Hydraulic geometry of the Platte River in south-central Nebraska

Eschner, T. R.

doi:10.3133/ofr82436

Cited by 9 publications

(8 citation statements)

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“…In the unvegetated model runs, a was an order of magnitude higher than in run 5 and the natural single-thread rivers. High a are characteristic of braided rivers [Ashmore, 1985], and a computed in runs 1 and 2 are consistent with a computed for other braided streams [Eschner, 1983]. Thorne, 1986].…”

Section: Charlton Et Al [1978] Andrews [1984] and Hey And Thornesupporting

confidence: 62%

Riparian vegetation controls on braided stream dynamics

Gran¹,

Paola²

2001

Water Resources Research

350

314

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Abstract. Riparian vegetation can significantly influence the morphology of a river, affecting channel geometry and flow dynamics. To examine the effects of riparian vegetation on gravel bed braided streams, we conducted a series of physical experiments at the St. Anthony Falls Laboratory with varying densities of bar and bank vegetation. Water discharge, sediment discharge, and grain size were held constant between runs. For each run, we allowed a braided system to develop, then seeded the flume with alfalfa (Medicago sativa), allowed the seeds to grow, and then continued the run. We collected data on water depth, surface velocity, and bed elevation throughout each run using imagebased techniques designed to collect data over a large spatial area with minimal disturbance to the flow. Our results show that the influence of vegetation on overall river patterns varied systematically with the spatial density of plant stems. Vegetation reduced the number of active channels and increased bank stability, leading to lower lateral migration rates, narrower and deeper channels, and increased channel relief. These effects increased with vegetation density. Vegetation influenced flow dynamics, increasing the variance of flow direction in vegetated runs and increasing scour depths through strong downwelling where the flow collided with relatively resistant banks. This oblique bank collision also provides a new mechanism for producing secondary flows. We found it to be more important than the classical curvature-driven mechanism in vegetated runs.

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Section: Charlton Et Al [1978] Andrews [1984] and Hey And Thornesupporting

confidence: 62%

Riparian vegetation controls on braided stream dynamics

Gran¹,

Paola²

2001

Water Resources Research

350

314

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“…Early studies, predominantly concentrating on stretches west of the study area (e.g., Williams, 1978;Eschner, 1983;Eschner et al, 1983;Kircher and Karlinger, 1983), demonstrated striking decreases in channel width since the 1860s. Johnson (1994), in a singularly important study, examined decreases in channel area and increases in island stabilization over small stretches of the upper and middle Platte and related them to the expansion of cottonwood-and willowdominated woodland, which was regulated by patterns of (i) June flows, (ii) summer droughts, and (iii) wintertime conditions in the channel belt.…”

Section: Discussionmentioning

confidence: 98%

“…A single operator performed all activities for the purposes of consistency and overall precision. Unfortunately, serial measurements of stream depth and surveyed cross sections (the "third dimension" of change) are unavailable, but earlier studies (e.g., Williams, 1978;Eschner, 1983;Eschner et al, 1983;Kircher and Karlinger, 1983) demonstrated that these constraints do not negate the value of examining river planform change over decadal timescales. Moreover, no a priori reasons exist to assume that channel depths have increased dramatically as planform changes have occurred.…”

Section: Methodsmentioning

confidence: 97%

“…Historical geomorphic change is particularly relevant in the case of the Platte River because of emerging concerns about threatened and endangered species, whose life histories are intimately tied to the physical condition of the river's bed, mobile bars, and banks (National Academy of Sciences, 2004). Long before the strongest concern about habitat change on the Platte River emerged, benchmark studies of historical change (Williams, 1978;Eschner, 1983;Eschner et al, 1983;Kircher and Karlinger, 1983) documented dramatic channel narrowing, the stabilization of mobile bars and banks by woody vegetation, and extensive island-to-bank accretion since the 1860s. These studies focused on the river west of Grand Island, Nebraska, and on the tributaries North and South Platte River even farther west, relying on serial measurements of channel width at single stations.…”

Section: Introductionmentioning

confidence: 97%

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Channel and island change in the lower Platte River, Eastern Nebraska, USA: 1855–2005

Joeckel

Henebry²

2008

Geomorphology

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“…In general terms, they increase the flow resistance and sedimentation of fine particulate matter, reducing flow velocity and generally producing a lentic condition (Pitlo and Dawson 1990;Harper and Everard 1998). In intermittent and regulated rivers, these phenomena are often enhanced by the absence of high flow periods that are able to limit macrophyte growth (Eschner 1983;Johnson 2000). The presence of organic debris (CPOM and FPOM) is considered an indicator of lentic areas because low flowsusually associated with rather lentic conditions-facilitate the sedimentation processes of organic matter (Bañuelos et al 2004;Lemly and Hilderbrand 2000).…”

Section: Hydraulic Habitat and Lrdmentioning

confidence: 99%

The lentic–lotic character of Mediterranean rivers and its importance to aquatic invertebrate communities

2009

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Hydromorphological features are crucial in structuring habitats for freshwater organisms. The quantification of these variables is often performed through accurate measuring or detailed estimation, but their assessment is not always feasible for river management purposes. Economic and time constraints often lead to difficulty in creating simple summaries of collected data for practical use. The Lentic-lotic River Descriptor (LRD) was developed to identify the character of a river site in terms of local hydraulic conditions. Information about the presence of flow types, channel substrates, in-stream vegetation, organic debris and artificial features is included in its calculation. The main aim of this paper is to investigate whether the lentic-lotic character of a river site, as summarized with the LRD descriptor, is relevant to aquatic invertebrate communities in nearly natural river sites. Invertebrate data were collected with multi-habitat, proportional sampling and hydromorphological information was gained by applying the CARAVAGGIO method (river habitat survey technique) in the field. The dataset was generated from High or Good ecological status river sites located in Mediterranean areas of Italy. Correspondence Analysis was performed to relate the invertebrate community structure to a set of catchment-scale, reach-scale and chemical environmental variables. The results of the multivariate analysis indicate that LRD provides a persuasive explanation of the most important axis of variation in benthic data. This paper also presents the optimal LRD range for a set of invertebrate taxa, accompanied by a short discussion of their potential use in conservation issues.

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Hydraulic geometry of the Platte River in south-central Nebraska

Cited by 9 publications

References 0 publications

Riparian vegetation controls on braided stream dynamics

Riparian vegetation controls on braided stream dynamics

Channel and island change in the lower Platte River, Eastern Nebraska, USA: 1855–2005

The lentic–lotic character of Mediterranean rivers and its importance to aquatic invertebrate communities

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