جستجوی مقالات مرتبط با کلیدواژه « hydrus-1d » در نشریات گروه « آب و خاک »

Soil hydraulic parameters play an important role in the water cycle and are part of the basic information for designing irrigation and drainage systems, hydrological issues, and soil quality assessment. These parameters can be measured or estimated through direct and indirect methods. Direct measurement requires a lot of money and time, and also due to the large spatial and temporal variability, a large number of samples must be taken for direct measurement under field conditions. An indirect method used to estimate soil hydraulic properties is the inverse solution method, which estimates the physical and hydraulic properties of soil using a numerical solution of the Richards equation. The results of the different researches show that this method has an acceptable accuracy in estimating the hydraulic characteristics of the flow into and out of the soil column, under both laboratory and field conditions. The inverse solution method is cheaper and faster than other methods. One of the advantages of this method is that it estimates the effective parameters and has the ability to simultaneously estimate the hydraulic properties and solute transfer. The HYDRUS-1D model developed by Simonek et al. (2002) in the laboratory, is an advanced model and able to simulate the one-dimensional movement of water, vapor, salts, and heat in soil. This model can simulate the wetting soil water characteristic curve with a very high accuracy by using the cumulative water infiltration data under constant head. Also, this model is capable of simulating infiltration into layered soils under falling head. Moreover, this model can estimate the hydraulic parameters and simulate the characteristic curve of the soil by using infiltration data and inverse solution method. The purpose of this study is to estimate the hydraulic parameters of the wetting soil water characteristic curve using the inverse solution of the infiltration equation under falling load by the HYDRUS-1D model.

Laboratory and field experiments were conducted to measure water infiltration into the soil under falling head in two and three soil textures, respectively. For the laboratory experiment, the data of Mohammadzadeh-Habili and Heidarpour (2019) were used, where they measured the falling head infiltration in the transparent acrylic cylinder with an inner diameter of 7 cm with different initial soil water contents. The soil column was filled with sandy texture soils (passed through two different sieves). Another experiment was conducted under field conditions to measure cumulative falling head infiltration using a double ring. The field experiment was conducted in 3 different sites with different soil textures of loam, sandy loam, and clay loam named Kooye Asatid, Shekarbani, and Daneshkade, respectively. In both laboratory and field experiments, the characteristic curves for different soil types were first obtained using pressure plates and moisture measurement. Then the amount of residual moisture, saturated water content of the wetting soil water characteristic curve, and cumulative infiltration data were given as input data to the HYDRUS-1D model, and thereafter, the hydraulic parameters of the wetting soil water characteristic curve were estimated using the inverse solution method. In the HYDRUS-1D model, van Genuchten and Brooks-Corey equations were used for laboratory conditions, and the van Genuchten model was used for field conditions. Finally, the SSQ index was used by the HYDRUS-1D model to optimize the parameters estimated by the model. Also, to determine the accuracy of the HYDRUS-1D model in simulating characteristic curve, the correlation coefficient (R2) and normalized root mean square error (NRMSE) were used.

For the laboratory experiment, the results showed that the HYDRUS-1D model was able to simulate the characteristic curve with high accuracy using both the van Genuchten and Brooks-Corey equations, but the van Genuchten equation was slightly performed better than the Brooks-Corey equation for both A and B soil textures. The comparison of the measured characteristic curve of Kooye Asatid, Shekarbani, and Daneshkade soils with the characteristic curve simulated by the HYDRUS-1D model showed the effect of hysteresis quite well, as the measured values obtained by drying soil, while the HYDRUS-1D model simulated the wetting front of characteristic curve. In conclusion, a comparison of the values of the simulated parameters with the measured values showed that the HYDRUS-1D model can estimate the hydraulic parameters of the wetting soil water characteristic curve with high accuracy using the reverse solution method of infiltration process under the falling head.

Livestock manures are a source of pathogenic microorganisms that cause contamination of water surface and groundwater. The aim of this study was to simulate the effect of cow manure granulation on the transmission coefficients of Escherichia coli in a column of sand under saturated flow. Cow manure with particle sizes of 0.25, 0.5, 1 and 2 mm equivalent to 30 (ton/hec) in terms of dry weight was used. The effect of fertilizer treatments on the transmission of Escherichia coli in the soil was investigated by measuring the number of bacteria and chloride detector in the drainage water, up to 20 cm3 of pore volume. In order to determine chloride, Levenberg-Marquardt algorithm and nonlinear optimization were used, and to determine bacterial retention and transfer, a two-site kinetic Attachment-Detachment equation and inverse solution were used. The results showed that the bacterial transfer simulation was performed well for all fertilizer treatments by HYDRUS-1D using a two-site kinetic model (average of mean deviation and coefficient of determination was 0.056 and 0.905 respectively). The 0.25 mm treatment had the best agreement with the simulation results. The highest concentration of wastewater bacteria was obtained in the fertilizer treatment of 2 mm, which is due to the coarseness of fertilizer particles and faster and earlier removal of bacteria from its particles. The lowest attachment coefficient rate, was obtained in the fertilizer treatment of 2 mm (5.59*10-6 s-1) due to the release of more bacteria in this fertilizer treatment and as a result of increasing the rate of detachment coefficient (3.61*10-1 s-1). Also, with increasing soil depth, the amount of bacterial retention increased, which is probably due to the accumulation of bacteria on the surface of soil particles at lower depths.

Soil degradation caused by salinization and sodification is one of major problem in arid and semi-arid regions. To overcome this problem, leaching of accumulated salts from such soils is necessary. In this research, HYDRUS-1D model was used to predict desalination process in saline-sodic soil located in north of Ahvaz. Therefore, Leaching experiments in both with (sulfuric acid) and without reclaiming material was performed in in 11 m2 plots. All experiments were accomplished by applying 100 cm of water in four-25 cm intervals. Desalinization leaching curves were measured. Also, soil texture, field capacity and permanent wilting point water contents, saturated hydraulic conductivity and solute distribution in soil profile were measured. Then, solute transport during leaching process was simulated using HYDRUS-1D by inverse method. The results of the study indicated that all the used amendments showed a pronounced difference in EC compared with control but the difference wasn't significant. Because of, the soils have enough calcium carbonate and gypsum which provide requirement calcium for reclamation. The model predicted solute transport in depths less than 100cm better than other. The simulated results indicated that amount of estimated EC in the first and second period of leaching fit to observed data better than other periods. Over all, the results of solute transport simulation during leaching experiments revealed that HYDRUS-1D provide reasonable description EC distribution in soil profile. So HYDRUS-1D model can be introduced as a suitable tool for prediction solute transport in soil under field condition.

Infiltration is a key process which can be considered for scheduling, design, management and optimization of irrigation systems. Therefore, it is necessary to choose an appropriate infiltration model to optimize water consumption in agriculture and to study the water cycle on a small and large scale. The purpose of this study was to investigate the sensitivity of the coefficients of Kostiakov, Kostiakov-Lewis and Horton infiltration equations to the simultaneous changes of initial moisture and soil bulk density and its effect on the performance of infiltration equations in different soils. In order to represent the effect of the sensitivity of the coefficients of infiltration equations on the efficiency of those equations at different moisture and bulk densities, first the coefficients of the equations are calculated for all infiltration data (fitting step) and then at a specific moisture and bulk density for each soil are calculated and for the moisture and other densities were used (evaluation step). For this purpose, cumulative infiltration data in eight soil textures, three bulk densities including 1.3, 1.4 and 1.5 g / cm3 and five volumetric moisture levels of 0.1, 0.15, 0.2, 0.25 and 0.3 was prepared using HYDRUS-1D. Based on the results, sensitivity of the coefficients of infiltration equations to changes in moisture and bulk density from high to low, respectively, the coefficient of the Kostiakov equation (ak), the coefficient of the Kostiakov-Lewis equation (akl), the power of the Kostiakov equation (bk), the coefficient of the Horton equation (bh) And the power of the Kostiakov-Lewis equation (bkl) was obtained. The mean increase of RMSE of the Kostiakov, Kostiakov-Lewis and Horton equations in the evaluation stage was respectively 3.25, 34 and 2.8 times the fitting stage. Therefore, the lowest and the highest sensitivity occurred in the Horton and the Kostiakov-Lewis equations respectively.

The aim of this study was to investigate the effect of straw mulch on water content distribution in a soil profile and simulating water flow in soil under shallow saline groundwater using HYDRUS-1D. Lysimetric experiments were conducted in two soil textures (sand and loam) at three water table salinity levels of 5, 10 and 15 dS m-1 mulch and no mulch with three replications in a three-month interval. Soil moisture content was continuously monitored in the depths of 5, 10, 20, 30 and 50 cm. Evaporation was also measured using Marriott bottle technique on a daily basis. The results showed that mulch cover retained soil moisture by 16 % and 20 %, and reduced evaporation by 27 % and 8% in surface layer of loamy and sandy soil, respectively. Our findings highlighted a strong correlation between measured and simulated soil moisture data using HYDRUS-1D with R2 ranging from 0.89 to 0.97 and 0.90 to 0.96 in sand and loamy soils, respectively. The numerical model estimated soil moisture with RMSE of 0.0121- 0.0489 cm3 cm-3 for loamy and 0.0129-0.0521 cm3 cm-3 for sand. The simulation results revealed that HYDRUS-1D overestimates moisture content of layers close to water table.

Since many parts of Iran are located in arid and semi-arid regions of the world, groundwater recharge is an important component of the water cycle in these areas. In this paper, groundwater recharge under different irrigation scenarios for thirty logs lied in Neishabour plain was investigated. Daily data, including precipitation, evapotranspiration and leaf area index were used to run HYDRUS-1D software. Thirty observation logs with different depths of water table were selected at different locations in the plain. Analysis of the recharge rate in the wheat-fallow scenario showed that for different soil textures, groundwater recharge is dependent on the number of irrigation applications. For the logs with sandy soil textures, the maximum amount of recharge was obtained in five irrigation events scenario by an average of 325.23 mm year-1. For the logs with sandy clay loam soil texture, the highest recharge rate was obtained in the seven irrigation events scenario by an average of 67.43 mm per year-1. In the logs dug in loamy soil texture, due to the high depth of the soil block, the same recharge rate was obtained at different scenarios. In the case of a double-cropping scenario, groundwater recharge increased due to irrigation of tomato in summer. In this scenario, the highest recharge rate was obtained in observation log drilled in sandy soil texture with a depth of 15 m which was equal to 440.47 mm year-1.

The precise simulation of water and solute transfer in porous media is very important in soil and water studies. The purpose of this study was to measure and simulate water movement and solutes transfer of layered soils. In this study, the effect of soil bulk density changes and different soil layering on water and solute movement were measured and simulated with HYDRUS-1D model in 5 treatments and two replications. For this purpose, 10 columns of PVC with a height of 105 cm and an inner diameter of 31.5 cm, and three soil textures including loamy sand, sandy-clay loam and clay loam were used. The columns were irrigated with irrigation water and saline water with salinity of 0.67 and 4.46 ds/m, respectively. During the experiment, moisture content (using TDR moisture meter) and salinity (by saturated mud extraction method) were measured at depths of 10, 20, 30, 40 and 60 cm. The results of the study showed that the water movement in the soil is affected by the position of the layers with the least permeability and when the fine texture layer is placed on top, the time of water exit is the highest. Also, the results showed that in all columns the EC value was the highest in the upper layer and decreased from top to bottom regardless of the order of the arrangement of the layers. The survey of the nRMSE index indicates the high accuracy of the HYDRUS model in simulating the movement of water and solute in the layered soil. The lowest error in simulation was in homogeneous soil.

Moisture flow through unsaturated zone is vital in agricultural engineering, soil science, groundwater hydrology, and environmental engineering. Moisture flow through unsaturated zone is complex due to the dependencies of flow and storage properties on the pressure head and is commonly analyzed by solving Richards’ equation. Solution of Richards’ equation requires the knowledge of soil hydraulic conductivity and water content versus pressure head functions referred to herein as the soil hydraulic properties. Since these functions are highly nonlinear, direct laboratory and field measurements are tedious, time consuming, and involve considerable uncertainty (Hari Prasad et al., 2010). An alternative to the direct determination is to employ the parameter estimation methods using inverse procedure for the determination of hydraulic properties. Indirect methods are divided into several categories, including methods based on pedotransfer functions, semi-physical, and inverse methods (Abbasi, 2007). Determination of hydraulic properties by inversion of in situ measured moisture contents, pressure heads and cumulative infiltration have become an alternative to direct measurements due to decrease in the computational costs and development of efficient optimization algorithms. Inverse solutions based on the Richards’ equation are now increasingly used for estimating the unsaturated soil hydraulic properties. The HYDRUS-1D model is one of the advanced models have been widely used to simulate one-dimensional water movement in soil. Examples of numerical studies in which infiltration data were used to inversely estimate the near-saturated soil hydraulic properties using HYDRUS model are by Simunek and van Genuchten (1996) and Rashid et al (2015). Water quality can impact on soil hydraulic conductivity changes. The effect of salinity on the hydraulic conductivity of soil has been studied by many researchers, including Moutier et al. (1998) et al. and Levy (2005). The researchers reported that increasing the salinity has increased the hydraulic conductivity of the soil. The purpose of this research was to evaluate saline water effect on unsaturated hydraulic properties and estimate these properties inversely using infiltration data.

Infiltration is one of the important parameters of the soil, which affects many hydrological processes in the watersheds. The importance of the Infiltration has led to various laboratory methods used to measure this process. Various methods have been developed for measuring the infiltration, which are based on the measurement of the vertical flow of water to the soil. One of the standard methods for measuring infiltration, is double-ring infiltrometers method. In this method, it is assumed that the external cylinder prevents lateral flow and creates a completely vertical flow in the soil. Therefore, the present study was conducted to evaluate the double-ring infiltrometers method for measuring the vertical infiltration compared to actual vertical infiltration data simulated using HYDRUS-1D software. In this study, in order to evaluate the double- ring infiltration data, infiltration was measured in several regions with different soil textures by double- ring infiltrometers. Then, HYDRUS-1D numerical model was used to simulate infiltration and the vertical infiltration data were obtained through forward solution of the Richards equation. van Genuchten-Mualem model was used to quantitatively soil hydraulic properties of the Richards equation. In order to the hydraulic parameters of van Genuchten-Mualem model were optimized using inverse modeling in the HYDRUS, for each region's soil Assessment of measured data was performed using mean error (ME), root mean square error (RMSE), coefficient of determination (R2) and normalized mean square root (NRMSE). Findings: Comparison of simulated and measured infiltration data showed that double ring infiltration data is much higher than the simulated vertical infiltration data. The measured infiltration data in all soil texture was much different from that of simulated data. The lowest error in the measurement of vertical infiltration was observed in sandy loam soil that is a light texture. The values of coefficient of determination, root mean square error, mean error and normalized mean square root (R2, RMSE, ME and NRMSE) were 0.87, 8.51, -4.45, and 0.18 respectively in this texture. In measuring the infiltration of a double-rings, the size of the cylinders used, as well as the buffer index, is of great importance. Therefore, the use of cylinders of different sizes influences on the final infiltration values. The double-ring infiltrometers method has a lower error in the Sandy texture than heavy texture and the contribution of lateral infiltration is less in this texture. Therefore, the double-ring infiltrometers has a higher accuracy in light texture.

In this research, an operational simulation model was developed to indicate the importance of agricultural bore wells as an irrigation water resource and sustainable management of them to supply irrigation demand of paddy fields. The main approach of this research was based on maximum using of local water resources (e.g. wells, ponds). In the proposed model, crop evapotranspiration, irrigation requirement and interval and water head in soil and bore well are daily calculated based on input data and simulation equations. Then, using of obtained irrigation scheduling and considering the limitation of minimum permission level in bore well, water harvesting days from bore well, pumping discharge and time, pond water in fields and runoff are calculated. Simulation of groundwater level fluctuation in the out of paddy rice growing season in unsaturated condition of soil was computed by Hydrus-1D. The model was run for paddy fields of Rasht Rice Research Institute for normal year; The results indicated that 10 irrigation events were required that six and four of them were supplied by bore well and canal, respectively. The obtained results in the studied paddy fields showed that shallow groundwater level was discharged by precipitation in the out of paddy rice growing season and raised from depth of 4.85 m to 1.82 m. Therefore, operation of bore wells during paddy rice growing season as well as considering minimum permission water head does not cause considerable groundwater drawdown and unsustainable operation

In recent years, using pedotransfer functions (PTFs) has been considerated as a way to estimate the hydraulic properties of soil from easily to measured parameters. In this research, soil water retention curve of a clay loam soil was estimated using some of the global and regional PTFs. Soil water retention curve (SWRC) was constructed using direct measuring methods in laboratory and the validation of PTFs for estimation of the mentioned curve was evaluated. By entering the measured and estimated SWRC to Hydrus-1D, soil water flow was simulated and the accuracy of the PTFs for simulation of water flow was quantitatively compared. The results showed that the functions of Sepaskhah (Sepas), Yaghubi-1(Y-(1)), Yaghubi-2(Y-(2)) and Ghorbani-2(Gh- 2)) with normalized root mean square error (NRMSE) values of less than 0.1 could reasonably predict SWRC of the surface soil. In prediction of SWRC of subsurface soil, the NRMSE values of most global PTFs were less than 0.3 and for most of the regional PTFs were less than 0.2. NRMSE values in simulation of water content of surface and subsurface soils using Hydrus by applying different PTFs were between 0.07 to 0.84, respectively. It can be concluded that in running validating phase one should consider the objective for which the PTFs may be applied.