pubs + calcs, publications + calculations, publications plus calculations, publications with online calculations, Victor Miguel Ponce

360. Online publications featuring
online calculations [190611]

[Urban drainage, open-channel hydraulics, unsteady flow]


36023.  The control of roll waves in channelized rivers [190611]

ABSTRACT:   The theoretical foundations and relevant experience with open-channel flow instability are examined with the objective of controlling roll waves. The latter recur with relative frequency in channelized rivers where the Vedernikov number V has increased above the threshold V = 1 due to the channelization. Several examples show conclusively the existence of a definite relation between β, the exponent of the discharge-area rating, and V. As the cross-sectional shape departs from rectangular, β decreases accordingly, resulting in a drop in the value of V. A sufficient decrease in β will cause a drop in V below the threshold of flow instability V = 1.

[Water Chemistry,
Environmental Hydrology]


36022.  The Properties of Water [190607]

ABSTRACT: This article explores the properties of water, including physical, chemical, and biological properties. Most of the properties of water span more than one field, such as physics and chemistry, or chemistry and biology, or biology and physics. Understanding the nature of water requires a thorough interdisciplinary approach to science.

[Sedimentation Engineering]


36021.  Froude number for initiation of motion calculated online [180417]

ABSTRACT:   The classical Shields criterion for initiation of motion is expressed in terms of the Froude number and associated mean velocity required for initiation of motion in a sand-bed channel. To solve the problem exactly, an iterative algorithm is developed to calculate these values using an online calculator.

[Sustainability of groundwater]


36020.  How much water could be pumped from an aquifer and still remain sustainable? [180206]

ABSTRACT: The concepts of safe yield and sustainable yield of groundwater are analyzed and compared in the context of a hydrologic balance. It is surmised here that vertical recharge, i.e., the recharge originating in local precipitation, is the only recharge that may be tapped for capture by groundwater to avoid encroachment on established rights. A methodology to evaluate vertical recharge is developed and tested. The methodology is based on L'vovich's cybernetic hydrologic balance. This coefficient represents the fraction of precipitation that reaches the water table; therefore, it may be used to evaluate and assess sustainable groundwater yield.

[Surface-water hydrology]


36019.  Why is the cybernetic hydrologic balance better suited for yield hydrology than the conventional approach? [180115]

ABSTRACT: A comparison between the conventional approach to the hydrologic balance and L'vovich's catchment wetting approach, referred herein as the cybernetic approach, reveals fundamental conceptual differences. The conventional approach is seen to be mostly suited to event hydrology, particularly for applications of flood hydrology and related urban hydrology. On the other hand, the cybernetic approach is suited to yield hydrology, i.e., for determinations of the availability of water resources on an annual basis.

[Flood routing]


36018.  The Thomas problem with online computation [161209]

ABSTRACT:   An online calculator has been developed and tested using the Muskingum-Cunge method to solve the classical Thomas problem of flood routing. The calculator can vary peak inflow, time base, and channel length. The choice for peak inflow qp (cfs/ft) is: (a) 200, (b) 500, and (c) 1,000. The choice for time base Tb (hr) is: (a) 48, (b) 96, and (c) 192. The choice for channel length L (mi) is: (a) 200, and (b) 500. The results are in agreement with analytical results of the Thomas problem.

[Open-channel hydraulics]


36017.  The inherently stable channel with online computation [160530]

ABSTRACT: The inherently stable channel is reviewed, elucidated, and calculated online. Theoretically, such a channel will become neutrally stable when the Froude number reaches infinity. Thus, constructing an inherently stable channel provides an unrealistically high factor of safety against roll waves. This suggests the possibility of designing instead a conditionally stable cross-sectional shape, for a suitably high but realistic Froude number such as F = 25, for which the risk of roll waves would be so small as to be of no practical concern.

[Computational Hydraulics]


36016.  Muskingum-Cunge amplitude and phase portraits with online computation [160430]

ABSTRACT: A comprehensive review of the amplitude and phase portraits of the Muskingum-Cunge method of flood routing is accomplished. Expressions for the amplitude and phase convergence ratios are developed as a function of: (a) spatial resolution Lx; (b) Courant number C; and (c) weighting factor X. It is concluded that the Muskingum-Cunge routing model is a good representation of the physical prototype, provided: (1) the spatial resolution is sufficiently high, (2) the Courant number is around 1, and (3) the weighting factor is high enough in the range 0.0 ≤ X ≤ 0.5. Two online calculators of the convergence ratios are developed and tested.

[Open-channel hydraulics]


36015.  Design of channel transitions [151117]

ABSTRACT:   The hydraulic design of a channel transition is described and explained. The calculation of an inlet transition between canal and flume is shown by an example, originally presented by Hinds (1928) and subsequently cited by Chow (1959). The example is reproduced with detailed explanation and minor corrections for rounding accuracy. An online calculator is provided.

[Channel morphology and sediment transport]


36014.  The Lane relation revisited, with online calculation [150223]

ABSTRACT: A new Lane relation of fluvial hydraulics is derived from basic principles of sediment transport. It is expressed as follows:

Qs (ds/R)1/3 γ Qw So

Unlike the original Lane relation, this new relation is dimensionless. An online calculator is developed to solve the sediment transport equation arising from the new Lane relation.

[Open-channel Hydraulics]


36013.  Chow, Froude, and Vedernikov [140624]

ABSTRACT: The concepts of Froude and Vedernikov numbers are reviewed on the occasion of the 50th anniversary of the publication of Ven Te Chow's Handbook of Applied Hydrology. While the Froude number (F) is standard fare in hydraulic engineering practice, the Vedernikov number (V) remains to be recognized by many practicing engineers. A comprehensive description of the variation of β, the altogether important exponent of the discharge-flow area rating - 1 = V/F) , is accomplished to recognize the contributions of Professor Ven Te Chow to the hydraulic engineering profession. Two online calculators are presented to round up the experience.

[Unsteady Open-channel Flow]


36012.  Runoff diffusion reexamined [140611]

ABSTRACT:   The concept of runoff diffusion is reexamined. Diffusion is inherent to reservoirs and it is always produced in flow through reservoirs. In channel flow, diffusion is produced in the absence of kinematic wave conditions, i.e., under diffusion wave conditions, provided the Vedernikov number is less than 1. In catchment runoff, diffusion is produced: (1) for all wave types, when the time of concentration exceeds the effective rainfall duration, a condition which is usually associated with midsize and large basins, or (2) for all effective rainfall durations, when the wave is a diffusion wave, which is usually associated with a sufficiently mild catchment slope.

[Unsteady Open-channel Flow]


36011.  The dynamic hydraulic diffusivity reexamined [140429]

ABSTRACT: The concept of hydraulic diffusivity and its extensions to the dynamic regime are examined herein. Hayami (1951) originated the concept of hydraulic diffusivity in connection with the propagation of flood waves. Dooge (1973) extended Hayami's hydraulic diffusivity to the realm of dynamic waves. Subsequently, Dooge et al. (1982) expressed the dynamic hydraulic diffusivity in terms of the exponent of the discharge-area rating. Lastly, Ponce (1991) expressed it in terms of the Vedernikov number, further clarifying the mechanics of flood wave propagation.

[Open-channel Hydraulics]


36010.  The limiting contraction ratio revisited [140409]

ABSTRACT: Henderson's formulations of the energy-based and momentum-based limiting contraction ratios are reviewed (Henderson 1966). Henderson's explicit energy-based equation is found to be correct, however, his implicit momentum-based equation is found to be incorrect. A new explicit momentum-based equation is derived, rendering the implicit formulation unnecessary. An online calculator enables the calculation of the limiting contraction ratio for both energy and momentum formulations.



36009.  The Penman-Monteith Method [140312]

ABSTRACT:   The Penman-Monteith combination method for the calculation of evaporation is reviewed and clarified. Unlike the original Penman model, in the Penman-Monteith model the mass-transfer evaporation rate is calculated based on physical principles. An illustrative example is worked out to show the computational procedure. An online calculation using ONLINE PENMAN-MONTEITH gives the same answer.

[Open-channel Hydraulics]


36008.  Comparison of sharp-crested weirs for discharge measurement in open-channel flow [131104]

ABSTRACT: This document provides a tabular comparison of several sharp-crested weirs for discharge measurement in open-channel flow. The following weirs are considered: (1) V-notch, fully contracted; (2) V-notch, partially contracted; (3) Cipolletti; (4) rectangular; (5) standard contracted rectangular; and (6) standard suppressed rectangular. Descriptions follow the USBR Water Measurement Manual.

[Rainfall-runoff transform]


36007.  Comparison of two Clark unit hydrographs [131006]

ABSTRACT:  Clark's original unit hydrograph and Ponce's somewhat improved version are explained and compared. Clark's procedure routes, through a linear reservoir, the discrete time-area-derived unit-runoff hyetograph, while Ponce's procedure routes the continuous time-area-derived unit hydrograph. Since the unit hydrograph has a longer time base than the unit-runoff hyetograph, Ponce's procedure provides a somewhat smaller peak discharge than Clark's. The difference, however, does not appear to be substantial.

[Flood hydrology]


36006.  Creager and flood wave diffusion [130821]

ABSTRACT:   The Creager curves are reinterpreted in light of the theory of flood wave diffusion. Experience shows that greater flood wave diffusion corresponds with larger drainage areas. Thus, the trend of the Creager curves admirably reflects the flood wave diffusion that is likely to be present in the real world.



36005.  Evapotranspiration using the Shuttleworth-Wallace formula [130516]

ABSTRACT: An online calculator of the Shuttleworth-Wallace method for calculating evapotranspiration from sparse crops is developed.   The method can be used to complement evapotranspiration calculations based on the Penman-Monteith method.

[Gradually varied flow]


36004.  Gradually varied flow profiles using critical slope and online calculators [130302]

ABSTRACT:   Gradually varied flow water-surface profiles are expressed in terms of the critical slope Sc. In this way, the flow-depth gradient dy/dx is shown to be strictly limited to values outside the range encompassed by Sc and So, in which So is the bed slope. This new approach improves and completes the definition of flow-depth-gradient ranges in the analysis of water-surface profiles. Online calculators are provided to round up the experience.

[Catchment water balance]


36003.  Catchment wetting and water balance [100728]

ABSTRACT:   The concept of catchment wetting due to L'vovich (1979) enables a better water balance than that possible with conventional methods. Given precipitation and streamflow data, and using an appropriate baseflow separation technique, L'vovich's method enables the calculation of the matrix of precipitation/runoff/surface_runoff/baseflow/wetting/vaporization. This provides a clearer understanding of all the components of the water balance for a given gaged catchment.

[Unit hydrograph theory and practice]


36002.  Cascade and convolution: One and the same [090525]

ABSTRACT:   The methods of cascade of linear reservoirs and unit hydrograph convolution are shown to be one and the same when the cascade parameters are used to calculate the unit hydrograph of the convolution. In the absence of gaged data, the cascade parameters may be estimated based on geomorphology. Once the parameters are established, the composite flood hydrograph is uniquely determined.

[Unit hydrograph theory and practice]


36001.  A general dimensionless unit hydrograph [090521]

ABSTRACT:   A general dimensionless unit hydrograph (GDUH) based on the cascade of linear reservoirs is formulated and calculated online. The GDUH is shown to be solely a function of the Courant number and the number of linear reservoirs. Since the GDUH is independent of the basin drainage area and the unit hydrograph duration, it is applicable on a global basis. Each GDUH ia a function only of the basin's prevailing runoff diffusion properties. The model's two-parameter feature provides increased flexibility for simulating a wide range of diffusion effects.