JWSS - Journal of Water and Soil Science

In recent years, a lot of research has been done on the Aquacrop model, the results show that this model simulates the product performance for deficit irrigation conditions. But this model, like other models, is sensitive to values of independent variables (model inputs). In this research, the sensitivity of the Aquacrop model was analyzed for 4 input parameters of reference evapotranspiration, normalized water productivity, initial canopy cover percentage and maximum canopy cover for barley. Irrigation treatments included full irrigation and two deficit irrigation treatments of 80% and 60%, the experiment was done in 2014-15 growing season in the field of Abourihan College. The values of measured biomass were used as the base values for treatments. The Beven’s method (Beven et al., 1979) was used for sensitivity analysis of Aquacrop model. The results showed that the model is most sensitive to the reference crop evapotranspiration, So the sensitivity coefficient for this parameter for full irrigation treatments, 80% full irrigation and 60% full irrigation were -1.1, -1.2 and -2.3 respectively. The negative sign indicates that if the value of reference evapotranspiration input is exceeded the actual value into the model, Yield performance is simulated less than actual value. In the meantime, the higher the degree of deficit irrigation, the greater the sensitivity of the model.

In this study, the effect of some soil parameters on the life forms and total aboveground net primary production (ANPP) in meadow rangelands in Fandoghlou region of Namin county in Ardabil Province were investigated. ANPP in 180 plots of 12 by harvesting and weighting method were measured. Eighteen soil samples were collected along transects. Some physical and chemical attributes of the soil were measured by standard methods. The relationship between these parameters and ANPP was performed using multivariate regression (enter) method. To determine the effects of important soil parameters on ANPP variation, principal component analysis (PCA) was used. The results of regression analysis showed that electrical conductivity (EC), magnesium (Mg), spreadable clay (WDC), volumetric moisture content (VM), organic carbon (OC), soluble potassium (KS), exchangeable potassium (Kexch), sodium (Na) and phosphorus (P) were the effective parameters on the life forms and total ANPP (p<0.01). The accuracy of obtained equations for grasses, forbs and total ANPP were calculated 79, 76 and 70%, respectively. Moreover, results of PCA showed that soil parameters justify 84.52 percent of total ANPP variation and in comparison, with regression results with 28% it provides better results.

Shortage of water resources and renewable per capita in last 30 years is put Iran on crisis threshold. Wastewater reuse is one of the battle solutions for water shortage and prevents wastewater depletion and environmental pollution. Thus, a pilot scale experiment was carried out to evaluate an integrated anaerobic/aerobic treatment for removal of BOD₅ and COD, also to reduction of hydraulic retention time by considering optimum removal efficiency. The pilot was an anaerobic/aerobic bioreactor type under continuous-feeding regime based on a central composite design. The pilot was studied in different retention time and aeration was carried out between 5-15 hours. According to different retention times for COD removal efficiency, 24 hours was selected as optimum hydraulic retention time, that it is comparable to those obtained for 48 hours and over in plant roughly and could remove COD and BOD in acceptable ranges, results showed that average removal efficiency for BOD₅ were 63.86 and 83.99 percent in aerobic and anaerobic phases, respectively. The average removal efficiency for COD was 76.5 and 74.35 percent for anaerobic and aerobic sections, respectively. The average removal efficiency for BOD₅ and COD in this integrated aerobic-anaerobic pilot 95.24 and 94.8 percent, respectively.

Due to water use increasing, attention to optimal water resources allocation is needed. In recent decades, the use of intelligent evolutionary methods for optimization of water allocation was focused more by researchers. The aim of this study is to development on water resources planning model that determined the proper cultivation, optimal exploitation of groundwater and surface water resources although water allocation among crops is a way to minimize the adverse effects of dehydration and increase its revenue. In this study, for maximizing profits, estimating crop water requirements at different periods to optimize the management of cropping patterns and irrigation management in cultivation in Varamin irrigation network using a new evolutionary algorithm was called the water cycle. Then for validation of this method is that a new approach and ensure the integrity of its performance Its results are compared with a genetic algorithm model and linear programming as our base (R²=0.9963). The results showed that the area cropping pattern was not optimal and the area under cultivation of crops such as wheat, barley, tomatoes, Bamjan, melon, alfalfa reaches zero and the new paradigm of the largest area under cultivation to industrial goods and then was assigned cucumbers. While our revenues have increased about 11 percent. In addition to amount of water in different months remain in the network that can be used for many that such as injection into underground aquifers or other crops based on the amount of water available.

The using of soil conditioners to water and soil conservation is essential and also, the effect study of soil moisture on the soil conservation process and its role on changing runoff, soil erosion and sediment yield is necessary for understanding and simulating the hydrologic response of soil. Therefore, the present study was carried with the aim of investigating the effect of biochar with amount of 1.6 t ha-1 on the components of  time to runoff, runoff volume, runoff coefficient, soil loss and sediment concentration in different soil moisture including air-dried, 15, 20 and 30 percent with three replications in plot scale. The results showed that after application of biochar conditioner, time to runoff compared with control treatment at soil moistures of air-dried of 15, 20 and 30 percent happened later 66.66, 186.6, 150.5, and 475.47 respectively. The results also showed that the runoff volume at soil moistures of air-dried of 15, 20 and 30 percent decreased 44.49, 55.65, 36.47 and 41.08 percent, respectively, and the runoff coefficient reduced 55.71, 66.39, 48.44 and 37.82 percent, respectively. The adding biochar caused the decreasing soil loss with rates of 91.19, 85.055, 85.63 and 88.066 percent, respectively, and the sediment concentration with amounts of 84.19, 66.53, 76.57 and 79.59 percent, respectively. Also the results showed that the changes of soil moisture had the significant effect on changing the time to runoff, runoff volume, and soil loss and sediment concentration in level of 99 percent.

Droughts are natural events and could lead to declining surface water quality of regional basin. Understanding the complex impacts of drought may help authorities to monitor changes in different regional basin and to make appropriate decision on development of a river basin management plan. In this study 20 years annual precipitation time series from 1994-2013 from 7 synoptic weather stations located in the Halil-Rood basin were analysed using both Standard Precipitation Index (SPI) and Reconnaissance Drought Index (RDI) and then dry (-1.35 to -1.75) and wet years (1/7 to 2.45) were determined by model simulation studies. Several climate based drought indices and remotely sensed based drought indices were used for monitoring and evaluating of drought. The impact of drought on the water quality parameters in the study area was evaluated. Results showed that there was significant relationship between most of the examined water quality parameters (Ca²⁺, Mg²⁺, HCO^3-, SO4²⁺, Na⁺, total dissolved solids TDS, SAR) and drought, however there was no significant relationship between water pH and drought. The study indicated that focus on the drought indices might be helpful as a tool in improving surface water resources management under drought condition and may promote sustainable water resources utilization and management in the study area. Also, dividing the Halil-Rood basin into several homogeneous regions is recommended for future studies to prepare a better ground for studying the effect of drought on the quality of water at a regional scale.

Simulation of water and salt transfer in soil is very effective in managing optimal water and fertilizer use in the field. In this study, the HYDRUS-1D model was used to simulate the transfer of water and bromide in a laboratory column of soil with clay loam texture. Soil hydraulic parameters (including air entry point) α, (saturated hydraulic conductivity) ks, (residual moisture content) θr (saturation moisture content) θs, (pore and particle joint parameter) l (parameter of moisture curve shape) n through measurement and using Retc software was obtained Solubility transfer parameters including difiusion coefficient and actual velocity were estimated using soil hydraulic parameters and bromide concentration data by reverse modeling method. According to the target coefficients, the sensitivity analysis of the physical model was performed .The results showed that the correlation coefficient of observation and simulation bromide concentration in optimal mode was 0.84%. accordingly, the diffusion coefficient was estimated to be 4.9 cm. based on the results of the sensitivity analysis, the saturation hydraulic conductivity had the greatest effect on the variation of this parameter, so that the amount sensitivity coefficient of this parameter was 2.64 The RMSE coefficient with a value of 0.04 was the lowest and ME coefficient with the value of -0.0001 had the most parameter variations.

Heavy metals in street dust, as one of the most important environmental consequences of human activities, have attracted many researchers' attention in recent years due to their toxicity and sustainability. Therefore, this study aimed to investigate the hazard of heavy metals (lead, zinc, copper, chrome, cadmium, nickel, vanadium, arsenic and cobalt) on human health in street dust in Dezful. To this end, 30 dust samples collected from sidewalks of main streets of Dezful were analyzed by Atomic Absorption (AAS). The level of heavy metals pollution was estimated based on the pollution index and Nemro Integrated Pollution Index. Moreover, the spatial pattern of the concentrations of metals in street dust was prepared in GIS. The average concentrations of heavy metals in Pb, Zn, Cu, Cr, Cd, Ni, V, As and Co were 54.2, 223.6, 50.6, 44.4, 0.4, 45.8, 37.8, 3.3 and 7.6 (mg/kg), respectively. The average concentration of all heavy metals except As, V and Co in the samples of dust in the city of Dezful was several times higher than that of the background one. Based on the average EF and PI in the target area, heavy metals of Zn and Pb have high contamination. Based on the evaluation of NIPI, 100% of samples have high degree of contamination. The results showed that the source of pollution of the studied metals such as urban transport and burning of fossil fuels was anthropogenic.

Experimental and numerical study of scouring pattern on the direct and polo-shaped groynes have been investigated in this paper. In this study, direct and polo-shaped groynes models with a length of 0.12 meter have been used in discharges of 10.5, 15, 20 liters per second in a direct flume. The results showed that the maximum scour depth formed around the groyne head of direct and polo-shaped types has increased with augmentation of flow discharge, which was 0.095 and 0.104 meter in the case of 20 L/s discharge respectively. Also, the width of scour hole was 2.25 and 2 times of effective length of the groyne in direct and polo-shaped groynes respectively. In this regards, maximum scour depth around the head of groyne was seen 0.87 and 0.79 times of the effective length of the groyne. Sand form located at downstream of the direct groyne at the distance of 0.09 and 0.15 meters from the side wall of direct groyne was stretched and extended to about 1.3 times of the channel width as well. While the length of the sand form for direct groyne was 1.15 times of the channel width. Overall, the dimensions of the scour hole around the polo-shaped groyne, was less than the direct groyne. In addition to understanding the hydraulic behaviour around the groyne, Flow3D software was used. Statistical survey of the results obtained by experimental and numerical models attested that the relative error of the numerical model could be about 20%, which shows an appropriate performance of using Flow3D for predicting the maximum scour depth.

Deterioration of groundwater resources in coastal regions due to the progression of saline water in aquifers in these regions is currently one of the important issues in providing water needs in these areas. In coastal regions, saline water enters the aquifer from below in shape of wedge. Due to the difference in the density between fresh and salty water, an interface zone forms between two fluids. In order to better understanding the importance of this issue, experiments and numerical investigations of density-depended flow and transport through a tank filled with a variety of sand, are great help in achieving this. In this research, the real sand tank was simulated using SUTRA model. This simulation includes configuration, discretization, property assignment and boundary conditions determination. Finally, the transverse macro-dispersivity coefficient was estimated for different scenarios of the solute transport in this tank. The purpose of this research is to analyze of the solute dispersion, in mixing salt and fresh water, and the effect of seepage velocity, concentration of pollutant source and heterogeneity of porous media on the flow dispersivity property. In this research, after studying the effect of different boundary conditions in SUTRA model on the development of the salt water plume, simulation of the model of heterogeneous sand tank and comparing its results with laboratory model and homogeneous model were performed. As a practical result of this research, the diagram of changes in the coefficient of transverse dispersivity against the source concentration and seepage flow velocity was plotted. In numerical simulation of heterogeneous Porous media, for all concentrations, with the exception of the concentration C₀= 35000, with increasing flow velocity, the values of the transverse dispersivity coefficient AT calculated by SUTRA decreased. Also AT for all seepage velocities, with the exception of seepage velocity u=4 m/day, increased with increasing source concentration. Also, the values obtained AT from the SUTRA model were more than the values of AT obtained from experiments. In numerical simulation of the homogeneous porous media, for all velocities, as the concentration source C₀ increases, the transvers macro dispersivity coefficient AT increases. According to the applied results, suitable solutions can be found to improve the quality of groundwater and prevent the mixing of fresh and saltwater resources.

Furrow irrigation is the most common method of surface irrigation. However, the accurate estimation of the soil water infiltration equation is the most important challenge for evaluating this method of irrigation. In this study, a fast and simple method that is named soil intake families and presented by USDA-NRCS (RSIF), evaluated for estimation of the Kostiakove-lewis infiltration equation parameters based on soil information. Also, this method was developed based on irrigation condition and considering soil characteristics (D-RSIF). Two treatments including constant and variable inflow discharge were tested with 4 repetitions and different irrigation phases including advance, storage and recession were simulated by developed Zero-Inertia model using RSIF and D-RSIF methods. The results showed that using the zero- inertial model, the difference between simulated advance times and simulated runoff were significant at 5% level for D-RSIF and RSIF methods. For variable inflow discharge, the error of estimating runoff volume was 10%, 6%, 12% and 41% for RSIF, D-RSIF, multilevel calibration and two-point methods respectively. Also, the irrigation scheduling error, based on soil physics characteristics (RSIF) was 14% that means consuming water more than required.

To preserve soil as a productive resource, a balance between natural capability and utilization must be established to achieve through land suitability evaluation. The aim of this study was to compare the run-off and deposition of different land uses of Beheshtabad watershed in the current situation and in compliance with standardized land use fitted situation. For this purpose, land use map in its current state was provided using Landsat 7 images and land use suitability map was obtained by FAO (1979) instructions. SWAT model was then applied to simulate runoff and sediment yield by using these land use maps. To do this, the curve number method was used for calculating the runoff, the Muskingam was applied for channel routing, and Hrgrave-samani was employed for potansial evapotranspiration. The results confirmed that considering suitability in using lands in Beheshtabad watershed caused the reduction of the average runoff from 99.4 mm/yr to 82.8 mm/yr (17%) and sediment rate of 10.7 to 7.8 t/ha. yr (27%). Also, the reduction percentage in some land uses, such as dry, irrigated cropland and downstream ranges, was much more.

River discharge is among the influential factors on the operation of water resources systems and the design of hydraulic structures, such as dams; so the study of it is of great importance. Several effective factors on this non-linear phenomenon have caused the discharge to be assumed as being accidental. According to the basics the chaos theory, the seemingly random and chaotic systems have regular patterns that are predictable. In this research, by using methods of phase space mapping, correlation dimension, largest Lyapunov exponent and Fourier spectrum power, a period covering 43 years of Zayandehrud River discharge (1971-2013) was evaluated and analyzed based on the chaos theory. According to the results, the non-integer value of the correlation dimension for Eskandari and Ghale Shahrokh stations (3.34 and 3.6) showed that there was a chaotic behavior in the upstream of Zayandehrud-Dam Reservoir. On the other hand, in the Tanzimi-Dam station, the correlation dimension curve was ascending with respect to the embedding dimension, showing that the studied time-series in the downstream of Zayandehrud-Dam Reservoir was random. The slope of the Lyapunov exponent curve for Eskandari, Ghale Shahrokh and Tanzimi-Dam stations was 0.0104, 0.017 and 0.0192, respectively, and the prediction horizon in the chaotic stations was 96 and 59 days. The non-periodical feature of time series was studied by using the Fourier spectrum power. The wide bandwidth, besides other indices, showed that river discharge in the upstream stations of Zayandehrud Reservoir was chaotic.

The Kor River in Fars province supplies an important part of water requirement in the Doroodzan dam basin and its surrounding area. In this study, the meteorological and hydrological droughts of this area were investigated in the last four decades. For this purpose, the temporal and spatial trend variability of the stream flow was investigated in monthly, seasonal, and annual time scales in the 6 selected stations. The trends of Standardized Precipitation Index SPI, as the drought index, in the 5 selected stations were also studied by the modified Mann-Kendall method. The results indicated that the trend in the stream flow was decreasing in all time scales. Significant downward trends were observed at 95% confidence level on monthly, annual and monthly time scales, especially in the warm months from May to September. These significant downward trends were located spatially in the stations located near the agriculture area, in the middle part of the basin. The significant upward trend existed only at the Doroodzan dam station, at the outlet in the area and in the warm months of the year. In the case of the SPI index, trends were  decreasing in all time scales and were  significant only at 2 stations in the long-term periods, 9, 12, and 18 months, at 95% confidence level. The results, therefore, indicated the occurrence of severe droughts (SPI<-2) during 1982-83 and 2007-8 periods.

Occurrence of local scour is one of the most significant causes of damage to the pipes. Therefore, safe and economical design of pipes in the flow path requires a good estimate. In this study, based on the important and effective parameters in the scouring phenomenon, in order to develop educational patterns according to the data obtained in the laboratory of Ahvaz Islamic Azad University, models based on artificial neural networks were created with the NeuroSolution5 software. MLP, GFF and RBF were the models used in this study; after comparing, MLP was selected as the basis for our study. Finally, the effect of each parameter on scouring was determined using the  artificial neural networks technique, based on which the  shields parameter with a very high effect (more than 95 percent) was determined as one of the most effective causes of the local scour.

One of the most important problems in flood manegment is the damages induced by this phenomenon. Expected annual damage (EAD) is an important index for basin vulnerability against flood. Prediction of flood damages requires the analysis of spatial and temporal risk and must be calculated by the combination of hydrologic, hydraulic and economic models. In this research, the uncertainty was considered in the flood risk analysis. The probability of flood occurrence was calculated by the parabolistic model. By using the river analysis systems software (HEC-RAS) and the geographic information system (GIS) and utilizing the Google-Earth software, the floodplains of Zayande Roud river in Esfahan province were investigated with the  return period of 25, 50, 100, 200 and 500 years. The Monte Carlo method was also sed to perform the uncertainty analysis in the proposed method. The logarithmic persion type III was selected as the best distribution of flood. The damage-stage relationship was calculated as well. Based on the uncertinity analysis, the river discharge could be regarded as the major parameter in the uncertainty of EAD.

In this research, conjunctive and integrated operation of surface and ground water resources of Behbahan plain (Maroon dam's reservoir and existing wells, respectively) was investigated. Simulation of allocation of water demands in this basin was performed by four scenarios, using WEAP software: 1) current conditions (M1), 2) reference scenario for the next 16 years (M2), 3) land development scenario (M3), and 4) optimal scenario (M4). The optimal scenario was performed with multi-purpose linear programming. Based on the results, drinking water demands was satisfied completely in all scenarios. Under the scenario of current conditions, all agricultural demands, except the traditional rights, supplied more than 50% in the low-flow months. In the reference scenario, water supply for agricultural demands in some months was less than 100% and even in June and July, the water supply for North and South Irrigation networks of Behbehan plain was less than 10%. In the land development scenario, agricultural demands of all irrigation networks, except Ramhormoz network, satisfied more than 90% in all months. The optimal scenario performed better than other scenarios for minimum Maroon River flow and volume of storage in the reservoir. Comparison of the four scenarios in satisfying the environmental needs also revealed that the optimal scenario performed better than the other three scenarios in the spring months. However, it provided less than 100% of water needs in the whole year. Comparison of the four scenarios also showed that the first two scenarios had the highest reliability percent in the Jayzan-Fajr, South Behbahan and North Behbahan Irrigation Networks and traditional water rights. Frequency of storage-time-probability from the storage volume in the optimal scenario also showed that maximum storage lifetime of the lasting storage volume was 558 million m3 (which was equal to half of the volume of Maroon dam’s reservoir) with the highest probability (60%).

River discharge is among the influential factors on the operation of water resources systems and the design of hydraulic structures, such as dams; so the study of it is of great importance. Several effective factors on this non-linear phenomenon have caused the discharge to be assumed as being accidental. According to the basics the chaos theory, the seemingly random and chaotic systems have regular patterns that are predictable. In this research, by using methods of phase space mapping, correlation dimension, largest Liapunov exponent and Fourier spectrum power, a period covering 43 years of Zayandehrud River discharge (1971-2013) was evaluated and analyzed based on the chaos theory. According to the results, the non-integer value of the correlation dimension for Eskandari and Ghale Shahrokh stations (3.34 and 3.6) showed that there was a chaotic behavior in the upstream of Zayandehrud-Dam Reservoir. On the other hand, in the Tanzimi-Dam station, the correlation dimension curve was ascending with respect to the embedding dimension, showing that the studied time-series in the downstream of Zayandehrud-Dam Reservoir was random. The slope of the Lyapunov exponent curve for Eskandari, Ghale Shahrokh and Tanzimi-Dam stations was 0.0104, 0.017 and 0.0192, respectively, and the prediction horizon in the chaotic stations was 96 and 59 days. The non-periodical feature of time series was studied by using the Fourier spectrum power. The wide bandwidth, besides other indices, showed that river discharge in the upstream stations of Zayandehrud Reservoir was chaotic.

One of the main reasons for bridge failure is the local scour around the pier. Pier groups are popular in the structural designs due to economical and geotechnical reasons. The mechanism of scouring at the pier groups is more complicated than the single one. In this study, the scour around group piers in the sandy soil and a mixture of sand and clay in some relative compaction equal to 90% and the optimum moisture was studied. The arrangement of the group piers was 1pier * 3pier and 3pier * 1pier along and transverse of the flow direction, respectively, at the interval space of D, 2D and 2.5D intervals. The effect of the Bentonite clay content was investigated. Finally, by using Kaolinite clay, the effect of the clay mineral was studied. The results showed that the scouring depth was different not only in cohesive and non- cohesive soils, but also according to the type of the clay mineral. The use of 10% bentonite clay mixed with sand reduced scour more than 90%, as compared to the sandy soil. On the other hand, using 15% of kaolin in the similar conditions reduced scour depth by only a 34%, in comparison to the sandy soil.

Soil erosion and its consequences are important factors in forest road network management. Cutslopes are the most important source of making sediment among different parts of the forest roads structure. For this research, a new and bare road in district No. 2, series No. 5 of NekaChoob forest, was selected; then the study data was measured. The study design was a completely randomized design in 10 plots with the size of 2 m² along 500 meters of road with the 8 natural rainfall events. The results of the Pearson correlation showed that among soil properties, the contents of the liquid limit at the 5% confidence level and the plastic limit at the 1% confidence level had positive correlations with runoff and soil loss. Also, organic matter at the 1% confidence level and the contents of the sand at the 5% confidence level had negative correlations with runoff and soil loss. With increasing the soil moisture and bulk density, runoff and soil loss were enhanced. The results of the multivariate model showed that soil loss could be estimated using the Plastic Limit and sand percentage variables with a the correlation coefficient of 0.948.