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 Experimental determination of the time of concentration, Sapucajuba creek small watershed study

2021 ◽  
Vol 10 (6) ◽  
pp. e35210612757
Author(s):  
Giovanni Chaves Penner ◽  
Thiago Rodrigues de Matos ◽  
Hélio da Silva Almeida ◽  
Julio Cesar de Souza Inácio Gonçalves ◽  
Moisés Marçal Gonçalves
Keyword(s):  
Response Time ◽  
Maximum Flow ◽  
Empirical Models ◽  
Great Variability ◽  
Percentage Error ◽  
Small Watershed ◽  
Time Of Concentration ◽  
Future Project ◽  
High Absorption

Time of concentration (tc) is a parameter that indicates the response time of a river catchment to a rainfall. Frequently, empirical equations are used to determination of tc for the design of the maximum flow. However, the determination of this response time by equations sometimes results in an erroneous application, that is, outside its field of validity. Thus, the present work aimed to determine tc in an experimental and simplified way in the Sapucajuba creek, from measurements in the field, with saline tracer, and to make a comparison with 13 empirical models, which require the morphometric characteristics of the small watershed. It was observed that they underestimated the time of concentration value, in general, by empirical models, overestimating the future project flow. DNOS (sandy-clay condition, intense vegetation, high absorption) was the most indicated model for the estimate of tc, that provided the lowest percentage error, 1.92%, compared to tc measured in the field. However, such error exceeded 70.00% by other models, showing great variability. Therefore, it is strongly recommended the determination of tc in field, that will provide a real result, contributing to the economic dimensioning of hydraulic-hydrological works and projects.

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.

scholarly journals Spatial Patterns in Baseflow Mean Response Time across a Watershed in the Loess Plateau: Linkage with Land-Use Types

2020 ◽  
Vol 66 (3) ◽  
pp. 382-391 ◽  
Author(s):  
Xu-dong Huang ◽  
Dong Wang ◽  
Pei-pei Han ◽  
Wen-chuan Wang ◽  
Qing-jie Li ◽  
...  
Keyword(s):  
Land Use ◽  
Response Time ◽  
Overland Flow ◽  
Agricultural Land ◽  
Least Squares Regression ◽  
Unit Hydrograph ◽  
Mean Response Time ◽  
Impervious Area ◽  
Land Use Types ◽  
Instantaneous Unit Hydrograph

Abstract Understanding the relation between land-use types and baseflow mean response time (BMRT) is important to explore the response mechanism of baseflow processes in watersheds. BMRT was determined using an instantaneous unit hydrograph. The instantaneous unit hydrograph parameters were estimated by autocorrelation functions. The relative importance of land-use types in determining BMRT dynamics was assessed by hydrological model and partial least-squares regression. Our study suggests greater effects of urban area on BMRT than the effects of forest and agricultural land. This may be because the urban interception impervious area may impede baseflow generation over a short timescale. The effects of agricultural land are greater than those of forest in areas with steeper hillslopes, but lower than those of the forest in areas with more plains, reflecting the varied ability of forest and agricultural lands with different topography to hinder overland flow. Variations of BMRT are strongly linked to land use in the watershed. Overall, our study provides insight into the BMRT and dominant factors of land-use types in watersheds, planning of sustainable water resource use, and ecological protection in watersheds.

scholarly journals Effects of Roughness Coefficients and Complex Hillslope Morphology on Runoff Variables under Laboratory Conditions

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2550 ◽  
Author(s):  
Masoud Meshkat ◽  
Nosratollah Amanian ◽  
Ali Talebi ◽  
Mahboobeh Kiani-Harchegani ◽  
Jesús Rodrigo-Comino
Keyword(s):  
Soil Erosion ◽  
Peak Discharge ◽  
Control Measures ◽  
P Value ◽  
Rainfall Runoff ◽  
Runoff Generation ◽  
Mean Values ◽  
Time Of Concentration ◽  
Significant Difference ◽  
The Impact

The geometry of hillslopes (plan and profile) affects soil erosion under rainfall-runoff processes. This issue comprises of several factors, which must be identified and assessed if efficient control measures are to be designed. The main aim of the current research was to investigate the impact of surface Roughness Coefficients (RCs) and Complex Hillslopes (CHs) on runoff variables viz. time of generation, time of concentration, and peak discharge value. A total of 81 experiments were conducted with a rainfall intensity of 7 L min−1 on three types of soils with different RCs (i.e., low = 0.015, medium = 0.016, and high = 0.018) and CHs (i.e., profile curvature and plan shape). An inclination of 20% was used for three replications. The results indicate a significant difference (p-value ≤ 0.001) in the above-mentioned runoff variables under different RCs and CHs. Our investigation of the combined effects of RCs and CHs on the runoff variables shows that the plan and profile impacts are consistent with a variation in RC. This can implicate that at low RC, the effect of the plan shape (i.e., convergent) on runoff variables increases but at high RC, the impact of the profile curvature overcomes the plan shapes and the profile curvature’s changes become the criteria for changing the behavior of the runoff variables. The lowest mean values of runoff generation and time of concentration were obtained in the convex-convergent and the convex-divergent at 1.15 min and 2.68 min, respectively, for the soil with an RC of 0.015. The highest mean of peak discharge was obtained in the concave-divergent CH in the soil with an RC of 0.018. We conclude that these results can be useful in order to design planned soil erosion control measures where the soil roughness and slope morphology play a key role in activating runoff generation.

scholarly journals Estimation of Flood Discharge in Complex Basins and Assessment of Downstream Conveyance in Development Areas

2021 ◽  
Vol 21 (4) ◽  
pp. 187-195
Author(s):  
Hojun Keum ◽  
Haksoo Kim ◽  
Taekjo Ko
Keyword(s):  
Impact Assessment ◽  
Rural Areas ◽  
Hydrological Modeling ◽  
Rainfall Runoff ◽  
Unit Hydrograph ◽  
Design Standards ◽  
Area Method ◽  
Disaster Impact ◽  
Urban And Rural Areas ◽  
Domestic Design

The rainfall-runoff characteristics of urban and rural areas differ. Hence, major domestic design standards recommend using the rural basin rainfall-runoff models (the unit hydrograph method) for rural areas and the urban rainfall-runoff models (time-area method) for urban areas when estimating the amount of floods. Further, the guidelines for consultations on disaster impact assessment in Korea describe the selection of rainfall-runoff models according to basin types such as urban and rural areas. However, in complex watersheds where rural and urban basins coexist, the type of rainfall-runoff model is selected based on the modeler’s (or business operator’s) experiences rather than model selection guidelines. This study aims to analyze the impacts of uncertain design standards on disaster impact assessment in Korea. To this end, the parameters for each model (the unit hydrograph method, time-area method) were optimized using the measured datasets. The accuracy of the models was evaluated, as well as the appropriateness of flood reduction measures based on whether there was an assessment of downstream conveyance in development areas. The results of this study are expected to contribute to improving the reliability of the evaluation of flood reduction measures by assessing the accuracy of results in hydrological modeling and supplementing the uncertain flood estimation guidelines.

Copula-based interpretation of continuous rainfall–runoff simulations of a watershed in northern Iran

2012 ◽  
Vol 49 (5) ◽  
pp. 681-691 ◽  
Author(s):  
Saeed Golian ◽  
Bahram Saghafian ◽  
Ashkan Farokhnia
Keyword(s):  
Soil Moisture ◽  
Peak Discharge ◽  
Rainfall Runoff ◽  
Antecedent Soil Moisture ◽  
Rainfall Duration ◽  
Initial Soil Moisture ◽  
Hourly Rainfall ◽  
Copula Method ◽  
Initial Soil ◽  
Rainfall Depth

In the present work, the joint response of key hydrologic variables, including total precipitation depths and the corresponding simulated peak discharges, are investigated for different antecedent soil moisture conditions using the copula method. The procedure started with the calibration and validation of the soil moisture accounting (SMA) loss rate algorithm incorporated in the Hydrologic Engineering Center – hydrologic modeling system (HEC–HMS) model for the study watershed. A 1000 year long time series of hourly rainfall was then generated by the Neyman–Scott rectangular pulses (NSRP) rainfall generator, which was then transformed into the runoff rate by the HEC–HMS model. This long-term continuous hydrological simulation resulted in characterizing the response of the watershed for various input conditions such as initial soil moisture content (AMC), total rainfall depth, and rainfall duration. For each initial soil moisture class, the copula method was employed to determine the joint probability distribution of rainfall depth and peak discharge. For instance, for dry AMC condition and 1 h rainfall duration, the Joe family fitted best to the data, compared with six other one-parameter families of copulas. Results showed that the bivariate analysis of rainfall–runoff using the copula method can well characterize the watershed hydrological behavior. The derived offline curves could provide a probabilistic real-time peak discharge forecast.

scholarly journals Analisis Debit Puncak Sungai Lubuk Banyau Kabupaten Bengkulu Utara Menggunakan Metode Hidrograf Satuan Sintetik

2020 ◽  
Vol 12 (2) ◽  
pp. 83-90
Author(s):  
Agam Sanjaya
Keyword(s):  
Return Period ◽  
Rainfall Intensity ◽  
Peak Discharge ◽  
Peak Time ◽  
Type I ◽  
Unit Hydrograph ◽  
Distribution Method ◽  
Pearson Type ◽  
Synthetic Unit Hydrograph ◽  
Log Normal

ANALISIS DEBIT PUNCAK SUNGAI LUBUK BANYAU KABUPATEN BENGKULU UTARA DENGAN MENGGUNAKANMETODE HIDROGRAF SATUAN SINTETIK Agam Sanjaya I1), Khairul Amri II2), Muhammad Fauzi III3) 1) 2) 3)Jurusan Teknik Sipil, Fakultas Teknik UNIB Jl. W.R. Supratman, Kandang Limun, Kota Bengkulu 38371, Telp. (0736)344087e-mail: [email protected], [email protected] , [email protected] aliran sungai (DAS) Sungai Lubuk banyau merupakan salah satu DAS yang berada di Bengkulu Utara. DAS Sungai Lubuk banyau mengalir dari daerah hulu yang terletak diwilayah Kabupaten Bengkulu utara. Tujuan dari penelitian ini adalah menganalisa debit puncak rencana akibat intensitas curah hujan pada DAS Lubuk Banyau dalam menganalisis hidrologi dengan menggunakan metode Hidograf Satuan Sintetik (HSS) Gama I, HSS Nakayasu dan HSS Snyder. Berdasarkan hasil perhitungan dari penelitian ini distribusi frekuensi terhadap tiga metode curah hujan, yaitu metode ditribusi Gumbel Tipe I, Log Pearson Tipe III dan Log Normal maka metode yang digunakan untuk perhitungan curah hujan rencana pada penelitian ini adalah Metode Gumbel Tipe I dengan periode ulang 2, 5, 10, 25, 50 dan 100 tahun, yaitu 181,164 mm, 275,356 mm, 337,709 mm, 416,518 mm, 474,974 mm dan 532,998 mm. Dari hasil analisis hidrologi pada penelitian diperoleh debit puncak pada DAS Lubuk Banyau untuk periode ulang 100 tahun dengan metode HSS Snyder adalah 1531,111 m3/detik dengan waktu puncak sebesar 5 jam merupakan debit puncak yang paling besar diantara HSS Gama I dan Nakayasu. untuk hasil debit puncak dengan metode HSS Gama I adalah 776,91m3/detik dengan waktu puncak sebesar 4 jam dan HSS Nakayasu 1023,87 dengan waktu puncak 2,46 jam. Maka didapatkan tinggi permukaan air pada DAS Lubuk Banyau yaitu 1,134 m.Kata kunci: hidrograf satuan sintetik, debit puncak, gama I, nakayasu, dan snyderAbstractWatershed Lubuk Banyau is one of the watersheds in North Bengkulu. The Lubuk River watershed flows from the upstream area located in the northern Bengkulu regency. The purpose of this study is to analyze the planned peak discharge due to rainfall intensity in the Lubuk Banyau watershed in analyzing hydrology using the Synthetic Unit Hydrograph (HSS) method of Gama I, HSS Nakayasu and HSS Snyder. Based on the results of calculations from this study the frequency distribution of three rainfall methods, namely the Gumbel Type I distribution method, Pearson Type III Log and Normal Log, the method used for calculating the planned rainfall in this study is the Gumbel Type I method with a return period of 2, 5, 10, 25, 50 and 100 years, namely 181,164 mm, 275,356 mm, 337,709 mm, 416,518 mm, 474,974 mm and 532,998 mm. From the results of the hydrological analysis in the study, the peak discharge in the Lubuk Banyau watershed for a 100-year return period with the Snyder HSS method was 1531,111 m3 / second with a peak time of 5 hours being the largest peak discharge between Gama I and Nakayasu HSS. for the peak discharge using the HSS Gama I method is 776.91m3 / sec with a peak time of 4 hours and Nakayasu HSS of 1023.87 with a peak time of 2.46 hours. Then the water level obtained at the Lubuk Banyau watershed is 1,134 m.Keywords: synthetic unit hydrograph, peak discharge gama I, nakayasu, and snyder.

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.  

Rational Method Time of Concentration Can Underestimate Peak Discharge for Hillslopes

2021 ◽  
Vol 147 (10) ◽  
pp. 06021014
Author(s):  
Dana Ariel Lapides ◽  
Anneliese Sytsma ◽  
Octavia Crompton ◽  
Sally Thompson
Keyword(s):  
Rational Method ◽  
Peak Discharge ◽  
Time Of Concentration
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