scholarly journals Integrating XAJ Model with GIUH Based on Nash Model for Rainfall-Runoff Modelling

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 772 ◽  
Author(s):  
Yingbing Chen ◽  
Peng Shi ◽  
Simin Qu ◽  
Xiaomin Ji ◽  
Lanlan Zhao ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Network Flow ◽  
Model Performance ◽  
Efficiency Coefficient ◽  
Effective Rainfall ◽  
Unit Hydrograph ◽  
Nash Model ◽  
Average Flow Velocity ◽  
Time To Peak ◽  
Flood Estimation

The geomorphologic instantaneous unit hydrograph (GIUH) is an applicable approach that simulates the runoff for the ungauged basins. The nash model is an efficient tool to derive the unit hydrograph (UH), which only requires two items, including the indices n and k. Theoretically, the GIUH method describes the process of a droplet flowing from which it falls on to the basin outlet, only covering the flow concentration process. The traditional technique for flood estimation using GIUH method always uses the effective rainfall, which is empirically obtained and scant of accuracy, and then calculates the convolution of the effective rainfall and GIUH. To improve the predictive capability of the GIUH model, the Xin’anjiang (XAJ) model, which is a conceptual model with clear physical meaning, is applied to simulate the runoff yielding and the slope flow concentration, integrating with the GIUH derived based on Nash model to compute the river network flow convergence, forming a modified GIUH model for flood simulation. The average flow velocity is the key to obtain the indices k, and two methods to calculate the flow velocity were compared in this study. 10 flood events in three catchments in Fujian, China are selected to calibrate the model, and six for validation. Four criteria, including the time-to-peak error, the relative peak flow error, the relative runoff depth error, and the Nash–Sutcliff efficiency coefficient are computed for the model performance evaluation. The observed runoff value and simulated series in validation stage is also presented in the scatter plots to analyze the fitting degree. The analysis results show the modified model with a convenient calculation and a high fitting and illustrates that the model is reliable for the flood estimation and has potential for practical flood forecasting.

scholarly journals A Comparison of Some Methods of Deriving the Instantaneous Unit Hydrograph

1985 ◽  
Vol 16 (1) ◽  
pp. 1-10 ◽  
Author(s):  
V. P. Singh ◽  
C. Corradini ◽  
F. Melone
Keyword(s):  
Peak Flow ◽  
Central Italy ◽  
Effective Rainfall ◽  
Unit Hydrograph ◽  
Time To Peak ◽  
Wide Range ◽  
Instantaneous Unit Hydrograph ◽  
Similar Accuracy ◽  
Two Parameters ◽  
Range Of Values

The geomorphological instantaneous unit hydrograph (IUH) proposed by Gupta et al. (1980) was compared with the IUH derived by commonly used time-area and Nash methods. This comparison was performed by analyzing the effective rainfall-direct runoff relationship for four large basins in Central Italy ranging in area from 934 to 4,147 km2. The Nash method was found to be the most accurate of the three methods. The geomorphological method, with only one parameter estimated in advance from the observed data, was found to be little less accurate than the Nash method which has two parameters determined from observations. Furthermore, if the geomorphological and Nash methods employed the same information represented by basin lag, then they produced similar accuracy provided the other Nash parameter, expressed by the product of peak flow and time to peak, was empirically assessed within a wide range of values. It was concluded that it was more appropriate to use the geomorphological method for ungaged basins and the Nash method for gaged basins.

scholarly journals Derivation of S-Curve from Oscillatory Hydrograph Using Digital Filter

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1456
Author(s):  
Kee-Won Seong ◽  
Jang Hyun Sung
Keyword(s):  
Digital Filter ◽  
Model Performance ◽  
Performance Criteria ◽  
Rainfall Runoff ◽  
Small Watershed ◽  
Unit Hydrograph ◽  
Time To Peak ◽  
S Curve ◽  
And Performance ◽  
Smooth Data

An oscillatory S-curve causes unexpected fluctuations in a unit hydrograph (UH) of desired duration or an instantaneous UH (IUH) that may affect the constraints for hydrologic stability. On the other hand, the Savitzky–Golay smoothing and differentiation filter (SG filter) is a digital filter known to smooth data without distorting the signal tendency. The present study proposes a method based on the SG filter to cope with oscillatory S-curves. Compared to previous conventional methods, the application of the SG filter to an S-curve was shown to drastically reduce the oscillation problems on the UH and IUH. In this method, the SG filter parameters are selected to give the minimum influence on smoothing and differentiation. Based on runoff reproduction results and performance criteria, it appears that the SG filter performed both smoothing and differentiation without the remarkable variation of hydrograph properties such as peak or time-to peak. The IUH, UH, and S-curve were estimated using storm data from two watersheds. The reproduced runoffs showed high levels of model performance criteria. In addition, the analyses of two other watersheds revealed that small watershed areas may experience scale problems. The proposed method is believed to be valuable when error-prone data are involved in analyzing the linear rainfall–runoff relationship.

Development of geomorphological instantaneous unit hydrograph (GIUH) model for a new un-gauged watershed

2017 ◽  
Vol 2 (01) ◽  
pp. 54-59
Author(s):  
Jeetendra Kumar ◽  
R. Suresh ◽  
Safi Hassan
Keyword(s):  
Peak Discharge ◽  
Prediction Errors ◽  
Effective Rainfall ◽  
Storm Events ◽  
Unit Hydrograph ◽  
Time To Peak ◽  
Initial Stage ◽  
Damodar Valley ◽  
Geomorphological Instantaneous Unit Hydrograph ◽  
Instantaneous Unit Hydrograph

A geomorphological instantaneous unit hydrograph (GIUH) model was developed for a watershed of Damodar valley corporation, Hazaribagh, using Nash (1959) and Itrube (1982) methods to compute peak discharge (qpeak) and time to peak (tpeak). The model was calibrated and validated for five storm events, i.e. June 24-25 (1992), October 12-13 (1993), November 2-3 (1993), June 28 (1994) and August 6 (1996) by comparing their ordinates with the ordinates of instantaneous unit hydrograph (IUH). The GIUH was tested with absolute prediction errors (APE) of the ordinate of peak discharge. On comparison, it was found that, most of the GIUH models overestimated the runoff at initial stage, while underestimated at the latter stage in comparison to the IUHs, which was mainly due to consideration of const ant value of Ф-index, for computation of effective rainfall. The absolute prediction errors (APE) were computed to be 5.97, 18.09, 23.32, 9.64 and 7.52% of the ordinates of peak discharge for the storm events of June 24-25 (1992), October 12-13 (1993), November 2-3 (1993), June 28 (1994) and August 6 (1996) respectively.

scholarly journals Improved flood forecasting using geomorphic unit hydrograph based on spatially distributed velocity field

2021 ◽  
Author(s):  
Wen-chuan Wang ◽  
Yan-wei Zhao ◽  
Kwok-wing Chau ◽  
Dong-mei Xu ◽  
Chang-jun Liu
Keyword(s):  
Velocity Field ◽  
Kinetic Energy ◽  
Flow Velocity ◽  
Network Flow ◽  
Overland Flow ◽  
Flood Forecasting ◽  
Geomorphic Unit ◽  
Hunan Province ◽  
Gravitational Potential Energy ◽  
Unit Hydrograph

Abstract This paper presents an energy model for determining the overland flow velocity in order to improve the low accuracy problem in flow concentration simulation. It furnishes a novel idea for studying flow concentration in ungauged basins. The model can be widely applied in analysis of spatial velocity field, extraction of instantaneous geomorphic unit hydrograph and development of distributed hydrological model. A distributed flood-forecasting model is constructed for Lianyuan Basin in Hunan Province of China. In the proposed method, gravitational potential energy is transformed into kinetic energy via an analysis of energy distribution of water particles in the basin. Based on the kinetic energy equation, the overland flow velocity simulating the geomorphic unit hydrograph is computed. Rainfall-runoff simulation is then performed by integrating with runoff yield and concentration model. Results indicate that the model based on energy conversion leads to more accurate results. The model has the following advantages: firstly, the spatial distribution of the velocity field is appropriate; secondly, the model has only one parameter, which is easily determined; and finally, flow velocity results can be used for the computation of river network flow concentration.

About time lag and some morphometric characteristics of streams of the forest zone

2016 ◽  
Author(s):  
Н.А. Белоногова ◽  
А.Ю. Виноградов ◽  
Т.А. Виноградова ◽  
Д.А. Догановский ◽  
А.Н. Кондратьев ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Average Rate ◽  
Time Lag ◽  
High Water ◽  
Spatial And Temporal Variability ◽  
Forest Zone ◽  
Average Flow Velocity ◽  
Small Watersheds ◽  
Maximum Water ◽  
General Movement

Расчет максимальных расходов воды дождевых паводков на малых водосборах, в целях эффективного проектирования лесохозяйственных инженерных дорожных сооружений, представляет собой весьма сложную задачу вследствие отсутствия достаточных наблюдений за характеристиками дождевого стока. Кроме того, характеристики дождевого стока и определяющие их факторы обладают большой пространственной и временной изменчивостью, что еще больше затрудняет их определение. Рекомендуемая действующими нормативами методика определения максимального дождевого стока, как показывает практический опыт, нуждается в незамедлительном редактировании с точки зрения сопоставления размерностей и правильности ссылок. Особое внимание в статье уделено определению времени добегания, включенного в расчетные формулы в качестве определяющего параметра. В настоящее время понятие «время добегания» однозначно не определено. В связи с тем, что наполненность русел рек имеет высокую пространственную и временную неоднородность и изменчивость, общее движение воды в створе проектируемого инженерного сооружения можно представить достаточно упорядоченным и единообразным, с практически постоянной паводковой средней скоростью. На основе натурных наблюдений известно, что во время паводка средняя по сечению скорость потока сохраняется постоянной в пределах верхней десятипроцентной части амплитуды уровней воды. Такие данные с конца 70-х годов не публикуются. Обработка имеющихся данных говорит о том, что существует незначительное увеличение скоростей течения с ростом площади бассейнов. Поэтому предлагается принять время добегания τi, определенное по характерным отрезкам руслового пути от исследуемого створа до истока с помощью интерполяции измеренных на гидрометрических постах данных по скоростям течения. The calculation of the maximum water flow during the high water, especially on small watersheds, in order to effectively design engineering of road structures, is a very difficult task due to the lack of sufficient observations. In addition, the characteristics of rainfall, and their determinants have a high spatial and temporal variability, which further complicates their definition. Currently recommended method of determining the characteristics of the maximum rainwater, as the experience, needs immediate clarification of dimensions and verify links. Particular attention is paid to the calculation of lag time, included in the formulas as the defining parameter. Fullness riverbeds has high spatial and temporal heterogeneity and variability. The general movement of water in the closing alignment ordered and uniform. The average rate of slightly increased or decreased depending on the dryness of the season. Each cross-section corresponds to the value of average flow velocity. These data are from the late 70-ies are not published. Processing of existing data suggests that there is a slight increase in the flow velocity with increasing basin areas. Therefore, as a constant time lag is invited to take the time determined by the characteristic segments of the channel path from the source to the alignment of the test.

On the stable geometry of self-formed alluvial channels: theory and practical applicationThis article is one of a selection of papers in this Special Issue in honour of Professor M. Selim Yalin (1925–2007).

2009 ◽  
Vol 36 (10) ◽  
pp. 1667-1679 ◽  
Author(s):  
Ana Maria Ferreira da Silva
Keyword(s):  
Flow Velocity ◽  
Laboratory Data ◽  
Alluvial Channels ◽  
Cross Sectional ◽  
Late Professor ◽  
Average Flow Velocity ◽  
Effective Roughness ◽  
Self Formation ◽  
Gibb's Equation ◽  
Selection Of

On the basis of previous work by the late Professor M. Selim Yalin and the author, the process of self-formation of alluvial streams and the final (equilibrium or regime) geometry of the self-formed stream are considered in the light of thermodynamic principles, including the first and second laws, and the Gibb’s equation; the stream is treated as an isolated and irreversible system. The present analysis suggests that stream self-formation is guided by the need of the stream to progressively decrease its average flow velocity to accommodate the increase in the entropy of the system with the passage of time. The reduction in flow velocity is achieved by an appropriate alteration of stream slope, cross-sectional geometry, and effective roughness, the regime development being the process of this appropriate alteration. A method is presented for the computation of regime width, depth, and slope. The method rests on the channel formation criterion derived from thermodynamic principles and the expression of regime flow width determined on the basis of zero net cross sediment transport rate at the regime state. The regime channels computed from this method are compared with field and laboratory data from various sources.

scholarly journals The Cascade device – In vitro tests to assess coil protrusion into the parent vessel

2020 ◽  
Vol 26 (4) ◽  
pp. 494-500 ◽  
Author(s):  
P Bhogal ◽  
K Wong ◽  
HLD Makalanda
Keyword(s):  
Flow Velocity ◽  
In Vitro Tests ◽  
Parent Vessel ◽  
Single Episode ◽  
Average Flow Velocity ◽  
Velocity Reduction ◽  
Temporary Support ◽  
Aneurysmal Neck ◽  
Aneurysm Model

Background Balloon and stent-assisted coiling of aneurysms have increased the number of aneurysms available for endovascular treatment. Newer devices that allow flow within the parent vessel but coverage at the neck have recently entered the market. The Cascade is a new non-occlusive fully retrievable neck-bridging support device that has been designed to provide temporary support during coil embolisation of intracranial aneurysms. Methods Using a silicone aneurysm model three different aneurysms were catheterised with the coiling microcatheter placed in three different positions within each aneurysm – at the neck, centrally, and looped within the aneurysm. Multiple different coils were then deployed within each aneurysm with the Cascade device deployed across the neck to provide protection. In total 480 attempted coilings were performed. Aneurysm flow was used to calculate the change in intra-aneurysmal flow with the Cascade device deployed across the neck of the aneurysm. Results We did not observe a single episode of coil protrusion through the Cascade mesh nor did we observe any coil protrusion into the parent vessel when the Cascade was deployed across the neck. There was an average flow velocity reduction of 23% with the Cascade device deployed across the neck of the aneurysm. Conclusion The Cascade device offers robust protection of the aneurysmal neck and parent vessel as well as inducing significant intra-aneurysmal flow velocity reduction.

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.

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