In this study SWMM software has been calibrated with real meteorological and hydrometric data at the North of Tehran basins and simulation parameters have been obtained. For this purpose, five rainfall events and runoff data related to these rainfalls, recorded at the outlet of Zargandeh catchment were used. This model is calibrated with three events and verified with two other events. Also, in this simulation the peaks of flood, outflow hydrographs, runoff volumes and peak flood times is obtained. The root mean square error are obtained for outlet hydrographs for the first to fifth events were 0. 05, 0. 22, 0. 4, 0. 37 and 0. 16, and the Nash-Sutcliffe coefficient are obtained 0. 91, 0. 94, 0. 93, 0. 9 and 0. 94, respectively. Also, the percentage of difference of the flood discharge peak modeling and observations for first to fifth events are calculated 7. 33%, 9. 69%, 5. 8%, 5. 6% and 9. 93% and for runoff volume, this percentage difference are calculated-8. 82%,-3. 08%, 8. 8%,-19. 43% and 5. 11%, respectively. Based on these results, the performance and application of this model to simulate runoff in this area is acceptable and can be used to manage and control urban runoff.

The change of land use and the reduction of permeable surfaces due to urban development have caused an increase in the peak discharge and volume of runoff due to rainfall, which causes flooding of roads and damage to urban areas. By accurately estimating the amount of runoff and properly designing the urban drainage network, as well as managing this runoff, the damages of urban floods can be reduced. SWMM rainfall-runoff model is one of the most efficient models in the design of drains and urban runoff management. Since the hydrological models must be evaluated before use, in this study the SWMM model was evaluated using 6 rainfall-runoff events for the city of Shahrood and the efficiency of the urban drainage network for floods with return periods of 2 to 15 years was investigated. For this purpose, six flood hydrographs of precipitation events was measured at the two main outlets of the city. he results showed that the SWMM model with the mean square root of the normalized error (NRMSE) of about 20% and R2= 0.90 in the validation stage has a suitable efficiency in simulating the flood hydrograph. Also, also the examination of the performance of urban drains showed for precipitation with a return period of 2, 5, 10 and 15 years, 9.1, 31.8, 36.4 and 41% of the canals are flooded, respectively.

In this research, a model is developed for the optimal design of storm water networks.The model uses the powerful genetic algorithm as the search engine. The "Transport" module of "SWMM 4.4h" is used as the hydraulic analyzer of the model. Two different approach are used to formulate the problem with varying degrees of success in reaching a "near optimal" solution. The proposed model is applied to some benchmark examples in the literature leading to achieve good solution compared to previous results.

Detention basins are one of the structural measures for floodwater control in urban environments. They are effective tools in flood mitigation, but some studies have shown that they may aggravate the condition if not properly sited. This study presents an innovative approach which directly incorporates hydrologic-hydraulic modeling results to the site selection procedure for flood control detention basins. Darakeh Catchment located in Tehran is selected as the case study. Hydrologic, physiographic, and economic parameters are considered as siting criteria. SWMM model is employed for simulating hydrologic-hydraulic processes and evaluating the current drainage network against low-frequent storms. Modeling results, including flooded junctions and the flow hydrographs, are used as input parameters to the spatial decision making framework. The framework employs Analytical Hierarchy Process (AHP) as the decision making structure and geographic information system (GIS) as the spatial analyst tool. The output is a raster map which shows each cell potential for the placement of the detention basin. The proposed approach aims to improve the siting procedure based on these measures and other BMPs in an urban environment.

Background and Aim: Increasing population and urbanization density and as a result, increasing impermeable surfaces, has led to an increase in the volume of urban runoff. Applying simulation models is a suitable way to know the runoff quality parameters. This study aimed at evaluating the quality of urban runoff in Shushtar city using the Storm Water Management Model (SWMM). Materials and Methods: Two given rainfall events in 2016 were considered for calibration and validation of the model. The parameters related to the first rainfall event were measured at the outlet of the urban drainage system. The quantitative and qualitative calibration of the model was performed using the data of the first rainfall and model validation was performed using the data of the second rainfall. Results: In the hydraulic calibration, the mean values of impermeability, slope, catchment width, and Manning’ s coefficient were estimated to be 50%, 75%, 25 m, and 0. 013, respectively. In the qualitative calibration, the coefficients of the Build-up equations for TSS, COD, and Zn were equal to 95-25, 48-1, and 1-0. 09, respectively. The coefficients of Wash-off equations for TSS, COD, and Zn were estimated at 0. 21-0. 8, 0. 2-0. 8, and 0. 19-0. 78, respectively. Conclusion: The results showed that the accurate calibration of the model enhances the ability of the model to estimate the quantitative and qualitative parameters in future rainfall events for the study area. According to the results, modeling is a powerful tool that can be very useful to improve runoff management.

Integrated catchment management ensures optimal use of the water resources. Change in the natural catchments' characteristics like percentage of impermeability, Manning coefficient have caused change in the runoff hydrograph at the outlet of urban basin. Models could help the policy makers in design of better solutions for management of the urban runoff using simulation and assessment of different scenarios without needing trial and error. The goal of this present research is, simulating of runoff due to precipitation in the sub-basin khezr of Hamedan city using the Storm Water Management Model (SWMM). For this purpose, the quantitative amounts of runoff during seven precipitation events were recorded. The sensitivity analysis of input parameters showed that the values of impervious areas' percentage, equivalent width, and Manning coefficient of the impervious area have the highest effects on the runoff volume and peak flow. The results of the verification to estimating the peak flow and volume using the coefficients of Nash-Sutcliffe (0.69-0.95), RMSE (0.14-0.29) and %BIAS (-13.6-18.8) on the three precipitation events showed that the model has good performance for simulating the volume and peak flow of runoff in sub-basin Khezr. Finally two scenarios were defined and applied based on the percentage of extension of impervious areas for year 2041 and precipitation intensity. The results showed, Increasing runoff is significant and its prediction and management for reducing probable damages in the future is necessary.

Background and Objective: In a natural watershed, most of the surface is impervious and covered with vegetation, so a large amount of precipitation is lost through plant interception, infiltration into soil and evapotranspiration. However, in an urban watershed due to urbanization, impervious surface of the watershed increases, which tends to increase the volume of runoff and peak discharge, the erosion of the bed and the edges in the downward of canals, and decrease in water level as well as degradation of water quality. The purpose of this research is to apply SWMM simulation for estimating runoff and runoff hydrograph and the effects of land cover changes and low impact development tools on hydrologic response of urban watersheds. Method: In this research, implementation of SWMM model in one of the urban areas of Qom was considered. The study area is 256 hectares in northwestern part of Qom. Findings: In this study, it was concluded that in sub watershed of 2 and 6, the increase of 70% and 40% in impervious surfaces resulted in 30% increase in runoff volume. Also, 10% increase in impervious area of upstream and downstream of watershed tends to 6/51% and 6/87% increase in peak discharge volume, respectively. The use of storage devices has also had a significant impact on reducing urban runoff. Discussion and Conclusion: The results of SWMM model in urban runoff estimation indicate that in order to properly manage runoff in arid areas, the status and location effects of land use on urban runoff rate as well as the use of rain storage tools in these areas should be considered.

Water harvesting and surface runoff control systems are the important components of urban planning and development and ignoring these issues is likely to raise crisis. In order to decrease the urban flood damages, the urban runoff is needed to be evaluated correctly. Today some of models are developed for urban runoff simulation. One of the most important models in evaluating and management of urban runoff is SWMM. The aim of this study is to evaluate SWMM efficiency on urban runoff simulation in Izeh urban basin. To define design rain, concentration time was computed while considering the duration of the cloudburst as equal to this time. Also three performance indexes of Nash-Sutklif, errors sum of squares and Bias were used in order to model calibration and validation. Moreover, areas of high susceptibility were determined for two, five, 10, 20 and 50 years of return periods. Later, it was found that the principle reason of inundation is the lack of sufficient capacity of water ways. In some points, even with sufficient capacity, inundation occurs, confirmed by model. In these cases the causes stem from the improper design and construction of bridges which has lessen the size of water ways and caused junk clogging. Three rainfall events were recorded on March 13, 2017, March 28, 2017 and April 6, 2017 which were considered in order to calibrate and evaluate the model performance. Along with that, the discharge, depth and velocity of water at the outlet were considered as well. The results of the SWMM application gave indication of a good matchup between discharge, depth and the velocity of runoff for observed and estimated data. In this case, this model could be utilized to well predict the inundation hazard, design and the estimation of the cost and volume of drainage systems, management of watershed and prioritization of region to address flooding issues.

Introduction and GoalDue to the large volume of human and commercial activities, one of the most important goals of infrastructure is to collect and transfer urban runoff, control floods and prevent flooding in cities. To correctly estimate the runoff and characteristics of hydrological units and channels, it is important to use appropriate hydrological and water models. Considering the importance of this topic, this research was conducted with the aim of estimating the urban runoff of the Malayer to determine the potential flooding points using a storm water management model (SWMM).Material and MethodsOn the basis of available technical reports, the area of the sub-watersheds, nodes and main channels of the city were first determined. Flow direction and slope of the area was determined using a digital elevation model and 11 sub-watersheds were identified. In addition, 11 nodes were determined, regardless of the initial water depth and water level. Using the daily rainfall data of the Malayer synoptic station during the 1992–2020 statistical period, a nine-hour rainfall with a return period of 2 years was calculated and entered into the model. The geometrical shape of the channels was an open rectangle and the flow trend in the channels was determined using the kinetic wave method. The size of the maximum flow of water through the channels was calculated using the relationship between the cross-section of the flow and the speed of the flow a 9-hour the rainfall with a return period of 2 years. To calibrate the model, the variables of percentage of impervious areas, pond storage and roughness coefficient of impervious areas were used in the change range of the allowed modification range. In order to evaluate the model, Nash-Sutcliffe efficiency coefficient and the root mean square error were used.Results and DiscussionThe results showed that after optimizing the sizes of the variables, the Nash-Sutcliffe efficiency coefficient and the root mean square error were 0.73 and 0.02, respectively. Of the total rainfall of 14.54 mm, 5.53 mm was related to infiltration losses, 7.55 mm was related to surface runoff, and 1.45 mm was related to pond storage. The results showed that the sub-watersheds that were in the north of the city and overlooking the heights and leading to node number 10 had more volume and drainage and it is necessary to revise the design and expansion of the channels in this area. In addition, the sub-watersheds of the western part of the city (sub-watersheds no. 4) and the southwestern part (sub-watersheds no. 8) had the highest and lowest flood potential of 0.651 and 0.547, respectively.Conclusion and SuggestionIn this research, the results showed that almost half of the city would be affected by flood risks in the event of rains. Therefore, the current drainage network does not have the necessary efficiency to discharge urban runoff in the northern part of the city, and it is necessary to determine the optimal dimensions of the channels. Because the eastern elevations of the studied area are snow-covered and considering the geology of the area, in future research, models capable of calculating the runoff caused by snow melting should be used.