Iranian Journal of Irrigation and Drainage
Year:2017 | Volume:10 | Issue:6 |Papers Count:14

Systems monitoring and mitigation measures defined in the main component of drought management plan and link between these two can be a timely and effective implementation of program management in relief operations to help. This study is an attempt to design such a system with the use of a probabilistic approach. In this approach, drought alert thresholds based on reservoir storage volume and the probabilities are defined. A simplified model of the water resources system is built to assess the threshold values and the management rules.short term simulations are carried out using the software package WEAP. Threshold values are identified considering the probability to assure a given fraction of the demand in a certain time horizon. The results of reservoir-deficit/risk curves in the study area showed, Alert levels Can be considered Between the curve risk 25% and deficit 15% and the curve risk 70% and deficit 30%. Also the reservoir-deficit/risk curves show that in each month of the year, for volume of 108 million cubic meters, deficit greater than or equal to 654 million cubic meters until the next year will occur.

Iran's influential role in intensifying water scarcity water crisis, especially in arid and semi-arid plains such as Birjand, South Khorasan province is, that only by relying on groundwater resources to agricultural production occurs. In this study by groundwater balance modeling, the required equations for estimating fluctuations of the water table levels have been determined; Then the objective function based on the concept of virtual water is the function Stewart, was created. Then, because too many variables in the objective function in the optimization of water use, using heuristic and intelligent Genetics (GA) which requires fewer calculations than the other methods are more efficient, optimized crop pattern and density studies Plains 4 the scenario was set. Results showed areas of crops cultivation were not optimized and water use in agriculture is not appropriate to the circumstances of Birjand plain. Given those results the best answer among of the scenarios is the fourth scenario, because profitability not only has increased 4times, but also reduces the amount of water to approximately 8%.

Nitrogen fertilizers used in agriculture are a source of environmental and water resources pollution and using simulation model to recognize its cycle could be important role to control and reduce environmental pollution. In paddy fields, nitrogen has complex cycle due to irrigation management and submerged condition. In this study, HYDRUS model was used to simulate and study nitrogen cycle under different fertilizer management treatments including 24, 48 and 72 hours remaining duration of fertilizer and releasing it by runoff. Micro lysimeters were used for simulating the nitrogen cycle in paddy field. The soil texture of this experiment soil was silty clay loam and after applying the urea fertilizer and treatments of the research, ammonium, nitrate and nitrite concentrations were measured for 4 months (June to September) at depths of 15 and 30 cm. Changes rate of ammonium to nitrite, nitrification and denitrification was obtained more at depth of 15 cm than depth of 30. Model could be simulated ammonium and nitrate more accurately than nitrite so that correlation coefficient of simulation were 0.79, 0.70 and 0.60, respectively. At a depth of 30 cm changes rate of ammonium to nitrite did not affect by fertilizer management treatment.

Drought is called to a long period of time that an insufficient amount of rainfall to be revealed and dry weather lasts for a long time. Drought is abnormally low and long term moisture that has adverse effects on plants, animals and human. In this study, the accepted definition of climate drought is periods of precipitation that is lower than average. Actually, this is” the comparison between lack of rainfall and its long-term average”.Because of the importance of drought in water projects, in this study, we investigate the frequency of drought for period of last thirty-years ago on Karkhe basin in Lorestan province. After checking the data, or data quality of statistical errors was to evaluate quantitative data. To reconstruct the missing data, Aystgah Ha with full statistics, position and altitude of the stations with incomplete statistics were used. Drought frequency is the most important feature for studying in a region that considered which can be different in scales of time (yearly, monthly, quarterly). In this study, we investigate rainfall data from eight meteorological stations for thirty years in KARKHE basin in different months to evaluate drought frequency. These data about the amount of thirty years of the rainfall have been prepared from meteorological of LORESTAN province. Although, the operation of review and restoredata is in processing. Buffering method and Excel software was used for the project.

The objective of this study was to evaluate SIMDualKc crop model and then simulating different scenarios of surface residue cover. This model estimates evapotranspiration with dual crop coefficient approach. Therefore, that enables investigation of various mulch effects on evapotranspiration amount. Five management scenarios (organic mulch with densities of 0.2, 0.3, 0.4, 0.5 and 0.6) were simulated with SIMDualKc crop model during the 2001 and 2002 growing seasons. SIMDualKc model calibration and validation was performed with the results of 2 years data obtained from wheat field experiments located in Aboreihan University College of Tehran University. Then, climate, soil, crop and irrigation management data were inserted into model. The model estimated soil available water with model efficiency (EF) of 0.902 and calculating the following evaluation criteria: RMSE=1.34 mm, absolute error=0.955 mm and mean relative error=4.67 %.with lack of required data for calibration, using FAO-56 standard crop and soil evaporative parameters resulted in reasonable accuracy.Various scenarios of crop residue mulch simulation results showed that with increase of organic mulch density, the ratio of evaporation to evapotranspiration (E/ET) decreased and transpiration rate increased. While ratio of E/ET was 18% w/o crop residue mulch, by applying organic mulch with density of 0.6 Kg/m2 decreased to 8%.

Parameter uncertainty arises uncertainty in the result of model performance and prediction of a system behavior. Therefore uncertainty estimation into modeling is inevitable. This study aimed to analyze and quantify amounts of uncertainty in model parameters of Bojnurd aquifer with an area of 65.2 km2 due to the highly uncertain available data and the increasing importance of Bojunrd aquifer caused by the expansion of its urban areas to the plains. A steady-state groundwater flow model of Bojnurd aquifer was developed and calibrated employing ten years of data (1380-1390) and 11 observation wells. The prior distributions of model parameters including hydraulic conductivity and recharge were assumed uniform and uncertainty bounds and posterior distributions were derived within the generalized likelihood uncertainty estimation (GLUE) framework. The results showed high amounts of uncertainty in recharge parameters. The pre and posterior distributions does not showed a significant change. Hydraulic conductivity as the most sensitive parameters, reduced the uncertainty of the model output. Most of the observed head values fall within 95% confidence interval and only a few number of points were out of it. It can be concluded that the GLUE approach has been successfully applied to Bojnurd MODFLOW model and the modeling results are reliable to decision makers for water resources management projects.

Due to the water crisis in Iran, the application of a greenhouse cultivation of optimum use for the water resources is expanding. The main objective of this research is to determine the frequency and amount of proper irrigation water in the cultivation of greenhouse tomato (cv Falkato).For this reason, an experiment was performed in completely randomized block split plot experiment design at three replications. Irrigation frequency as main plot consists of daily, two and three days. The effect of irrigation interval on a constant basis daily, two or three days once were imposed and treatments of irrigation water levels in the first year, 75%ETc, 100%ETc and 125%ETc and in the second year 50%ETc, 75% ETc and 100%ETc were considered. Results showed that the effect of irrigation frequency and levels on tomato yield and some quantitative variables were not significant. Although the yields showed reduction with increasing irrigation frequency. The least average weight of a tomato belonged to three days frequency. The highest value of WUE in the first and second years was observed in 75% ETc and 50%ETc irrigation level. Differences between the water use efficiency in irrigation frequencies was not significant. The interaction between irrigation frequency and levels showed in the first year the highest yield occurred in 100% and 125% ETc irrigation levels and 2 days irrigation frequency and the least yield occurred in 2 days irrigation frequency and 100% ETc. Mean comparisons of interaction between irrigation frequency and levels showed the highest yield in the first year occurred in 100% and 125% ETc of irrigation levels and intervals 2 days and the least for 3 days and 100%. Also in second year, the highest yield related to 75% ETc irrigation level and 2 days irrigation frequency and the lowest were related to 2 days irrigation frequency and 50% ETc, respectively. According to the results, two or three day irrigation frequency can be used instead of daily irrigation. Leaching is needed when irrigated with 75% ETc irrigation level.

An important factor in increasing the scour around bridge piers is the accumulation of debris and trees. The effect of discharge, water depth, location of the debris, thickness, diameter and shape of the debris on pier scour been studied experimentally.45 samples in the laboratory hydraulic and hydraulic structures, water engineering shahid Bahonar University of Kerman. The results showed that the maximum scour depth increases with increasing water depth less discharge occurs. The thickness and diameter debris on pier scour effective and maximum scour depth increases. The location of debris on the scouring effect. If the water level up to the debris hsub, Water depth is h, In the range 0< hsub/h<0.3 with debris submerged increase the scour depth increases. For hsub /h>0.3 scour reduced by increasing the submergence. The shape of the debris can affect scour, debris rectangular, cylindrical and triangular respectively scour more. Accumulation of debris such as branches and trunks of trees around the pier of the bridge scour increases about 90%.

Temperature and precipitation are two main factors of climate and their variation may lead to change the climate of every region. For this reason, investigation of rainfall and temperature trend, in different temporal and spatial scales, forms a large part of climatology and water resources engineering researches. In this study, trends of temperature and precipitation of the NW of Iran (10 synoptic stations) were examined in monthly, seasonal and annual time scales in the period of 1961-2010 using the Mann-Kendall method after the removal of the effect of all significant autocorrelation coefficients. The Sen's slope estimator was used for determining the slope of temperature and precipitation trend line. Results showed that there is a positive trend in the most of months for the NW of Iran's temperature. The most numbers of stations with significant positive trend were observed in April and September. In the case of precipitation, the monthly series showed a decreasing trend. In seasonal time scale, summer, winter and autumn seasons have experienced the highest increase in temperature, respectively, and spring and winter seasons have the highest negative rate in precipitation. In annual time scale, 60% of stations have experienced a significant positive trend in temperature which it led to a negative trend in precipitation of 70% of considered stations. In average, across the North West of Iran in the recent half of the century, the temperature increased about +1.20oC and the precipitation decreased about -88.9 mm.

In recent years, the single ring Beerkan infiltration experiment has gained increasing attention as it is cheap and simple to implement. The BESTslope, BESTintercept and BESTsteady algorithms were developed to estimate the soil hydraulic properties (e.g. saturated hydraulic conductivity (Ks) and sorptivity (S)) through the Beerkan infiltration experiment. The purpose of this study is to compare these algorithms for estimating hydraulic properties, retention curve and hydraulic conductivity curve. For this purpose, 40 Beerkan infiltration tests were carried out in an experiment field in Sistan dam region. The negative and positive values with a relative error (Er) of more than 5.5% were eliminated and a set of 31 experiments in soils with loam and sandy loam textural classes was selected for the rest of analysis. The results showed that the BESTsteady algorithm has the simplest calculating process and the Ks and S values as well as water retention and hydraulic conductivity curves estimated by this algorithm were similar to those obtained by the original algorithm with an acceptable accuracy.Therefore, it could be concluded that in soils with loam and sandy loam textures, the BESTsteady algorithm is an appropriate alternative, which could be applied instead of two other algorithms.

Scarcity and excessive water use in agricultural sector is one of the most important challenges of planner and policy makers. So that water demand management has been introduced as a new approach and then considered water pricing as one of the most important tools. Using of water policies to water resource management not only impact on water demand, but also will have the economic, social and conservation effects that should considered.In this paper, were investigated the economic, social and conservation effects (opportunities and threats) of water pricing reforms policies in case study Mashhad- Chenaran. To achieve this objective, first calculate the final price and value of water marginal product to make scenarios of water price. Then, using of positive mathematical programming and maximum entropy approach to investigate the economic, social and conservation effects of impose designed scenarios in two groups of farmers that theyare low and high water user. The results of this study showed that current price is very lower of final price and value of marginal product. On the other hands, achieve to water price that covering final price and value of marginal product have negative impact on income and profit of farmer and reduction of employment in the region although this policies has positive effect on water consumption management especially in higher prices. Also, the results showed that current water price cannot remove the negative balance of water, while determination the water price equal to the cost of water supply and value of marginal product can remove this problem respectively after 3 and 6 years. According to results, the effects of water pricing policies has suggested as the complementary policies to support of farmers.

Implementation of subsurface drainage in Northern Iran paddy fields is crucial to achieve the feasibility of round-cropping and improve sustainable use of limited soil and water resources. One of the subsurface drainage systems is bi-level system that can be installed because of lower costs than conventional and better control in drains discharge. Installation of this system needs suitable knowledge of designing of subsurface drainage systems due to layered soil of paddy fields. In this study, an analytical solution of two dimensional transient saturated flow of Bear equation to subsurface drainage in a paddy field is presented to investigate the bi-level drainage systems operation. Also, due to importance of vertical head in clay and layered soils, a modified procedure was performed to separately involve vertical head. Validity of the solution has been evaluated by comparing with the field data collected at paddy fields of Northern Iran. The two dimensional solution was not able to reasonably predict the water table profile. But the obtained results indicated that considering the vertical resistance in the media improved the simulated data in the bi-level subsurface drainage systems and provided good representation of water table dynamics. The differences between field data and results were only 21% for modified procedure in comparison with 61% for two dimensional solution. Totally, it would be mentioned that in future work for designing bi-level drainage systems in paddy fields, the vertical head loss should be considered.

Considering the importance of agriculture in developing countries, it is quite necessary to apply a programmed planning pattern based on different goals. His study used the linear and multi objective programming patterns following three main purposes such as maximizing the gross margin, water productivity and energy efficiency to determine the crop pattern of the small farms in Mashhad – Chenaran span. To gather data, a questionnaire was given to 79 farmers in farms below 5 hectare in planting year 92-93. The result showed that determining the crop pattern using a linear program aiming at water benefit will decrease water demand about 27 percent in this study zone. His will increase the income of the farmers and also the water benefit about 2/88 time and 28 percent respectively. The crop pattern based on three purposes mentioned above following weighting and constrained methods like linear programming patterns has a stable agricultural index. It also enjoys more variety of products than linear programming patterns but it will intensify the paucity of the storage aquifer in the study zone. With respect to the paucity of water sources in the district and the policies of the country in the realm of agriculture, the crop patterns aimed at maximized water productivity and weighting method, the triple purposes mentioned above is recommended.