SCS Method Research Articles

Minimization of deep percolation by a parabolic simulation model in a blocked end furrow irrigation method

AbstractSurface irrigation methods enable a lower cost of investment and energy requirements than pressurized systems if they are designed and managed properly. The aim of this investigation was to devise a new simulation model that would enable the determination of the optimum water application time and furrow length in a blocked end furrow system. The infiltration properties of the soil, net irrigation water requirement of the crop and inflow to the furrow constitute the main variables of this process. Deep percolation and the cross‐sectional area of the wetting pattern where the net irrigation water requirement of the crop is met along the furrow are the main components that were simulated interactively in the model. They were described as a function of time. The proposed model devised in this investigation was run for two different sample applications. While values of 93 and 94% water application efficiencies were obtained by running the USDA SCS method for the first and second sample applications, respectively, values of 92 and 94% were obtained, respectively, from the proposed model. These results indicate that the proposed model can be used in the design of a blocked end furrow system.

Flood control simulation for disaster management in Wai Batu Merah River Basin

Ambon City, located in Maluku Island, experiences flood disaster every year. It has been considered that the flood in this city occurs more often compared to the other city in the same island. One of the river that is related to the flood occurrence in Ambon City is Wai Batu Merah River. This study aims to find appropriate structural measurement by using modelling simulation to control flood disaster in Wai Batu Merah River Basin. The modelling used HEC-RAS 5.0.7 software for coupled 1D and 2D hydraulic simulation. Flood discharge was calibrated by applying flood event in 2013. The SCS method was selected to generate flood hydrograph by using synthetic method. The records of water depth in the flood event were compared to the hydraulic model results and it showed good agreement. Based on the model, flood control scenarios i.e. normalization and dike were exercised for 25 year return period as required by government regulation. The combination of both scenarios can manage flood in Wai Batu Merah River Basin effectively. However it might need high cost to construct the structures. Therefore, it is necessary to have priority between the scenarios.

Hydrological Analysis In Selecting Flood Discharge Method In Watershed Of Kelara River

For Engineers involved in planning and construction of water resources building, hydrology becomes very important data. In terms of planning stage in water resources especially waterworks, it is known that design flood discharge closed to field realistic conditions is often needed in order that a planned construction is able to control flood discharge. Several previous researches in choosing flood discharge selection method have diverse depending on observed watershed. One method in determining selected flood discharge by verification using Creager diagram, by comparing discharge calculation results of several Synthetic Unit Hydrograph (SUH) with infrastructure flood discharge (AWLR result) in observation point. This research aims to obtain the most suitable synthetic unit hydrograph and close to analysis result of measured discharge frequency, and Creager diagram in Kelara watershed (DAS). Based on the calculation of design flood discharge according to rainfall data using synthetic unit hydrograph of Nakayasu, ITB I, ITB II, and SCS (HEC-HMS) as well as the calculation of design flood discharge according to collected data, it is concluded that the synthetic unit hydrograph method closest to design flood discharge with measured discharge rate and Q1000 rate of Creager diagram is SCS. Flood discharge rate obtained according to HSS SCS method using HEC-HMS 4.8 application in period of 2 years is 658,40 m3/s, 25 years is 682,70 m3/s, 50 years is 787,00 m3/s, 100 years is 885,70 m3/det, and 1000 years is 1202,60 m3/s

An improved cuckoo search algorithm with Stud crossover for Chinese TSP problem#

The travelling salesman problem (TSP) is an NP-hard problem in combinatorial optimization. It has assumed significance in operations research and theoretical computer science. The problem was first formulated in 1930 and since then, has been one of the most extensively studied problems in optimization. In fact, it is used as a benchmark for many optimization methods. This paper represents a new method to addressing TSP using an improved version of cuckoo search (CS) with Stud (SCS) crossover operator. In SCS method, similar to genetic operators used in various metaheuristic algorithms, a Stud crossover operator that is originated from classical Stud genetic algorithm, is introduced into the CS with the aim of improving its effectiveness and reliability while dealing with TSP. Various test functions had been used to test this approach, and used subsequently to find the shortest path for Chinese TSP (CTSP). Experimental results presented clearly demonstrates SCS as a viable and attractive addition to the portfolio of swarm intelligence techniques.

A GIS Based Methodology to Obtain the Hydrological Response to Storm Events of Small Coastal Basins, Prone to Flash Flooding

The present study aims to investigate the hydrological response of small coastal watersheds to storm events. Areas around the Mediterranean Sea are usually characterized by streams with intermittent flows and flash floods are common. Firstly, we analyze the geomorphological, soil and land cover characteristics of the watershed in order to estimate their effect on surface runoff. Furthermore, the rainfall characteristics of an extreme event that caused flash flooding in the past are analyzed. By combining these factors, we are able to predict the response of this basin to severe storm events. The study area is located in the island of Samos, in Eastern Greece, where flash flood events are usual and pose a risk to areas located around rivers. In this area runoff is intermittent, occurring mainly during storm events and there is a lack of discharge or other instrumental measurements. By applying the SCS-CN method we estimate the response of two of the largest watersheds in Samos Island, through the construction of a Synthetic Unit Hydrograph (SUH). Firstly, we examined the record of historic floods in the area, selecting a large flash flood event (November 2001) and then obtained the daily rainfall data, which are used by the SCS method for the calculations. We applied the SCS methodology in order to estimate various parameters (e.g. lag time, time of concentration, maximum discharge), which also required the calculation of the Curve Number (CN) for each watershed. During this event (136 mm rainfall), we calculated a direct runoff (excess rainfall) of 44%-48% for these watersheds. This methodology can be particularly useful in simulating the hydrological response of small Mediterranean watersheds and to introduce better strategies for the management of the whole drainage basin.

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

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.

Study of Modeling Method Selection in Flood Discharge Calibration Using HEC-HMS Software

Flood disaster management requires analysis and modeling, especially for the decision making of flood events. One way to analyze flood events is to use HEC-HMS software. HEC-HMS has three submodels: Loss, Transform, and Baseflow. In the flood discharge analysis, the selection of this sub-model is important because it is not certain that the method offered in this sub-model is suitable for all conditions, so it is necessary to choose which one is more suitable. Based on the results of the research, the SCS method can model well as evidenced by the good objective function values (RMSE (0.70 m; 49.05 m3 / s), Correl (0.931; 0.992), and DELTA PEAK (16.88%; 13.75%). The verification results are also show similar results (RMSE (0.63 m; 66,198 m3 / s), Correl (0.977; 0.916) and DELTAPEAK (43.04%; 32,754%). Therefore, it can conclude that the combination of benchmarking techniques that can be used for HEC-HMS modeling is the SCS curve number for losssubmodel, SCS unit hydrograph for transform submodel, and Recession constant for baseflowsubmodel.

A Framework of Dam-Break Hazard Risk Mapping for a Data-Sparse Region in Indonesia

This paper introduces a new simple approach for dam-break hazard mapping in a data-sparse region. A hypothetical breaching case of an earthen dam, i.e., the Ketro Dam in Central Java, (Indonesia) was considered. Open-access hydrological databases, i.e., TRMM and CHIRPS, were collected and compared with the rainfall ground station data to ensure data quality. Additionally, the 3-h rainfall distribution of the TRMM database was employed and validated with the measured data to establish the 24-h rainfall distribution of the probable maximum precipitation. The probable maximum flood discharge was computed with the SCS method, and the reservoir routing computation was conducted to determine the possible breaching mechanisms. The result shows that the Ketro Dam proves safe against overtopping, and thus only the piping mechanism has been taken into consideration. Using the breaching hydrograph, the open-access Digital Elevation Model MERIT Hydro, and the high-performance shallow water model NUFSAW2D, the flood propagation to the downstream part of the dam was simulated, enabling fast computations for different scenarios. The quantification of the susceptibility rate of urban areas was eased with overlay analysis utilizing InaSAFE, a plugin for the QGIS model. This study shows that even for a data-sparse region, the recent open-access databases in terms of hydrological and hydraulic aspects may be used to generate a dam-break hazard map. This will benefit the related stakeholders to take proper action to reduce the loss of life.

HYDROLOGICAL PARAMETERS AFFECTING FLASH FLOODS: CASE STUDY WADI AL-BAROUD EL-ABIAD, SAFAGA CITY, RED SEA GOVERNORATE

Flash flood is one of the most important natural hazards all over the world. It is very dangerous because of its effect on people’s lives and can lead to death. So we must be aware of the flash flood by studying the factors that affect it and predict it. In this paper, hydrological parameters that affect flash floods in arid or semi-arid areas are studied. The study area is Wadi Al-Baroud El-Abiad which is located to the northwest of Safaga city on the red sea coast that is frequently subjected to a severe flash flood. Parameters affecting floods are considered i.e. meteorological (climatic), morphological, and geological factors. Climatic data are analyzed to reach the design storm values for different return periods by knowing the annual rainfall values of the study area by using rainfall data from a rain gauge station near the area. In this research, the mean monthly rainfall values of Safaga meteorological station from 1994 to 2018 are used and the annual maximum values of rainfall rates are extracted from it. Digital elevation model (DEM) and digital terrain data of the catchment are obtained from the USGS EathExplorer website and inserted into WMS and ArcGIS software. To obtain the hydrological characteristics such as unit hydrograph, concentration-time, delay time, and storage coefficient, the land use and soil type in the study area must first be determined by the geomorphological and geological study. SCS and curve number methods are used in estimating the soil type and land use of the basin. Many software and tools are used in data analysis and watershed delineation among them, GIS, WMS, SURFER, HYFRAN, GOOGLE EARTH. From this study, watershed morphological characteristics, flood quantity, and flow hydrograph at Wadi Al-Baroud El-Abiad dam are estimated for different rainfall intensity, duration, and return periods. Moreover, the storage capacity of the dam reservoir at different rainfall intensity, duration and return periods is estimated and the time required for storage water to evaporate and infiltrate into the subsurface soil is identified. The results of this research can help the developer, planners, and decision-makers for flood management in arid areas.

A COMPARATIVE ASSESSMENT OF DIFFERENT LOSS METHODS AVAILABLE IN MIKE HYDRO RIVER-UHM

Hydrologic modelling studies usually involve data series with a large temporal scale, especially in Romania, focusing on a long-term impact analysis. Nevertheless, event-based runoff models are essential tools for short-term purposes such as flash flood forecasting. Suitable methods or models must be considered in order to ensure the validity of such research based on parameter calibration to a particular area. Therefore, a comparative analysis of methods must be conducted first, in order to determine the optimal ones that can be used for future data prediction. The aim of the present study is to apply and validate the MIKE HYDRO River modeling system - the UHM module, through a comparative analysis of the SCS, Generalized SCS and Proportional Loss methods available, to a small-sized mountainous watershed, where no research has been conducted in this field. To this end, three spring rainfall events were chosen, but with different antecedent moisture conditions, in order to examine how well the chosen methods can reproduce the available observations in such circumstances. The SCS method yielded the highest quality performance, but the Proportional Loss method has also proven effective under these conditions.

The uncertainties of synthetic unit hydrographs applied for basins with different runoff generation processes

ABSTRACT Synthetic unit hydrographs (SUH) are useful tools for the estimation of maximum flows in basins lacking historical records of measurements. However, these methods have many uncertainties and do not always produce results consistent with reality. This study comparatively analyzed the uncertainty of the application of the Snyder, SCS, and Clark HUS methods, widely used, in relation to the observed hydrographs, in the Pequeno River and the Espingarda River basins, located in the State of Paraná, considered small from the point of view of the drainage area. The simulation was performed using the HEC-HMS 4.2.1 software considering a combination of parameters that produced the higher and lower peak flow, respectively named as conservative and bold approaches. It was verified that the SUH methods, in general, overestimated the peak flows for both basins under study. In addition, the results obtained showed that SUH are fundamentally conservative models so that a bold approach in estimating the parameters input leads to results with smaller errors in simulated peak flows. Even running the SUH with the real excess rainfall as input there is an overestimation of the peak flow. SCS SUH produced the highest peak flows and consequently the largest errors while Snyder’s SUH produced the smallest errors. The magnitude of the overestimation of the peak flow for the Pequeno River was up to 60 folds. Its geology features suggest a Dunnian runoff generation process, which explains the larger errors.

Effect of lithium borate coating on the electrochemical properties of LiCoO2 electrode for lithium-ion batteries

The effect of a protective coating of fused lithium borate, Li3BO3, on the physicochemical and electrochemical characteristics of LiCoO2 has been studied. A cathode material produced by the SCS method using binary organic fuel, glycine and citric acid. The influence of the experiment conditions on the morphology, crystal structure and specific surface of lithium cobaltite was studied. Electrochemical testing of LiCoO2∙nLi3BO3 samples, n = 5 and 7 mass %, has been performed in the cathode Li|Li+-electrolyte|LiCoO2∙nLi3BO3 half-cell using 1M LiPF6 in EC/DMC mixture (1:1) as electrolyte in the 2.7-4.3 V range at normalized discharge current С/10, С/5, С/2. The maximal initial discharge capacity of 185 mAh/g was detected for the samples with 5 mass % Li3BO3. The coulomb efficiency of optimal materials in the 40th cycle was 99.1%.

A new method for synthesizing test accuracy data outperformed the bivariate method

ObjectivesThis study outlines the development of a new method (split component synthesis; SCS) for meta-analysis of diagnostic accuracy studies and assesses its performance against the commonly used bivariate random effects model. MethodsThe SCS method summarizes the study-specific diagnostic odds ratio (on the ln(DOR) scale), which mainly reflects test discrimination rather than threshold effects, and then splits the summary ln(DOR) into its component parts, logit sensitivity (Se) and logit specificity (Sp). Performance of SCS estimator was assessed through simulation and compared against the bivariate random effects model estimator in terms of bias, mean squared error (MSE), and coverage probability across varying degrees of between-studies heterogeneity. ResultsThe SCS estimator for the DOR, Se, and Sp was less biased and had smaller MSE than the bivariate model estimator. Despite the wider width of the 95% confidence intervals under the bivariate model, the latter had a poorer coverage probability than that under the SCS method. ConclusionThe SCS estimator outperforms the bivariate model estimator and thus represents an improvement in the approach to diagnostic meta-analyses. The SCS method is available to researchers through the diagma module in Stata and the SCSmeta function in R.

The flood prediction model using Artificial Neural Network (ANN) and weather Application Programming Interface (API) as an alternative effort to flood mitigation in the Jenelata Sub-watershed

Jenelata is a sub of the Jeneberang watershed in South Sulawesi which has rainfall intensity from 2,800 mm to 4,000 mm per year on the upstream area, some of the rainfall occurs in a short period with high intensity, resulting significant rise to river water level. It potentially to cause floods downstream. Topography of the upstream area is mountainous with an average slope of ± 0.024 along the river, with flow length of 38,314 km it has a large velocity flow. Purpose of this research is to providing alternative for flood mitigation using rainfall predictions and runoff calculations, hypoteticaly it can reduce the impact of possible flood. This research was conducted using Artificial Neural Network (ANN) as rainfall predictor and input variable for runoff calculation using SCS method. ANN input variable will use weather prediction data from the global weather API, while SCS method will calculate maximum runoff in the catchment for the next 24 hours. Results of the rainfall prediction model get deviation of 28.81 mm and accuracy of 58% compared to the observations. Meanwhile, runoff model discharge acquires deviation of 1181.7 m3 and water level ± 0.19 m at the designated location of water level gauge.

The comparative study of peak discharge at Ngotok watershed by using the method of SCS, Snyder and Nakayasu for flood control needs

Flood problems often hit the Ngotok River watershed every year. The problem of flooding is generally caused by changes in land use and a decrease in river functions in the Ngotok River watershed area as well as frequent back water from rivers which empties into Brantas River when experiencing maximum discharge. For that reason, a comparative study of peak flood discharge needs to be done because there is no research on flood control. So that research is conducted on the analysis of synthetic unit hydrograph models. The synthetic unit hydrograph method used is SCS, Snyder, and Nakayasu. Rainfall data used is data from 1998-2016 from 14 rain stations in the Ngotok River watershed. The Thiessen polygon method is used to determine the amount of rain scattered in the Ngotok River watershed. The average rainfall in the Ngotok River watershed in the period 1998-2016 was 97.05 mm. In the modeling phase, the sub-catchment division of the watershed is carried out by dividing it into 5 sub-catchments. The modeling results using the SCS, Snyder, and Nakayasu methods show the amount of discharge for the return period of 2 years, 5 years, 10 years, 20 years, 25 years, 50 years, 100 years, and 200 years which varies. AWLR data approaching the modeling results are 2014 data. The hydrograph calibration results for the SCS method with a 25 year return period are 0.88, for the Snyder method with a 25 year return period of 0.74, and the Nakayasu method with a 25 year return period of 0.43. Thus the SCS hydrograph approaches the existing hydrograph model based on the AWLR data that exists and is following the observations during the population survey.

Curve Number Method to Determine the Runoff Height in the Upper Cimanuk Watershed

Run off is one of the most important hydrological variables in supporting water resources development planning and activities. To predict the amount of runoff can be done in various ways one of them with the SCS-CN method. The SCS method was developed from years of rainfall observation and involved many agricultural areas in the United States. This method seeks to link watershed characteristics such as soil, vegetation, and land use with a runoff curve number which indicates the potential runoff water for a particular rainfall. The location of this research is Garut Regency, upstream of the Cimanuk river, which often floods every year due to overflowing of the Cimanuk River. Data used to determine CN values and runoff height are Digital Elevation Model (DEM), land use, soil, and rainfall data for the last 10 years, from 2009 to 2018, then the maps are processed using the Arc-Map program. From the analysis it can be seen that the CN value is 66.54%, and the runoff height is 1.17 cm with a 2 year return period, and 2.84 cm at 25 return period. Based on the CN value, it is known that the type of soil in the upstream Cimanuk watershed has a small infiltration rate and has bad properties in infiltrating water, so that it can cause run off for a long time, because the smaller CN value on a land use, so soil’s retention ability is greater and the less chance of runoff. The results of this study can be used for planning flood control buildings in the upper Cimanuk watershed.

An Improved SCS-CN Method Incorporating Slope, Soil Moisture, and Storm Duration Factors for Runoff Prediction

Soil Conservation Service Curve Number (SCS-CN) is a popular surface runoff prediction method because it is simple in principle, convenient in application, and easy to accept. However, the method still has several limitations, such as lack of a land slope factor, discounting the storm duration, and the absence of guidance on antecedent moisture conditions. In this study, an equation was developed to improve the SCS-CN method by combining the CN value with the tabulated CN2 value and three introduced factors (slope gradient, soil moisture, and storm duration). The proposed method was tested for calibration and validation with a dataset from three runoff plots in a watershed of the Loess Plateau. The results showed the model efficiencies of the proposed method were improved to 80.58% and 80.44% during the calibration and validation period, respectively, which was better than the standard SCS-CN and the other two modified SCS-CN methods where only a single factor of soil moisture or slope gradient was considered, respectively. Using the parameters calibrated and validated by dataset of the initial three runoff plots, the proposed method was then applied to runoff estimation of the remaining three runoff plots in another watershed. The proposed method reduced the root-mean-square error between the observed and estimated runoff values from 5.53 to 2.01 mm. Furthermore, the parameters of soil moisture (b1 and b2) is the most sensitive, followed by parameters in storm duration (c) and slope equations (a1 and a2), and the least sensitive parameter is the initial abstraction ratio λ on the basis of the proposed method sensitivity analysis. Conclusions can be drawn from the above results that the proposed method incorporating the three factors in the SCS method may estimate runoff more accurately in the Loess Plateau of China.

Rainfall-runoff estimation and comparative analysis using SCS method based on GIS

Rainfall-runoff estimation and comparative analysis using SCS method based on GIS

Assessment of storm direct runoff and peak flow rates using improved SCS-CN models for selected forested watersheds in the Southeastern United States

Study regionSoutheastern United States Study focusThe objective was to evaluate the ability of two modified SCS-CN models to predict direct runoff (DRO) and peak discharge rate (Qp) for selected storm events in three forested watersheds in the region - one low-gradient system in South Carolina, two high-gradient upland systems in North Carolina, and a mid-gradient upland system in Arkansas. New hydrological insights for the regionThe calculated peak discharge rate Qp values by all methods were unsatisfactory when using the default pond and swamp adjustment factor (Fp) value of 0.72 recommended in the SCS TR55 guideline, indicating that use of the default Fp value may result in erroneous Qp estimates for forest watersheds with high retention capacities. These findings, indicating the superiority of the modified Sahu-Mishra-Eldo (SME_m) method to the original SCS method in runoff calculations and substantially lower Fp values in the associated Qp method, are significant for hydrologists and engineers who frequently apply the methods in design of storm water management structures including road culverts on forested landscapes.

The representative synthetic unit hydrograph in Juana watershed

Rainfall-runoff transformation is carried out when the series of discharge data is limited or unavailable. One of the components of rainfall-runoff transformation is unit hydrograph, which can be derived synthetically. The selection of the representative synthetic unit hydrograph is fundamental related to the results of the further calculation. This study compared three types of synthetic unit hydrograph, that were Gama I, Nakayasu and SCS. The study was conducted in Juana Watershed, which is located in Central Java Province and composed of 52 sub-watersheds. The calculation was carried out in the control point of Sentul Weir by using HEC-HMS version 4.2.1, in the case of January 2014 flood events. The results showed that the peak discharge from Gama I, Nakayasu, and SCS synthetic unit hydrograph were 80.78 m3/s, 85.32 m3/s, and 78.89 m3/s respectively. Those results then compared with the flood mark in Sentul Weir, which was estimated 76.53 m3/s. Therefore, the SCS method was determined as the representative synthetic unit hydrograph in Juana Watershed, refers to the minimum error value of 3.08%. Then the analysis of design flood hydrograph for the 52 sub-watersheds in Juana Watershed can be approached by using the SCS synthetic unit hydrograph method.