Journal of Water Resources Engineering
Year:2018 | Volume:11 | Issue:38 |Papers Count:11

Precipitation is one of the most important meteorological criteria whose quantity significantly varies throughout the earth. One of the methods to study precipitation trends in the past and present is the analysis of time series in different time scales. In this study, time series analysis was used for modeling and forecasting the average annual precipitation in Shiraz. Accordingly, the annual precipitation data in Shiraz were collected in the time interval 1951-2010. The results of this study indicated that 2. 5, 5, 10, 12 and 20-year cycles cover in the study area and the third Compatible with a return period of 20-years and variance about 12 percent was dominanted in the study area. In the end, to make sure of the trend in the past and also forecasting the future precipitation, the ARIMA modeling was used. Finally, by trial and error in the ARIMA patterns family, a final pattern called M4(0, 1, 1) CON was selected as the optimum pattern in terms of statistical criteria. This pattern has suggested a 1. 44 mm decline in precipitation until the year 2020. According to the results (the decreasing annual precipitation) and according to the climate change as a main topic, a comprehensive planning for the management of water resources unavoidable in Fars province and Shiraz city.

The research in order to identify the best function salinity of sorghum forage yield and harvest time was carried out in the Sistan region. Testing in three levels of salinity (2, 5 and 8 ds/m) and four levels of irrigation water (50, 75, 100and 120% water requirement) were conducted at three time points and four linear production function, cob-douglas, quadratic and transcendental evaluated. for each harvest production function was evaluated separately. Then, considering the time of harvest, evaluated and the best function was determined. After determining the best function to separate effects of salinity and irrigation water from the final production indicators of the depth and salinity of water, Marginal rate of technical replacement for salinity and water irrigation, the final output value of the irrigation water depth and salinity were used in each drawing. Final manufacturing index showed the depth of irrigation water for irrigation to increase water depth of one centimeter per impression, first impression least change operation (1. 22) and third harvest the maximum amount (2. 9) had. Final Manufacturing Index showed to salinity Reduction in salinity low performance in the second and third were less than first impressions and is the second largest fresh forage yield The final replacement rate the quality and quantity of water than fresh forage yield of forage sorghum showed For the performance does not change with increasing salinity units, should be 5. 86 inches in the first harvest, 1. 97 and 1. 72 second harvest third harvest irrigation water depth increases.

One of the ancient hydraulic structure that mankind make it’ s in the past until now is spillway. This structure use for regulator and change the water direction in the rivers. So that this structure must be a stable structure and have good hydraulic performance. The aim of research was simulation Molasadra spillway dam with laboratory scale 1: 40 height and its performance analyzed using different discharge. The result shown that discharge coefficient have average value 2. 1. Meanwhile result of cavitation index indicated have degradation trend and in the large than 1000 (m3/s) discharge, cavitation index reached to critical value with additive trend. Cavitation index in the range of discharge that used in this investigation permanently is more than critical value but with increase discharge the cavitation phenomena is occurred in the end way of the spill way. Minimize and maximize pressure take placed for large discharge respectively in section 4, 9 and 10.

Impact of atmosphere CO2 concentration on crop transpiration and photosynthesis is undeniable. In this study, the impact of increased CO2 concentration on wheat, barley and maize, as the main cereals of the Qazvin Plain, was studied under A1B, A2, B1 and B2 scenarios using the calibrated and validated AquaCrop model. Under these scenarios (increased CO2 concentration, unchanged weather data and the assumption of unchanged level of irrigation water supply), average wheat yield will increase between 11. 5 and 14. 4% for the 2010-2035 period as compared to the 26-year base period (1984-2009). For barley and maize, this average increase will be 8. 5 to 11. 3% and 3. 7 to 4. 3%, respectively. Total crop transpiration will decrease on average by 7, 5 and 1% for wheat, barley and maize, respectively. Moreover, increases in water productivity of the studied crops were estimated as 13, 6 and 4% respectively. These results confirm more significant impact of increased atmosphere CO2 concentration on C3 crops (like wheat and barley) as compared with C4 crops (like maize).

Abstract Spillways are structures used for releasing the surplus floodwater in necessary conditions from storage dams. Ogee spillway is one of the most common and simplest structures. . In this research, a three dimensional flow field over the spillway was simulated with Flow-3D, using two turbulence models, namely RNG and. First, for precise prediction of hydraulic specifications of over spillway flow, the mentioned turbulence models were validated using data gathered from a laboratory flume (Sivakumaran et al., 1983). Data collected from software validation showed that the RNG turbulence model produced better results than. In the next stage, this model was used for simulating the physical prototype of the Nimrod Reservoir Dam. The measurement factors included pressure and water surface profile. The obtained values were compared to the existing laboratory measurements. Results from the simulation were well consistent with experimental measurements. Keywords: Flow Pattern, Nimrod Reservoir Dam, Spillway, Flow-3D, Turbulence Model.

Zayandeh rood River flows from West to East with a length of about 350 km. This river supplies agricultural, municipal and industrial water requirements. 9 sampling stations from different sections of river was selected for evaluation of impact of land use on Water quality parameters in this region and boundary of sub-basin in each station was extracted by ArcGIS and relationship between land use of sub-basins related to each station with water quality parameters was scrutinized. Seasonal sampling was performed from summer 2013 to spring 2014 and to determine water quality, 7 parameter DO, COD, BOD, TSS, PH, NO3, and PO4 was measured. The results show a direct correlation between the decline in water quality and increased use of agricultural and industrial activities in the region. The nitrate and phosphate in stations that have a high proportion of agricultural lands continues to increase The BOD also in Zarinshahr drain, due to high activity of agricultural and industrial activities in this area has been a growing trend. The amount of dissolved oxygen in winter and autumn showed a sharp drop in the downstream stations. Also amount of TSS has increased dramatically in downstream stations in winter. Overall the results showed that water quality parameters over from upstream to downstream areas significantly reduced.

Due to population growth and urban development, need to water increases and comprehensive plan for providing sufficient and good quality of water is vital. The modelling is one of the important tool for management and programming of water supply and consumption. For managing the pressure and velocity in water distribution networks the Gorgan city is divided to different pressure zone based on topography and the storage tank is used in each zone to supply the water. The storage tanks in different pressure zone interact with the others to reduce the difference between water supply and water demands. In this study, the optimum volume of storage tanks are obtained based on MODSIM and metaheuristics PSO models. MODSIM is a water resources management decision support system for analysis of long term, planning, medium term management, and short term operations. The daily data were used during the years of 2012 to 2013 for calibration of model and the results were evaluated based on reliability and vulnerability criteria. The results show that the Zone1 (the northern part of the Gorgan city), Zone 8, 9 and 10 (the southern part of Gorgan) don’ t need to increasing the volume of storage tank in all scenarios for long term operations (2041). The results also showed that the Zone 2 to 7 need to increase the storage tank volume. Among all pressure zone, the Zone 3 is critical zone in term of water shortage and the amount of vulnerability is 11500 cmd(cubic meter per day

Correctly predictions of flow hydraulics and sediment parameters are very important for proper operation and management of rivers. Today, quasi two-dimensional (2D) mathematical models are widely have been used as efficient solutions in flow hydraulics and sediment problems in rivers. In these models, lateral velocity distribution is simulated by numerical solution of Navier-Stokes equations in steady and uniform flow conditions. In this paper, using the quasi 2D mathematical model of Shiono and Knight (1991), the velocity lateral distributions at the river Gharehsoo were calculated. Then using these results and several empirical sediment transport formulas, lateral distribution of bed material load and sediment transport capacity of the river were obtained. The results showed good performance of the quasi 2D model for prediction of velocity lateral distribution with 8. 7 percent relative error. Furthermore, among different sediment transport formulas, Yang and Ackers-White equations have the highest accuracy with mean errors of 45% and 67%, respectively. Larson’ s equation with mean error of 245% corresponds to very low accuracy.

Rivers are the main sources of water for various uses, so consideration of the hydraulic conditions and sedimention is of great importance and necessity to completely investigation. According to complex process of erosion and sedimentation of rivers and river morphology changes in organization design of flood control and design of hydraulic structures, it is necessary to recognize of river characteristics. Karun River in Khuzestan province has meander patterns and also according to the formation of islands and sedimentation of the river within Ahvaz, floods occurred with an increasing in water level. In this study, two-dimensional CCHE2D software use to assuming to cut off the meander in choniebeh and Krishan 2. Results of simulation show that by eliminating of Meanders, Caused to increase the slope of the river and velocity of flow in and thereby increasing power of erosion. According to the model predicted average velocity of flow increased by 50% compared to the existing path, which reduces the deposition in river will be 40%.

The algorithm of Sufrace Energy BALance (SEBAL) is one of the most widely used methods for determining actual evapotranspiration through remote sensing. However, assuming a linear relationship between temperature difference (dT) and land surface temperature (LST) and the visual identifi cation of hot and cold pixels are the weak points of the method. Modified SEBAL (M-SEBAL) on the other hand, replaces two new concepts as hot and cold edges, with a significant impact on increasing the accuracy and automation of the execution of the algorithm and removing the need for skilled user. Although, determining the warm edge requires high computing and thus increase in computing time and possible errors. In this study, a simplified form of the M-SEBAL (SM-SEBAL) is developed and the results of executing of the three method on MODIS images and comparing the results with the observed data are shown. Results show that SEBAL overstimates the ET values and M-SEBAL and SM-SEBAL underestimate the same values. The highest sensible heat flux calculation error comes from M-SEBAL (33. 87%) and SEBAL shows the lowest error rate (11. 23%). The highest error in the calculation of the latent heat (LE) retrives from M-SEBAL (11. 66%) and the lowest error rate retrives from SEBAL (5. 05%). However, the maximum daily evapotranspiration observed error was for SEBAL (3. 56%) and the lowest error was retrived from SM-SEBAL (1. 81%) and then M-SEBAL (2. 47%). In addition, the time required to perform SEBAL algorithm is up to four times more than the time needed to run other two algorithms.

Lateral intakes are one of the most common structures of dividing the flow in irrigation and drainage systems. Due to complexity of the velocity profile in divide zone, measurement of mean flow velocity is become very difficult. In this paper the velocity profile of lateral intakes were calculated whit high accuracy by using of artificial neural network. To do this, the following steps have been taken: (1) Computational fluid dynamic model of lateral intakes in various wide ratios were modeled and validated with a published experimental study. The results shown that the numerical model has high accuracy in modeling the flow of lateral intakes. (2) By using the computational fluid dynamic model, the velocity that measured with a hypothetical flowmeter that placed at the middle of the cross section were extracted. (3) A multilayer perceptron model were designed to predicting the mean flow velocity by using of the flowmeter measured velocity, width ratio and longitudinal coordinate. The results shown that using of combination of flowmeter measurement and artificial neural network could predict the accurate mean flow velocity in lateral intakes.