Journal of Irrigation and Water Engineering
Year:2013 | Volume:3 | Issue:12|Papers Count:9

Water transmission Channels in irrigation networks usually constructed on soils. Geotechnical properties of the soils must be evaluated exactly in channel routs. Fine grain soils that may be swelling, dispersion, collapsible and soluble, can make most problems for channels. If the soil has been a swelling function, its volume will be increase during wetting and it cause to raise and break the channel concrete lining. While the soils have dispersion and collapse properties or contain some soluble materials, its structure will be changed and settled. Then, the channel will be destroyed.This paper evaluate the geotechnical properties of south Roudasht and Mahyar irrigation channels in Isfahan province and Soork irrigation channel in Chaharmahal va Bakhtyari province. As encounter to soluble, dispersive and collapsible soils, we present suitable treatments such as soil exchange, flooding with loading and channels waterproofing.

There are different methods for evaporation estimation that are applied according to the type of application and the required accuracy. Different remote sensing methods have been in the concern of many researchers recently. It is believed that these methods could provide more accurate results in watershed studies. On the other hand, there is an increasing demand for spatial and temporal evapotranspiration estimation. We used SEBAL and METRIC models to investigate the feasibility of their application for Mashhad watershed and also compared the results obtained from these two models. Surface flux was calculated for each pixel by applying these two models and ASTER images, then actual evapotranspiration was calculated as a residual of the energy balance equation. The results showed that SEBAL algorithm underestimates actual daily evapotranspiration in the order of %8.39 in relation to METRIC model. It was also concluded that both of the models are capable to estimate actual evapotranspiration by considering spatial and topographic conditions and also vegetation cover of the catchment.

The use of solar distillation of saline water resources are in areas that are available in many convenient ways to obtain fresh water resources. But the sites that produce waste water and desalination of sea water is much higher salt concentrations. Waste must be disposed of in such a way that the least effect on the acceptor water environment (sea, in most cases). Initial dilution of effluent disposal into the sea and its characteristics play an important role in designing plays. Using the mixing model estimates of initial dilution is very common. In this study the waste disposal site in Bandar Khamir solar desalination using empirical equations have been addressed. Initial dilution related to water depth, diameter, flow rate, the distance between the openings, the velocity of the water is. The most critical with regard to different environmental conditions and the best initial dilution was determined.

Atmospheric General Circulation Models have great scale and weak separate power so downscale stations have used. Therefore for downscale weather generator must be used. Using the output of general circulation models and weather generators can be used to simulate the regional climate. In this study, output data of HADCM3 atmospheric general circulation model with three climate change scenarios, A1B, A2 and B1 is downscale by the LARS-WG model in Kerman. Results has been assessed and analysed from the nine synoptic stations in Kerman in the recent period from 1991 to 2010 and future periods from 2011 to 2030. In LARS-WG model analysis, amount of error and real data evaluated for suitable region way and after that, rain changing, wet and dry spell length was surveyed. The results of the average rain during the next 20 years show that most rain be long Bam and Rafsanjan station with 26.5% and lowest rain belong to Kahnouj station with 11%. Results of this study show that the average annual increase in average annual rainfall is at all stations. Findings showed that during wet and dry spell lengths is growing for all stations in the period 2011-2030 in summer. Although winter rainfall is decreasing, but the average rainfall total is rising.

With construction of storage dams, a large amount of sediments are accumulated behind them. Therefore, water released from the dam is so clear and possesses high sediment transport capacity, which causes the river erosion at downstream the dam. In this research, Polerood river morphological variations predicted in downstream of dam using mathematical models for a short period post dam construction. Then, results were compared with lack of dam existence manner. Results showed that, the presence of the dam causes more erosion in the river. Maximum erosion in presence and lack of the dam were 4.7 and 3.7 m, respectively. The maximum influence of the dam construction on river morphology is up to 10 km downstream from the dam axis. At far distances, river bed variations in both the presence and lack of the dam were the same and the intensity of these variations was very low. The most river variations occurred at early years and variations intensity reduced gradually. Results also showed that erosion and sedimentation in the river is balanced by the time and river will be arrived at a regime case.

Estimating the soil moisture curve has an important role in modeling water movement and solute transport in the soils. Saturated water content is one of the important parameters in soil studies which is used to estimate the soil water retention curve and unsaturated hydraulic conductivity. Pedotransfer functions are as undirected methods which estimate soil time consuming parameters from readily measured parameters. The multi-linear regression and artificial neural network methods were used to develop the pedotransfer functions. In this research, soil texture, bulk density, soil particle density, organic material percent and lime content percent as readily measured parameters and saturated water content as time consuming parameter were considered. In this study, using soil readily measured parameters in 136 soil samples, 14 models of multi-linear regression and 6 models of artificial neural network were evaluated in order to estimate saturated water content. Finally, measured and estimated values of soil saturated water content were compared and each model ability was evaluated by statistical indices. The indices of Geometric Mean Error Ratio (GMER), Akaike's Information Criterion (AIC) and Root Mean Square Error (RMSE) showed that Minasny et al and shinoset et al models had better estimation of saturated water content. The results showed that low content of organic materials had the significant effect on the accuracy of neural network models estimation but lime percent had not the significant effect on the so called models.

Agricultural flood loss estimation is the first step toward non-structural management of rural areas and requires the combination of flood frequency analysis, flood hydraulic simulation and loss function estimation for each growth stage of the crop. Due to the amount of investment and plant resistance, agricultural loss varies according to different growth stages; that is, agricultural flood loss is a time dependent phenomenon. In the proposed algorithm, which is based on the Monte Carlo technique, the chance of the flood occurrence at each growth stage is generated via a repetitive sampling from the Uniform probability density function while an insignificant difference between two consecutive summations of the losses at different stages gives the final total loss. Rice as the main crop of the north of Iran was selected for the study. The results showed that the loss is a non-linear function of the growth stages and increases as follows: transplanting, clustering stemming and harvesting. In contrast to the existing methods that suppose 100% loss for flooded areas, the 100, 200, and 500 return period floods caused losses equal to 21, 27, and 47% respectively.

Surface waters, especially rivers are important sources of water for drinking and farming. Cham Anjir river is a main water resource in Lorestan province. The main purpose of this study was assessment of water quality parameters and routing using graphical methods such as Wilcox, Schoeller and Piper Diagram. Quality and quantity data (1968 - 2010 Cham Anjir station) were analyzed. According to Piper diagram, type of water quality was in calcium-magnesium range. Schoeller diagram showed that all water samples are in potable and acceptable class. Result of chemical water quality analyze by Wilcox Diagram showed that the most samples are located in low salinity class (c2s1) that are suitable for farming. Menn-Kendal test was used for water quality routing. According to results, pH and discharge decreased consequently, acidity of the water increased. A significant increase in other parameters has been observed (such as: Electrical conductivity, bicarbonate, chlorine, calcium, magnesium, residual salts, total anions, total hardness and temporary hardness). Uptrend of water dissolved salts show a reduction in water quality and an increase in soluble salts.

The purpose of this study is using compromise multi criteria decision making for water resources optimal allocation in different districts in Yazd city. Step method (STEM) is used and payoff matrix is calculated to determine weights of two objectives maximum benefits of economy and the environment and then using excel software, programming model is solved. Data were collected from the regional water corporation, the organization of water and sewage, agriculture Jahad, the organization of industry, mine and trade of Yazd from 2001 to 2010. The results indicated that there is a possibility to improve mentioned objectives simultaneously by changing in the weights of programming model and priority is with maximum benefits of economy and then environment. Therefore, it is imperative to consider some policies in order to optimum allocation of water resources.