JOURNAL OF WATER AND SOIL RESOURCES CONSERVATION
Year:2014 | Volume:3 | Issue:4|Papers Count:6

Development of pressurized irrigation systems is of great important from optimal water resources point of view. The objectives of this study were to investigate the influence of pressurized irrigation systems development scenarios on agricultural sustainability in Varamin, and to study the effect of government facilities on development of these systems. This study developed a system dynamics model for water resources management in Varamin, Iran. Results indicated that unplanned development of pressurized irrigation systems not only didn’t save the water resources, but it resulted in damaging groundwater resources. Result also indicated, while using surface water resources, if cultivated area did not increase, then development of sprinkler systems leads to increase national income and groundwater level, otherwise with increase of cultivated area results in reduction of gross national income. Development of sprinkler systems leads to improvement of groundwater quality and quantity level with and w/o cultivated area increment, thus, development of sprinkler systems can help to sustainable development only if cultivated area remains constant and water consumption reduces. To achieve sustainable agriculture, it is proposed that the granted governmental facilities to farmers be prioritized. This means that governmental facilities for irrigation development be granted to groundwater users in first priority, the development of micro irrigation systems (type and diameter) due to reduce evaporation, in second priority, mechanized surface irrigation systems, new sprinkler irrigation systems as LESA in the next priority.

The largest amount of water in Iran is used in agricultural sector. Thus, efficient use of water in this sector will be significantly effective in maintaining water resources and optimum use of available water. In many regions, surface reservoirs are responsible for providing water to downstream agriculture. Optimal operation of reservoir is one of the major parts of surface water resource optimization. So far, several optimization approaches have been used, among them, the most popular methods are Evolutionary Algorithms. In this study, Firefly Algorithm (FA), as a new method, was proposed for optimal operating of Bazoft reservoir. The operation modeling was carried out for a period of 120 months related to 1986 to 1995 years. The considered objective function was defined as minimizing the sum of squared differences between the demands and the release from the reservoir divided by maximum demand during operation. The model performance was examined compared to Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). These two mentioned algorithms are known as common and standard methods. The results indicated that firefly algorithm can better perform than other methods. The mean value of the objective function of this method was 0.408, and the mean of the objective function for the GA and PSO were 0.618 and 0.913, respectively. In addition, FA has created less deficiency values and milder deficiency compares to GA and PSO.

Assessment of interactive effects of salinity and nitrogen deficiency is of great importance for optimal management of soil and water resources in arid and semi-¬arid regions. The objective of this study was to model canola (Brassica napus L.) response to salinity under nitrogen deficiency conditions. For this reason, the soil fertility models including Liebig- Sprengel (LS) and Mitscherlich- Baule (MB) that are originally proposed for nutrient deficiency were derived such to account for simultaneous salinity and nitrogen deficiency. To obtain the required data and to assess the proposed models, an extensive experiment was conducted by different levels of salinity and nitrogen. The experimental treatments were consisted of five levels of none saline water, 3, 6, 9 and 12 dSm-1 and four nitrogen levels of 0, 75, 150 and 300 mgKg-1. Some statistics including maximum errors, root mean square error, modelling efficiency, coefficient of determination and coefficient of residual mass were used to evaluate the three proposed models. Results of these statistical analyses indicated that the proposed LS-based model can provide better estimates for relative grain yield in different nitrogen levels. The proposed MB-based model, in the salinity levels of irrigation water and interaction of salinity and nitrogen levels provided better results. It can be concluded that the proposed models can predict the interactive effect of salinity and nitrogen deficiency reasonably well.

Water quality management is a key element for maintenance of sustainable irrigation systems. Index-based appraisal of water quality can be used to demonstrate progress towards the targets, by plotting trends in the temporal and spatial variations of water quality. This study aimed to evaluate the water quality of Darreh-rood river located in Moghan region (NW-Iran) for irrigation purpose, using CCME-WQI model. Consequently, four sampling points were selected to collect the river-water samples on a half-yearly frequency sampling related to low and high flow basis (2 times year). Water samples were analyzed for 30 parameters including basic physicochemical, nutrients, biological and heavy metals. Afterwards, levels targeted by researchers along with measured parameters, were included in the model. Three factors including F1 (scope), F2 (frequency) and F3 (amplitude) were determined and normalized. Results showed that the suitability of river water quality for irrigation purpose is in class B (categories: Good and Good/Fair), during low-flow and high-flow periods, respectively. In conclusion, the consequences of this model as a diagnostic tool, necessitates to be considered the best management practices (about 12 to 18 percent BMPs) for conserving and improving the river-water quality and to develop future sustainable mitigation plans.

Using pressurized irrigation is one of the most effective practices for conservation of water resources. Emitters clogging are the most important problems in operating drip irrigation system which reduces the emission uniformity and irrigation efficiency. Evaluating the anti-clogging performance of emitters and clogging thresholds, are the first and most important step in optimal design of irrigation water filtration system. The objective of this study was to evaluate the physical anti-clogging performance of three types of pressure compensation emitters including Micro flapper, Corona and Eden in laboratorial scale. For this purpose, a physical model of drip irrigation system with water and sand mixing tank was established and the discharge rate of emitters by various concentration and particle sizes was measured at eight phases. The average discharge, clogging rate and uniformity coefficient indices were calculated for the three types of emitters in different phases. The result showed that Corona and Eden emitters with 12 and 37 percent of clogging rates have the best and worst performances, respectively. The results also indicated that the uniformity coefficient of corona emitters is larger than 95% in all phases during the experiment. Based on the results of the study, Corona emitter stand as the best physical anti-clogging performance and it can be recommended to be use in farms and gardens.

Soil erosion is one of the most challenging issues in optimal conservation of soil and water resources. Land surface cover affects runoff production and soil loss processes. Nowadays, miscellaneous amendments and conditioners are being applied to conserve water and soil worldwide. However, the role of environmentally friend and available organic amendments has been rarely considered. This study was therefore taken place in order to assess the effect of rice straw (0.5 kg m-2) on runoff volume and soil loss on a sandy clay loam placed in three small plots (0.5´0.5´0.3m) with 20% slope steepness using rainfall simulator. The study plots were then subjected to 50 and 90 mm h-1 rainfall intensities for 15 minutes after spreading rice straw on the soil surface. The results showed that the rice straw treatment under 50 and 90 mm h-1 rainfall intensities and in comparison with control plot reducing the runoff about 90% and 96%, respectively. In addition, soil loss was completely controlled in treated plots and under both studied rainfall intensities. All differences were found statistically significant at 1% significancy level.