Discharge Coefficient of a semicircular labyrinth weir is a function of total head, effective length of crest and Discharge coefficent. Discharge Coefficient of such a weir is influenced by total head over the weir, height of weir, radius of weir, thickness of weir and shape of crest. In this paper the effect of imporant parameters affecting Discharge Coefficient are investigated. It was found that by increasing the radio us of weir, Discharge Coefficient increases. The rate of variations of Discharge Coefficient decreases by increasing depth of flow and finally maintain a constant value.Appropriate equations for Discharge Coefficient are introduced. New method of design is introduced.

Submerged rectangular orifice is among Discharge measuring device which is suitable in small canal especially when the amount of fallis not adequat for application of weir, during the past decade many study have been conducted for evaluation of Discharge Coefficient of orifice. For free the case of submerged orifice only an average value of 0.61 has been mentiond in the literature. Since this Coefficient depends to the flow characteristics and the orifice dimensions, an equation for determination of Discharge Coefficient is needed. The development of such formula is the main goal of this study. To do so an experimental program was conducted and applying the dimensional analysis and data obtained from these tests, one relation was developed. This relation can be used where an accurate value of the Discharge Coefficient and consequently the flow Discharge is needed.

In this research, the Discharge Coefficient values of side orifices are modeled using ANFIS and the ANFIS-GA methods. To simulate the Discharge Coefficient, the effects of the ratio of the main channel width to the side orifice length (B/L), the ratio of the side orifice height to its length (W/L), the ratio of the flow depth in the main channel to the side orifice length (Ym/L) and the Froude number (Fr) were considered. Eleven different models were introduced for each of the ANFIS and ANFIS-GA models to estimate the Discharge Coefficient. Next, in order to compare the soft computing models’ results with the results of the computational fluid dynamics (CFD), the side orifice Discharge Coefficient was simulated using FLOW-3D model. To model the flow field turbulence, the standard k-ε and RNG k-ε turbulence models were used. According to the CFD model results, the RNG k-ε turbulence model simulated the flow field turbulence with higher accuracy as compared to k-ε model. Also, the MAPE and RMSE values for the estimated Discharges by the CFD model were equal to 12. 204 and 0. 001, respectively. By analyzing the results of the ANFIS, ANFIS-GA and CFD models, the ANFIS-GA model was introduced as the premier model.

Intake structures have been widely used for flow diversion in the irrigation and drainage networks. In this paper, the multivariate adaptive regression splines (MARS), artificial neural network (ANN), and support vector machine (SVM) techniques were utilized for prediction of Discharge Coefficient (Cd) of lateral intakes. The experimental data pertaining to dimensionless parameters on Cd were collected to develop the models. The results indicated that the best performance in modeling is related to the MARS model with R2=0.98 and RMSE=0.023 and the MARS model outperforms the ANN and SVM models. The tangent sigmoid and radial basic functions were found to be the most efficient transfer and kernel functions for ANN and SVM, respectively. Moreover, Froude number (Fr1) and the ratio of the weir height to the upstream flow depth (P/d1) were the most effective factors for predicting Cd. Evaluation of the performance of applied models in term of developed discrepancy ratio (DDR) index shows that the minimum data dispersivity is related to the MARS model.

Filling of locks in low lifts, generally accomplish by slots in gates and energy of flow dissipates by stilling basin and baffles. In this new system gate has been designed in the form of box and openings are made in two, upstream (U/S) and downstream (D/S) walls and flow control is done by these gates. This system includes a few orifices in U/S and some under sluice in D/S. Some laboratory tests have been done for determining Discharge Coefficient (Cd). Results show that (Cd) for this system is different from (Cd) for orifices and sluice gates. Generally the latter (Cd) is lower than the former. This is due to difference in orifice edges and hydraulic loss between two walls. An equation has been developed in this research for multi dabble orifices.

According to available statistics and information and given the population growth as well as the ever-increasing development of agriculture, there is an upward trend in withdrawals from surface water and groundwater resources in different regions of the country such as Mahabad to provide water for the region. The optimal conjunctive use of surface and groundwater resources is one way to providing the water demands in crisis and drought situations. In this study, a management model based on effective techniques of optimization and simulation has been developed to solve the optimization problem. Variation of groundwater table level in Mahabad plain was simulated using GMS software initially. Then based on the results of this simulation, artificial neural network was trained to use in simulate-optimization system. Genetic algorithm was used to solve the optimization problem. The results indicate that this model is powerful and effective for solving large-scale problems and optimal conjunctive use of surface water and groundwater resources of Mahabad. Based on the results obtained of the research and running of optimization conjunctive use quantitative model, the share of water supply of water resources, is respectively 13. 5 percent and 86. 5 percent of surface water and groundwater resource.

Labyrinth weirs are one of the kind of nonlinear crest weirs causing the increase of Discharge capacity for specified height of water level in canals and dams. In this study, the effects of dentate and orifice labyrinth weirs on increasing the Discharge capacity were investigated. Experiments were conducted in a laboratory flume with length of 12 m and width of 0.8 m. The nine experimental models with 15 cm height were used. The results showed that for L/W=2 and H/P=0.2, the Discharge Coefficient of the orifice-dentate labyrinth weir and the dentate labyrinth weir are 75.6% and 17.5%, more than the simple labyrinth weir, respectively. However, dent and orifice may decrease their efficiency in high heads and the Discharge Coefficient will be close to simple labyrinth weir. The reason for these changes was increasing the flow interference in downstream of labyrinth weir between dents, orifices and weir with increasing Discharge. Also, the result showed the efficiency of orifice and dentate on labyrinth weirs will decrease with increasing the weir magnification (L/W) and they lose their effect.

The effect of the entrance geometry of a culvert on the Discharge Coefficient is studied. The experimental results of a sharp edge model, which is compared with Bodhaine's, are taken as the comparison base. The curved up edge model and the curved edge of a side walls model, was shown to be effective on increasing the Discharge Coefficient. In addition, the bottom slope, culvert length, and Discharge variation have no effect on the Coefficient of Discharge for flow types 1, 2, and 3.

Bottom racks is a hydraulic structure which is placed in the bed of stream through which, part of flow in the main channel is diverted. These structures have very wide application in industry, irrigation, drainage and etc. Of course much attention had been paid to the study of such structures, but characteristics of flow through bottom racks are complex. The present study was directed to estimate the Discharge Coefficient of a new kind of bottom racks including both transverse and longitudinal bars that named "mesh panel racks" without considering any solids in the fluid. This kind of bottom intake has advantages from structural point of view and has less deformation under static and dynamic loads. Laboratory setup with three mesh panel intakes was built and the effects of various parameters such as racks slope, porosity and geometry were explored. A dimensional analysis using Buckingham theory showed the effective hydraulic and geometric factors that affect the Discharge Coefficient (Cd) of bottom racks. Then, a statistical approach to determine the Discharge Coefficient of a rack structure was developed with linear and nonlinear regression using SPSS software. The efficiency of the proposed technique is high enough that the associated error is limited to 10%. Finally, hydraulic performance of mesh panel intakes was compared with regular type of bottom intakes, which consist of longitudinal bars. For this purpose, diverted Discharge through both type of intakes calculated in same situation.

Side weir is used as a regulator structure to control Discharge and water level in rivers and channels. A labyrinth side weir is a kind of weirs which does not  have a direct and smooth edge in the plan view. When the opening length is limited, these side weirs can divert more water out of the channel by increasing the effective length. To evaluate performance of the side weir and estimate the rate of flow passing through it, the Discharge Coefficient should be determined. In this research, hydraulic behavior of a labyrinth side weir with a trapezoidal plan in the single-cycle has been studied experimentally. Upstream Froude number of the side weir was modified in each test and the effects of opening length, height and side angels on the Discharge Coefficient were investigated. The results of the tests were analyzed to find out the effect of defined dimensionless parameters such as length, height and angle on the Discharge Coefficient in subcritical flow. The results obtained showed that in comparison with the normal side weirs the Discharge Coefficient of the trapezoidal labyrinth side weir increased about 15-30 percent. Also, the Discharge Coefficient decreased with increasing the Froude number and side angles and increased with increasing the opening length and height of the weir. In the range of experiments, the angle of 30 degrees gives the highest Discharge Coefficient that is approximately 1.5 times the other angles.