WATER AND SOIL SCIENCE (AGRICULTURAL SCIENCE)
Year:2020 | Volume:30 | Issue:3|Papers Count:13

Current research with the purpose of applying the governing equations related to hydraulics of flow in plant root zone and use of modern technology in field measurements for measuring soil water content and soil suction of the plant root zone for continuous monitoring of relevant factors and smart management of irrigation system in order to optimized use of water consumption has been done. This research was carried out in Saeed Abad Gardens in Tabriz in two consecutive years, 1977 and 1998. Using a 20-channel data logger, the root zone was instrumented with soil moisture sensors and the soil moisture instantaneous data were transmitted to the server via the Internet, allowing online data viewing and data storage provided. In this study, by equipping the treatment under study to research drip irrigation system with ability of changing hydraulic parameters including controlling the discharge rate of different treatments and by continuously data logging, the actual soil wetting pattern and shape at different times obtained and the accuracy of the theories and experimental relationships were validated. Maximum absorption was at 20 cm depth and daily intake was calculated to be 30-50 liters. In this study, HYDRUS-2D software was used to simulate different scenarios. The most important issue in this software is to calibrate the governing equations coefficients. In this study, models related to root motion and absorption parameters were calibrated and validated based on accurate field measurements (RE = 2. 87 and NRMSE = 2. 14 %). Based on the results, water movement and plant consumption were calculated and presented. Accordingly, the results of matching the wetting pattern with the root zone of the plant were used to manage the system and ultimately save water consumption. The highest amount of water uptake was at 40 cm depth, which is 74% of the total water uptake. By controlling this soil profile, an intelligent irrigation system can be managed.

Evapotranspiration (ET), a major component of the hydrologic cycle, is important in water resources management and irrigation scheduling. Nowadays, due to the lack of the lysimetric data in weather stations, the ET values calculated by the standard FAO Penman-Monteith model (𝐸 𝑇 0) are used as benchmark values of grass reference crop. Also, the Penman-Kimberly model is widely applied for computing the alfalfa-reference crop ET (𝐸 𝑇 𝑟 ). In the present study, the meteorological data from 6 weather stations located in the Sistan-Va-Baluchestan Province covering a period of 10 years were used to calculate the 𝐸 𝑇 0 and 𝐸 𝑇 𝑟 values. Then, the 𝐸 𝑇 𝑟 to 𝐸 𝑇 0 ratios were computed for all six stations during the studied period. The Penman-Kimberly model at Mirjavah station had the worst result compared to other stations. The NS coefficient values for this station are the lowest (0. 07) and the SI and RMSE values for this station are 0. 43 and 2. 48, respectively, which is the highest value among the study stations. Finally, the contributions of the energy balance and aerodynamic components on the final ET values were determined using the Penman-Kimberly model, which showed the important influence of both components on the ET process. Consequently, the use of radiation-based models e. g. Priestly-Taylor model in these stations should be carried out by special care.

Proper plant nutrition is one of the most important factors in improvement of crop quality and quantity. Potassium is one of the essential macronutrients for plant growth. Understanding the different forms of potassium is important in evaluation the situation of this element in soil fertility and plant nutrition. Incorrect understanding of the potassium dynamics in soil off leads to improper management of soil fertility. Soil potassium exists in four forms: soluble, exchangeable, non-exchangeable and structural that their availability for plant are different. Soluble and exchangeable forms are widely used for determination of the potassium availability for plants. In addition to the exchangeable potassium, non-exchangeable potassium plays an important role in plant nutrition. This study was done to evaluate the different chemical forms of potassium and effect of pistachio seedlings planting on changes of their forms in some calcareous soils of Rafsanjan. For determination of the chemical forms of their form's potassium in 20 calcareous soils samples of Rafsanjan before and after planting, 1 M NH4OAc, boiling 1 M HNO3 and distilled water were sample used. Results indicated that there was no significant difference between the soluble potassium before and after the planting. However, amount of exchangeable potassium increased from 239 mg kg-1 soil before planting to 270 mg kg-1 soil after planting and non-exchangeable potassium decreased from 683 mg kg-1 soil before planting to 570 mg -1 kg soil after planting. Multiple regression equations indicated that the different forms of potassium in soils were correlated with the physical and chemical properties of the soil such as clay content.

In this study, three domestic biofertilizer samples including Azotobarvar, Potabarvar, Ruein, and a sample of Indian biofertilizer called Phosco were studied in terms of microbial population count and plant growth promoting characteristics. The results of plate counting revealed that Potabarvar had no alive bacterial population, but the number of viable cells of Azotobarvar, Ruein and Phosco were 3. 5 × 10 8 8, 5. 2 × 10 and 6. 9 × 10 3 -1 CFU g, respectively. Moreover, two isolates (Az1 and Az2), three isolates (R1, R2 and R3) and three isolates (P1, P2 and P3) were isolated in Azotobarvar, Ruein and Phosco, respectively. The in-vitro results of plant growth promoting characteristics showed that in the solid LG medium R1 and Az2 and in the liquid LG medium, P1, R1 and Az2 and had the highest nitrogen fixation, respectively. In phosphate solubilizing from tricalcium phosphate, Az1 and Az2, in potassium releasing ability, Az1 and P1 isolates from biotite and Az1 and P2 from muscovite and in production of auxin P1 in the presence of tryptophan had the highest performance, respectively. The isolates P1, P3, R1 and R3 had antifungal activity against Fusarium solani. Summarizing the results of microbial population counts as well as plant growth promoting characteristics showed that the both Ruein and Azotobarvar biofertilizers were in desirable condition and Phosco biofertilizer, despite having some growth-promoting properties, lacked a sufficient microbial population and the Potabarvar biofertilizer lacked the microbial population.

Slope steepness is one of the very important factors in soil erosion which has been defined as slope steepness factor (S) in soil erosion models such as the Universal Soil Loss Equation (USLE) and its versions. Sufficient information is not available on the accuracy of the erosion models in estimating the S-factor in semi-arid rainfed lands. Therefore, in this study, six rainfed lands with 8, 11, 15, 18, 20 and 24% slopes were selected in a semi-arid region of Zanjan and soil loss was measured at 1. 5 m × 2. 5 m plots under natural rainfalls during a-year period from early October 2015 to end of September 2016. Based on the obtained results, eight rainfalls among 82 rainfall events caused soil loss at the plots during the study period. The S-factor was measured using the ratio of soil loss from the plots to the soil loss from a land with 9% slope and estimated using the USLE, RUSLE, USLE-MM and AUSLE models. A strong relationship was found between soil loss and slope steepness of rainfed land (R 2 = 0. 92). Soil loss increased strongly with increasing the slope steepness and the S-factor values estimated using the USLE and USLE-MM were about 4% and 15% higher than the measured value, respectively. The AUSLE and RUSLE showed about 13% and 10% lower estimations than the measured ones, respectively. This study revealed that the USLE is more sutible model than the other models to estimate the S-factor in the semi-arid rainfed lands.

Over the last years, artificial intelligence models have been widely and successfully applied in many fields. In the present study, the efficiency of adaptive neuro-fuzzy inference system (ANFIS), SVM (Support Vector Machine) and Least Squares Support Vector Machines (LS-SVM) have been investigated to estimate the sediment concentration in four gauging stations, namely Jangaldeh, Nodeh, Arazkoosh, and Gazaghly along the Gorganrood River in Golestan province, Iran. The models were defined based on the five different combinations of the river flow and precipitation using time lags from 0 to 2 previous days. The results showed that the LS-SVM model with simplex search procedure had a better performance than the grid search method. Meanwhile, the results obtained from ANFIS model which estimated sediment concentration in Jangaldeh, Nodeh, Arazkoose and Ghazaghli stations with MEF Error of 5. 3, 13. 4, 4. 8 and 2. 8 percent, respectively, suggested a higher performance than other models. Overall, at all stations except Gazaghly, considering the antecedent flow with two-day time lag as the input data of the model increased the error magnitudes. Furthermore, the rainfall of the same day and one-day time lag could only enhance the efficiency of the model at Arazkooseh station.

Considering the importance of scouring in the design of bridges, nowadays, to increase the accuracy of scour depth estimation, artificial neural networks are used. In this research, a model for estimating scour depth around the bridge pier group was used by a new method called support vector machine. In this method, the statistical parameters of RMSE, R 2, DC, were used to evaluate the performance of the models. The results showed that using compounds of the sedimentary and hydraulic parameters in the support vector data model provided better results in estimation of scour depth. For example, in tripod mode, the assessment criteria values for the scenario 1 (hydraulic parameters), were R 2 = 0. 9914, DC = 0. 9758 and RMSE= 0. 0576, and for scenario two (hydraulic and sediment parameters), were to R 2 = 0. 9924, DC = 0. 9803 and RMSE = 0. 0529, which indicated better performance of the support vector machine in the second scenario. Finally, non-linear equations were presented for calculating the scour depth around the inclined Single and group piers.

This research was an attempt to investigate the quality and quantity of groundwater resources in Yazd-Ardakan plain as the biggest watershed in Yazd Province and its relationships with the geological formations. For this purpose, qualitative data of the wells in the plain for the decades of 80 and 90 (according to the Iranian calender for the pre-and post-water transfer from Zayandehroud River to Yazd) were studied. Furthermore, the geological formations map of the region was prepared based on the geological maps and Google-Earth images. Then, the type and facies of water for each well was determined using Aq. QA 1. 1 software. The suitability of water usage for agriculture and drinking purposes was also evaluated. Results showed that the chloride type of the groundwater was dominant in the southern and central parts of the watershed and also in 90s rather than 80s. Results of the qualitative zoning showed that the amount of EC was increased as 3 dSm-1 from 80s to 90s. Quantitative zoning of the groundwater showed that the elevation of the water surface decreased toward northern part of the watershed. The water depth in the wells was also decreased on the average of 10 m from 80s to 90s. Results also showed that the wells were dug often on the alluvium formations. Correlation analysis between water quality and frequency percentages of geologic formations revealed that the highest correlation (r=0. 99) was observed between calcareous geologic (Ktl) unit and EC of the groundwater; whereas, there was the least correlation between Acidic volcanic rocks (Pc-cr) geologic unit and EC of the groundwater (r=0. 07).

Finding of new water resources is a strategic necessity for Ardabil City as the capital of a province. Because the Ardabil aquifer is faced with problems of negative water budget and drinking water supplied from Yamchi dam which provides 60% of Ardabil's drinking water has a low quality. Also, colonization of half of the province population in Ardabil city and population growth horizon are other key reasons to prepare new water resource for the city. Saein area was chosen for exploration of groundwater new resources for suppling of drinking water for Ardabil city, because of relative high annual precipitation, fractured rock distribution with suitable water quality and proximity to the water treatment site located adjacent to the dam and water convey line from Yamchi dam, . Volcanic units with pure fracture porosity have formed fractured rock aquifers with high quality groundwater. In order to determine the groundwater resources of the study area and preparing the potential zoning map, nine rasteric map developed according to nine main parameters including lithology, fracture density, height as precipitation and as basin area, moisture, slope, stream density, slope direction and vegetation coverage index. The rasteric layers have been overlaied using two methods, ordered weighted averaging (OWA) and weighted overlay methods. The resultant potential map was prepared with five order of zoning, very high, high, moderate, low and very low potential. Calibration of two resulting map with springs location showed that the OWA method is more consistant with the field findings. Olivine basalt, pyroxene bearing andesite and trachits have been covered the areas with high groundwater potential. Factures and faults have the second role in the rainfall percolation and forming of aquifers.

Side weirs are installed on the side wall of main channels. By reaching the flow to the side weir, the exceeded flow falls from the side weir crest and is directs to the side channel. The flow within the channels with side weirs is considered as spatially varied flow. In this study, the threedimensional flow in a rectangular channel with side weir was simulated by the FLOW-3D software. For simulating the turbulence of the flow, the standard and RNG turbulence models were used. According to the modeling results, the accuracy of the RNG turbulence model was higher than that of the standard model. Furthermore, the Volume of Fluid (VOF) model was used for estimating the variations of the flow free surface. In the study, the velocity was predicted with an acceptable accuracy. Also, the MARE values for the longitudinal, transverse and vertical components were estimated 0. 480, 0. 468 and 3. 519 percent, respectively. Then, the effects of sharp and broad crested weirs on the characteristics of the flow field in the main channel along the side weir for three different models with width of 0. 01, 0. 05 and 0. 15 m were investigated. According to the numerical modeling results, by increasing the width of the side weir crest the shear stress value in the vicinity of the side weir crest increase significantly.

Duckbill weir is one of the water level control structures in irrigation networks which has been attracted by many engineers. Since sediments are transported in irrigation networks, they are accumulated at upstream of the duckbill weirs and cause some operational problems. In this study, side slots and submerged vanes were used in addition of frontal slot to prevent sediment accumulation in upstream of weir. The experiments were conducted in a rectangular flume with 12 m length and 0. 6 m width. The vanes had different heights and were arranged in two column with four rows which were perpendicular to side wall direction. The results showed that the submerged vanes induced the secondary flow which was so effective for sediment flushing through the side slots especially for higher value of H p (H was head over side wall and p was the height of weir). Submerged vanes having the identical heights of the weir not only increased the sediment flushing to downstream, but also increased the discharge ratio up to 7 percent. The results showed that duckbill weir efficiency (which was defined as the ratio of sediment trap to flow capacity of weir minus one) was increased to 65 percent by use of the submerged vanes indicating that the maximum flushing and flow conveyance were occurred in a given upstream head. For preventing the sediment accumulation in upstream of the duckbill weir, use the side slots together with submerged vanes for a values of H/p= 0. 1-0. 5 is proposed.