Journal of Hydrosciences and Environment
Volume:5 Issue: 9, Jun 2021

Precipitation is predicted for different days of the year using fuzzy logic, the Mamdani fuzzy system, and IF-THEN rules. The input variables include five parameters of relative humidity, cloud cover, wind direction, temperature, and surface pressure, each with three membership functions ranging from  0 to 1. The final answer will likely be the amount of rainfall. All input variables are fuzzy, and two types of membership functions are selected. As many as 51 rules are considered for each station. Finally, the best situation of precipitation is chosen, and PMP obtained is applied to Kahir catchment basin, Sistan and Baluchistan. The fuzzy PMP is then calculated and compared with the Hershfield classic method for calculating PMP. Results show that fuzzy PMP estimation is more accurate and reliable for the studied area than the Hershfield method. All implementations are performed with MATLAB.

Pontoon breakwaters are one of the most common types of floating breakwaters. Floating breakwaters are mainly used for wave reflection and energy dissipation. Wave energy loss by turbulence in the current is caused by the transmission of waves through the structure. Also, since waves break on the upper side of the structure, wave energy decay occurs. The efficiency of floating breakwaters is generally presented by a factor that is called transmission coefficient. The transmission coefficient is a ratio of the transmission wave height to the incident wave. This study tries to investigate the performance of floating breakwaters. For a realistic assessment, the Caspian sea’s hydrodynamic conditions are used. Also, two types of floating pontoon breakwaters have been modeled. This research aims to evaluate the performance sensitivity of breakwaters in relation to their geometry and wave characteristics like wave height and period. Hydrodynamic conditions are simulated by ANSYS AQWA finite element software. At first, a rectangular model (No.1) was simulated by hydrostatic analysis and time history analysis by applying average 20-year wave conditions and then using time history analysis by applying the critical wave characteristics. Then, the same procedure was performed on a trapezoidal model (No.2). According to the results, the transmission coefficient increases with increasing the wave period, but the increase in wave height has no effect on the breakwater efficiency.

The type and height of foundations of embankment dams are among the factors affecting their seismic responses. The kinds and heights of these foundations and the other conditions play fundamental roles in transmitting, attenuating, or amplifying the seismic waves. Considering 6 different types of shear stiffness and 7 different heights for Mashkid Olia dam foundation, the effect of shear stiffness and height of the foundation on the seismic behavior of the dam through the equivalent linear method were investigated. It was indicated the undeniable effect of conditions and height of foundation on the seismic behavior of the embankment dam.

The optimal utilization of dams water resources in order to meet the water needs of different departments is an important problem in the management and engineering of water resources. Evolutionary algorithms have provided great success to create balancing in supply of water resources shortages with the goal of controlling the water resources storage and dams release rates. Differential evolution (DE) is an efficient search technique and method to solve numerical optimization problems and real-world applications. DE suffers from numerous weaknesses that usually due to the use of a mutation strategy and consideration of constant settings for parameters. In this paper, an adaptive DE algorithm titled Combined Improved Multi-Population Ensemble DE (CIMPEDE) is suggested. In CIMPEDE, the entire population is divided into four sub-populations; three mutation strategies are considered to achieve a better, and two adaptive and self-adaptive schemas are proposed for setting parameters. CIMPEDE has been able to achieve the optimal solution with the highest quality by choosing the best mutation strategy in each repetition, dynamic adjustment of parameters and exchange of information between sub-populations. For prove the performance of CIMPEDE, extensive experiments have been performed on mathematical benchmark functions (entitled CEC 2013) and a real-world problem for modeling of the single-reservoir system of Golestan dam in Iran with the aim of decreasing irrigation deficiencies. CIMPEDE has also made comprehensive comparisons with DE-based applied approaches. In the case of Golestan dam problem, mean absolute error between real demand and released water by CIMPEDE was zero MCM. While, the comparable algorithm in second rank could not get a value better than 1.81E-220 MCM. Also, in test of reliability and vulnerability indices and test of mean violations intensity between demand and released water in an annual average, the best results were recorded among the comparable evolutionary algorithms for CIMPEDE.

The velocity of only one point from normal to the wetted perimeter must be known to obtain local shear stress at a point along the wetted perimeter. Then, the local shear stress on the wetted perimeter is calculated using the viscous shear stress relation and defining the non-dimensional variable ξ. ξ is considered a parametric function of some non-dimensional hydraulic and geometric variables of channel and fluid. Several experimental data are used to achieve a general form for the function, and the parameters are obtained by minimizing the MAPE (Mean Absolute Percentage Error). MAPE between the data observed and calculated by a genetic algorithm is minimized to modify the model for trapezoidal sections. Experimental data from twenty trapezoidal sections have been selected. Twelve are used for training, and the remaining eight are for testing. The average value of MAPE is 7.1%. However, one section is rectangular, with a calculated MAPE of about 16%. The high discontinuity of the wetted perimeter of the rectangular cross-section due to the 90 ° angle between the bed and the walls is responsible for approximately a large amount of MAPE. MAPE is less than 7% in 14 selected sections, twelve are used for training, and the remaining eight are for testing. The average value of MAPE is 7.1%. However, one of the sections is rectangular in which the calculated MAPE is about 16%. The high discontinuity of the wetted perimeter of the rectangular cross-section due to the 90 ° angle between the bed and the walls is responsible for approximately a large amount of MAPE in that case. MAPE is less than 7% in 14 selected sections.