Geomorphic segmentation, hydraulic geometry, and hydraulic microhabitats of the Niobrara River, Nebraska — Methods and initial results

Alexander, Jason; Zelt, Ronald B.; Schaepe, Nathaniel J.

doi:10.3133/sir20095008

Cited by 8 publications

(11 citation statements)

References 47 publications

(43 reference statements)

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“…Mean daily discharge recorded at the nearest U.S. Geological Survey gaging station (#06461500), relative to mean annual discharge of 21 m 3 /s (Alexander et al, ).…”

Section: Study Area and Methodsmentioning

confidence: 99%

“…The Niobrara gains substantial base flow as seepage from the High Plains aquifer, and much of the basin is undammed; despite some hydrologic alteration, the Niobrara maintains a relatively natural flow regime. The mean annual flow at the nearest U.S. Geological Survey gaging station (#06461500) since 1964, when a tributary was dammed, is 21 m 3 /s (Alexander et al, 2009) with a 1.5-year recurrence interval flow of 52 m 3 /s (Schaepe, Alexander, & Folz-Donahue, 2016). The river occasionally flows over bedrock, but bed material is dominated by sand originating from the surrounding Nebraska Sandhills and breakdown of the Cenozoic sedimentary bedrock underlying much of the basin (Alexander, Zelt, & Schaepe, 2010).…”

Section: Study Area and Imagesmentioning

confidence: 99%

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Spectrally based bathymetric mapping of a dynamic, sand‐bedded channel: Niobrara River, Nebraska, USA

Dilbone

Legleiter

Alexander

et al. 2018

River Research & Apps

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Methods for spectrally based mapping of river bathymetry have been developed and tested in clear‐flowing, gravel‐bed channels, with limited application to turbid, sand‐bed rivers. This study used hyperspectral images and field surveys from the dynamic, sandy Niobrara River to evaluate three depth retrieval methods. The first regression‐based approach, optimal band ratio analysis (OBRA), paired in situ depth measurements with image pixel values to estimate depth. The second approach used ground‐based field spectra to calibrate an OBRA relationship. The third technique, image‐to‐depth quantile transformation (IDQT), estimated depth by linking the cumulative distribution function (CDF) of depth to the CDF of an image‐derived variable. OBRA yielded the lowest depth retrieval mean error (0.005 m) and highest observed versus predicted R2 (0.817). Although misalignment between field and image data did not compromise the performance of OBRA in this study, poor georeferencing could limit regression‐based approaches such as OBRA in dynamic, sand‐bedded rivers. Field spectroscopy‐based depth maps exhibited a mean error with a slight shallow bias (0.068 m) but provided reliable estimates for most of the study reach. IDQT had a strong deep bias but provided informative relative depth maps. Overprediction of depth by IDQT highlights the need for an unbiased sampling strategy to define the depth CDF. Although each of the techniques we tested demonstrated potential to provide accurate depth estimates in sand‐bed rivers, each method also was subject to certain constraints and limitations.

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“…Mean daily discharge recorded at the nearest U.S. Geological Survey gaging station (#06461500), relative to mean annual discharge of 21 m 3 /s (Alexander et al, ).…”

Section: Study Area and Methodsmentioning

confidence: 99%

Section: Study Area and Imagesmentioning

confidence: 99%

Spectrally based bathymetric mapping of a dynamic, sand‐bedded channel: Niobrara River, Nebraska, USA

Dilbone

Legleiter

Alexander

et al. 2018

River Research & Apps

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“…According to Alexander et al (2009), the hydraulic geometry relations use stream-flow discharge-measurements from either individual stream-flow gauging stations (at--a-station geometry) or data from multiple stream-flow gauging stations, common measurement increments, and common periods of record to relate wetted-channel geometry and water velocity to river discharge through a series of empirical models in the form of power functions. Leopold and Maddock (1953) referred to these models as downstream hydraulic geometry relations.…”

Section: Channel Parametersmentioning

confidence: 99%

“…Altera-tions in the natural flow regime of any river or stream can result in adjustments to the overall planform (geometry), cross-sectional channel geometry, bed configuration, and channel-bed. These changes in the hydrogeomorphic attributes of a river channel may cascade into degradation of its physical habitat attributes, which are important for aquatic and riparian life (Alexander et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Channel dynamics and hydraulic geometry of two tropical deltaic catchments in Southern Nigeria

Aisuebeogun¹,

Ezekwe²

2014

Landform Analysis

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This paper attempts to explain the channel processes and dynamics of two river systems running through a rapidly urbanizing humid tropical deltaic environment with visible threats from industrialization and pollution. Hydraulic processes and parameters were compared with established power function relations for hydraulic geometry and it was discovered that the fundamental relations between channel-geometry dimensions, velocity, and flow can be expressed for the catchments. Ten gauging stations in each catchment were studied and results showed that the studied catchments adjust their geometry to changing discharges. High values of coefficients of determination among variables indicated that much of the downstream variation in channel width to depth ratio can be accounted for by changes in discharge. Also in this study the width/depth ratio (F) was found to be related to the percentage of silt + clay (M) in channel perimeter and that downstream hydraulic-geometry relations are in general agreement with previously published hydraulic and channel adjustment data.

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“…The USGS performs periodic measurements of channel flow properties (velocity, water depth, section area, and water width) in diverse locations around the United States to supplement or verify the accuracy of time-series measurements. The viability of using these measures to estimate the parameter of hydraulic geometry has been demonstrated by several authors (Castro and Jackson, 2001;Sweet and Geratz, 2003;Lee and Julien, 2006;Alexander et al, 2009;Faustini et al, 2009;Metcalf et al, 2009).…”

Section: Hydraulic Geometrymentioning

confidence: 99%

A framework for flood risk assessment under nonstationary conditions or in the absence of historical data

Cunha

Krajewski

Mantilla

2011

Journal of Flood Risk Management

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We present a diagnostic framework to assess changes in flood risk across multiple scales in a river network, under nonstationary conditions or in the absence of historical hydro‐meteorological data. The framework combines calibration‐free hydrological and hydraulic models with urban development information to demonstrate altered flood risk. Our models utilize hydraulic geometric data and high‐resolution remote‐sensing information provided on a nearly global basis. The need for calibration is eliminated because model parameters are directly related to the physical properties of the system. We apply the methodology in a case study for Mecklenburg County, NC, in which we assess the effects of land cover changes on flood frequency. We obtained maps of expected inundated zones under different conditions of land cover and storm return periods and compared them with the 100‐year return period inundation maps developed by Federal Emergency Management Agency that are based on more complex hydraulic models. The close agreement supports our framework's applicability and generality.

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Geomorphic segmentation, hydraulic geometry, and hydraulic microhabitats of the Niobrara River, Nebraska — Methods and initial results

Cited by 8 publications

References 47 publications

Spectrally based bathymetric mapping of a dynamic, sand‐bedded channel: Niobrara River, Nebraska, USA

Spectrally based bathymetric mapping of a dynamic, sand‐bedded channel: Niobrara River, Nebraska, USA

Channel dynamics and hydraulic geometry of two tropical deltaic catchments in Southern Nigeria

A framework for flood risk assessment under nonstationary conditions or in the absence of historical data

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