scholarly journals A Combination between Synthetic Unit Hydrograph (SCS) and Rational Method in a similar Conditions Water Shed

2021 ◽  
Vol 9 (3) ◽  
Author(s):  
Mona Fathi ◽  
Neveen B. Abelmageed ◽  
M. Hassan
Keyword(s):  
Rational Method ◽  
Rainfall Data ◽  
Return Periods ◽  
Unit Hydrograph ◽  
Engineering Applications ◽  
Watershed Characteristics ◽  
Time Of Concentration ◽  
Excess Water ◽  
The Difference ◽  
Peak Runoff

Studying watershed characteristics and choosing the most applicable methods to determine the amount of access rainfall that ran off is very important in many engineering applications, especially hydrology applications. That is to know the more suitable methods for protection against floods and to maximize benefits from the excess water. This study aims to establish a relation between the rational method and the SCS method. A subbasin in Wadi Dahab in Sinai, Egypt is investigated as a study area. To achieve the study aims, HEC-WMS software is chosen, which can analyze a watershed by using DEM and delineating basin. It calculates also important watershed parameters like area, runoff distances, and slope. The rainfall data is compiled and arranged. A statical analysis is executed to obtain the IDF curves. Hyfran-plus software is employed to locate the maximum depths for different return periods. Various values for the time of concentration are studied. It is concluded that the difference between the rational and SCS methods is great for the time of concentration till 2 hours, then it decreases obviously from 2 till 6 hours. Also, it is concluded that the difference between the two methods is bigger for the small return periods of 2 and 5 years for all values of the time of concentration. Employing the obtained equations, the peak runoff for one of the two methods (the rational and SCS methods) can be calculated knowing the time of concentration and the peak runoff for the second method.  

scholarly journals STUDI PENGEMBANGAN MODEL HIDROGRAF SATUAN SISTETIS SNYDER UNTUK SUNGAI –SUNGAI DI SULAWESI SELATAN

GANEC SWARA ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 126
Author(s):  
MUHAMAD YAMIN
Keyword(s):  
Model Verification ◽  
Rainfall Data ◽  
Peak Time ◽  
Reliability Testing ◽  
Unit Hydrograph ◽  
Observation Unit ◽  
Discharge Data ◽  
Watershed Characteristics ◽  
Testing Model ◽  
South Sulawesi

This study aims to analyze the parameters that influence the Snyder synthetic unit hydrograph method. The study was conducted on 11 watersheds in South Sulawesi Province, 8 watersheds for modeling and 3 other watersheds for reliability testing (model verification).     With rainfall data, the discharge data and watershed characteristics obtained from each watershed were analyzed for parameters that affected the hydrograph breakdown of the Snyder HSS method. Then compared to the hydrograph of the observation unit which was analyzed by the Collins method.     After calibration was done with the NASH criteria obtained Peak Time (Tp) = 97.996%; Peak Discharge (Qp) = 98.331% and Basic Time (Tb) = 99.700%. The curved delineation of the hydrograph uses the auxiliary point W, which gives the result of volume deviation, namely: 7.980%, 9.227%; 6.855%; 4.966%; 10.972% and 9.843% are relatively small when compared to the model using Alexejeyev Arch with deviations: 22.362%; 29.991%; 26,319%; 19.602%; 29,786% and 17,633%.

scholarly journals A history of the concept of time of concentration

2020 ◽  
Vol 24 (5) ◽  
pp. 2655-2670 ◽  
Author(s):  
Keith J. Beven
Keyword(s):  
Response Times ◽  
Rational Method ◽  
Unit Hydrograph ◽  
Surface Flows ◽  
Time Of Concentration ◽  
Water Particle ◽  
Subsurface Flows ◽  
History Of ◽  
The 1960S ◽  
Catchment Responses

Abstract. The concept of time of concentration in the analysis of catchment responses dates back over 150 years to the introduction of the rational method. Since then it has been used in a variety of ways in the formulation of both unit hydrograph and distributed catchment models. It is normally discussed in terms of the velocity of flow of a water particle from the furthest part of a catchment to the outlet. This is also the basis for the definition in the International Glossary of Hydrology. While conceptually simple, this definition is, however, wrong when applied to catchment responses where, in terms of how surface and subsurface flows produce hydrographs, it is more correct to discuss and teach the concept based on celerities and time to equilibrium. While this has been recognized since the 1960s, some recent papers and texts remain confused over the definition and use of the time of concentration concept. The paper sets out the history of its use and clarifies its relationship with time to equilibrium but suggests that both terms are not really useful in explaining hydrological responses. An Appendix is included that quantifies the differences between the definitions of response times for subsurface and surface flows under simple assumptions that might be useful in teaching.

scholarly journals Conformity evaluation of synthetic unit hydrograph (case study at upstream Brantas sub watershed, East Java Province of Indonesia)

2017 ◽  
Vol 35 (1) ◽  
pp. 173-183 ◽  
Author(s):  
Dwi Priyantoro ◽  
Lily Montarcih Limantara
Keyword(s):  
Water Resources ◽  
Unit Hydrograph ◽  
Time Of Concentration ◽  
Main River ◽  
Synthetic Unit Hydrograph ◽  
The Difference

AbstractThis study intends to analyse the suitable hydrograph in upstream Brantas sub watershed. The methodology consists of comparing the result of hydrograph due to the methods of Nakayasu synthetic unit hydrograph (SUH), Limantara synthetic unit hydrograph, and the observed unit hydrograph. In detail, this study intends to know the difference of hydrograph parameters: α and Tg as recommended by Nakayasu and in the study location; to know the influence of main river length which is used in the methods of Nakayasu and Limantara to the time of concentration; to know the hydrograph ordinate deviation between Nakayasu and Limantara due to the observed hydrograph. Result is hoped for recommending the suitable hydrograph in upstream Brantas subwatershed so that it can be used accurately for the further design of water resources structure.

scholarly journals A history of the concept of time of concentration

2020 ◽  
Author(s):  
Keith J. Beven
Keyword(s):  
Response Times ◽  
Rational Method ◽  
Unit Hydrograph ◽  
Surface Flows ◽  
Time Of Concentration ◽  
Use Of Time ◽  
Subsurface Flows ◽  
History Of ◽  
The 1960S ◽  
Catchment Responses

Abstract. The concept of time of concentration in the analysis of catchment responses dates back over 150 years to the introduction of the Rational Method. Since then it has been used in a variety of ways in the formulation of both unit hydrograph and distributed catchment models. It is normally discussed The concept of time of concentration in the analysis of catchment responses dates back over 150 years to the introduction of the Rational Method. Since then it has been used in a variety of ways in the formulation of both unit hydrograph and distributed catchment models. It is normally discussed in terms of the velocity of flow of a water particle from the furthest part of a catchment to the outlet. This is also the basis for the definition in the International Glossary of Hydrology. While conceptually simple, this definition is, however, wrong when applied to catchment responses where, in terms of how surface and subsurface flows produce hydrographs, it is more correct to discuss and teach the concept based on celerities and time to equilibrium. While this has been recognized since the 1960s, some recent papers and text remain confused over the definition and use of time of concentration. The paper sets out the history of its use and clarifies its relationship to time to equilibrium but suggests that both terms are not really useful in explaining hydrological responses. An appendix is included that quantifies the differences between the definitions of response times for subsurface and surface flows under simple assumptions that might be useful in teaching.

Movement of Large Convective Rainstorms in Relation to Winds Aloft

1958 ◽  
Vol 39 (3) ◽  
pp. 129-136 ◽  
Author(s):  
C. W. Newton ◽  
Sey Katz
Keyword(s):  
Wind Speed ◽  
Wind Direction ◽  
Rainfall Data ◽  
Squall Lines ◽  
Hourly Rainfall ◽  
The Difference ◽  
Strong Winds

By means of hourly rainfall data from the Hydroclimatic Network, the motions of large rainstorms, of the kind associated with squall lines, are examined in relation to the winds aloft. Very little correlation is found between the speed of movement of the rainstorms and the wind speed at any level, although the fastest moving storms were associated with strong winds aloft. Significant correlation is found between direction of motion of rainstorms, and wind direction at 700 mb or higher levels. On the average, the rainstorms move with an appreciable component toward right of the wind direction. The difference between these results, and those from other studies based on small precipitation areas, is ascribed to propagation. The mechanism involved is discussed briefly.

scholarly journals The Watershed Influence on Storm Runoff in Small Norwegian Rivers

1978 ◽  
Vol 9 (5) ◽  
pp. 277-292 ◽  
Author(s):  
Erik Ruud ◽  
Torulv Tjomsland ◽  
Kjell Nordseth
Keyword(s):  
Soil Moisture ◽  
Drainage Density ◽  
Storm Runoff ◽  
Main Stream ◽  
Lake Area ◽  
Watershed Characteristics ◽  
Moisture State ◽  
Peak Runoff ◽  
Basin Area

A procedure to isolate and investigate the watershed influence on storm runoff is presented. It offers an opportunity to study also the change in influence of particular watershed characteristics by changing the input or soil moisture state of each catchment. Weighted lake area, area of bare rocks, main stream gradient, drainage density and basin area are found to be the most significant characteristics in affecting peak runoff and time of rise on storm hydrographs in small Norwegian rivers. The intercorrelation structure of the watershed properties is examined.

Modified rational method for sizing infiltration structures

2002 ◽  
Vol 29 (4) ◽  
pp. 539-542 ◽  
Author(s):  
A Osman Akan
Keyword(s):  
Storage Time ◽  
Rational Method ◽  
Storm Water ◽  
Water Runoff ◽  
Practical Application ◽  
Simple Method ◽  
Infiltration Basin ◽  
Storm Water Runoff ◽  
Runoff Rate ◽  
Peak Runoff

A simple method is presented to size infiltration structures like infiltration basins and trenches to control storm water runoff. The runoff hydrograph is assumed to be trapezoidal in shape with a peak runoff rate calculated using the rational formula. Given the watershed time of concentration and the allowable runoff rate, the method determines the required size of the infiltration structure. A practical application section is included to demonstrate the use of the method.Key words: rational method, infiltration basin, infiltration trench, capture volume, storage time.

scholarly journals The floods in Greece: the case of Mandra in Attica

2018 ◽  
Vol 52 (1) ◽  
pp. 131 ◽  
Author(s):  
Georgios Soulios ◽  
Georgios Stournaras ◽  
Konstantinos Nikas ◽  
Christos Mattas
Keyword(s):  
Climate Change ◽  
Natural Disasters ◽  
Rational Method ◽  
Peak Discharge ◽  
Human Intervention ◽  
Return Periods ◽  
Flooding Event ◽  
Stream Characteristics ◽  
Extensive Damage

Floods are one of the most common natural disasters and are extremely dangerous in a global range since they can cause extensive damage to properties or losses in human lives. According to the opinion of many expert scientists, climate change has led to the increase of flooding phenomena over the last years worldwide, as well as in Greece. The aim of this paper is to examine the flooding event that occurred in Mandra area, Attica (Greece) on 14-15 November of 2017. The peak discharge of the Agia Ekaterini and Soures streams was calculated using the rational method (Giandotti) for return periods equal to 10, 100 and 1000 years. The stream characteristics were studied and their behavior during the flood was investigated. Many of the impacts were attributed to the human intervention in the streambeds.

scholarly journals Parameter Adjustment to Prevent the Overestimation of Peak Discharge in a Small Watershed

2021 ◽  
Vol 21 (6) ◽  
pp. 285-291
Author(s):  
JongChun Kim ◽  
Jongho Jeong
Keyword(s):  
Response Time ◽  
Peak Discharge ◽  
Small Watershed ◽  
Unit Hydrograph ◽  
Area Method ◽  
Time Of Concentration ◽  
Rainfall Duration ◽  
Reasonable Range ◽  
Specific Discharge ◽  
Basin Response

We revisit empirical methods to prevent the overestimation of peak discharge in a small watershed, in particular investigating the time-area method, which has not been considered in the overestimation problem of peak discharge. To avoid misapplying the same inlet time between the unit hydrograph and rational formula, distinct parameter adjustments for each method are proposed. We adopt the secondary basin response time for the unit hydrograph, rainfall duration for the rational formula, and time of concentration for the time-area method, as suitable parameters to adjust the estimation of peak discharge. In conclusion, adding 10 minutes to secondary basin response time, 20 minutes to rainfall duration, and 30 minutes to time of concentration, respectively, yields estimates within a reasonable range of specific discharge in a small watershed.

scholarly journals Development of Intensity Duration Frequency (IDF) Curves for Rainfall Prediction within the Middle Niger River Basin

2020 ◽  
Vol 4 (2) ◽  
pp. 382-397
Author(s):  
J. O. Ehiorobo ◽  
O.C. Izinyon ◽  
R. I. Ilaboya
Keyword(s):  
River Basin ◽  
Rainfall Intensity ◽  
Rainfall Data ◽  
Annual Maximum ◽  
Return Periods ◽  
Maximum Rainfall ◽  
Niger River ◽  
Idf Curves ◽  
Intensity Duration Frequency ◽  
Best Fit

Rainfall Intensity-Duration-Frequency (IDF) relationship remains one of the mostly used tools in hydrology and water resources engineering, especially for planning, design and operations of water resource projects. IDF relationship can provide adequate information about the intensity of rainfall at different duration for various return periods. The focus of this research was to develop IDF curves for the prediction of rainfall intensity within the middle Niger River Basin (Lokoja and Ilorin) using annual maximum daily rainfall data. Forty (40) year’s annual maximum rainfall data ranging from 1974 to 2013 was employed for the study. To ascertain the data quality, selected preliminary analysis technique including; descriptive statistics, test of homogeneity and outlier detection test were employed. To compute the three hours rainfall intensity, the ratio of rainfall amount and duration was used while the popular Gumbel probability distribution model was employed to calculate the rainfall frequency factor. To assess the best fit model that can be employed to predict rainfall intensity for various return periods at ungauged locations, four empirical IDF equations, namely; Talbot, Bernard, Kimijima and Sherman equations were employed. The model with the least calculated sum of minimized root mean square error (RMSE) was adopted as the best fit empirical model. Results obtained revealed that the Talbot model was the best fit model for Ilorin and Lokoja with calculated sum of minimized error of 1.32170E-07 and 8.953636E-08. This model was thereafter employed to predict the rainfall intensity for different durations at 2, 5, 10, 25, 50 and 100yrs return periods respectively.

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