Synthetic Unit Hydrograph Research Articles

Development of the Synthetic Unit Hydrograph Tool – SUnHyT

Unit hydrographs (UH) are widely used in scientific research and engineering projects to simulate rainfall-runoff processes. There are four main approaches for calculating UH: the traditional, the conceptual, the probabilistic, and the geomorphological approaches. Most software designed to facilitate the estimation of UH is usually based on only one UH approach, limiting its applicability for scientific hypotheses testing. This paper presents the Synthetic Unit Hydrograph Tool (SUnHyT), which provides nine different UH models from the four main approaches used in UH applications. SUnHyT is an open-source application that can be used intuitively through a graphical user interface. We tested the model in a case study that highlights the need for alternative approaches of UH when the traditional approach does not perform well. SUnHyT allows the estimation of design hydrographs in gauged and ungauged catchments and can be useful for hydrologists, water managers and decision-makers.

Runoff hydrographs using Snyder and SCS synthetic unit hydrograph methods: A case study of ungauged watersheds of Imam Turki Bin Abdullah Royal Nature Reserve (ITBA) - Saudi Arabia

Background: The estimation of surface runoff and discharge peak using the Snyder’s model and SCS Dimensionless UH (SCS-DUH) method are one of the best alternatives solutions appropriate for analyzing the hydrologic systems in the ungauged watersheds. These two methods were applied to estimate the discharge peak and design their hydrographs in the drainage basins of Royal Nature Reserve (Imam Turki Bin Abdullah) in Saudi Arabia. - Aims: To estimate the discharge peak by applying Snyder’s model and SCS-DUH method using the morphometric parameters deriving from the SRTM DEM30m and three rainstorms of 40, 50 and 60mm. - Methods: The estimation of discharge peak (Qp) using Snyder’s model was depended on the SRTM DEM30m outputs and the hydrology parameters of the duration (Td) of Unit Hydrograph (UH), time to peak (Tp), time base of the UH (Tb), UH width at 50% and 75% of the peak discharge. However, the estimation of the discharge peak by The SCS-DUH method was computed using the drainage area (A), the direct runoff (Qd) and the time to peak (Tp). The direct runoff was determined by the runoff ratio 0.20 of the unimproved areas, proposed by the Soil Conservation Service (SCS). But, the time to peak was computed using the average of the concentration time obtained from Johnstone-Cross and Dooge models. The hydrographs design was done by the time ratio method recommended by the SCS. - Results: The estimated discharge peak computed by Snyder’s model varies with a maximum of 93.4 to 2092.9 m3/s, an average of 61.1 to 1368.4 m3/s and a minimum of 28.7 to 644.0 m3/s in Al Shuwaiki and Khtal watersheds, respectively. The estimated discharge peak computed by SCS-DUH method was ranged from 21.5 to 482.3 m3/s for the rainstorm of 40mm in Al Suwayki and Khtal, respectively, from 28.5 to 602.9 m3/s for the rainstorm of 50mm and from 34.1 to 723.5 m3/s for the rainstorm of 60mm, in Um Nqy and Khtal, respectively. - Conclusion: The hydrology study of ungauged basins in Royal Nature Reserve (ITBA) shows the great potential of the integrated emplyement of GIS technics and the hydrology models to estimate the discharge peak and design their hydrographs.

Flood Water Level Simulation Bringin River, Semarang City By Using The HEC-RAS 6.3.1 Programming

The Bringin River is a river in West Semarang, Semarang City, with the Tugu Region drainage subsystem. The Bringin watershed covers parts of the area in Tugu District, Ngaliyan District, and Mijen District. The overflow of water caused by high rainfall resulted in river flooding. The cross-section of the Bringin River cannot accommodate the magnitude of the flood discharge. The purpose of this study was to determine the cross-section of the Bringin River which was experiencing an overflow by carrying out a Hydrological Analysis and using the HEC-RAS 6.3.1 Program as a 1-dimensional cross-sectional design. Calculation of the planned flood discharge with periods of 2, 5, 10, 25, and 50 years using the Nakayasu Synthetic Unit Hydrograph method with a peak discharge Q2years : 52.45 m3/second, Q5years : 62.43 m3/second, Q10years: 68.44 m3/second, Q25years : 75.09 m3/second, and Q50years : 79.95 m3/second. The results of the calculation of the design discharge will be used in the HEC-RAS 6.3.1 programming so that from these results it can be seen that several cross-sections of the river have flood overflows that exceed the capacity of the Bringin River under review.

ANALYSIS OF FLOOD HYDROGRAPH IN THE LANDAK SUB WATERSHED

This research is motivated by the natural flooding disaster in the Landak sub-watershed area, which can be caused by river overflow due to high rain intensity. Flood discharge can be calculated using the Synthetic Unit Hydrograph method if the available data is limited, such as only obtaining rainfall data and watershed characteristics.Several Synthetic Unit Hydrograph (SUH) methodologies, including SUH Snyder, Nakayasu, Soil Conservation Services (SCS), Gama I, ITB, and Limantara, were utilized in this study. The analyzed data included precipitation data and measured discharge data. Rainfall data are analyzed using the homogeneity test, statistical descriptors, and chi-squared to determine the planned flood discharge. Then, continue with the study of rainfall frequency and analysis of rainfall intensity so that the maximal discharge can be analyzed using three SUH methods: HSS Snyder, Nakayasu, and SCS. The analysis of measured release is conducted by statistically analyzing estimated discharge data.The analysis results are then compared to obtain the percentage error between the discharge plan and the minimum measured discharge. The results showed that the HSS Snyder method was selected for analyzing flood discharge in the Landak sub-watershed basin because it has the minimum percentage error from comparing planned release and measured discharge values. Therefore, for the calculation of flood discharge analysis of the Landak sub-watershed basin, the HSS Snyder method is used with the acquisition of flood discharge plans for the return period of 2, 5, 10, 20, 50, and 100 years of 648,880 m3/sec, 896,335 m3/sec, 1025,954 m3/sec, 1132,006 m3/sec, 1252,788 m3/sec, 1335,273 m3/sec.

A Case Study on GIS Based Method to Develop Geographically Distributed Synthetic Unit Hydrograph using Geo-Spatial Tools in Ungauged Sub-watershed of Ambika River Basin, Gujarat

Abstract In this work, using Snyder, SCS, and the geographically distributed approaches, synthetic unit hydrographs are developed for the recurring flood-impacted ungauged sub-watershed in the Ambika river basin of Gujarat. Due to the scarcity of observed rainfall-runoff data, enforcement of effective flood control measures have not been implemented in this area. Hence the districts in the Ambika river basin regularly experience unexpected floods during the monsoon season, resulting in loss of life and property. The unit hydrograph of a watershed is essential for developing a flood hydrograph, which is useful for flood forecasting. The majority of Indian watersheds are not gauged, and there is not enough rainfall-runoff data to develop a unit hydrograph. However, there are several approaches available that may be used to develop synthetic unit hydrographs using different regionally based empirical equations, and some of them are mentioned above. Using geospatial tools is one of the GIS-based methods for obtaining synthetic unit hydrographs that solely take into account the digital elevation model (DEM) which eliminates the use of regional empirical constants. The geographically distributed synthetic unit hydrograph (GDSUH) approach is employed here on the idea of distributed time-area unit hydrograph and spatial distribution of overland and channel flow velocity. The cumulative travel time map has been divided into isochrones to develop a time-area curve and the resulting unit hydrograph. In this technique, a pure translation flow process is assumed. This approach is most appropriate for watersheds of smaller size. Hence, in this present study, a smaller, unmeasured sub-watershed with an area of 46 km2 is chosen, and the synthetic unit hydrographs are derived using each of the three approaches. The findings from this study were analyzed to determine the most appropriate method for this region. It was observed that the GDSUH is more suitable in comparison to the other two conventional synthetic unit hydrograph approaches. In smaller and un-gauged watersheds, this method gives a conceptual model for forecasting stream flow hydrographs that will capture the geographically distributed nature of the rainfall-runoff process. Additionally, it has the advantages of being simple, quick, inexpensive, and time-saving, especially for smaller regions that lack rainfall-runoff data.

Analisis Debit Banjir Rancangan Dan Kapasitas Tampang Sungai Di Sekitar Kawasan Sempadan Sungai Sokong Kabupaten Lombok Utara

In line with the North Lombok Regency (KLU) government program to prioritize handling and structuring residential areas and disaster-prone areas in the Pemenang-Tanjung sub-district in 2022, it is necessary to carry out several technical studies to support the program. One of the technical studies that can be carried out is an analysis of the design flood and river capacity around the Sokong River section in Tanjung Village, which is a location that is classified as densely populated, with slums and residential areas close to the river border. This study aimed to determine the magnitude of the design flood discharge and the cross-sectional capacity of the Sokong river section. The method used in this study is a hydrological analysis using the Nakayasu Synthetic Unit Hydrograph method to determine the amount of design flood discharge for the 25-year return period (Q25th) and analysis of river cross-sectional capacity using Hec-RAS 4.1.0 software. The results of the analysis show that the Q25th that occurs along the Sokong River section is 131.32 m3/s and the simulation results use Hec-RAS 4.1.0 software. shows that the capacity of the Sokong River segment cannot accommodate the Q25th. Therefore, it is necessary to plan the arrangement of residential buildings around the border area of ​​the Sokong River by raising the elevation of the building to be free from flood inundation.

Comparison of flood hydrograph prediction between synthetic unit hydrograph methods and rain-on-grid model for Katulampa watershed, Indonesia

Comparison of flood hydrograph prediction between synthetic unit hydrograph methods and rain-on-grid model for Katulampa watershed, Indonesia

Evaluation of Flood Control Performance in the Talangsari Watershed, Samarinda, East Kalimantan

The flood issues in the Talangsari River in Samarinda City were not only caused by high rainfall but also by the significant sediment accumulation and waste along the river, the encroachment of residential areas onto the river section, and the lack of public awareness regarding environmental cleanliness. As a result, flooding occurs throughout the Talangsari River, from upstream to downstream, indicating significant damage to the river. Considering these issues, proactive measures are necessary to address the flood problems. One such measure is the normalization of the Talangsari River to ensure smooth land transportation from and to Apt Pranoto Airport in the Sei Siring area, Bontang City, Sangatta, and Kutai Kartanegara. The flood discharge plan was estimated using Nakayasu and SCS synthetic unit hydrograph method. The analysis revealed a peak discharge of 6.39 m3/s for the existing conditions (2-year return period) and 13.38 m3/s for the normalization conditions (25-year return period). Subsequently, the simulations were performed using the HEC-RAS program by two scenarios: the existing river condition and the normalization scenarios. Following the simulation with the 2-year return period discharge for the existing conditions, the Talangsari River experienced upstream to downstream flooding, underscoring the need for flood mitigation measures. The river normalization simulation using the 25-year return period discharge considered dimensions such as a channel width of 7m and a depth of 3.5m. As a result of the normalization simulation, the Talangsari River successfully accommodated a flow of 13.38 m3/s without experiencing flooding, confirming that the decision to pursue normalization was the best choice.

THE SEROK RIVER CATCHMENT FLOOD HYDROGRAPH

Global climate change is expected to cause an increase in the intensity and duration of extreme rainfall events that occur today. The leading cause of flooding in various world regions, including flat coastal areas such as the Serok River catchment in Kota Pontianak, influenced by tides, is excessive rainfall. This article presents the results of an analysis of the impact of extreme precipitation on the peak discharge of flood hydrographs in the Serok River catchment, Kota Pontianak.Maximum daily rainfall data for 2009-2020 recorded at PTK-11 Pontianak Station were selected using the Annual Maximum Series Method. Frequency analysis was conducted using the best distribution method selected from Normal, Log Normal, Log Pearson Type III, and Gumbel Type I to obtain the design rainfall. The design rainfall was transformed into flood hydrographs at the next stage using the Snyder Synthetic Unit Hydrograph based on several return periods.The results of the analysis show that there are changes in flood discharge in the Serok River catchment area for each return period. The location of land use and the value of rain intensity significantly affect the calculation of plan discharge; the more significant the land area and the higher the rain intensity, the greater the resulting release. The most considerable flood discharge (Qmax) in the 2, 5, and 10 years return occurs at STA 1 + 100, w.290 m3/s, 0.347 m3/s, and 0.377 m3/s, respectively. Thus, this causes periodic flooding/inundation conditions, especially in areas that have low elevations.

PENINGKATAN JARINGAN IRIGASI DAERAH IRIGASI KRIPIK KOTA SEMARANG

Water is a very basic need for All living things on this earth without exception. The Kripik River is currently not being utilized by community optimally. For this reason, it is necessary to increase Irrigation Area which aims to increase agricultural production. Currently, the Bendung Kripik area serves an irrigation area of 95,94 Ha with the height of the exsisting weir lighthouse is 1 m.The improvement of the irrigation network is carried out based on secondary data with other supporting data. The analysis carried out includes: hydrological analysis which includes : watershed, maximum rainfall, flood discharge, average rainfall, average climatology, Eto – Penman, F.J Mock mainstay discharge, planting patterns then carried out channel design, weir design and calculation of weir stability.In this study, it was proposed to increase the rice field area by 130.17 Ha From the results of hydrological analysis, the flood discharge value of the Nakayasu Synthetic Unit Hydrograph (HSS) method was obtained when repeating 100 th by 40.10 m3 / s. The water requirement for irrigation of D.I Kripik after the addition of the area is 0.086 m3 / s. As for the bed, a weir width of 30 m with a weir height of 1.05 m is required, a weir lighthouse width of 28 m, a rinse width of 1 m and a pillar width of 1 m (2 Pillars of 1 m each). The radius of the spherical threshold type weir is 0.5 m, the olak pond type is USBR Type IV with a length of 3.50m. Keywords: Irrigation, Weir, Flood Discharge

Analysis of Peak Flood Discharge in Small-Scale River Flow Area

Purpose: Flood discharge is a critical component in reducing the impact of flooding in a given location. An analytical technique based on a watershed's morphometric properties is a method for those without a gauge, particularly in small-scale watersheds.
 Design/methodology/approach: The synthetic unit hydrograph (HSS) approach is used in this study to analyze flood output. This study was conducted in the Akelaka watershed, a sub-watershed of Tayawi. This analysis relies on spatial and attributes data. A spatial study of watershed morphometric properties was obtained by integrating digital elevation model (DEM) data into geographic information system-based applications (GIS). Meanwhile, using rainfall data from 2019 to 2021, a statistical approach is used to calculate the design rainfall intensity, which is then used as an input variable in the HSS analysis.
 Findings: The findings of hydrographic analysis using Nakayasu HSS demonstrate that the peak flood time (Tp) is 2.8 hours with a maximum flood discharge (Qp) of 56.636 m3/s, 76, 987 m3/s, 88,091 m3/s, and 101,279 m3/s for return periods of two years, five years, ten years, and 25 years.
 Paper type: Research paper

Analysis of Debris Flow Hazard in Volcanic Soil by the Flood Flows Modelling (DFLOWZ) and Nakayasu Synthetic Unit Hydrograph

Analysis of Debris Flow Hazard in Volcanic Soil by the Flood Flows Modelling (DFLOWZ) and Nakayasu Synthetic Unit Hydrograph

Intercomparison of Rainfall Estimates of Three Distributions for Computation of PFD using Rational Formula and SUH Approach

Peak flood discharge (PFD) for a given return period is considered as one of the most important parameters for planning and design of hydraulic structures, river protection works, and development of integrated water resources management projects. This can be achieved by adopting various methods such as flood frequency analysis, rational formula, envelope curves and Synthetic Unit Hydrograph (SUH) approach. Out of which, rational formula is applied for estimation of PFD for ungauged catchments with catchment area less than 25 km2 while SUH approach is adopted for ungauged catchments with catchment area more than 25 km2. This paper aims to investigate the study on intercomparison of probability distributions for estimation of extreme (i.e., 1-day maximum) rainfall for computation of PFD by adopting rational formula and SUH approach for the Vadhavan Port Project (VPP). The annual 1-day maximum rainfall series is extracted from the daily rainfall data observed at Dahanu site during the period 1969 to 2019 and also used for estimation of rainfall. The probability distributions viz., Extreme Value Type-1, 2-parameter Log Normal and Log Pearson Type-3 (LP3) adopted in extreme value analysis of rainfall is evaluated through diagnostic test using root mean square error and accordingly LP3 is adjudged as the best fit for estimation of rainfall. The 1-day maximum rainfall obtained from LP3 is considered to compute the rainfall intensity by applying one-third rule of IMD (India Meteorological Department) and also used for computation of PFD through rational formula. In SUH approach, the areal rainfall, physiographic and SUH parameters of the ungauged catchments are considered for computation of PFD. The study suggests the 25-year, 50-year and 100-year return period PFDs at six locations within the study area using rational formula and SUH approach could be considered for design purposes while designing any civil and hydraulic structures in the VPP.

POLA DISTRIBUSI HUJAN DAN PENGARUHNYA TERHADAP PENYIMPANGAN HIDROGRAF BANJIR DAS JANGKOK

Determining the rain pattern distribution is believed to affect the design flood. Providing hourly rainfall observations can be obtained, and the distribution patterns can be determined. However, in areas that do not have one, flood discharge calculations are carried out by distributing daily rainfall using empirical methods. This study distributes daily rainfall into hourly rainfall in the Jangkok watershed using ABM and Mononobe methods and calculates the flood hydrograph using the Nakayasu model. The synthetic unit hydrograph obtained from the actual rain distribution is then compared with the unit hydrograph generated from the empirical distribution, then the deviation is measured. The results showed that the Mononobe and ABM rain distribution gave the same hydrograph shape as the observation one, only for 2 hours of rain duration. As long as the rain lasts 3-6 hours, the peak flood discharge (Qp) tends to be lower, 7-20% for Mononobe and 2-7% for ABM. Then the Qp becomes overestimated (5-12%) for a rain duration of >6 hours. Mononobe gives the same flood peak time (Tp) as observation rain for 1-5 hours rain duration and becomes 1 hour earlier for >6 hours. In contrast, ABM produces peak times 1 hour longer than hydrographs with observation rain. Generally, the two methods provide a more significant hydrograph deviation for a longer duration of rain.

Effect of Debris Flow Event on the Affected Areas in Putih River, Indonesia

Debris flow is a natural phenomenon that can cause some damage and fatalities. Debris flow from Mount Merapi frequently happens through the Putih River, so it is necessary to do research. Anticipating the occurrence of debris flows can be done with predictions to reduce the number of casualties and material losses. This research used a simulation method based on Ashida, Takashi, and Mizuyama equation that applied the Nakayasu synthetic unit hydrograph through modeling on SIMLAR V2.1 application by modifying the hyetograph pattern and the rain intensity value. The test result contained flood area, velocity, volume, flow height, and the value of degradation and aggradation that happened in each simulated pattern. The velocity value in simulation with rain intensity of 56.8 mm and one peak hyetograph is 1.36 m/s, and in simulation with rain intensity of 56.8 mm and two peak hyetograph is 1.42 m/s. It means the parameter increases by 4.4%. Based on the results, it can be concluded that the hyetograph pattern is very influential on the impact of lava floods. The increase in the hydrograph value is also directly proportional to the increase in flow velocity. The value of rain intensity and rain pattern also affects the number of areas affected by the lava flood. The increasing value of the intensity and pattern of rain is also directly proportional to the increase in the area affected by flooding.

Analysis of Flood Hydrograph Metro Sub Watershed with Synthetic Unit Hydrograph Snyder and SCS (Soil Conservation Service) Methods

Metro Sub-watershed is in Malang City. Based on data from BPBD Malang City, flood disasters have continued to increase from 2016 - 2022. The purpose of this research is to analyse the synthetic unit hydrograph (SUH) which will be used as the basis for planning water resources management. The rainfall data used in 2012-2021 with an average maximum rainfall height of 108 mm... Metro sub-watershed with an area of 31.371 km2 and a river length of 42 km and land use data with 59% of the residential. All data will be analysed for SUH in return periods Q2 = 2th, Q5 = 5th, Q10 = 10th, Q25 = 25th, Q50 = 50th, and Q100 = 100th. SUH analysis using HEC-HMS auxiliary program with Snyder and SCS (Soil Conservation Service) methods. The peak discharge results of the SUH in the Snyder method are Q2 = 47.8 m3/s, Q5 = 48.6 m3/s, Q10 = 50.7 m3/s, Q25 = 52.8 m3/s, Q50 = 54.1 m3/s, Q100 = 55.2 m3/s, and in the SCS method are Q2 = 37.5 m3/s, Q5 = 37.9 m3/s, Q10 = 39.8 m3/s, Q25 = 41.8 m3/s, Q50 = 43 m3/s, Q100 = 44 m3/s.

Artificial viscosity technique for direct runoff calculation

In this study, an Artificial Viscosity (AV) technique was developed for direct runoff calculation, instead of using the conventional Synthetic Unit Hydrograph (SUH) methods. We solved the Shallow Water Equations (SWE) with second-order accurate Godunov finite volume model and fourth-order Runge-Kutta explicit scheme. The AV technique was devised with a Laplacian and a biharmonic operator, and employed to solve the convective terms of the SWE. This technique was applied to rainfall-runoff laboratory cases with the measured rainfall and observed direct runoff values. For comparison purpose, several SUH methods commonly used such as SCS, Snyder, GAMA-1, ITB-1, ITB-2, and Nakayasu, were also used to compute the direct runoff values. The results showed that the AV technique could predict three parameters (i.e., peak discharge, time-to-peak, and shape of the direct runoff hydrograph) accurately. Meanwhile, significant discrepancies were shown by the SUH methods in estimating such parameters, thus indicating that the SWE modeling with an AV technique is significantly more accurate than the SUH methods in predicting the direct runoff hydrograph. This study shows an interesting example of how modern numerical computations can improve the runoff prediction and may be included as a standard technique for runoff computation in the future.

PEMANFAATAN DEM-SRTM DAN DEM-NAS SEBAGAI DASAR SIMULASI HUJAN-DEBIT DI DAS KALIWADAS

The accuracy of flow prediction in a watershed for water resource development is highly dependent on various factors such as the transformation model used, the availability and accuracy of hydrological data and watershed characteristics such as topography, drainage networks, land cover and soil texture. Watershed characteristics are considered as the most dominant determinants in various hydrological analyzes, especially with regard to the data used to compile the watershed model, in this case the Digital Elevatian Model (DEM) data. This study aims to develop a watershed model based on National DEM (DEMNAS) data to estimate daily discharge using the HEC-HMS model and design discharge using the Nakayasu Synthetic Unit Hydrograph (SUH) method. The research was conducted in the Kaliwadas watershed, which is located in Kandang Serang District, Pekalongan Regency, Central Java Province. Kaliwadas River is one of the sub-watersheds with a drainage area of approximately 165.78 km2 which has a good enough potential to supply hydro-based electricity. The performance of the DAS model formed with DEMNAS data is compared with the performance of the watershed model formed with the DEM Shuttle Radar Topography Mission (SRTM) data, where these two DEM data have a resolution of 8 meters and 90 meters, respectively. Performance testing is based on the Root Mean Square Error (RMSE) number of the two predictive flow from the HEC-HMS Model to the observed discharge. The results showed that the estimated discharge of the HEC-HMS Model using the DEMNAS Watershed Model showed slightly better performance than using the SRTM DAS Model, with a RMSE difference of 0.27.

MODELLING OF GROUP DECISION SUPPORT SYSTEMS FOR FLOOD ALERT WITH NAKAYASU SYNTHETIC UNIT HYDROGRAPH IN GADANG WATERSHED

Natural disasters still occur regularly and continuously in Indonesia and in the world, such as floods, earthquakes, tsunamis, and landslides. The impact of natural disasters such as floods can be reduced through flood hazard mitigation activities. Flood hazard mitigation can be done by knowing early rainfall in history and today and river water levels river flow to a region upstream of the history and current. This study aims to make a group decision support system modeling for early detection of candidate flooding caused by the condition of the watershed, in this case is Gadang Watershed. The system is designed as a tool to detect candidate field hydrometric flood early. Modelling Group Decision Support System (GDSS) was developed based on the analysis of flood design represented in a Nakayasu Synthetic Unit Hydrograph. A group of Decision Support Systems is a type of computer-based interactive system that is designed for a group of decision-making. The users of the decision support system are a group that consists of some people. Hydrograph is in accordance with the conditions of the watershed, especially in tropical Indonesia. The results of the design flood serve as a reference to the operational unit, the data management unit, and the planning unit of the institution of the watershed maintenance such as Perum Jasa Tirta I. A suitability test is intended to determine whether the distribution of the selected distributions may be used or not, in a series of data available. Analysis of the suitability test using the Chi Square distribution. From the results of the distribution test that the distribution can be accepted and the system can support for analysing flood hazards as preliminary information early detection of flooding. Keywords: Group Decision Support System, Flood Hazard, Nakayasu Synthetic Unit Hydrograph, Water Level DOI： https://doi.org/10.35741/issn.0258-2724.58.1.13

Synthetic unit hydrograph for ungauged basin using Synder, Taylor- Schwarz model, SCS method by GIS techniques

In hydrology, estimation of the design hydrograph (DH) is a crucial challenge because of lack of rainfall- runoff data. The lack of rainfall-runoff data makes developing credible DHs particularly difficult in small and ungauged basins. A synthetic unit hydrograph(SUH) is a way to represent the flow of water in a stream or river as a single point. It is used to calculate runoff and other hydraulic functions by using watershed characteristics for similar watershed. On the basis of watershed and watershed features or characteristics, equations for estimate of synthetic unit-hydrograph parameters based on rainfall and runoff data for small watersheds were developed. Estimating runoff is a crucial part of river basin planning, development, and management. This paper discusses the application of synthetic unit hydrographs in the Dhamani drainage basin in Maharashtra, India. Traditional method of SUH are used to calculate the peak discharge and time to peak. The calculated discharge by using Synder method, Taylor- Schwarz model, SCS method were compared with each other. In a drainage basin, the relative mean error (RME) and the root of mean square error (RMSE) were compared for selection of better option or to find minimum error method.