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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Surveys in geophysics 1 (1972), S. 61-84 
    ISSN: 1573-0956
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Stochastic methods in hydraulics and hydrology of streamflow are presented. The hydraulics part consists of mechanics of streamflow and sediment transport. A technique presented herein enables one to analyze a limited amount of field data to determine the stochastic structure of irregular stream geometry so that cross-sections and slopes of a stream may be simulated wherever, or as many as, needed. It provides the rational basis of efficient use, interpolation, and extrapolation of field data of irregular stream geometry for any studies to understand and control transport processes in streams. Stochastic modelings of motion of a single sediment particle, either in suspension or on the stream bed, help in understanding the complex mechanism governing sediment transport and, hence, improving techniques for calculating the spatial distribution and transport rate of sediment. For practical applications, however, the technique combining the stochastic and deterministic methods should be most effective. In the hydrology part, Markov and non-Markov models are presented which may be used to simulate streamflow data. Markov models, which dominated stochastic hydrology in the past, have short memories and, therefore, cannot preserve or simulate long-term persistence characterizing physiscal streamflows. Non-Markov models which are currently being developed, and may or may not belong to the Brownian domain, have very long or infinite memories. This paper is dedicated to the idea of coupling the stochastic and deterministic methods in hydraulics and hydrology, so that the two methods may contribute their strengths while complementing each other for their weaknesses.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2020-04-20
    Description: Near-field remote sensing of surface velocity and river discharge (discharge) were measured using coherent, continuous wave Doppler and pulsed radars. Traditional streamgaging requires sensors be deployed in the water column; however, near-field remote sensing has the potential to transform streamgaging operations through non-contact methods in the U.S. Geological Survey (USGS) and other agencies around the world. To differentiate from satellite or high-altitude platforms, near-field remote sensing is conducted from fixed platforms such as bridges and cable stays. Radar gages were collocated with 10 USGS streamgages in river reaches of varying hydrologic and hydraulic characteristics, where basin size ranged from 381 to 66,200 square kilometers. Radar-derived mean-channel (mean) velocity and discharge were computed using the probability concept and were compared to conventional instantaneous measurements and time series. To test the efficacy of near-field methods, radars were deployed for extended periods of time to capture a range of hydraulic conditions and environmental factors. During the operational phase, continuous time series of surface velocity, radar-derived discharge, and stage-discharge were recorded, computed, and transmitted contemporaneously and continuously in real time every 5 to 15 min. Minimum and maximum surface velocities ranged from 0.30 to 3.84 m per second (m/s); minimum and maximum radar-derived discharges ranged from 0.17 to 4890 cubic meters per second (m3/s); and minimum and maximum stage-discharge ranged from 0.12 to 4950 m3/s. Comparisons between radar and stage-discharge time series were evaluated using goodness-of-fit statistics, which provided a measure of the utility of the probability concept to compute discharge from a singular surface velocity and cross-sectional area relative to conventional methods. Mean velocity and discharge data indicate that velocity radars are highly correlated with conventional methods and are a viable near-field remote sensing technology that can be operationalized to deliver real-time surface velocity, mean velocity, and discharge.
    Electronic ISSN: 2072-4292
    Topics: Architecture, Civil Engineering, Surveying , Geography
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  • 3
    Publication Date: 2004-06-08
    Description: Discharge, especially during flood periods, is among the most important information necessary for flood control, water resources planning and management. Owing to the high flood velocities, flood discharge usually cannot be measured efficiently by conventional methods, which explains why records of flood discharge are scarce or do not exist for the watersheds in Taiwan. A fast method of flood discharge estimation is presented. The greatest advantage of the proposed method is its application to estimate flood discharge that cannot be measured by conventional methods. It has as its basis the regularity of open-channel flows, i.e. that nature maintains a constant ratio of mean to maximum velocities at a given channel section by adjusting the velocity distribution and the channel geometry. The maximum velocity at a given section can be determined easily over a single vertical profile, which tends to remain invariant with time and discharge, and can be converted to the mean velocity of the entire cross-section by multying by the constant ratio. Therefore the mean velocity is a common multiple of maximum velocity and the mean/maximum velocity ratio. The channel cross-sectional area can be determined from the gauge height, the water depth at the y-axis or the product of the channel width multiplied by the water depth at the y-axis. Then the most commonly used method, i.e. the velocity-area method, which determines discharge as the product of the cross-sectional area multiplied by mean velocity, is applied to estimate the flood discharge. Only a few velocity measurements on the y-axis are necessary to estimate flood discharge. Moreover the location of the y-axis will not vary with time and water stage. Once the relationship of mean and maximum velocities is established, the flood estimation can be determined efficiently. This method avoids exposure to hazardous environments and sharply reduces the measurement time and cost. The method can be applied in both high and low flows in rivers. Available laboratory flume and stream-flow data are used to illustrate accuracy and reliability, and results show that this method can quickly and accurately estimate flood discharges. © 2004 John Wiley and Sons, Ltd.
    Print ISSN: 0885-6087
    Electronic ISSN: 1099-1085
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by Wiley
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  • 4
    Publication Date: 2005-01-01
    Description: Regularities exist in fluid flows and can be represented by a set of constants. These constants are functions of the parameter of a probability distribution that exhibits resilience and stability under various flow conditions. Together, these regularities form a network and interact with each other, such that if one is known then the others can be determined from it. The regularities and their network explain the various fluid-flow phenomena and can be used in analysis of rivers and streams. For example, they can be used as the basis to develop simple and efficient methods of discharge measurements as presented herein, which only require velocity sampling at a single point on a water surface or a few points on a single vertical. Because of their simplicity and the short time requirement, these methods can be easily automated for collecting discharge data in unsteady, high flows that are badly needed for real-time flow forecasting and design of flood control structures, and for advancing the fundamental, scientific knowledge in hydrology. Copyright © 2005 John Wiley & Sons, Ltd.
    Print ISSN: 0885-6087
    Electronic ISSN: 1099-1085
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by Wiley
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  • 5
    Publication Date: 2001-01-01
    Description: The potential benefits of increased application of water to paddy fields in Taiwan are investigated in this paper. A conceptual model is used to represent the hydrological system of the paddy field. A technique is presented to estimate the parameters of the model. Field experiments also are performed for parameter estimation and model verification. The simulated results are in good agreement with the observed during model verification. With parameters estimated from the field data, the model is used to simulate the effects of applying water beyond current practice. The simulation results show that the downward percolation increases when the irrigation water increases. However, the percolation reaches a capacity rate no matter how large the amount of water applied. This phenomenon results from the existence of a hard layer below the paddy field. The effects of raising the height of levees around paddy fields are also studied. Copyright © 2001 John Wiley & Sons, Ltd.
    Print ISSN: 0885-6087
    Electronic ISSN: 1099-1085
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by Wiley
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  • 6
    Publication Date: 2007-03-01
    Print ISSN: 0022-1694
    Electronic ISSN: 1879-2707
    Topics: Architecture, Civil Engineering, Surveying , Geography , Geosciences
    Published by Elsevier
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  • 7
    Publication Date: 2002-08-01
    Print ISSN: 0022-1694
    Electronic ISSN: 1879-2707
    Topics: Architecture, Civil Engineering, Surveying , Geography , Geosciences
    Published by Elsevier
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  • 8
    Publication Date: 2006-01-01
    Print ISSN: 0022-1694
    Electronic ISSN: 1879-2707
    Topics: Architecture, Civil Engineering, Surveying , Geography , Geosciences
    Published by Elsevier
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  • 9
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    ASCE (American Society of Civil Engineers)
    Publication Date: 2023-05-24
    Description: Mathematical models have been developed that can completely describe the distribution of sediment concentration from the channel bed to the water surface. These models can be used to estimate the mean (depth-averaged) sediment concentration by a quick, point sampling in river engineering practice. The developed models are products of a combined application of the deterministic and probabilistic concepts. The complementary nature of the two concepts strengthens the methodology of describing the various features of sediment transport. The models incorporate a velocity distribution equation that corresponds to a probability distribution derived by maximizing the information entropy. The probability distribution is a compact description of the system at a channel section, and its resilience or stability explains the applicability of the developed models of velocity and sediment distributions in a wide range of flows, steady or unsteady.
    Type: Article , PeerReviewed
    Format: text
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