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One of the usual problems during the construction of underground structures has been the water seepage into these structures. Water seepage into the tunnel, especially during excavation, could reduce the excavation procedure’s rapidity and make the walls unstable. Furthermore, to embed the required pumps for draining leaked water into the tunnel, it is necessary to estimate the tunnel's approximate inlet flow rate. The purpose of this study is to estimate the flow rate in the width of the tunnel inlet portal of the second part of Isfahan metro line 2, which has been done using numerical modeling and matching the results with analytical models. Observation of the sensitivity analysis results showed that the two parameters significantly affect the inlet flow rate of seepage into the tunnel: (1) Soil permeability coefficient, and (2) Groundwater level. Finally, the seepage flow rate was estimated in high water and water scarcity seasons, compared with the analytical results. Comparative parameters of NSE and RMSE were used to estimate the differences between analytical and numeral methods. This estimation showed that Lei (Groundwater 37: 23, 1999), and Lombardi (2002) could estimate the tunnel portal’s flow rate.

In recent decades, the accumulation of residential regions has increased due to the expansion of urbanization. This has led to an increase in the impermeable areas and, thus, increasing surface runoff in the cities. Therefore, it is necessary to control surface runoff using Low Impact Development (LID) methods in cities. In this research, using the hydraulic-hydrological SWMM model, the collection network of surface runoff of Shahrekord city was simulated in 2, 5, and 10 years return periods. The calibration of the model was performed in two rainfall events. Afterward, validation was performed using sensitivity analysis with calibrated values, which NSE, RMSE, and% BIAS indices showed good simulation accuracy. After this stage, three methods of the green roof, permeable pavement, and rain barrels were located in 14 selected sub-catchments of Shahrekord. The results of these methods on the volume and peak runoff of selected sub-catchment showed that green roof, permeable pavement, and rain barrels, respectively, reduce the volume and discharge peak runoff by 46, 21, and 25%, on average. Moreover, increasing the rainfall period would increase the effectiveness of using these methods. Also, the results of investigating the value of the discharge and volume of runoff within the drainage canals, the capacity of the canals, and downstream of selected sub-catchment, indicated the reduction of these values due to the application of LID methods. As a result, it was concluded that the effect of using a green roof was greater than the others.

The water flow in the dam spillway has a lot of energy. This energy can cause an increase in flow velocity, damaging the installations as well as erosion of the riverbed in downstream. The use of stepped spillways is one of the common methods to dissipate energy during the flow of spillway and reduce the dimensions of the stilling basin in the dams. One of the main parameters affecting the rate of energy loss in stepped spillways is the spillway geometry. In this study, the effect of using five different stairs with new and different geometries, in comparison with previous studies, was investigated in terms of energy dissipation. The simulation was performed by Flow 3D software and by the turbulence model (RNG) for discharges between 0.00213 and 0.0121 m3/s. The (RNG) and (k–e) turbulence models were used for calibration, which (RNG) had better results. The simulation results were compared with the experimental model results where the RMSE error index for type A–E spillways, 0.035, 0.014, 0.021, 0.032, and 0.031, respectively. After this step, to improve the experimental model, barriers were placed on the type D spillway, which was the best experimental model for energy dissipation. Numerical simulation results show that adding these barriers increases the energy dissipation by 15%.