Journal of Water Resources Engineering
Year:2019 | Volume:12 | Issue:42 |Papers Count:12

The investigations in recent two decades have demonstrated the global sea level rise which is much more related to climate change phenomena and its impacts. In this study the impact of climate change on sea level rise at the southern coastal line of Iran is evaluated. The climatic output data of a GCM (General Circulation Model) named CGCM3 under climate change scenario of A1b was used. Among different variables simulated by this model, those of maximum correlation with sea level changes in the study region and least redundancy among themselves are selected for sea level rise prediction using stepwise regression. Two models of Discrete Wavelet Artificial Neural Network (DWNN) and Discrete Wavelet Adaptive Neuro-Fuzzy Inference system (DWANFIS) are developed to explore the relationship between climatic variables and sea level changes. In these models wavelet is used to disaggregate the time series of climatic variables as well as sea level data into different components and then ANFIS/ANN are used to relate the disaggregated components of predictors and predictands to each other. The results of this study show a significant increase of sea level in future under climate change impacts which should be incorporated in coastal areas management. The selected model (Anfis-Haar), which had a high performance index, showed that the sea level changes from 48 centimeters in the west of the Persian Gulf to 16 centimeters in the east of the Oman Sea. The changes in shallow and enclosed waters appear to be greater than other parts of studied area.

In this article the phenomenon of land subsidence and the resulting cracks and fissures of artificial recharge plan of Hamedan Shahid Mofateh power generation as case study has been investigated. This is an unusual phenomenon and in this research the geometrical properties of the fissures of recharge ponds are measured. The results reveal the existence of fine layers in the geology of the aquifer, which are displaced in the long run as the consequence of groundwater overdraft. Sand making of some of the water wells around study area is proof of this claim. At the site of the artificial recharge subject of this research, the difference between the quality of recharge water and the aquifer and their interaction have intensified the instability and the movement of the fine sediments. In addition, the neglect of hydraulic principles of the groundwater during the construction and operation of the recharge wells has resulted in turbulent and speed flows, intensified displacement of fine sand and ultimately the localized subsidence at the site of the plan.

Routing is one of the oldest methods for calculating output hydrographs. Dynamic wave dynamics is one of the most complex and precise methods of routing, which is accomplished by solving a complete number of Saint Vincent's equations. With regard to the flow hydrograph of a stream as problem information and flow path characteristics, the equations of Saint-Venant and the finite difference method were solved and the input hydrograph was calculated. This method was investigated as a reverse order and its results were compared with laboratory observations. An uncontrolled flow was created and, regardless of the path loss, the laboratory was taken and laboratory data was controlled with the program written for adjustment. Then, using the statistical parameters of the obtained results, it was examined and shown that the created model for calculating the input hydrographs has high accuracy. The results of the reverse routing analysis of the tested hydrograph showed that there is good agreement between the program outputs and experimental observations, which resulted in a relative error of maximum 5% in hydrographs 4 and 5. Also, in this study, increasing the amount of discharge flow increased the error rate, which reached the lowest value in the hydrograph 9. In general, this method has high accuracy for laboratory fluxes less than 40 liters per second.

Weirs are usually constructed by concrete and are impervious so that the water can only flow above the crest. In this between, Gabion weirs with instinctive characteristics including stability, conductivity and economic justification are strongly advised. In this study, the effects of material size, upstream and downstream slopes were investigated on the discharge reduction factor of gabion crump weirs under submerged flow conditions. For this purpose, 8 models of gabion weirs and 3 models impervious weirs constructed in a horizontal flume with 15m long, 0. 3m wide and 0. 5m deep. The tests were carried out for different variables, including discharge, upstream and downstream depths, material size and upstream and downstream slopes. The results showed that the flow reduction factor decreased as the ratio of the upstream depth to the downstream (Y2/Y1) increased. For a constant ratio of Y2/Y1, the flow reduction factor decreased when upstream or downstream slope increased. It was found that the material size has no significant effect on the flow reduction factor. Based on regression analysis, an empirical equation was developed for estimation of the flow reduction factor which its correlation coefficient variation was in the range of 0. 79 to 0. 96.

Prediction of surface and subsurface runoff as elements of direct runoff of catchment is very important for designing hydraulic structures. In many of the catchments with high permeability and suitable vegetation, subsurface flow is also highly important. In this research, Hortonian mechanism has been used for predicting surface runoff of catchment overland using Kinematic wave method. For prediction of subsurface runoff of catchments hillslopes, Richard equation in an unsaturated zone by means of Hydrus software was used. Runoff hydrograph of subsurface runoff was calculated. For verification, experimental data from rainfall simulator with length of 2 meters, width of 1 meter and depth of 0. 35 with loamy sand was used. The experiments were conducted under three angles of 0. 1, 6. 3 and 9 degrees and under rainfall intensity of 31. 73, 47. 6 and 63. 46 millimeter per hour (mm / h), respectively. The subsurface and surface flow of the system were compared with the results of the kinematic wave in the surface flow and the results of the Hydrus model in the subsurface flow. The peak runoff mean error predicted by the kinematic wave method in the 12 events calculated is 3. 5% and the mean prediction error of the subsurface runoff peak in 9 events is 10%, which is an acceptable value. The results of the Hydrus model for predicting the slope of zero tilt angle had 40% error in calculating the subsurface runoff peak that has not been acceptable.

Using flip buckets as a part of the flow dissipaters in vertical case in dams would lead to dissipation of the energy from the flood passage. This structure is used to reduce costs in comparison with other energy dissipaters. Water jet collision with the river bed leads to the creation of scouring hole which can reduce the stability of dams and relevant structures. In the present study, the scouring phenomenon of the downstream of a flip bucket in free conditions and also in the presence of slots with rectangular and triangular shapes in various intervals distances with 9 flow rates and a total of 45 tests have been investigated. The results of this study showed that the presence of a slot would have a lot of effects on the depth and extent of scouring, so that a flip bucket with alternate rectangular slot compared to a non-slotted case causes about 13 percent less scour. Also, the maximum scour depth in bucket mode with alternate rectangular slots occurred in a more favorable range than the rest of the models. Then, the obtained results were compared with a number of empirical formulas and it was determined that Martinez B relation provides closer results to real values.

One of the most important factors in pipeline hydraulics and its protection against probable damages is keeping the pressure in a specific limit and also knowing how the pressure functions in the pipe through the pipeline route. Pressure function and pressure amount differ from each other regarding the phase of the fluid (single phase or multiple phase), and when gas phase (air) enters the pipeline, it affects the flow regime (simultaneously when gas-liquid flows there are such regimes as stratified, slug, etc. ) and the applied pressure. The present study aims to investigate the effects of flow patterns and phases on maximum pressures along pipelines and to compare it with those of single-phase flows. Results show that the geometry and the percentage of entrained air are the main factors affecting flow patterns and pressure experienced by pipeline systems. For single phase mode, pressure is increased up to 26% in vertical upward flows compared to air-water flows with a different air percentage. Moreover, among various geometries considered in this research for two-phase flows, pressure at most has a 23-percent increase compared to that of single-phase flows.

In this research, by considering the variable-speed pump, the effect of speed on pump performance, network hydraulics and energy consumption in a water distribution network in both single-objective and multi-objective models was investigated by using the new G-JPSO algorithm. The objective function in the single-objective problem is to minimize the amount of energy consumption throughout the day, and the decision variables are the amount of pump rounds in different hours of the day and night. In the multiobjective optimization problem, the first goal was to minimize the cost of consuming energy and the second goal was to maximize the hydraulic reliability. In order to determine optimal pump operation program, an optimization-simulation model based on G-JPSO optimization algorithm was developed. In this model, the algorithm was integrated into the MATLAB environment with the hydraulic part of the EPANET model as the reference of the commands and information. The proposed model was used in the Vanzyl distribution network and the optimal exploitation instructions were extracted and the results were compared with the JPSO algorithm and the ACO. The results of the paper showed that in the single-objective problem, the G-JPSO algorithm's results are 3. 28 and 0. 38 percent better than JPSO and ACO, respectively. In general, the energy consumption of variable-speed pumps was lowers the constant-speed pumps. In a multi-objective problem, in all optimization scenarios, the G-JPSO algorithm was able to achieve points in comparison with the ACO algorithm, which, in addition to cost reduction, has higher reliability.

The emitters are the most important part of drip irrigation systems, so the evaluation of the hydraulic performance of drippers is very important to have an efficient irrigation system. Therefore, in this study, 8 Trickle Tube with in Line Emitter, 6 model of non-compensating and 2 model compensating was tested on the constructed physical model of trickle irrigation in the water laboratory of University of Kurdistan. Experiments in 4 different water temperatures of 13, 23, 33 and 43 ° C was investigated on the models in different pressures ranging from 0 to 1. 2 times the maximum pressure. The results showed coefficient of variation manufactured of all models excluding 3 models were at the highest level of quality at all temperatures. The percentage flow rate measurements error, were good in the 4 models, acceptable in the 2 models, the average degree in the 1 model and unacceptable in the 1 model. The emission uniformity of all Trickle Tube with in Line Emitter excluding 2 models were excellent or good at all pressures and temperatures. In all Trickle Tube with in Line Emitter, Christiansen uniformity coefficient was more than 70 percent in the all models. The coefficient of variation of the discharge Trickle Tube with in Line Emitter, were in the ranging from 7. 7 to 37. 2 percent and was two models good, 4 model acceptable and 2 model unacceptable. In summary, the overall condition tested Trickle Tube with in Line Emitter in terms of production quality hydraulic indicators are desirable assessed.

Detention rockfill dams are one of the structural methods that can control flood risks with no impermeable core or membrane. These dams decrease the maximum discharge of flood hydrograph and postpone the time of its occurrence reducing life and financial losses in downstream. In this research study, maybe for the first time, a new methodology based on Multi-Layer Perceptron (MLP) artificial neural network meta-model and genetic algorithm optimization model is proposed for optimum design of detention rockfill dam. Hence, results of experiments done on the rockfill dam model, from Khorramshokouh (1391), are used in order to train and validate the MLP neural network model. The MLP neural network model is in fact a meta-model of simulating the hydraulic performance of detention rockfill dam which is linked to genetic algorithm optimization model to determine the optimal features of detention rockfill dam regarding the relationship between design variables and flood hydrograph passed through the porous media. Results of the proposed methodology depict that for the total discharges of probable floods, the optimum thickness of detention rockfill dam and the mean diameter of rockfills in the porous media are 17. 6 cm and 2 cm, respectively. Also, in the optimum state, the peak discharge of flood hydrograph has 47. 18% reduction and flood duration increases 39. 94%.

Climate change impacted of the amount, timing and type of precipitation, also was impacted on water quality, increased droughts, increased demand for water, changes in the management of water resources, as well as sea level rise and its complications. Climate change also had great influence on the temperature changes so that maximum and minimum values and extreme temperature. The aim of the present study was to evaluate the impact of climate change on rainfall, minimum and maximum temperature use with 15 of atmospheric general circulation model under two scenarios A1B and B1 in the period 2039-2011. For this purpose, the use of beta statistical distribution of rainfall changes, minimum and maximum temperatures were calculated from 15 general circulation model, the probability of 20, 50 and 80 percent, respectively. The results showed that the probability of 20 to 80 percent under both scenarios A1B and B1 minimum and maximum temperatures are rising and the rain is falling. The minimum and maximum temperatures under A1B increased more than B1 scenario and precipitation reduced under B1 more than A1B scenario. The results showed that 19 to 22% decrease in precipitation and minimum temperature of 13 to 20% and a maximum temperature of 2. 4 to 6. 4 percent increase compared to baseline the Tuyserkan catchment.