Sharif Digital Repository

Over the past several decades, human activities have resulted in a significant increase in surface and ground water pollution. Human activities have caused significant pollution of surface and groundwater, with pollutants like nitrates, phosphorus, heavy metals, toxins, and chemical fertilizers degrading water quality. In order to control pollution and reduce the concentration of pollutants in water, it is necessary to use appropriate numerical criteria to evaluate and manage the quality of water resources. The water quality index, as a scoring method for investigating the combined effects of independent parameters on overall water quality, is a widely-used metric for measuring the quality... 

It is inevitable to simulate the phenomena that govern nature to make decisions and policies on water and environmental issues. Therefore, researchers have tried to make a good prediction of water's quantitative and qualitative status by using modeling and computer processing power. One of the primary and essential issues in modeling is using sensitivity analysis techniques. Using this knowledge, much information will be obtained on how to influence the model's output regarding various factors such as parameters, input data, and initial and boundary conditions. Global sensitivity analysis based on variance as one of the most well-known and, at the same time, the most widely used sensitivity... 

Water quality is a fundamental pillar of public health, sustainable development, and food security, and monitoring pollutants such as total phosphorus (TP) plays a crucial role in the effective management of surface water resources. Phosphorus is an essential element for agricultural production; however, its loss from soil to aquatic systems can lead to environmental issues such as eutrophication, biodiversity loss, and degradation of water quality. Although monitoring TP concentrations is vital for effective water quality management, many countries face a lack of sufficient and consistent data. Numerical models, particularly data-driven approaches based on machine learning, can help bridge... 

Phosphorus is a key nutrient in the Earth's biogeochemical cycle and plays a crucial role in agricultural productivity and global food security. It is primarily utilized in the manufacture of chemical fertilizers. At the global scale, phosphorus concentrations in surface waters are regulated by a complex interplay of environmental, climatic, and anthropogenic factors. Excessive phosphorus input into aquatic systems, particularly through agricultural runoff and industrial wastewater, can lead to eutrophication, water quality degradation, and serious ecological issues. Understanding the drivers of phosphorus concentration on a global level is therefore essential for sustainable water resource... 

The country's increasing demand for water makes effective dam management essential. Beyond environmental concerns, constructing new dams and their components involves relatively high costs. One of the most critical components of a dam is its spillway, which accounts for a significant portion of the total construction costs and plays a vital role in water resource management. To reduce spillway construction costs, a specific type of spillway that combines a stepped spillway with cascading basins can be employed. Designing this type of spillway can be considered as an optimization problem, requiring the use of optimization methods. Metaheuristic algorithms, which have gained significant... 

The increasing rate of population and agricultural development over the past few decades has led to a significant rise in the pollution of surface and groundwater. The application of animal and synthetic fertilizers containing phosphorus, which increases the levels of this element in the soil, can be considered one of the factors endangering the environment, especially the quality of surface waters. The transport of phosphorus, which is one of the pollutants in agricultural runoff, can lead to the degradation of aquatic ecosystems and reduce the quality and usability of water resources. Accordingly, various numerical models have been developed to simulate phosphorus loss from the soil. They... 

This study investigates the seismic demand in diaphragms, chords and collectors in typical floor systems used in steel structures. These systems include joist-block slabs, open web steel joists, and composite steel decks. The lateral load resisting systems considered were Special Concentrically Braced Frames (SCBF) and Special Moment Frames (SMF) of varying heights. For each system, the influence of using shear connectors for perimeter beams, joist orientation, geometric configuration, and number of stories on lateral force transfer was examined. Nonlinear static and time history analyses were conducted on selected models. Key findings are as follows:
• In joist slab system without shear... 

Since seepage-related problems account for the cause of more than forty percent of dam failure seepage analysis serves as one of the most significant stage in the design process of an embankment dam. Currently a steady seepage analysis in a typical or maximum cross section of the dam is formed instead of transient seepage analysis for simplicity. In this way, for the change of condition (unsaturated to saturated) in the first filling of dams and it’s effects on behavior and reaction of dams until the steady seepage condition established; the results of steady seepage analysis cannot be satisfactory. In this thesis, based on finite element method and with assumption of saturated-unsaturated...