Direct Runoff Hydrograph Research Articles

Estimation of Synthetic Unit Hydrographs’ Parameter Values: The Case of Wadi Al-Badan Sub-Catchment, West Bank, Palestine

Developing unit hydrographs is critical in gauged catchments. Due to the lack of local data, engineers should strive to estimate discharges based on empirical (synthetic) methods in ungauged catchments. Synthetic unit hydrograph methods, such as the Snyder and Soil Conservation Service are popular and play an essential role in hydrology. These methods are simple, requiring only catchment characteristics. Therefore, these methods are valuable tools for simulating runoff in ungauged catchments. This research paper focuses on the Al-Badan sub-catchment, which is located in the northeastern part of the West Bank in Palestine with an area of 83 km2. The study used a de-convolution matrix approach to develop an average one-hour unit hydrograph by selecting four significant rainfall events in the period (2005-2007), and the direct runoff hydrographs which are measured by Al-Badan flume located in the outlet of the sub-catchment. By computing the characteristics of the average one-hour UH with a peak discharge of 4.52 m3/sec and time to peak of 5 hours, Snyder and SCS UHs were developed to suit Al-Badan sub-catchment physical characteristics. The parameters were determined for the Snyder; peaking coefficient depends on the storage capacity of the catchment Cp = 0.88 and the non-dimensional regional coefficient representing catchment storage effects and slope Ct = 1.26 and for the SCS; Cp = 1.90 and the coefficient depending on the total runoff volume occur before peak discharge C = 2.92. These synthetic one-hour UHs were examined for two selected rainfall events that occurred in the period (2017–2019) by comparing observed and simulated direct runoff hydrographs. The performance was tested statistically. Results showed that the synthetic UHs are suitable for application and that the SCS method is more applicable.

Alternative streamflow-based approach to estimate catchment response time in medium to large catchments: case study in Primary Drainage Region X, South Africa

Event-based estimates of the design flood in ungauged catchments are normally based on a single catchment response time parameter expressed as either the time of concentration (TC), lag time (TL) and/or time to peak (TP). In small, gauged catchments, a simplified convolution process between a single observed hyetograph and hydrograph is generally used to estimate these time parameters. In medium to large heterogeneous, gauged catchments, such a simplification is neither practical nor applicable, given that the variable antecedent soil moisture status resulting from previous rainfall events and spatially non-uniform rainfall hyetographs can result in multi-peaked hydrographs. In ungauged catchments, time parameters are estimated using either empirical or hydraulic methods. In South Africa (SA), unfortunately, the majority of the empirical methods recommended for general use were developed and verified in catchments ≤ 0.45 km² without using any local data. This paper presents the further development and verification of the streamflow-based approach developed by Gericke (2016) to estimate observed TP values and to derive a regional empirical TP equation in Primary Drainage Region X, SA. A semi-automated hydrograph analysis tool was developed to extract and analyse complete hydrographs for time parameter estimation using primary streamflow data from 51 flow-gauging sites. The observed TP values were estimated using three methods: (i) duration of total net rise of a multi-peaked hydrograph, (ii) triangular-shaped direct runoff hydrograph approximations, and (iii) linear catchment response functions. The combined use of these methods incorporated the high variability of event-based time parameters, and Method (iii), in conjunction with an ensemble-event approach sampled from the time parameter distributions, should replace the event-based approaches to enable the improved calibration of empirical time parameter equations. The conceptual approach used to derive the regional empirical TP equation should also be adopted when regional equations need to be derived at a national scale in SA.

Estimation of Runoff in Data Scare Watershed of Middle Gujarat, India Using HEC-HMS Model

The accurate estimation of the hydrologic response in water resources planning and development is crucial. In this study, the rainfall-runoff relationship and hydrologic response of the Devgadh Baria watershed in the Panam river catchment were investigated. Due to limited availability and accuracy of runoff data, Clark UH, and SCS UH models were explored for runoff estimation. Remote sensing and GIS techniques were integrated to assess the ungauged watershed in the Middle Gujarat region.
 Rainfall and discharge data, Sentinel-2 data, 12.5m ALOS PALSAR DEM, base maps, and soil maps were collected from various sources. The study area's five different events were randomly selected, and a Thiessen map was prepared to calculate weighted rainfall. Geomorphological parameters and Horton's ratios were estimated using remote sensing and GIS software ILWIS.
 The composite curve number (CN) for the watershed was found to be 77.69. Excess-rainfall hyetographs were separated using the SCS-loss method, and the time to peak estimated by the models matched well with observed data, except for a one-day delay in the HEC-HMS based Clark UH model.
 Four performance indices, namely NSE, PBIAS, RMSE, and d, were used to compare model performance. The SCS UH model demonstrated the highest NSE value (-0.28) for event-1, while the HEC-HMS based SCS UH model showed the lowest NSE value (-0.28) for event-1. The SCS model outperformed the other models based on performance indicators NSE, RMSE, and d. Overall, the SCS UH approach provided the best estimation of peak discharge and time to peak discharge. The direct surface runoff hydrographs estimated using.

Developing an Empirical Relations between Nash Model Parameters and Watersheds Topographical Characteristics for Predicting Direct Runoff Hydrograph

The limited availability of the recorded rainfall-runoff data for many watersheds restricts the development and management of different activities of water resources. To overcome this limitation, the Natural Resources Conservation Service (NRCS) for estimating storm excess rainfall and momentum and optimization methods were combined in a mathematical model to estimate the optimal parameters of Nash Instantaneous unit hydrograph (IUH) and resulting direct runoff hydrograph (DRH), using a developed computer program in MATLAB. The available recorded data of 14 storms (out of 18) of four watersheds in northern Iraq have been applied in the calibration stage. An empirical relationship was developed between the average of each IUH optimal parameter (obtained by optimization as an optimal method according to the applied tests) and the effective watershed topographical characteristics. The developed empirical relations were used in the verification stage to estimate the IUH parameters and DRH for the verification storms and compare with that resulted from Haan’s empirical relations and optimization method. The statistical tests showed that the developed empirical relations efficiency was better than that of Haan’s method and close to that of the recorded storm by optimization method, where the average value of the Nash-Sutcliffe Efficiency for the four watersheds resulted from applying the optimization method, Haan’s method and the developed empirical relations were 0.925, 0.587, 0.883 respectively. The results indicated the developed model’s ability to estimate the IUH and direct runoff hydrograph for ungauged watersheds in northern Iraq.

Evaluation of the Storms Direct Runoff Prediction Methods used for Goizha-Dabashan Watershed

The Momentum and Aron & White evaluating methods have been adopted to estimate the Nash Instantaneous Hydrograph parameters (IUH), while the two methods of excess rainfall (Ф-index and Natural Resources Conservation Service (NRCS) were applied in a model using a developed computer program in MATLAB to predict the direct runoff hydrograph for Goizha-Dabashan watershed located in the northeast of Iraq. In the verification stage, both Nash IUH optimal parameters of the storms and the average optimal values of the same parameters estimated in the calibration stage were applied and compared. The statistical tests showed a preference for the NRCS method with the momentum method in estimating direct runoff hydrograph (the average Nash-Sutcliffe Efficiency (NSE) was equal to 0.815 and 0.77 using optimal parameters verification storms and the average calibrated IUH parameters values, respectively). Also, satisfactory results (NSE was equal to 0.77 and 0.76 using storm parameters and the average calibrated IUH parameters values, respectively) were obtained by applying Aron & White with the NRCS methods, which indicated the ability of both methods for estimating direct runoff hydrograph.

Direct runoff hydrograph model’s collation for a Pakistan’s region

Rainfall-Runoff modeling is among the classical applications of hydrology. This paper examines the results of 3 hydrologic approaches, particularly Clark Model, Nash Model, and Geomorphic Instantaneous Unit Hydrograph Model. Assumptions are forwarded for the long run use of the Rawalpindi Division, Pakistan’s Small Dam Organization. The catchment of Shahpur Dam was an area under consideration for the study. The Digital elevation model (DEM) was implicated to measure the Nash and Clark model’s geomorphic parameters. Using ArcGIS, catchment satellite imagery was processed to estimate geomorphological parameters. The models have been applied to multiple storm cases. Geographic Instantaneous Unit Hydrograph (GIUH) model gave direct surface runoff hydrograph, whereas, on measured precipitation excess rainfall hyetograph was obtained. Four types of statistical parameters, namely efficiency of the model (EFF), percentage defect in time to attain peak (PETP), percent defect in attained peak Q (PEP), percentage defect in runoff rate (PEV) are used to check model’s efficiency. The comparison is done between the findings of Clark and Nash GIUH models and the original Clark and Nash models. It was observed that GIUH models are equally good even when optimization is done for Clark and Nash model’s parameters. Since the results obtained from these models are more credible, so, these models can be used in ungauged catchments to estimate the hydrographs.

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.

Unit Hydrograph Peak Rate Factor Estimation for Texas Watersheds

In many cases, estimation of the peak discharge is the primary goal of hydrologic modeling. We employed a dataset of 1,648 rainfall-runoff events in 104 watersheds in Texas to explore the peak rate factor (PRF) of 2.08 recommended by the Natural Resources Conservation Service (NRCS) for determining peak discharges with the unit hydrograph method, as well as the PRF’s dependency on watershed and storm characteristics. For each event, a unit hydrograph—assumed to follow a two-parameter gamma distribution—was determined by deconvolving the direct runoff hydrograph with the excess rainfall hyetograph. Results showed PRFs reaching up to 9.75 in Houston watersheds with a median of 0.58 and PRFs up to 11.02 with a median of 1.42 for the rest of Texas. It was also found that the recommended PRF of 2.08 falls between the 75th and 90th percentile of the 1,043 events analyzed in all regions except Houston, and is above the 95th percentile in all 605 events analyzed in Houston. Finally, statistical analysis showed that the PRF is primarily dependent on the watershed’s geomorphology but not on its slope, as was suggested earlier. This dependency, however, although statistically significant, explains only marginally the PRF variability.

Examining the implications of spatial variability of saturated soil hydraulic conductivity on direct surface runoff hydrographs

Saturated soil hydraulic conductivity (Ksat) and soil moisture content (Θ) are key soil hydraulic properties for the understanding of hydrological processes at the watershed scale. Previous approaches in the use of Ksat to describe hydrological processes have mainly applied standardized or derived Ksat values, although the high spatial variability of this soil parameter has been frequently reported. Hence, this study aims to assess the influence of Ksat and Θ spatial variabilities on direct surface runoff (DSR) hydrographs resulting from isolated rainfall events using the Limburg Soil Erosion Model (LISEM) in conjunction with measured Ksat data. Data sets were obtained from a grid of 179 points established in the Ellert creek watershed (ECW), with a drainage area of 0.7 km2. The hydrological monitoring in the ECW consists of an automatic rain gauge and a water level gauging station, which provides rainfall-runoff data every 5 min. Ordinary Kriging was used to map Ksat in the area. Five 5-minute interval rainfall-runoff events were selected from 2017 to 2019 for the hydrological modeling in LISEM, whose water level did not go beyond the reliable applicability of the stage-discharge rating curve generated for the ECW’s outlet. The rainfall depth of these events varied from 24.0 to 66.4 mm, and peak discharge varied from 0.49 to 4.92 m3/s. The effects of Ksat spatial variability and its uncertainties on DSR hydrographs were assessed using the Sequential Gaussian Simulation. As the depth and average intensity of rainfall decreased, there was a greater propagation of the uncertainties of Ksat to peak discharges. The simulated DSR hydrographs and their peak discharges were adequately represented by LISEM. However, LISEM was unable to simulate the hydrological response of the watershed to a two peaks event separated by lower rainfall intensity.

Surface runoff hydrograph derivation using a dynamic wave based instantaneous unit hydrograph

AbstractRainfall‐runoff models based on unit hydrographs and geomorphological instantaneous unit hydrographs have been widely used because of their simplicity and applicability. However, they are conceptual approaches, and not a reflection of physical phenomena. As an alternative, dynamic wave models have been introduced, but they are not appropriate for practical purposes because of their numerical instability and high computational cost. In this study, we present a hybrid method composed of a dynamic wave approach and instantaneous unit hydrograph (IUH) to predict surface runoff physically, stably, and instantly. We generate the S‐hydrographs of a watershed using a dynamic wave model, and the IUHs of the watershed are derived by numerically differentiating the S‐hydrographs with respect to time. Finally, a direct runoff hydrograph is produced through the convolution of the temporally varying rainfall excess rate and the IUHs of the watershed. A dynamic wave model is used, and therefore, only a single parameter related to friction needs to be calibrated for the S‐hydrograph generation, and the nonlinearity of the rainfall‐runoff process can be partially considered. From a computational perspective, the proposed method after the IUH derivation ends instantly and stably. Tests for ideal and real watersheds show good agreement between measurements and dynamic wave modelling results.

Comparison of snyder synthetic unit hydrograph with measured unit hydrograph on Bionga Kayubulan

Generally, the synthetic unit hydrograph had to be developed just like a kind of Snyder that found accord empire scientific in the United States. Determination of their parameters has been presented by various criteria, but so far, the results are still relatively deviated for watershed-watersheds in Indonesia. The study was conducted to Bionga Kayubulan sub-watershed that has properties and characteristics that need to be conducted regarding irregularities by comparing models HSS Snyder with unit hydrograph observations on sub-watershed. Hydrograph water level readings AWLR derived from a flood hydrograph, using the are discharge. to separate the base flow with runoff straight-line method is used to produce direct runoff hydrograph. From the data obtained ARR hourly rainfall records were then analyzed, using the equation effective rainfall of index Φ. Direct runoff hydrograph and rainfall effectively revealed to be the observation unit hydrograph using collins method. Based on topographic maps obtained watershed physical factors were then used to analyze HSS Snyder. Further comparison of the HSS Snyder constant adjustments made using software Microsoft Excel-Solver. Observation unit hydrograph Bionga Kayubulan sub watershed has a peak time (Tp) of 4.5 hours with a peak discharge (Qp) of 2.81 m3/sec while Snyder HSS obtained from the analysis of Tp and Qp of 5.15 hours of 0.33 m3/sec. The test results showed that the predicted ratio Snyder HSS HSS calibration better than Snyder before calibration. CE adjusted value is 0.11 and as adjusted to 0.93. The value of EV adjusted is 65.20% before and after adjustment to 2.70%. EQP value addition, AETR values, and values after adjusting widened AETp 0 hours.

Evaluation of geomorphological approaches combined with digital elevation models for the Nash's instantaneous unit hydrograph

Methodologies for estimation of direct surface runoff (DSR) hydrographs have been proposed, especially for the Unit Hydrograph (UH) and Instantaneous Unit Hydrograph (IUH). The widely used IUH developed by Nash (NIUH) has two main parameters: number of reservoirs (n) and storage coefficient (k), which by definition are determined based on observed rainfall-runoff events. In order to overcome the need for hydrological data for application of NIUH, geomorphological approaches (GAs) have been developed to provide the aforementioned parameters for ungauged watersheds, thus allowing for the estimation of DSR hydrographs using only relief information. The aim of this study was to evaluate the performance of 4 GAs (GA1 - Nash, 1960; GA2 - Wu, 1963; GA3 - Rosso, 1984; GA4 - Bhaskar et al., 1997). Moreover, this study sought to investigate the influence of different digital elevation models (DEMs) (TOPO, ASTER, SRTM-30 and SRTM-90) on the determination of geomorphological attributes necessary for the application of the above-mentioned GAs. Twenty rainfall-runoff events observed in a small Brazilian watershed were used to evaluate the performance of NIUH combined with different GAs and DEMs for estimation of DSR hydrographs. In view of the results found in this study, the main conclusions are: i) the GAs exert more influence on the parameters n and k than the DEMs; ii) GA1 and GA2 outperformed GA3 and GA4; and iii) GA2 coupled with the ASTER DEM results in the best estimates of DSR hydrographs.

Coupled empirical–mechanical modeling of debris flows occurred in small ungauged basins

On 28 July 2013, an intense torrential rainfall occurred at the boundary of Yamaguchi and Shimane Prefectures in western Japan, and triggered a debris flow on an ungauged hillslope to bury the entrance of Shirai tunnel and to shutdown railway service in that region for 1 year. To assess this disaster, this study aims at numerically modeling this debris flow event through a methodology incorporating empirical hydrologic analysis and mechanical debris flow model. For hydrologic analysis, the SCS-CN method implemented by HEC-HMS was used to obtain direct runoff hydrograph with high-resolution precipitation data reanalyzed using observations from radars and rain gauges. Then, the obtained runoff-discharge information was applied as an input for numerically simulating the debris flow movement from source to deposition areas. The simulation result is verified by the field evidence from field survey. The study demonstrates the applicability of the proposed empirical–mechanical approach for assessing debris flows in ungauged basins.

Sensitivity analysis of relationships between hydrograph components and landscapes metrics extracted from digital elevation models with different spatial resolutions

Evaluation of sensitivity of hydrograph components and landscape metrics extracted from various spatial resolutions reveals relationships between landscape metrics and outflow properties with the lowest error. In the present study, 14 Digital Elevation Models (DEMs) with different resolutions derived from a vector and raster-radar source were analyzed to evaluate sensitivity of relationships between simulated hydrograph components and landscape metrics using multiple regression methods in the Galazchai Watershed, West Azerbaijan Province, Iran. To this end, DEM, slope, flow length and direction and time of concentration were developed in the vector and raster scales of 1:25000 and Advanced Land Observing Satellite-1 (ALOS) with different resolutions using ArcGIS 10.5 and ArcHydro software. Accordingly, 588 Direct Runoff Hydrographs (DRHs) were produced and clustered using Clark's Instantaneous Unit Hydrograph (IUH) model. The results showed that the best regression fits for flood volume and peak discharge were determined with Number of Disjunct Core Areas (NDCA) and Patch Density (PD) landscape metrics. Furthermore, the best regression fitted for time to peak and base time were observed with Core Area (CA) and Normalized Landscape Shape Index (NLSI) landscape metrics. In addition, the sensitivity analysis shows that the most sensitive spatial resolutions in modeling relationship between flood volume and peak discharge were determined at 5, 10, 20, and 30 m. The results revealed that hydrograph components in association with landscape metrics had high sensitivity to spatial resolutions, while the relationships between hydrological components and landscape metrics without considering the optimal spatial resolutions resulted in unacceptable results.

Rainwater storage in urban environments using green roofs

This article discusses the use of green roofs as rainfall water storage in its soil matrix. The methodology is analytical based on mathematical models, where runoff produced in an urban area is compared with current conditions of ordinary roofs with ceramic or bituminous materials as the original scenario, against another where green roofs are used. The study area is located in the Palavecino municipality of Lara state in Venezuela, in the flood zone of Quebrada Tabure. In this research, a quantitative comparison of the direct runoff hydrographs of the proposed scenarios was used, obtaining as a main result the reduction of runoff between 60% and 80% according to the period of return. An interesting point of this research was the incorporation of the routing of hydrographs on the roofs, reducing even more the peak flow over 90%, and delaying the peak time of the generated hydrographs between 10 and 12 minutes while the total duration of the hydrographs increase more than three times.

A New Algorithm For The Grid Cell-Based Runoff Routing Model Based on Travel Time Concept

The grid cell-based routing model has recently been used to simulate direct runoff hydrographs at catchment scales. This study develops a flexible event-based runoff routing algorithm to simulate a direct runoff hydrograph (DRH). The experiment was based on the spatiotemporal inputs of a hydrological data set. The flexibility is based on the time step and grid cell size applied in the original STORE-DHM. Rainfall distribution was obtained using radar data adjusted by the measured point ground, while the runoff yield was determined using the NRCS-CN method. The parameter distribution was captured in the GIS environment as raster data formats. Furthermore, it was converted into ASCII data formats for scripting the routing algorithm using Matlab programming codes. The model algorithm was tested for storm events within two small study river systems in Yogyakarta, Indonesia. One event in each catchment was selected and calibrated to the observed hydrograph, treating the Curve Number (CN) and Manning coefficient (n) values as parameter calibrations. In the end, two events were selected for validation. The proposed routing model algorithm simulates DRHs of all selected events in the study areas with excellent performance. The Nash-Sutcliffe coefficient was greater than 0.75 for all DRH during validation, and the volume bias and peak discharge error were less than 25%.
 Keywords: Algorithm; Cell-based runoff routing; Travel time; GIS; Direct runoff hydrograph.
 
 Copyright (c) 2020 Geosfera Indonesia Journal and Department of Geography Education, University of Jember
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Influence of river cross-section data resolution on flood inundation modeling: Case study of Kashkan river basin in western Iran

In this study, a coupling of a hydrologic and hydraulic model was utilized to assess the impacts of river geometry data resolution on the flood inundation characteristics in a data-scarce environment. Hydrological modeling incorporates soil conservation service curve-number (SCS-CN) and the geomorphologic based instantaneous unit hydrograph model (GIUH) to compute the direct runoff hydrograph in Kashkan river basin located in western Iran. 1D HEC-Geo-RAS model was used and performed to simulate inundation extent of 100-yr floods (~1800 m3/s) along 40 km reach of Kashkan river with a ground survey of river cross-section (2000 cross-sections, each including 500 data-points). The effect of cross-section spacing (20 m to 5000 m) and dataset resolution along cross-section (5–500 points) on 100-yr (~1800 m3/s) flood inundation extent area (FIA), average flow depth (FD), and velocity (FV) in river centerline were scrutinized. Results indicate that coarser cross-section spacing (20–5000 m) showed an overestimating tendency to simulate FIA (~5.75%), FD (391.34%), and FV (31.2%). While increasing grid resolution (5–500 points) on cross-section tends to underestimate of FIA (17.84%),FD (84.13%), and FV (49.12%). The predominant effect of cross-section spacing on FIA, FD, and FV was found compared to the number of data-points on a cross-section. Results of this study could potentially be considered as a baseline for mapping of flood inundation extent in the environment that ground or remotely sensed high-resolution topographic data of river cross-section are scarce while making a trade-off between model accuracy, computational time, and cost of data compilation is crucial.

Estimation of Energy Efficiency for Hydropower Generator

Electrical energy is getting more important in our daily life. With the coming development of the Sarawak Corridor of Renewable Energy (SCORE), hydropower plant is getting more interesting to face the demand on the domestic usage. Electrical energy can be used to carry out our daily routine. Small hydropower been very adaptive solution for rural area. Hence, this paper shows the estimation of energy efficiency for hydropower generator for Belawai river located at Sarawak. Excess rainfall hyetograph and direct runoff hydrograph been use to evaluate efficiency of the power generation based on river flow. Result show river flow strength depend on the rainfall which is about 38.56% of efficiency and other environmental factors which will affect the efficiency of the converter

Changeability of simulated watershed hydrographs from different vector scales and cell sizes

The effects of various vector scales (125000–1:250000) and cell sizes (5–200 m) on the modeling performance of hydrographs was evaluated using the time-area histograms (TAHs) based on Clark's Instantaneous Unit Hydrograph (IUH) model for the Galazchai watershed, Iran with an area of 103 km2. Some 960 direct runoff hydrographs (DRHs) were produced and clustered based on Relative Errors (REs) for hydrograph components, Coefficient of Efficiency (CE) and Root Mean Squared Errors (RMSEs). Results showed that the vector scales of 1:25000 with cell sizes of 30 and 100 m, and also 1:25000 with cell sizes of 20 and 200 m were the critical vector scales and cell sizes from the viewpoint of CEs and RMSEs, respectively. In addition, the mean relative errors resulting from flood volume, peak discharge, time to peak, and base time were estimated to be – 3.06, + 8, − 4.51 and + 5.42% for the critical scales and cell sizes as a result of clustered simulated hydrographs. The mean values of CE and RMSE were also estimated as 73 and 2%, respectively.

A Comparison of Continuous and Event-Based Rainfall–Runoff (RR) Modelling Using EPA-SWMM

This study investigates the comparative performance of event-based and continuous simulation modelling of a stormwater management model (EPA-SWMM) in calculating total runoff hydrographs and direct runoff hydrographs. Myponga upstream and Scott Creek catchments in South Australia were selected as the case study catchments and model performance was assessed using a total of 36 streamflow events from the period of 2001 to 2004. Goodness-of-fit of the EPA-SWMM models developed using automatic calibration were assessed using eight goodness-of-fit measures including Nash–Sutcliff efficiency (NSE), NSE of daily high flows (ANSE), Kling–Gupta efficiency (KGE), etc. The results of this study suggest that event-based modelling of EPA-SWMM outperforms the continuous simulation approach in producing both total runoff hydrograph (TRH) and direct runoff hydrograph (DRH).