Variations in unit hydrographs on a very small agricultural catchment

Soil Research ◽  
1981 ◽  
Vol 19 (2) ◽  
pp. 121 ◽  
Author(s):  
WC Boughton ◽  
DM Freebairn
Keyword(s):  
Simple Model ◽  
Surface Runoff ◽  
Iterative Procedure ◽  
Trial And Error ◽  
Unit Hydrograph ◽  
Surface Layers ◽  
Peak Runoff ◽  
Unit Hydrographs ◽  
Runoff Hydrographs ◽  
Runoff Component

Unit hydrographs (5-min 1 mm) were derived from six storms in the period November 1976 to March 1979 on a 1.2 ha catchment at Greenmount, about 25 km south of Toowomba in south-east Queensland. Peak rates of runoff in the six storms ranged from 1,12mm/h to 50.13 mm/h. All unit hydrographs were derived from multiperiod storms using an iterative procedure. Considerable variation occurred among the unit hydrographs with peak ordinate values ranging from 2.18 mm/h to 9.45 mm/h. It was found that each unit hydrograph could be separated into two components, surface runoff and interflow. The proportion of surface runoff in the unit hydrograph increased as the intensity of rainfall excess increased, and ranged from 5% in the storm with peak runoff of 1.12 mm/h to 86% in the storm with peak runoff of 50.13 mm/h. A large amount of runoff from the catchment occurred as interflow, consisting of water moving downslope through the porous cultivated surface layers of soil. The traditional separation of interflow from surface runoff prior to derivation of the unit hydrograph could not be done because of the complexity of the storm patterns. The study showed that it is possible to derive unit hydrographs which include an interflow component and to separate surface runoff and interflow in the unit hydrograph itself. A simple model was developed in which the proportions of surface runoff and interflow were allowed to vary from storm to storm. The proportions were adjusted by trial and error to match estimated runoff with actual runoff. The simple model reproduced observed runoff hydrographs with only minor errors of fit. The surface runoff component of the simple model behaved in accordance with traditional linear unit hydrograph theory. Variations in the unit hydrographs were accounted for by variations in the proportions of surface runoff and interflow from storm to storm.

scholarly journals A Simple Contact Mechanics Model for Highly Strained Aqueous Surface Gels

2021 ◽  
Author(s):  
A. L. Chau ◽  
M. K. Cavanaugh ◽  
Y.-T. Chen ◽  
A. A. Pitenis
Keyword(s):  
Simple Model ◽  
Contact Mechanics ◽  
Contact Lenses ◽  
Radius Of Curvature ◽  
Winkler Foundation ◽  
Surface Layers ◽  
Mechanics Model ◽  
Soft Surface ◽  
Simple Contact ◽  
Highly Strained

Abstract Background Soft, biological, and bio-inspired materials are often compositionally heterogeneous and structurally anisotropic, and they frequently feature graded or layered organizations. This design complexity enables exceptional ranges in properties and performance yet complicates a fundamental understanding of the contact mechanics. Recent studies of soft gel layers have relied on Hertzian or Winkler foundation (“bed-of-springs”) models to characterize the mechanics but have found neither satisfactory. Objective The contact mechanics of soft gel layers are not yet fully understood. The aim of this work is to develop a simple contact mechanics model tailored for compositionally-graded materials with soft surface layers under high strains and deformations. Methods Concepts from polymer physics, fluid draining, and Winkler foundation mechanics are combined to develop a simple contact mechanics model which relates the applied normal force to the probe radius of curvature, elastic modulus, and thickness of soft surface layers subjected to high strains. Results This simple model was evaluated with two examples of graded surface gel layers spanning multiple length-scales, including commercially available contact lenses and stratified hydrogels. The model captures the nonlinear contact mechanics of highly strained soft aqueous gel layers more closely than either Hertz or Winkler foundation theory while simultaneously enabling a prediction for the thickness of the surface gel layer. Conclusion These results indicate that this simple model can adequately characterize the contact mechanics of highly strained soft aqueous gel layers.

scholarly journals A simple model to estimate ice ablation under a thick debris layer

2006 ◽  
Vol 52 (179) ◽  
pp. 528-536 ◽  
Author(s):  
Han Haidong ◽  
Ding Yongjing ◽  
Liu Shiyin
Keyword(s):  
Heat Flux ◽  
Simple Model ◽  
Iterative Procedure ◽  
Indirect Comparison ◽  
Tien Shan ◽  
Balance Model ◽  
Complex Phase ◽  
Proposed Model ◽  
Koxkar Glacier

AbstractThis paper presents a simple model to estimate ice ablation under a thick supraglacial debris cover. The key method employed in the model is to establish a link between the debris heat flux and the debris temperature at a certain depth when the heat transfer in the debris is described by a diffusion process. Given surface temperature, debris thermal properties and relevant boundary conditions, the proposed model can estimate mean debris temperature at interfaces of different debris layers using an iterative procedure, and then the heat flux for ice ablation. The advantage of the proposed model is that it only requires a few parameters to conduct the modeling, which is simpler and more applicable than others. The case study on Koxkar glacier, west Tien Shan, China, shows, in general, that the proposed model gives good results for the prediction of debris temperatures, except for an apparent phase shift between modeled and observed values. We suggest that this error is mainly due to complex phase relations between debris temperature and debris heat flux. The modeled ablation rates at three experimental sites also show good results, using a direct comparison with observed data and an indirect comparison with a commonly used energy-balance model.

scholarly journals Evaluation of Infiltration Rainwater Drainage (IRD) System with Fully 3-D Numerical Simulation Approach

2021 ◽  
Vol 11 (19) ◽  
pp. 9144
Author(s):  
Jungkyu Ahn ◽  
Seongil Yeom ◽  
Sungwon Park ◽  
Thi Hoang Thao Nguyen
Keyword(s):  
Water Scarcity ◽  
Surface Runoff ◽  
Urban Areas ◽  
Model Simulation ◽  
Three Dimensional ◽  
Lag Time ◽  
Prototype Model ◽  
Scaled Model ◽  
Runoff Decrease ◽  
Peak Runoff

Water scarcity can mean scarcity in availability due to physical shortage, or scarcity in access due to the failure of institutions to ensure a continuously regular supply or due to a lack of adequate infrastructure. Water scarcity will be exacerbated as rapidly growing urban areas place heavy pressure on water resources. To solve these problems, various solutions have been applied, but a fundamental solution has not been applied. Recently, a researched and developed infiltration rainwater drainage (IRD) system is being applied with consideration of its applicability. In this study, features of surface runoff and infiltration according to various flow patterns were analyzed using a three-dimensional CFD (Computational Fluid Dynamics) model for calculating water flow in the IRD system. To estimate the optimal setup, a permeability test and scaled model simulation were performed. The runoff characteristics of the IRD system with respect to rainfall intensity and duration were analyzed with dimensionless variables. With the prototype model, the drainage characteristics of the IRD system were analyzed over time using the hydrological curves. From the simulated results, it was found that the IRD system analyzed in this study was appropriate in the field by comparative analysis with the existing system based on peak runoff, internal storage, and lag time. Therefore, by applying the IRD system in the future, it is expected that the IRD has benefits, such as delayed lag time, surface runoff decrease, and an attenuation of the peak runoff.

V—The Brownian Movement of a One-Dimensional Non-Harmonic Oscillator

1968 ◽  
Vol 68 (1) ◽  
pp. 70-82
Author(s):  
A. J. Allnutt
Keyword(s):  
Approximate Solution ◽  
Simple Model ◽  
Harmonic Oscillator ◽  
Langevin Equation ◽  
Iterative Procedure ◽  
Anharmonic Oscillator ◽  
Crystalline Solid ◽  
Brownian Movement ◽  
One Dimensional ◽  
Numerical Example

SynopsisThe Langevin equation for the harmonic oscillator is solved by a different method from that normally used. The approximate solution for the case of the slightly anharmonic oscillator is then obtained by an iterative procedure and the results are illustrated by a numerical example based on a simple model of a crystalline solid.

Hydrograph recession characteristics of some small agricultural catchments

Soil Research ◽  
1985 ◽  
Vol 23 (3) ◽  
pp. 373 ◽  
Author(s):  
WC Boughton ◽  
DM Freebairn
Keyword(s):  
Flow Rate ◽  
Surface Runoff ◽  
Surface Soil ◽  
New South ◽  
Published Data ◽  
Unit Hydrograph ◽  
Agricultural Catchments ◽  
South Wales ◽  
Catchment Size ◽  
Time Required

Five-min recession constants were calculated for surface runoff and interflow using hydrographs of runoff from five 1-ha catchments at Greenmount near Toowoomba in south-east Queensland. The recession constants were converted to half-flow periods, i.e. the time required for flow rate to halve during an exponential recession. The half-flow periods of surface runoff and interflow on the 1 ha catchment are compared with published data from catchments of much larger size in New South Wales, and it is shown that the ratio of interflow half-flow period to surface runoff half-flow period does not vary much over six orders of magnitude of catchment size. Calculations of maximum rates of interflow and volumes of interflow storage show that both rates and volumes are possible in the plough depth of surface soil. The results support the evidence of interflow obtained earlier in unit hydrograph studies of runoff on these same catchments.

scholarly journals The Role of Topography on the Shape of Unit Hydrographs in Small and Medium Sized Watersheds through a Physical Model

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2270
Author(s):  
Alicia A. Del Rio ◽  
Aldo I. Ramirez ◽  
Mauricio A. Sanchez
Keyword(s):  
Fuzzy Logic ◽  
Polynomial Regression ◽  
Synthetic Methods ◽  
Main Stream ◽  
Unit Hydrograph ◽  
Watershed Area ◽  
Time To Peak ◽  
Logic Models ◽  
Empirical Relations ◽  
Unit Hydrographs

This study intends to establish the main relations between topographic characteristics of the watershed and the main parameters of the unit hydrograph measured at the outlet. It looks to remove the subjectivity found in traditional synthetic methods and the trial and error setting of the main parameters of the hydrograph. The work was developed through physical experimentation of the rainfall-runoff process using the observed information of different watersheds of Chiapas, Mexico, as the reference. The experiments were carried out on a state-of-the-art semi-automatic runoff simulator, which was designed and built specifically for this study. Polynomial regression and fuzzy logic models were obtained to confirm the hypothesis of hydrological parameters being obtained from topographic data only by assuming uniform precipitation. Empirical relations were found for the peak flow, time to peak, base time and volume of the unit hydrograph and the watershed area, the main stream average slope, and the length of the stream of highest order. The main finding is that a unit hydrograph can be described based only on the watershed area when fuzzy logic models are applied.

scholarly journals Forest watershed runoff changes determined using the unit hydrograph method

2009 ◽  
Vol 55 (No. 2) ◽  
pp. 89-95
Author(s):  
V. Černohous ◽  
P. Kovář
Keyword(s):  
Least Squares ◽  
Least Squares Method ◽  
Forest Stand ◽  
Unit Hydrograph ◽  
Stand Growth ◽  
Total Runoff ◽  
Runoff Changes ◽  
Recession Limb ◽  
Unit Hydrographs ◽  
Maximum Runoff

Unit hydrograph is a basic method to show changes in runoff in the watershed. The investigation of runoff changes was carried out in the U Dvou louček watershed situated at the summit part of the Orlické hory Mts., East Bohemia. The waveform ordinates of recession limbs of unit hydrographs obtained using a common approach had to be approximated by the least-squares method. Final hydrographs reflected both drainage treatment and forest stand growth influencing the runoff from the watershed. Both factors increase culmination in synergy and reduce runoff on the recession limb of the hydrograph. We confirmed increased maximum runoff taking up 25–30% of the total runoff time when waterlogged sites were drained. The culmination increased by 0.2–0.8 mm/hour indicates the runoff increased by 2–8 m<sup>3</sup>/ha/hr.

scholarly journals Applicability of a Spatially Semi-Distributed Hydrological Model for Watershed Scale Runoff Estimation in Northwest Ethiopia

Water ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 923 ◽  
Author(s):  
Demlie Zelelew ◽  
Assefa Melesse
Keyword(s):  
Northwest Ethiopia ◽  
Distributed Hydrological Model ◽  
Unit Hydrograph ◽  
Protection Measures ◽  
Transform Methods ◽  
Model Set ◽  
Loss Method ◽  
Unit Hydrographs ◽  
Blue Nile River Basin ◽  
Ungauged Watersheds

Estimation of runoff is vital forplanning activities in relation to integrated watershed management and flood protection measures. This research was conducted at one of the catchments in Abbay River (upper Blue Nile River) basin to assess the applicabilityof the Hydrologic Engineering Centre Hydrological Modelling Software (HEC-HMS) modelfor simulation of runoff. It was aimed at selecting the best loss and transform methods in the model, as well as testing the applicability of the calibrated model to ungauged watersheds. Two loss methods such as soil conservation service (SCS) and initial and constant methods with two transform methods including SCS and Clark unit hydrographs were considered in the study for selecting the best combinations applicable in the area. While comparing the simulation results of each combination, better results were obtained in the model set containing the initial and constant loss method and SCS unit hydrograph with a Nash-Sutcliff Efficiency (NSE) of 82.8%, R2 of 0.83, and 10.71% of relative bias errors, followed by initial and constant with Clarks unit hydrograph, and it can be used for similar ungauged watersheds.

Regionalization of rainfall–runoff processes in rice agriculture dominated watersheds

2006 ◽  
Vol 53 (10) ◽  
pp. 131-139 ◽  
Author(s):  
N.V. Rajyalakshmi ◽  
S. Dutta
Keyword(s):  
Rice Field ◽  
Storm Event ◽  
Rainfall Runoff ◽  
Unit Hydrograph ◽  
Stream Network ◽  
Rice Agriculture ◽  
Watershed Response ◽  
Instantaneous Unit Hydrograph ◽  
Daily Water ◽  
Unit Hydrographs

An approach for computing the instantaneous unit hydrograph of rice agriculture dominated watesheds is proposed using the topology and hydraulic charcterstics of its stream network and the hydrologic behaviour of the rice agriculture area. The effect of rice agriculture on the watershed response is considered as partial sink areas. The sink factor, a time-variant weight factor for a particular storm event, is computed from the daily water balanace equation of the rice field. The critcal features of the simulated instantaneous unit hydrographs in three gauged watersheds located in the river Mahanadi, India were then compared with that of the observed 24-hr unit hydrograph. The comparison shows a significant correlation between the two results.

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