نشریه دانش آب و خاک
سال سی و یکم شماره 3 (پاییز 1400)

The wind erosion occurs when wind speed exceeds the soil erosion threshold and plants or their residues,surface roughness, or other obstacles do not protect the soil surface. Also wind erodibility is oneof the most important determining parameters of wind erosion under certain climatic conditions. The main objective of this research was mapping of soil erodibility through empirical relationship between satellite imagery and physicochemical properties and estimation of soil erosion using a comprehensive assessment model, on the east shore of the Urmia Lake. For this research work soil sampling carried out in 153 points of three elevation classes(1271-1273, 1273-1275 and 1275-1278meters)and4supervised classification methods such as, support vector machine(SVM), Maximum likehood classification (MLC), Minimum distance and Artificial neural network(ANN)were used in classifying and mapping of soil erodibility. Soil samples physicochemical properties measured and 26 samples of them randomly were selected for wind erodibility measurement in wind tunnel laboratory. Wind tunnel experiments at a distance of 20 cm from the tunnel floor, revealed wind erodibility of 2.92 grm-2.min-1/ms-1. Also stepwise regression (SPSSv.25) results showed that among the physicochemical properties of soils, erodible fraction were the most important soil properties, which used in estimating erodibility and have a positive correlation with soil erodibility. The mean weight of aggregate diameter had negative correlation with soil erodibility and no relationship was found between soil chemical properties and erodibility. Of the4supervised classification methods, the artificial neural network has a higher capability in classifying and mapping erodibility and finally the results showed that the overall classification accuracy is57.1%.

To study the simultaneous impact of conventional and alternate-furrow deficit irrigation and superabsorbent polymer on characteristics of corn, a field experiment was carried out at Research Farm of College of Agriculture, Islamic Azad University, Karaj, Iran, in 2013-2014 growing season. Conventional deficit irrigation with three levels including irrigation with 100, 75 and 50% crop water requirement, localized deficit irrigation with two levels including fixed alternate furrow irrigation and conventional furrow irrigation that were located in the main plots and superabsorbent polymer with two levels including control (non-use superabsorbent polymer Stockosorb) and use of superabsorbent (30kg/ha) that were located in the sub plots. The results showed the amount of fresh and dry forage yield and biological yield in fixed alternate furrow irrigation method were not different significantly as compared to the conventional furrow irrigation method, while the volume of irrigation water during the growing season in fixed alternate furrow irrigation decreased by 25.9 %. Superabsorbent consumption lead to reduced irrigation water at a rate of 13.4 % during the growth season. highest water use efficiency for dry forage yield (2.04 kg.m-3) was obtained in treatment of fixed alternate furrow irrigation in condition of moderate stress and used of superabsorbent, that increased by 75.9% as compared to control treatment and there was significant difference. In conventional furrow irrigation method, average of water use efficiency for dry forage yield and biological yield was obtained 1.32 and 3.52 kg.m-3, respectively; while in fixed alternate furrow irrigation was increased to 1.75 and 4.31 kg.m-3, respectively.

In this study, the performance of the competitive and cooperative game and side-payment technique in the analysis of the conflict of interest of environment and water resources users was evaluated. In a competitive game, the players decide to compete with each other in order to maximize their individual payoff. But in a cooperative game, the goal of the players is to maximize the total utility of both players that, this desirability is the maximum income per unit area for farmers and the minimum water demand per unit area for the environment. But farmers care more about their individual benefits and are more interested in competitive game. As an effective technique, side-payment, by transferring some of the benefits between the players, equalizes the individual benefits of the players in both cooperative and competitive conditions. In such circumstances, it is possible to obtain the consent of the agricultural water consumers to implement the desired environmental cropping pattern. In this study, the conditions of conflict between the economic interests of the agricultural sector and the environmental considerations of the Urmia Lake ecosystem in the Urmia plain with the independence of game theory innovatively evaluated. Based on the results, the amount of water demand of the optimal cultivation pattern and the amount of income per unit area (hectare) in the competitive and cooperative game are 4788 cubic meters and 21.24 million Tomans and 3492 cubic meters and 19.97 million Tomans, respectively.

In the river, velocity parameter is one of the most important hydraulic variables and is effectively used in many river engineering fields like development of stage-discharge curve and sediment transport. In some river engineering schemes, the calculation of average flow velocity is sufficient. However, for some other projects, such as designing hydraulic structures in the river, stable channel design, flood calculations in rivers and floodplains, the lateral and vertical distributions of flow velocity should be calculated. To calculate the two-dimensional distribution of the velocity of flow (in transverse and vertical directions) many mathematical models have been presented with many complexities from practical point of view. In this research, a simple and practical mathematical model of Kean et al in combination with eddy viscosity equation as well as Einstein's law of the wall velocity was used to determine the two-dimensional flow velocity distribution in the smooth and rough compound channels. By numerical solution of this mathematical model, using finite differences method, isovel curves data were calculated for some experimental compound channels with different flow depths and floodplain's roughness coefficients and then they were compared with the experimental data. Also, transverse distributions of the flow velocity were calculated in these channels and compared with the measured profiles. These comparisons showed that the proposed mathematical model with coefficient of determination (R2)= 0.92, root-mean-square error (RMSE)=0.036 and mean absolute percentage error (MAPE)= 2.8% had an acceptable accuracy. The proposed mathematical model was developed with steady and uniform flow assumption, neglecting the secondary flow effect.

Soil moisture is one of the important determinants of soil behavior in water and soil investigation. The usual methods of measuring soil moisture are costly and very time consuming; so in this study, the TDR device has been used as a fast method. This study aims to investigate the effect of magnetic irrigation water on the measurement accuracy of the water content of the soil by the TDR device. In this study, three soil texture (silty clay, sandy loam, and clay loam) were on different levels of the magnetic field (0, 0.3, and 0.6 T). In this study, soil moisture was estimated using a TDR and compared with volumetric method values of soil moisture. The results showed that the device has the highest accuracy in the sandy loam soils under different levels of magnetic irrigation water (RMSE in well water, magnetic water 0.3 teslas, and magnetic water 0.6 teslas were 15.2, 3.3, and 2.5, respectively) and by increasing the clay content, the accuracy of the device is reduced. The drawing of the coherence chart between the results of the TDR method and the volumetric method values showed that the highest and the least coincidence between the two methods were observed in sandy loam + irrigation with magnetic water of 0.6 T (R2 = 0.92) and clay loam soils + well water (R2 = 0.42). The results showed that irrigation with magnetized water was increased the accuracy of the device in all of the studied soil textures.

Population growth requires extending agriculture and ranching to meet food demand and optimizing water use is necessary for a sustainable agriculture and ranching activities. To water use optimization in livestock production procedure, Amount of water utilized in diet ingredient producing and livestock drinking and servicing water should be noted. This amount of water used to produce livestock production called virtual water of production. The aim of this paper is computing virtual water of Holstein milk production in East Azerbaijan considering three irrigation efficiency 33, 60 and 90 percent. Average virtual water content of wheat, barley, corn, soybean, beet and alfalfa were 1.2, 1.5, 0.13, 3.8, 2.2 and 2.4 cubic meters per a kilogram production by considering 33 percent irrigation efficiency. According to 33 percent of irrigation efficiency the virtual water of milk for after parturition, high yielding, average yielding and low yielding durations were 1.5, 1.4, 2.4 and 3.3 cubic meters per a kilogram production. If percentage of irrigation efficiency increased by 60 and 90, virtual water of milk would decrease 43 and 60 percent respectively.

In this research, the effect of climate change on rainfall is investigated using five AOGCM climatic models (HadCM3, CCSR-NIES, CSIRO-MK2, CGCM2 and GFDL R30) under emission scenarios A2 and B2 and Hybrid developed model resulting from these models based on Bayesian approach, in order to account for the uncertainties in the Qom-Kahak aquifer. Data were downscaled for current (2001-2017) and future (2054-2069) periods. Then, it is found that the HadCM3 and CCSR-NIES compared to other models have better performance using criteria of efficiency. By calculating climate change scenarios and taking into account uncertainties, seasonal variations of future rainfall were compared with observed rainfall. The trend of seasonal variations of rainfall simulated by HadCM3 and CCSR-NIES and Hybrid developed model will be negative under the A2 in the spring and summer. The highest decrease in rainfall was by -45.14% relative to the observed period, which was related to the HadCM3 in spring. Also, the results of prediction of models under the B2 indicate that the trend of rainfall changes in winter will be partly positive for most models and this trend is decreasing in the spring and summer. The highest decrease of rainfall under the B2 is relative to CCSR-NIES in summer (-22.61% compared to observed period). The hybrid model, which is a combination of different climatic models, predicts the negative trend for the rainfall changes of all seasons under the A2, and the highest rainfall reduction in this model is related to summer by -29.44% compared to the observed period.

Drought as one of the natural disasters has a major impact on parts of an ecosystem. Although it cannot be prevented, its negative effects can be mitigated by some measures. Considering the high importance of groundwater resources in the country, the study of hydrogeological droughts and factors affecting groundwater drawdown is essential for the management of these vital resources. In order to investigate the impact of droughts on each other, the groundwater level variations and evaluation of the groundwater drought in Karun watershed were analyzed using GRI and SDI drought indices over a ten-year statistical period (2008-2018). The results showed a correlation between GRI and SDI indices in most regions of the study areas. Although in some cases, the impact of hydrological drought on groundwater is delayed by 6 months to one year. Low correlation between two hydrological and groundwater drought indices and the high correlation between GRI and groundwater abstraction indicated that drawdown in the aquifers cannot be the sole cause of drought, rather, in some cases, excessive abstraction is more effective. Overall, the GRI indices are more obvious in the southeast and west of the Karun watershed during the ten-year statistical period. In the final years of this period the northern side of the basin has also been affected by more severe droughts, which also has a correlation with the values of the SDI indices.

Application of organic fertilizers in saline-sodic soils, can be helpful in their reclamation without chemical amendments. In this research, leaching experiments of a sline-sodic soil with clay loam texture in laboratory columns was conducted in CRD as split factorial. Main factors were: 1) amendment type including manure and compost, 2) amendment application rate including 1, 3 and 5 percentage by weight and 3) leaching stage with 5 levels including: without leaching, once, twice, three times and four times leaching with 30 days intervals. All columns were incubated for 30 days after the addition of amendments and then were leached. The parameters in each column, were studied in three depths as subplot. After the forth month of incubation-leaching period, the EC and SAR of all soil samples decreased from 15 to below 5dSm-1 and from 20.3 to below 13 (mmolc L-1)0.5, respectively. After determining the best level of leaching, the soil of that columns was air-dried and Barley (Hordeum vulgare L. Bahman cultivar) was cultivated in that soil. Pot experiment was conducted in CRD with 7 treatments (control and 6 amendments levels) and 3 replicate. Application of 1% by weight of manure and compost increased nitrogen concentration by 33.8 and 40.5 percentage, phosphorus concentration by 35.7 and 43.3 percentage, and potassium concentration by 8.7 and 19.2 percentage in shoot, respectively.

Zinc (Zn) is one of the micronutrients that is toxic in high concentrations. One of the best ways for removing heavy metals (HMs) from water and waste water is the adsorption of HMs by using different adsorbents. The main component of Gel-E-Sarshour (GES) is a Di-octahedral smectite with high layer charge. Therefore it can be used for removal of Zn from contaminated water. In order to study the competitive and non-competitive retention characteristics of Zn onto GES, a trial with 7 different concentrations of Zn in the absence or the presence of humic acid (HA) was conducted. Zn adsorption data onto GES the best fitted to the Freundlich model, followed by Langmuir and Redlich-Peterson models. Although, the Zn adsorption data showed a highly significant fit to the Langmuir isotherm, the fit of data to a two-surface Langmuir isotherm proved to be more desirable. In all treatments, bonding energy of the first surface criterion (KL′) was several times greater than bonding energy of the second surface criterion (KL′′), while, adsorption maxima for the second site (b′′) were higher than that of the first site (b′). This means that although, the first site had a much greater tendency for Zn adsorption, it was rapidly saturated with Zn. Since, GES has a low price, being natural and abundant in Iran and due to its high adsorption capacity for the removal of HMs, application of this substance is promising for the removal of HMs.