Analysis of changes in the step-pool morphology and channel profile of a steep mountain stream following a large flood

Molnár, Péter; Densmore, Alexander L.; McArdell, Brian W.; Turowski, Jens M.; Burlando, Paolo

doi:10.1016/j.geomorph.2010.08.014

Cited by 112 publications

(105 citation statements)

References 43 publications

(74 reference statements)

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“…), and a wide variety of shrubs and ground plants (Schleppi et al, 1999). The Erlenbach is a step-pool channel with high sediment load, which is mainly supplied by a series of slow-moving landslides along the channel banks (Schuerch et al, 2006;Turowski et al, 2009;Molnar et al, 2010). There are two discharge gauges located immediately upstream and downstream of a sediment retention basin where automatic basket samplers and indirect bedload sensors for sediment transport measurements are available (Rickenmann et al, 2012;Turowski et al, 2011).…”

Section: Field Sitementioning

confidence: 99%

The mass distribution of coarse particulate organic matter exported from an Alpine headwater stream

et al. 2013

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Abstract. Coarse particulate organic matter (CPOM) particles span sizes from 1 mm, with a dry mass less than 1 mg, to large logs and entire trees, which can have a dry mass of several hundred kilograms. Pieces of different size and mass play different roles in stream environments, from being the prime source of energy in stream ecosystems to macroscopically determining channel morphology and local hydraulics. We show that a single scaling exponent can describe the mass distribution of CPOM heavier than 0.1 g transported in the Erlenbach, a steep mountain stream in the Swiss pre-Alps. This exponent takes an average value of −1.8, is independent of discharge and valid for particle masses spanning almost seven orders of magnitude. Similarly, the mass distribution of in-stream large woody debris (LWD) in several Swiss streams can be described by power law scaling distributions, with exponents varying between −1.8 and −2.0, if all in-stream LWD is considered, and between −1.3 and −1.8 for material locked in log jams. We found similar values for in-stream and transported material in the literature. We had expected that scaling exponents are determined by stream type, vegetation, climate, substrate properties, and the connectivity between channels and hillslopes. However, none of the descriptor variables tested here, including drainage area, channel bed slope and the percentage of forested area, show a strong control on exponent value. Together with a rating curve of CPOM transport rates with discharge, the scaling exponents can be used in the design of measuring strategies and in natural hazard mitigation.

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Section: Field Sitementioning

confidence: 99%

The mass distribution of coarse particulate organic matter exported from an Alpine headwater stream

et al. 2013

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“…Coarse particulate organic matter (CPOM) in streams is typically defined as organic material with a diameter larger than 1 mm, and thus encompasses a wide range of different types and sizes, from leaves and twigs to wood fragments and entire trees (Naiman and Sedell, 1979;Bilby and Likens, 1980). CPOM is an important component both of the physical and the ecological system of the stream.…”

Section: Introductionmentioning

confidence: 99%

“…When entering the stream, organic matter is considered to be the main source of energy in headwater ecosystems and provides food, shelter, and variable habitats (Fisher and Likens, CPOM is degraded by various physical, chemical, and biological processes, or can be flushed out by fluvial processes. CPOM leaving the catchment represents a loss of nutrients and energy to the stream ecosystem (Fisher and Likens, 1973;Naiman and Sedell, 1979;Webster et al, 1999), and, in case of LWD, can lead to an increased hazard downstream (Comiti et al, 2006;Ruiz-Villanueva et al, 2014). It is known that CPOM export from a catchment strongly depends on discharge (e.g., Bormann et al, 1969;Fisher and Likens, 1973;Wallace et al, 1995;Iroumé et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

The role of log jams and exceptional flood events in mobilizing coarse particulate organic matter in a steep headwater stream

et al. 2015

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Abstract. Coarse particulate organic matter (CPOM) fulfills important functions in the physical and ecological system of a stream. CPOM delivery to and export from the stream has implications for the stream's morphology and sediment transport capacity as well as the energy budget and food availability. Export rates of CPOM from mountain catchments have been observed to strongly increase with rising discharge, but the mechanism leading to this strong relationship is unclear. Here, we show that log jams in the Erlenbach, a steep headwater stream in the Swiss Prealps, are an effective barrier for the transport of CPOM pieces, and thus become sites of storage of large quantities of material over time. Exceptional discharge events with return periods exceeding 20 years play a dual role in CPOM transport in the Erlenbach. First, they appear to destroy existing log jams, releasing the stored material (wood and sediment). Second, they intensify channel-hillslope coupling, thereby recruiting new logs to the channel, around which new jams can form. This allows for the formulation of a new, fully episodic endmember in a four-end-member model of CPOM dynamics of steep mountain streams based on wood delivery and export.

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“…The flowing stream drainage density in the upper parts of WS04, WS07, WS18 and WS19 increased by a factor of five between the very dry conditions at the end of August 2016 and the first rainfall events in fall 2016 (Sjöberg, 2015). The channels have a step-pool morphology (Molnar et al, 2010) and cut into the alluvium of weathered bedrock (Keller, 1970). However, most of the streams are relatively shallow and only the larger streams are incised by more than 0.5 m (Figs.…”

Section: Topographymentioning

confidence: 99%

Runoff generation in a pre-alpine catchment: A discussion between a tracer and a shallow groundwater hydrologist

Meerveld

Fischer

Rinderer

et al. 2018

CIG

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Runoff generation mechanisms vary between catchments and despite decades of research in many catchments, these mechanisms are still not fully understood. In this paper, runoff generation mechanisms in the steep pre-alpine catchments in the Alptal, Switzerland, are discussed. These fast responding catchments are characterized by low permeability soils on top of flysch bedrock. In combination with the high and frequent precipitation, this results in predominantly wet conditions. In many areas, the water table is close to the surface. We review the main results of recent (2009-2016) studies in these catchments that used isotope, stream chemistry and hydrometric data. These field studies focused on the spatial and temporal patterns in groundwater levels, spatial patterns in the isotopic composition and chemistry of streamflow during baseflow conditions, as well as the responses of streamflow and its isotopic composition during rainfall events. The combined results of these studies highlight the establishment of connectivity of areas with a different topographic position and areas with a different land use during rainfall events. They also show the importance of flow in higher conductivity near surface soil layers for runoff generation, as well as the frequent occurrence of surface runoff. Spatial differences in groundwater dynamics are related to topography. Streamflow responses are mainly affected by the rainfall characteristics; differences in streamflow and hydrochemistry between catchments with different portions of forest, meadows and wetlands, were relatively small. However, variations in the chemistry of baseflow along stream reaches within a catchment were considerable. Above all, these studies highlight the value of combining data on spatial patterns of groundwater levels and stream chemistry with long term data on streamflow to derive a more complete picture of the dominant runoff generation mechanisms.

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Analysis of changes in the step-pool morphology and channel profile of a steep mountain stream following a large flood

Cited by 112 publications

References 43 publications

The mass distribution of coarse particulate organic matter exported from an Alpine headwater stream

The mass distribution of coarse particulate organic matter exported from an Alpine headwater stream

The role of log jams and exceptional flood events in mobilizing coarse particulate organic matter in a steep headwater stream

Runoff generation in a pre-alpine catchment: A discussion between a tracer and a shallow groundwater hydrologist

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