JOURNAL OF WATER AND SOIL RESOURCES CONSERVATION
Year:2016 | Volume:5 | Issue:2|Papers Count:7

Increasing irrigation efficiency has been become one of the main solutions to be considered on-farm increasing water productivity due to limited water resources. The objective of this study was to apply a seasonal simulation model to determine irrigation performance indicators for different scenarios such as deficit irrigation, inflow rate and frequency of irrigation, under two different fields in Karaj (College of Agriculture and Natural Resources and Seed and Plant Improvement Institute farms) in order to decrease irrigation losses and improve irrigation water uniformity. The results showed that the College farm had more runoff losses due to heavier soil texture and shorter furrows compared with to the Institute farm. Irrigation efficiency increased when reducing inflow rate and frequency of irrigation, irrigation efficiency increased about 40% in the higher irrigation frequency by reducing inflow rate from 0.64 to 0.22 L/s. In addition, the highest efficiency happened in three-day irrigation frequency with 0.22 L/s inflow rate. However, the Institute farm had larger deep percolation losses than the college farm. Moreover, the results of simulated soil moisture during the growing season showed that the difference between the minimum and maximum soil moisture was less under lower values of inflow rate and irrigation frequency (such as three-day irrigation frequency and 0.3 L/s inflow rate in the Institute farm and three-day irrigation frequency and 0.22 L/s in the College farm). The seasonal simulation model had good capability to evaluate furrow irrigation performance under different on-farm water managements.

Incorrect designing of earth and rockfill dams with untrue safety factors causes internal scouring, downstream pitched roof submerged and break dam in torrential times. Breakage of earth and rockfill dams and also too much volume of torrential flow can destroy catchment areas and fen beds. Furthermore, correct designing of dams and obtaining suitable safety factors will prevent of these damages. In this study, first of all, series of geotechnical tests have been performed on the soil samples of the Chitgar earth dam to determine the soil strength parameters and material characteristics. The achieved parameters have been used as input parameters for PLAXIS which is a finite element geometrical program for analysis of deformation and stability of soil structures. Based on different layers of foundation and dam body, four homogeneous and non-homogeneous models on coarse and fine foundations have been simulated and the results have been compared. These comparisons revealed that during construction of earth dams, which are situated on fine clay foundation, if the water level is high, there would be lots of pore water pressure which will cause the dam foundation to be destroyed. Therefore, dam must be constructed using step-by-step method so excess pore water pressure can have enough time to be lessened. The analysis, which carried out on non-homogeneous earth dams with clay cores, discovered that if dam construction is simultaneous with water filling, there would be high pore water pressure in the earth dam’s core which will reduce the safety factor of the dam. Therefore, it will be better if the non-homogeneous earth dams are filled after the construction period. Finally, sometimes in loose foundation, safety factor was found 1.45 for homogeneous dams in the stepped construction. The safety factor was estimated 1.14 non-homogeneous dams in the same conditions. Therefore, homogeneous dam can play better role than non-homogeneous dams in loose foundation.

Conservation of surface water and groundwater resources need to be applied appropriate strategies and policies in this context that more understanding of farmers' behavior is vital. Therefore, in present study used of positive mathematical programming (PMP) and production function with constant elasticity of substitution (CES) approach to investigate farmers' behavior in surface water and groundwater usage and determination the appropriate policy programming to conservation of Qazvin plain water resources. The investigated strategies include increasing the price of irrigation water and reducing the availability water resources that each under the various scenarios was investigated. The required data in this study are related to year 2011-2012 that by referring to the relevant departments in Qazvin province was collected. The results showed that each two investigated approaches in this study leads to saving irrigation water, but the changes mean of gross margin by applying the availability water reducing policy and increasing the price of irrigation water policy 15.94 and 27.61 percent decrease respectively. The economic irrigation water productivity also in condition of above policy implementation changes of 0.435 to 0.331 and 0.434 to 0.230 the thousands of cubic meters respectively. Therefore, the reducing water availability policy according to the less reduction of the gross margin resulting from cropping pattern and more economic water productivity was proposed to conservation of Qazvin plain surface water and groundwater resources.

Optimal operation of local resources can be effected in conservation water resources of paddy fields and corrected water distribution. Therefore, in this study, a simulation-optimization model of exploit ponds has been developed for investigate the role of ponds to store local water and use it to supply irrigation water requirement of paddy fields. Evapotranspiration, irrigation water requirement, irrigation interval and pond balance were simulated and then number of canal intake, storage volume and released volume of pond were optimized by binary genetic algorithm. The developed model was applied for Fashtam pond in Sangar, Gilan province. The result showed that in normal year 54% of irrigation requirement of paddy fields were supplied by rainfall and runoff water saved in Fashtam pond and the rate of over flow water of pond to maximum volume of that were 74%. The model result for scenario of increasing pond storage two times showed the rate of pond in supplying irrigation requirement of paddy fields is increased to 91%.

Flood warning systems are the important and effective approaches to prevention or mitigation life and property loss in any flood event. All flood warning systems use one or more flood event indicator such as climatological signals. Rainfall threshold curve is one the conventional flood events indicator in many flood warning systems. In this respect, observed or forecasted rainfall was compared with rainfall threshold to notify flood event. Application of some assumptions like constant rainfall patterns and rainfall-runoff model parameters such as loss and base flow is known as the main drawback of using conventional rainfall threshold curves. This study has considered uncertainties of rainfall-runoff model parameters and variables for extracting rainfall threshold curve, while solving shortcomings of the previous works. Results of this study demonstrated that extraction of the rainfall threshold curves by considering uncertainties of the mentioned variables and parameters represents a very higher accuracy respect to conventional rainfall threshold curves.

The runoff and soil erosion is most basic of environmental, agricultural and food production problems in the world, that these had adverse effects on the natural ecosystems and man-managed. One of the most important factors of runoff and soil erosion control is using organic and inorganic mulches, that they have most role in runoff and soil erosion control. Therefore in this study, for studying time to runoff and runoff coefficient changes used from an organic mulch (wheat straw mulch) in laboratory conditions. The experiments was done using rainfall simulation, in slope of 30% and plot scale of 0.5 m2 with 3 replications, with two cover percent of 50 and 90% and rainfall intensities of 50 and 100 mm h-1 for 10 min and then the time to runoff and runoff coefficient rates measured. The results showed that in rainfall intensities of 50 and 90 mm h-1, the conservation treatment could increase and decrease time to runoff and runoff coefficient, respectively and the cover of 90% had more effect in increasing time to runoff and decreasing runoff coefficient. The enhancement percent of time to runoff in rainfall intensities of 50 and 100 mm h-1 (cover of 90%) was 102.37 and 70.80%, respectively. The reduction percent of runoff coefficient in rainfall intensities of 50 and 100 mm h-1 (cover of 90%) also was 36.58 and 27.31%, respectively. The effect of conservation treatment and rainfall intensity variables evaluated significant expect in the effect of rainfall intensity × conservation treatment.

Quality and quantity of water and soil are main goats of sustainable agriculture in Iran. Therefore, in this study aims to integrate environmental objectives including reducing water use, fertilizer and chemical pesticides, with increasing the gross margin (revenue) and gross margin was risk or variance. The data used, including the pattern of production, inputs and price of each of them were randomly selected from among the designated beneficiaries. Data used in the production model, inputs and price of each of them were randomly selected from among the designated beneficiaries. In compiling the annual gross margin period of risk of 1998-2013 was used in the province. Given the vast difference between the scale of activity, beneficiaries using the cluster analysis based on scale activities were divided into two groups. The study indicated that the environmental objectives and targets policy makers, operators are swapping and It is necessary to choose a combination of policy planning motion.