal lag in peak GEM levels observed with increasing depth. Downward diffusion was responsible for much of these patterns, although vertical advection also contributed to vertical redistribution. Destruction of GEM in the lower snowpack layers was attributed to dark oxidation of GEM. Analysis of vertical GEM / CO2 flux ratios indicated that this GEM destruction occurred in the snow and not in the underlying soil. The strong, diurnal patterns of photochemical GEM production at the surface ultimately lead to re-emission losses of deposited Hg back to the atmosphere. The NWT data show that highest GEM surface production and re-emissions occur shortly after fresh snowfall, which possibly resupplies photoreducible Hg to the snowpack, and that photochemical GEM reduction is not radiation-limited as it is strong even on cloudy days.

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Section: Study Sitementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mercury dynamics in the Rocky Mountain, Colorado, snowpack

et al. 2013

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“…However, it is generally not known whether smaller scale changes in temperature and precipitation since de-glaciation have a similar effect on sediment supply given the much smaller magnitude of change in vegetation type and cover. Bovis and Thorn, 1981;Caine, 1995). We therefore infer that high-elevation processes play a critical role in axial channel behavior at post-LGM timescales.…”

Section: Post-glacial Range Of Variability In the Conejos River Valleymentioning

confidence: 79%

“…If sediment was supplied to the axial channel via tributary fans during this time then, given the stability of lower hillslopes, early Holocene sedimentation was likely driven by (1) erosion of small, steep tributary basins with strongly convergent slopes, (2) erosion of upper hillslopes and valley divides and/or (3) the headward incision of tributary channels rather than wholesale movement of sediment from hillslopes throughout the drainage basin ( Figure 5). These sites can therefore be a significant source of fine-grained sediment for a fluvial system especially when exposed to intense summer rainstorms (Caine, 1976(Caine, , 1995. For example, climatic cooling at the time of fluvial deposition (8Á9 ka) likely led to longer-lived snowfields at higher elevations.…”

Section: Post-glacial Range Of Variability In the Conejos River Valleymentioning

confidence: 99%

Post‐glacial range of variability in the Conejos River Valley, southern Colorado, USA: fluvial response to climate change and sediment supply

Eppes

Johnson

Diemer

2012

Earth Surf Processes Landf

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Effective river management strategies require an understanding of how fluvial processes vary both spatially and temporally. Here, we examine the natural range of variability in the Conejos River Valley, southern Colorado, through documentation of terrace morphostratigraphic and sedimentological characteristics as well as through investigation of sediment contributions from headwaters, hillslopes and tributary streams. Additionally, soil development and radiocarbon ages, together with local and regional paleoclimate reconstructions, were used to infer the range of processes acting in this system. Since de‐glaciation, the Conejos River has fluctuated between episodes of bedrock strath formation, aggradation and vertical incision. Morphostratigraphic relationships, soil development and radiocarbon ages enable us to propose a chronology for periods of alluvial deposition (around 8·9–7·6 ka, 5·5 ka and from 3·5 to 1·1 ka), separated by intervals of fluvial incision. We infer potential forcing mechanisms by utilizing multiple working hypotheses. Specifically, we discuss the potential for increases in sediment supply during periods of (1) para‐glacial adjustment, (2) climatic cooling, (3) increased frequency of climate change and (4) increased fire frequency or severity. We also consider the effects of changes in stream discharge and extreme storm occurrence. We conclude that combinations of these processes, operating at different times, have contributed to sediment mobilization since de‐glaciation. Stream and landform morphology also varies longitudinally due to the influence of remnant glacial topography. In particular, valley bottom overdeepening at tributary junctions has resulted in incision and strath formation into unlithified glacial deposits (i.e. fill‐cut terraces) rather than bedrock in some reaches. Overall, the Conejos fluvial system has varied significantly both temporally and spatially since de‐glaciation and appears to be sensitive to changes in sediment supply related to Holocene scale climate fluctuations. This natural range of variability must therefore be a key consideration in any future stream management policies. Copyright © 2012 John Wiley & Sons, Ltd.

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“…It has an important influence on the timing and magnitude of snowmelt hydrographs [Caine, 1992] and on biogeochemical and geomorphological processes [Williams and Melack, 1989;Caine, 1995]. Adapting more physically-based approaches to understand and model flow through a snowpack should permit wider applications of operational snowpack models to more sites, and allow for year-to-year variability within a site [Melloh, 1999].…”

Section: Introductionmentioning

confidence: 99%

Meltwater Flowthrough Snow from Plot to Basin Scales

Williams¹,

Pfeffer²

2001

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Snowpack Influences on Geomorphic Processes in Green Lakes Valley, Colorado Front Range

Cited by 36 publications

References 32 publications

Mercury dynamics in the Rocky Mountain, Colorado, snowpack

Mercury dynamics in the Rocky Mountain, Colorado, snowpack

Post‐glacial range of variability in the Conejos River Valley, southern Colorado, USA: fluvial response to climate change and sediment supply

Meltwater Flowthrough Snow from Plot to Basin Scales

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