Prediction of velocity is an important parameter in curved channels. Recently, artificial intelligent methods are developing than the common costly and time-consuming experimental and numerical methods in estimation of flow variables. In the present study, Gene expression programming (GEP) model as developed genetic programming model is used to predict the flow velocity in the channel with a sharp 90° bend. Different input parameter combinations are examined in order to finding the optimum model then the model efficiency are evaluated in estimation of the flow velocity in training and testing phases. By comparing the results of the GEP model with experimental data, there is an acceptable accordance between results with the root mean square error (RMSE) values of 0.828 and 0.8197 in the training and testing phase. The results show that the input parameters of (r,q) (polar points coordinate and the flow discharge) are the most effective parameters in bend flow pattern surveying. With increasing the flow discharge, the model error at the end section of the bend in the outer channel wall is decreased. Also a practical and reliable relationship is proposed by the GEP model and the sensitivity of suggested equation to each of input parameter is evaluated. Furthermore, the uncertainty of the proposed GEP model in the velocity prediction is assessed and different confidence bounds are introduced.
When the bridge piers are located in front of the water flow, vortices are formed against it and due to their activity, the materials of the river bed are eroded around the bridge piers and the scouring hole is created. If the foundation depth and bridge pier piles are insufficient, the bridge will fail.The study of total shear stress in the flow bed at different leveling of the pile caps shows that the highest shear stress is created when the pile cap position is at the same level as the river bed; by installing the pile cap at a lower level than the river bed, the maximum shear stress decreases. This may be due to the fact that in this case, the distance between the pier group increases and the presence of the second pier decreases the flow rate in the pier group and different pier in the one pier group acts as the two independent piers in the formation of the flow pattern. By comparing the final longitudinal sections of the scouring at different leveling of the pile cap, it is concluded that the largest reduction in scouring depth occurs in aerofoil-shaped pile caps and pile caps with the sharper nose and better aerodynamic shapes are good options to control the horseshoe vortices and will reduce the scouring depth around the inclined pier group.
In this research, for the first time, a simulation-optimization system dynamic-based model with Anylogic software for reservoir eutrophication management is presented. Thus, the relationships of the elements related to eutrophication were formulated in different layers of Karkheh Dam and in relation to each other in the system dynamics form. comparing the presented results with the results of the CE-QUAL-W2 and Vensim simulation models over a one-year period showed that the value of the correlation coefficient (𝑅2) for the variables phosphate, ammonium, nitrate, Dissolved oxygen and Chlorophyll-A between the two models of Anylogic and CE-QUAL-W2 is equal to 0.89, 0.81, 0.78, 0.75 and 0.86, respectively, and the value of this coefficient for the mentioned variables is equal between the two models of Anylogic and Vensim. With 0.98, 0.94, 0.90, 0.93 and 0.97, which shows the high correlation between the results of Anylogic model with the two mentioned models. Then, by combining the developed model in Anylogic environment with a simulated annealing optimization model, a simulation-optimization model was developed to determine the optimal values of water releases from different layers of reservoir in 15 years’ horizon considering the quantitative and qualitative objectives. Here, the RMSE between the results of the two models for the lower, middle and upper layers of the reservoir is 0.004, 0.007 and 0.010, respectively, and 𝑅2 is 0.91, 0.9 and 0.79. The results indicated that the results of the two models were similiar. This study showed the effectiveness of the proposed model in the management of dam eutrophication.
Nowadays, the use of proper irrigation methods to increase the productivity of water use in the agricultural sector due to the limited water resources is considered essential. The aim of the present research was designed with the economical assessment of irrigation different methods (drip irrigation, center pivot and fixed classical sprinkler irrigation) in using new(solar) and traditional (network) energies in irrigated wheat production. This research carried out in Alborz province in 2016 and 2017. In this research, at first, water requirement of this product was determined by Karaj condition and then, the cost and benefits of irrigation different methods using electricity network and solar power in the production of wheat was determined. For economic analysis in order to selecting the best irrigation method used Partial Budgeting Method. In this method, used Cost and Benefits and Marginal Net Benefits. According to the results, water saving in drip irrigation, center pivot to fixed classical sprinkler irrigation were estimated 22.8 and 17.6 percent, respectively. That means the net Benefits of wheat production in fixed classical sprinkler irrigation, center pivot and drip irrigation using electricity network were estimated 84.6, 85.6 and 90.7 Iranian million rials per ha and using solar power were estimated 72.4, 79.7 and 85.3 Iranian million rials per ha. In general, drip irrigation system using electricity network was recommended as better treatment and economic in wheat production, because, substitution of others systems instead of this method, Marginal Net Benefits in this substitution would decrease.
In this research, a metaheuristic algorithm, called Water Cycle Algorithm (WCA), was developed in MATLAB software, with the purpose of optimal allocation strategies of a multi-reservoirs system (Golestan and Voshmgir dams) located at Gorganrood basin (north of Iran), for a five year period (from 2007-2008 to 2011-2012). At the first step, the performance of the developed algorithm was successfully assessed through several benchmark functions. Next, it was applied to the monthly allocation of Gorganrood multi-reservoirs system. The objective function was defined as the minimizing of the total deficit for the study period. The results of all applied algorithms were evaluated by reliability and vulnerability criteria. The results of WCA were compared with other developed evolutionary algorithms including Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). The WCA, GA and PSO were capable to supply 97.73, 87.07 and 94.3 percent of Golestan dam water demand, respectively. For the Voshmgir dam, the mentioned models could supply 97.06, 87.59 and 94.47 percent of water demand, in same order. The temporal reliability (α=0.9) for WCA, GA and PSO models, was obtained 95, 26.67 and 58.33 percent for Golestan dam and 91.67, 38.33 and 66.67 percent for Voshmgir dam, respectively, revealed that the WCA was superior in optimal allocation of multi-reservoirs system.
The reviews of past researches have shown that abutment scour plays an important role in bridge failures. Hence, protection of bridges against scour is a significant issue. For existing bridges, armoring methods, like riprap, has a wide application. In areas where providing stones is expensive concrete blocks or similar techniques have been applied. In this study for the first time, the application of six-legged concrete elements has been experimentally investigated. The six-legged elements have been placed in three different densities (open, medium and dense) and three different placement depths (under the bed, above the bed and medium case). Each alternative have been tested under different flow conditions. Generally the results proved that the six-legged elements can considerably reduce the scour depth under different flow conditions so as it reduced the maximum scour depth of abutment nose up to 100%. The maximum reduction of scour depth has been obtained when the high dense six-legged elements are placed above the bed. In this case, the elements protect the abutment by creating coverage and also alter the sour from the abutment tip to the channel midway.
In contrast with conventional impermeable weirs, Solid objects and dissolves substances can pass through gabion weirs. Thus, due to its minimal negative attributes, gabion weirs are considered environmentally friendly structures. This study aimed to assess the effect of upstream and downstream side slopes of the crump gabion weirs on the discharge coefficient for free flow conditions and compare it with those of impermeable weirs. To achieve this objective, a general non dimensional relationship was developed. Eight different Gabion weir models and 3 impermeable weir models were examined in a horizontal flume, 15.0m long, 0.3m wide, and 0.5m deep, respectively. Multiple, methodical experiments were performed using various discharge rates including: discharge, upstream and downstream depths, material size, and upstream and downstream slopes. It was observed that under the free flow conditions, a decrease in the upstream and downstream slopes led to an increase in the weir and a decrease in the discharge coefficient. Furthermore, an increase in the material size caused a decrease in the head on the weir and an increase in the coefficient development of a relationship to predict the gabion crump weirs’ discharge coefficient (R2=0.97) was achieved through dimensional analysis.
Problem Definition: For several hundreds of years, mining in Bolivia has been an important part of the economy. The mining activity has a negative effect on both the environment and the health of the people. Previous studies conducted in the Lake Poopo area show elevated concentrations of heavy metals and ions harmful to people and nature. Also, previous studies indicate that the contamination from mining activities is significant for the water quality. Four larger rivers flow through the studied area; the Poopo, Pazna, Urmiri and Antequera Rivers. A large quantity of mines but also farms and villages are situated in the basins of some of these rivers. This, together with the geological composition of the bedrock, highly pollutes the water that in turn is used by the people in these villages. Objectives: The main objective of this thesis is to gather knowledge of the present environmental condition of the Poopo, Pazna, Urmiri, and Antequera River basins, with focus on heavy metal concentrations in superficial waters. Also, to increase the understanding of how the heavy metal concentrations have changed during the years of studies conducted in the area. The questions to answer include: • What are the concentrations of the heavy metals cadmium, copper, zinc, manganese, iron, arsenic, and lead in the Poopo, Pazna, Urmiri, and Antequera River basins? • Do the heavy metal concentrations change over time? • How much of the heavy metal concentrations are caused by anthropogenic and natural contamination, respectively? • How is the water quality compared to the health-based WHO guidelines for drinking-water? Our hope with this study is that the gained knowledge will help in the effort of developing long-term sustainable plans for remediation and water resource management that will benefit the people living in the Poopo, Pazna, Urmiri, and Antequera River basins. Method: This thesis summarizes information from previous studies as well as analyzes data values from a field trip conducted in June 2013. During the field trip samples of surface water were collected and analyzed. In the field, the parameters pH, Eh, temperature, conductivity, TDS, and alkalinity were measured and the water samples were divided into two bottles for further analysis in laboratory. At the San Andres University in La Paz the water was analyzed regarding concentrations of the ions nitrate, sulfate, chloride, sodium, potassium, calcium, and magnesium and the concentrations of the heavy metals lead, manganese, arsenic, iron, copper, zinc, and cadmium. Data from previous studies were collected, organized and compared in order to see if and how the heavy metal concentrations change over time. Results and Conclusion: Current Situation The samples collected during the field trip in June 2013 make up the current situation analysis. The concentrations for nitrate, cadmium and arsenic all exceed the WHO health-based guideline values for drinking-water in the Antequera River. A thermal spring that leaks into the Urmiri River, together with the natural bedrock weathering, affects the water and elevates temperature, chloride, sodium, and cadmium concentrations. Since there is no larger mine activity contaminating the water in the Urmiri River, a comparison between the Antequera and Urmiri River gives an approximate indication of how much the mines affect the water quality. This comparison indicates that the Antequera River is highly polluted due to contamination from mines, especially regarding cadmium. The results also indicate that the characteristics of Pazna River are a mixture of those of Urmiri and Antequera River. Furthermore, it seems as though the mine-influenced sampling site MAD1, a tributary of the Poopo River, impairs the water quality of the main river to a great extent. Historical Situation The data from previous studies have been divided into dry and rainy period, respectively, where an analysis of heavy metal contamination has been made only of the dry season data values. This study, similar to the study of the current situation, indicates that the area north east of the Lake Poopo is polluted and that Antequera River is the river most affected by mining activity. In that particular river, the concentrations for cadmium, iron, zinc and manganese exceed the WHO guideline values at almost every sampling site and date. Especially cadmium vastly exceeds the WHO limit. Meanwhile, the values for the Urmiri River rarely exceed the WHO guideline values. The heavy metal values for Pazna River are also often above the WHO guideline values, probably due to the inflow from Antequera River. The sampling site MAD1 greatly affects the Poopo River and elevates the heavy metal concentrations. A clear trend for all four rivers is the constantly elevated concentrations of cadmium that is neither increasing nor decreasing up to June 2013. For sampling sites PAZR1 and POR3, where the data sampling starts as early as 2001, the arsenic and lead concentrations are high above the WHO guideline values until June 2007. After this, the levels seem to have stabilized close to or below the WHO guideline values. Sampling site MAD1 does not, however, follow this pattern but instead has extremely elevated arsenic and lead concentration up to June 2013. The sampling site AVR1 has only been studied since 2007. There, the levels of arsenic and lead have historically had one peak each but otherwise stay around the WHO guideline values for drinking-water.
The objective of this paper will be to examine the approach for evaluating unknown bridge foundations with the assistance of Geophysical test methods. These test methods, often referred to as Non Destructive Testing and Evaluation (NDT & E) methods, can generate new information on the bridge's foundation configuration and further quantify the risk from flood damage. A case study will be presented which will include various bridges in Connecticut, where a variety of NDT&E methods were used to determine new information about the bridge's foundation embedment into the river. The cost effectiveness of this type of investigation will be discussed with the results of different testing programs performed for the Connecticut Department of Transportation (CDOT). This work resulted in quantifying the bridge's foundation configuration and the assignment of an appropriate scour risk rating for the structure. Often the risk rating reported to the Federal Highway Administration was revised from high risk (scour critical) to a low risk rating.
Local scour measurements were made at a bridge piling in a tidal inlet on the Gulf of Mexico coast in Northwest Florida. The existing scour hole was filled with sand from the surrounding area and the scour process was monitored continuously for approximately ten days. Data from this experiment has been analyzed from the standpoints of equilibrium scour depths and the rate at which the scour occurs. Comparisons are made with laboratory data for steady, uniform flow.
Scale model piers subjected to clear-water scour conditions exhibit similar scour formation patterns over time. This similarity was found to be independent of approach velocity, sediment size, pier shape, and pier size after the first 24 hours of scour when it was normalized by the equilibrium scour depth. Based on the assumption that the relationship between time and scour is parallel, an extrapolation technique is developed to predict ultimate scour depths from shea duration experiments.
A simplified model of streambed armoring is used to extend Laursen's well-known equation to include the limiting effects of a coarse surface layer when calculating clear-water contraction scour at bridges. An empirical relation for selective entrainment of gravel from naturally sorted riverbed material is used to estimate the smallest nontransportable particle in the armor layer. If the smallest nontransportable particle approaches the largest-sized particles in the bed-material mixture, evidence indicates that the armor layer will be unstable and particles of all sizes will be nearly equally mobile. However, if the armor layer is stable, clear-water contraction-scour depth estimates might be significantly less than for nonarmored conditions. To calculate armor-limited contraction-scour depths, two equations need to be solved simultaneously, one for the depth of the so-called active layer provided by the armor layer model, and one for depth of clear-water scour in a long constriction, The simple computational procedure will be especially useful for evaluating clear-water contraction scour at flow relief bridges crossing floodplains composed of well-graded alluvial till where a coarse protective surface layer is likely to form.
