Iranian Journal of Soil and Water Research
Year:2012 | Volume:43 | Issue:2|Papers Count:10

The main objective in production of any rainfed crop, including barley farming is to increase water productivity along with stability in the production of the rainfed crop through improvement of the agronomic management including limited Single Irrigation (SI) and Sowing Date (SD). In order to determine optimal SI management and limited water allocation scenarios, a field experiment was conducted as split-split plot (Randomized Complete Block Design, RCBD) of three replications during two crop seasons, 2004-2006 for two advanced rainfed barley varieties at the main station of Dryland Agricultural Research Institute (DARI) in Maragheh county. The treatments included three SD, five SI scenarios and two rainfed barley varieties (V1=Abidar, V2=Dayton). Amounts and ranges of Rain Water Productivity (RWP), irrigation water productivity (IWP), and total water productivity (TWP) in producing grain, straw and biomass yields, were used to determine optimal program of single irrigation scenarios. Early sowing date for rainfed barley and heavy spring irrigation (100% depletion of available water at root zone) exerted no significant effect on rain water productivity. Early heavy irrigation (100 mm) increased straw. The results revealed that, 100 mm-SI at planting time, total water productivity increased up to 8.7 and 8.9 kg.mm-1 for V1 and V2, respectively and also irrigation water productivity increased by 37.4 and 38.5 kg.mm-1 for V1 and V2, respectively. One time limited spring irrigation (50% depletion of available water at root zone) in spring and during the heading to flowering stage, exerted significant effects on yield and increased TWP to 5.6 and 5.8 kg.mm-1 for V1 and V2, respectively. It also increased IWP up to 58.9 and 60.5 kg.mm-1 for V1 and V2, respectively. A comparison of the two rainfed barley varieties, showed that, rain water productivity of Dayton cultivar was equal to 3.2 kg.mm-1, 10 percent more than that of Abidar rain water productivity.

In this study, the pattern of changes in the values of soil Electrical Conductivity (EC) and soil Temperature (T) under Full Irrigation treatment (FI) as compared with PRD75 and PRD55 treatments (Partial Root-zone Drying which received 75 % and 55% water of FI at each irrigation event) was investigated in 1389 on a maize filed in Sari University of Agricultural Sciences and Natural Resources. Results demonstrated that there was a strong linear relationship between the values of T and soil water content and as well between EC and soil water content. Results also showed a strong exponential relation between the values of T and EC. Regardless of treatments, the values of EC and T decreased in response to any increase in the soil depth. However, the values of changes in the EC and T in the wetted part of PRD75 treatment were significantly higher than those of the same part in FI treatment. The value of total salt accumulation in the root-zone under PRD75 treatment was 27% less than that at FI treatment. Furthermore, in spite of a 25% water saving under PRD75 treatment, there was no significant decrease in the value of yield efficiency (6.9 ton/ha) as compared with FI treatment (7 ton/ha). Therefore, it can be concluded that applying PRD75 treatment can lead to the most suitable results in this study area.

The purpose followed in this study was to utilize the modern model method of Spatial Multi-Attribute Decision Making (MADM) to provide a comprehensive model for priority classification of vulnerable to drought area in the basin of Gavkhouni. The main preference of this method over other methods is that in addition to making use of the geographical data the judgment of decision makers is also made use of at the various levels of decision-making. Based upon the aim followed in the study, the criteria and sub-criteria were defined and weighted through AHP technique. Later, geographical data, in the framework of GIS based layers were standardized, consolidated together, and then the criteria maps produced. Results indicated that through this structure, one is able to simultaneously make several drought indicators, along with the variables affected by drought, as well as the knowledge of the experts (from different angles) plus the view points of the individuals who actually have touched upon the phenomenon of drought involved in the assessment of the drought.

Pumps are among the early instruments invented by humans to be taken advantage of in the use of water utilities. Design and operation problem of pumping stations is a type of mixed integer nonlinear programming, in which gradient based optimization methods are not efficient for solving complex problems of this type. In this regard, such evolutionary optimization algorithms as genetic algorithm (GA) have been employed in many scientific fields of application and specially design-operation of pumping stations as a search and optimization tool. Apart from all the capabilities and advantags of such algorithms, they need a large amount of execution time as well as converging to the near optimal solutions, which are considered as some of these methods' disadvantages. This paper addresses the optimal design and operation of a pumping station system using a hybrid method for optimization consists of nonlinear programming (NLP) method and GA (NLP-GA). After evaluating the developed hybrid model in a test example mathematical problem, it has been applied and examined in a real world design-operation optimization problem. Then, the results of the NLP-GA algorithm are compared with those of three other methods for the same problem, such as GA, honey-bee mating optimization (HBMO) algorithm, NLP and the Lagrange multipliers (LM) method. The results show that the hybrid NLP-GA performers better results and faster convergence in terms of number of function evaluations toward the optimal solution than those of other methods.

Most weather stations in Iran have been installed in arid areas, far from agricultural lands. Therefore, the data gathered are not valid for estimating reference evapotranspiration. The advantage of satellite imagery is the coverage of a wide surface region from where information regarding agricultural areas can be obtained. According to this issue, researchers have converted the Penman Monteith to a simple equation so that it only acts as a function of the surface temperature. The coefficients of this equation are functions of air aerodynamics and incidents of solar radiation and it has been demonstrated that, they are nearly constant as for a region in Argentina. Hence the reference evapotranspiration while using only surface temperatures was estimated with acceptable accuracy. The aim of this study was to evaluate the above mentioned simple equation for the Qazvin Irrigation System. A total of 231 images for a period of 3 years (2006- 2008) with no cloud cover of NOAA satellite images, covering the study area were made use of. The results of the study indicated that, the above mentioned coefficients were not constant for Gazvin irrigated area so as two equations were needed to estimate each coefficient from any day of the year were presented for making the needed estimations. The results showed that the simple equation is in demand of more calibration. The calibration was made and ET0 estimated with an R2 of 0.80 and a Root Mean Square Error (RMSE) of 0.47 mm d-1.

Underground dams have recently been considered as hydrological structures for the development of water resources, especially in the dry regions of Iran. In this investigation along with the basic studies and the aquifer flow modeling, the probable hydrogeological effects of an underground dam are investigated. The proposed place for the Ganjeh Underground Dam is Chehel-khaneh Aquifer located in Freydan, Isfahan province. In this study, climatological and hydrological studies, exact geological, geophysical and hydrogeological researches, and a completion of the required data based on different statistical methods have been utilized to examine the feasibility of application of PMWIN, an efficient model for simulation of fluid flow and solute transport in porous media for the Chehel-khane Aquifer modeling. Following the verification of the model, future behavior of the Chehel-Khaneh Aquifer, quantity of stored water, increase vs. decrease in yields of wells and Qanats are assessed and analyzed for various configurations of the underground dam. According to the influence of hydrological constructions on the water resources balance, groundwater balance is calculated and analyzed for the Chehel-Khaneh and Bouein (downstream aquifer) aquifers and the role of the underground dam on the fall of the level of water resources downstream is investigated. According to the findings of the research, optimum height of crest of the underground dam is 2290 m.s.l. Increased storage of the aquifer as a result is 0.47 Mm3 with the discharge of river, wells and Qanats significantly increased. Moreover, Ganjeh Dam would not exert any undesirable effect either on Ganjeh-Daran Road or Ganjeh Village. The effective radius of Ganjeh Dam on downstream aquifer is estimated as less than 700 meters. Due to the construction of the dam, there will arise a 6 meter decrease in water table of the downstream aquifer at the influenced regions.

Construction of porous barriers to collect flood flows and gradual release of water, later, is one of the effective techniques for flood control. In this study, by carrying out a set of experiments in a flume with the width of 0.6, depth of 0.8, and length of 14 m, the effects of gradation of stones and downstream slope on the stability of such structures has been investigated. Moreover, the influence of mean diameters of stones along with their standard deviations as regards the stability of the structure has also been scrutinized. Utilizing dimensional analysis technique as well as two-thirds of the observed data, a new relationship for calculating the stable downstream slope in term of discharge, gradation of material and water depths upstream and downstream, has been developed. To evaluate the new relation, the remained one-third of the observed data was compared with those calculated from the new relation. The root of mean square errors and the mean of relative errors were found as 0.04 and 0.09, respectively, indicating a reasonable accuracy of the new relation established.

Estimating snow melt water equivalent is one of the most important challenges in determining the hydrological regime in mountainous basins. There are some problematic obstacles in field observations, due to inaccessibility as well due to difficulties in snow sampling at snow covered peaks making researchers try to find indirect approaches. One of these methods in use is Degree- day model that is simple and used in snow melt estimations. In this study the model is applied along with MODIS images for predicting snow water equivalent at times of peak snow accumulation. For this purpose, following a determination of the time of snow accumulation peak, the degree-days needed for the snow to be completely melted is computed and then, the snow water equivalent at any point calculated by reversing degree-day equation. The results show that there is 13 percent difference between the observed and estimated data. This indicates that MODIS data and degree-day model can acceptably estimate snow water equivalent in not easily accessible areas. Therefore, the degree-day model would be helpful in hydrological monitoring programs in not easily accessible mountainous basins.

Polymers are among the proper materials for prevention of runoff and soil loss. The study was conducted to investigate the efficiency of Polyvinyl Acetate (PVAc) in decreasing runoff and sediment formation in a marl soil and in the laboratory conditions. PVAc was applied at five levels consisting of zero (control), 50, 100, 150 and 200 kg ha-1 with three replications in flumes filled with a marl soil. The flumes were exposed to five rainfall events with a constant intensity of 40 mm h-1 for 30 min. Results indicated that the rainfall event and polyvinyl acetate significantly (p<0.01 and p<0.05, respectively) affected the runoff and sediment yield. Runoff production and sediment yield increased from first rainfall event to the forth one due to an increase in soil disruption and decline in infiltration rate. The runoff production and sediment yield values in 50 kg ha-1 of the PVAc application amounted to 16.6% and 38% lower than those in the control treatment, respectively. Polyvinyl acetate of 50 kg ha-1 level was recognized as the most effective treatment for prevention of runoff and sediment production. In the coming studies, the effectiveness of the lower levels of the PVAc on control of runoff and sediment formation, as well as plant stabilization is suggested to be investigated.

To study the effects of biofertilizers in their different levels of nitrogen (N) and phosphorus (P) on yield related parameters of barley (Sahra cultivar), a split plot experiment based upon a randomized complete block design of three replications was conducted. Main plots consisted of: nitrogen at three levels (0, 50 and 100 kg N ha-1 as urea), while sub plots were: phosphorus at two levels (0 and 50 kg P2O5 ha-1 as triple super phosphate). Sub sub plots consisted of: biofertilizers at four levels (control, inoculation of phosphate solubilizing bacteria or PSM, inoculation of Nitrogen Fixation Rhizobacteria or NFB along with co-inoculation of PSM and NFB). Results revealed that N, P biofertilizer and interaction of N as well as P were highly significant in terms of all the yield related parameters. Mean comparison indicated that increasing of N with inoculation of biofertilizers coud markedly improve grain yield in which maximum grain yield (364.5 gm2) was recorded when the application of 100 kg of Nha-1 plus co-inoculation of PSM and NFB biofertilizers were involved.