Elham Rezaei; Babak Shahinejad; Hojatola Yonesi
Abstract
One of the important issues in rivers qualitative discussion is the prediction of amount of Total Dissolved Solids (TDS) in water. In this study, the performance of the intelligent models Support Vector Machines (SVM) with different kernel functions, Gene Expression Programming (GEP) and Bayesian Network ...
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One of the important issues in rivers qualitative discussion is the prediction of amount of Total Dissolved Solids (TDS) in water. In this study, the performance of the intelligent models Support Vector Machines (SVM) with different kernel functions, Gene Expression Programming (GEP) and Bayesian Network (BN) was investigated in the prediction of amount of total dissolved solids (TDS) in Kashkan River. For this purpose, quality parameters obtained monthly from Poldokhtar station in Lorestan Province from year 1991 to 2016, including hydrogen carbonate, chloride, sulfate, magnesium, calcium, sodium, electric conductivity, flow rate and PH these parameters were applied to predict the amount of total dissolved sediments of water in this reach. Correlation Coefficient (CC), Nash-Sutcliff coefficient (NS), Root Mean Square Error (RMSE), and bias were used to evaluate the performance of the models. The results showed that in all three models, the combined structures have acceptable accuracy. Also, based on the evaluation criteria, Support Vector Machines with kernel of the radial base functions (RBF) had the highest accuracy 0.982 and the lowest root mean square error (mg / lit) 0.232, and the lowest bias 0.001 and the Nissan Sutcliff coefficient 0.963 compared to other models.
Hassan Goleij; Amirhamze Haghiabi; Mojtaba Saneie; Hojattallah Yonesi
Abstract
The percentage of flow diversion is the major cause of the formation of dimensions of separation zone such that with increasing the percentage of flow diversion, width and length of the separation zone decreased in the basic and sill experiments. However, by adding a 10ᵒskimming wall, the changing ...
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The percentage of flow diversion is the major cause of the formation of dimensions of separation zone such that with increasing the percentage of flow diversion, width and length of the separation zone decreased in the basic and sill experiments. However, by adding a 10ᵒskimming wall, the changing trend is different. At low percentage of flow diversion, dimensions of the eddy area decreased significantly and it increased with increasing the percentage of flow diversion. However, in general, the simultaneous usage of a 10 degree skimming wall and sill structures compared to basic and sill experiments, dimensions of separation zone in lateral intake decreased and the useful width of outlet flow at lateral intake increased and the separation zone and sediment accumulation at the entrance of lateral channel decreased. By examining the effect of the Froude number of flow (inlet flow) on dimensions of the eddy region, this parameter did not have any significant effect on it and its low impact could be connived. By investigating the width of separation line of flow in the surface and near the bed of channel bend, it was found that the flow diversion rate was the most important factor affecting this hydraulic parameter; since, at surface level of flow with increasing flow diversion ratio, this parameter increases and due to the creation of secondary flow and the change of surface flow pattern under the influence of the simultaneous application of a 10 degree skimming and dike structures, this parameter increases more. However, near the bed, in basic and sill experiments, this parameter increases with increasing flow diversion rate. However, the simultaneous application of 10-degree skimming and sill structures, the width of separation line of flow near the bed reduces by increasing the diverted flow
amir moradinejad; Amir Hamzeh Haghabi; Mojtaba Saneie; Hojatola Yonesi
Abstract
Sediment entering lateral intakes depend on flow pattern in intake entrance. Using a structure in front of the intake entrance can change this pattern and as a result the entering sediment. One of the effective methods to change pattern and manage sediment entering lateral intake is using skimming wall. ...
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Sediment entering lateral intakes depend on flow pattern in intake entrance. Using a structure in front of the intake entrance can change this pattern and as a result the entering sediment. One of the effective methods to change pattern and manage sediment entering lateral intake is using skimming wall. By removing sediments from intake entrance, the skimming wall reduces the volume of sediments entering the intake. To direct the flow towards intake and increase skimming wall efficiency, a spur dike is used on the opposite side of the intake. The length and angle of the spur dike were 0.25B and 60° and was located at distances 2b from intake center. In this study, the effect of skimming walls angle with the bank, a combination of spur dike and skimming walls and discharge changes on controlling sediments entering the intake, intake ratio and bed topography were investigated experimentally. The effect of the skimming walls with three angles (β1=10, 14, and 18 degrees) and a combination of skimming walls and spur dike on opposite sides of the intake was investigated. Conducting dimensional analysis, non-dimensional ratios were extracted and test variables were specified. Results showed that in the case of having a skimming wall combined with spur dike, the amount of sediment entering the intake has decreased to 81%, 78.5% and 76% on average in walls with an angle of 10, 14 and 18 degrees respectively. The combination of using skimming wall and spur dike has a superior effect on reducing enterance sediments to intake than employing skimming wall alone, namely about 15% for three angles.
Hani Tabrizi; amirhamze haghiabi; Mojtaba Saneie; Hojjatollah Younesi
Abstract
The process of water diversion from the rivers always involve with sediment diversion in different sizes. The sediments that transported to the branch channel cause the expenditure to the water conveyance system and power-generation installations. One of the common methods to control the bed load and ...
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The process of water diversion from the rivers always involve with sediment diversion in different sizes. The sediments that transported to the branch channel cause the expenditure to the water conveyance system and power-generation installations. One of the common methods to control the bed load and water diversion increasing, is to modify the approach flow pattern by the control structures. In this study, the efficiency of spur dikes in modifying of diversion flow to the intakes that located at curved channels are investigated. Experiments carried out in ten main groups in a 180° curve channel with a diversion located at the 118° on the external curve. Results of this study show that the sediment discharge ratio increased by discharge ratio increasing and severely related to it. The spur dike at upstream of the intake decreases the sediment discharge ratio by modifying the approaching flow pattern such that in C2 experiments, the sediment discharge ratio until the discharge ratio is equal to 0.05, 0.15, 0.25, 0.35 decreased up to 86.6, 73.3, 64.7, 46.7 respectively. But this effectiveness limited to Qr=0.4, because the strength of secondary flow diminished due to flow diversion increasing. Also, study of the effect of spur dike on sediment volume fraction in diversion channel show that, the maximum value of Vr diminished from 0.4 in type A experiments to 0.18 in type D experiments by reduction of the distance between the spur dike and the intake centerline. According to the experiments, positioning the spur dike at upstream of the intake change the dimensions of stream tube and decrease the diversion from near bed high-sediment flow and increase the diversion from near surface low-sediment flow. The dimensions of the separation zone severely decreased in type D experiments by presence of spur dike and discharge ratio increasing.
