نشریه مهندسی آب
سال یازدهم شماره 2 (تابستان 1402)

Dust is created by wind erosion. In nature, based on the size of the particles, the movement of soil particles due to wind is carried out in three ways. Rolling, jumping and suspension. In the wind ranges that usually occur in nature, proportional to the diameter of the soil particles, these three modes of particle motion are somewhat separable. Particles smaller than 0.1 mm in diameter are usually suspended, soil particles with a diameter of 0.05 to 0.5 mm usually bounce, and soil particles with a diameter of 0.5 to 2 mm move in a crawling (rolling) manner. In the wind tunnel tests, which were conducted on the soil samples collected from the dust centers in the southeast of Ahvaz. It showed that at the reference point, when the wind blows, a lot of dust is formed in front of the soil mass.The obtained results show that the maximum amount of dust is formed in the first 150 seconds. The maximum amount of dust produced occurs in the first 85 seconds, which is about 7 times more than the dust after the first 150 seconds.

One of the effective and very important factors in the stability of earth dams is the shear resistance of earth materials in the body and foundation of the dam, and damages caused by the sliding of earth slopes can cause irreparable damage to an earth dam. Considering the importance of earth slopes, the effect of static forces and earthquakes on its stability is extremely important. In this research, the optimization of the design of the Droodzen earth dam body is done by performing quasi-static and dynamic analyzes using Plaxis software. Based on the obtained results, geocell reinforcements increase the safety factor of dam stability and reduce the lateral deformation of the slope due to tensile strength and bending anchor. Also, by increasing the depth of the geocell placement, the tensile strength and bending moment of reinforcing increases, and by reducing the length of the geocell cover, the shear resistance of the top and bottom joint of the geocell decreases. Finally, we should mention that soil compaction leads to a significant increase in tensile force and bending moment along the length of the geocell layer.

Water distribution network is a system consisting of pipe, water reservoir, pump and valves. Water-supply networks in the hydraulic systems for water transmission and distribution have always been considered by researchers. The hydraulic behavior of water transmission lines is based on speed, pressure and flow. The possible changes in the consumption pattern, population, network leak and diameter of pipe line as well as potential of pumps need to be reviewed. In this research, the evaluation of hydraulic management of urban water-supply networks was carried out using Water Gems software. This means that the diameter of pipe lines and the level (height numbers) are changed so that the pressure is reached to the standard level in the network. Additionally, with modeling this township in Water Gems network in addition to the management of pressure, other data including speed, flow and demand rate are also provided. The first mode is based on the true state of water and sewage network was modeled in Semnan province. The second mode network according to the first mode was modified by changing the diameter of the pipes used to supply standard pressure and negative pressures were destroyed. In the second case by changing the elevation of the standard pressure of the atmosphere was 5-7. The optimum diameter of 85 mm and 180 mm was determined. optimized elevation for reservoir is 1430 meters and by increasing, the low pressure or by reducing, the pressure level rises.

In this laboratory study, the longitudinal changes of the flooring to the depth of the downstream scour of Calvert (square calvert shape), the changes in the length of the flooring to the depth of scour downstream of the calvert are discussed. For this purpose, experiments were performed on the floor with different lengths. According to the results, 22%, 33% and 66% were observed in particle 2 landing, 15%, 20% and 40% in 2.5 particle landing, respectively, and 20% and 25% in particle 3 landing, respectively. And reduced scour depth by 31%. This showed that changes in floor length and characteristics have a positive effect on the scour depth downstream of Calvert. Therefore, all these results have been studied in the laboratory environment and are real numbers and have been taken on a small scale.

Protection of the downstream of culvert outlets against scour process, as a water conveyance structure, is a highly significant issue in design of culverts. In this study, the effect of bed litter length on downstream scour depth is investigated. For this purpose, experiments were carried out on the laminate with different lengths. According to the results, the particle landing at 22%, 33% and 66%, respectively, and the landing at particle landing of 2.5%, respectively. 15%, 20%, and 40% decreased particle depth by 20%, 25%, and 31%, respectively, indicating that bedding has a positive effect on decreasing downstream scour depth. The scour for the flooring considering the length of the layer showed that the scour depth decreases with the increase of the layer length due to the constant landing number.

Evapotranspiration is one of the most important components of the hydrological cycle and its accurate estimation is used in many studies such as water balance, water resources management and irrigation planning. The use of intelligent models can be a good tool for estimating nonlinear variables such as evaporation and transpiration. The present study used GEP gene expression programming methods and ANFIS fuzzy-adaptive neural inference system to predict monthly reference evapotranspiration. For this purpose, two different modeling modes were developed. The first case of baseline climate patterns and the second case of memory role in predicting monthly reference evapotranspiration, Shannon entropy method was used to select the most optimal inputs. According to the results of GEP model in Ent-CBM8 model with KGE = 0.91, WI = 0.87 and RMSE = 0.495 had the best performance in predicting the monthly reference evapotranspiration of the synoptic station. The results of the implementation of models with basic delay patterns and Shannon's entopy method were able to correctly identify the optimal delay.