JWSS - Journal of Water and Soil Science

Estimation of evapotranspiration is essential for planning, designing and managing irrigation and drainage schemes, as well as water resources management. In this research, artificial neural networks, neural network wavelet model, multivariate regression and Hargreaves' empirical method were used to estimate reference evapotranspiration in order to determine the best model in terms of efficiency with respect to the existing data. The daily data of two meteorological stations of Shahrekord and Farrokhshahr airport in the dry and cold zones of Shahrekord during the period 2013-2004 was used; these included the minimum and maximum temperature, the average nominal humidity, wind speed at 2 meters height and sunshine hours. %75 of the data were validated, and %25 of the data was used for testing the models. Designed network is a predictive neural network with an active sigmoid tangent function hidden in the layer. In the next step, different wavelets including Haar, db and Sym were applied on the data and the neural network-wavelet was designed. To evaluate the models, the method was used by the Penman-Montith Fao and for all four methods, RMSE, MAE and R statistical indices were calculated and ranked. The results showed that the wave-let- neural network with the db5 wavelet had a better performance than other wavelets, as well as the artificial neural network, multivariate regression and the Hargreaves method. The results of wavelet network modelling with the db5 wavelet in the Farrokhshahr station were calculated to be 0.2668, 0.2067 and 0.998, respectively; at the airport station, these were equal to 0.2138, 0.14 and 0.9989, respectively. The results, therefore, showed that the neural network-wavelet performance was more accurate than the other models studied in this study.

The present study was conducted to evaluate the ecological risk indices of Zn, Cu, Cd, Pb and Ni in the soils from Urmia region (Ghahramanloo village), as irrigated with treated wastewater. Accordingly, six different soil sites (five soil sites under wastewater irrigation and one soil site under well water irrigation as the control) were selected and sampled (AP horizon, 0-30 cm depth). Soil samples were air dried, passed through a 2-mm sieve, and analysed to determine the chemical properties and the studied heavy metals. The results showed that irrigation with the treated wastewater significantly increased the total elements in the order of Cd (228%)> Zn (118.5%)> Ni (81.5%)> Pb (54.2%)> Cu (23.5%). Nevertheless, with the exception of cadmium, other elements were within the admissible range based on the national and international standards. Ecological risk index (min = 125, max = 152, mean = 140) showed a considerable risk in all studied soils and Cd could be regarded as the major metal affecting the index yield.

Today, the use of refined urban wastewater for agriculture is growing considerably. One of the methods for the natural treatment of wastewater is the constructed wetland. In this study, the effects of three and six days retention time on the vertical, horizontal and hybrid constructed wetland (first vertical and then horizontal) with perlite beds and Cyperus plants on the urban wastewater were investigated. In this study, horizontal wetlands were designed with 0.75 m width, 0.5 m depth and 6 m length; the vertical wetlands were designed as cylinders with a diameter of 0.7 m and the height of 1.2 m. On average, for the three days retention time, in the wetland with the vertical flow, 5the horizontal flow and the hybrid wetland, nitrate was 31.0, 36.7 and 56.3 percent, ammonium was 7.6, 32.7 and 37.8 percent, and the fecal coliform was decreased by 53.3, 93.4 and 96.9 percent, respectively. Also, during the six days retention time in the wetland with the vertical flow, the horizontal flow and the hybrid wetland, nitrate was 45.7, 58.5 and 77.5 percent, ammonium was 16.8, 75.2 and 79.4 percent, and fecal coliform was decreased by 58.0, 97.5 and 99.0 percent, respectively. Overall, the results showed that constructed wetland with perlite beds and Cyperus plants had a good function in removing pollutants, especially fecal coliform.

Evaluation of groundwater hydro chemical characteristics is necessary for planning and water resources management in terms of quality. In the present study, a self-organizing map (SOM) clustering technique was used to recognize the homogeneous clusters of hydro chemical parameters in water resources (including well, spring and qanat) of Kerman province; then, the quality classification of groundwater samples was investigated for drinking and irrigation uses by employing SOM clusters. Patterns of water quality parameters were visualized by SOM planes, and similar patterns were observed for those parameters that were correlated with each other, indicating a same source. Based on the SOM results, the 729-groundwater samples in the study area were grouped into 4 clusters, such that the clusters 1, 2, 3, and 4 contained 73%, 6.2%, 6.7%, and 14.1% of groundwater samples, respectively. The increase order of electrical conductivity parameter in the clusters was as 1, 4, 3 and 2. The results of water quality index based on the entropy weighting (EWQI) showed that all of the samples with excellent and good quality (36.3% of samples) for drinking belonged to the cluster 1. According to the Wilcox diagram, 435-groundwater samples (81.7%) in the cluster 1 had the permitted quality for irrigation activities, and the other 285-groundwater samples were placed in all four clusters, indicating the unsuitable quality for irrigation. The Piper diagram also revealed that the dominant hydro chemical faces of cluster 1 were Na-Cl, Mixed Ca-Mg-Cl and Ca-HCO₃, whereas the clusters 2, 3, and 4 had the Na-Cl face. This study, therefore, shows that the SOM approach can be successfully used to classify and characterize the groundwater in terms of hydrochemistry and water quality for drinking and irrigation purposes on a provincial scale.

Selection of drainage equation with acceptable accuracy has always been a challenge for designers to design subsurface drainage systems. In this research, seven steady state drainage equations were used for predicting daily and cumulative drainage rate on a farmland of sugarcane in Imam agro-industrial Company. These drainage equation included Hooghoudt, Ernst, Kirkham and Dagan that have been developed in the past and Mishra and Singh, Henine and Yousfi et al that recently developed. The statistical indices consist of P-value, RMSE, R2 and Percentage Error of estimating cumulative drainage rate were calculated for Hooghoudt equation 0.9501, 1.49 (mm/day), 0.80 and -0.19%, respectively. For Ernst equation 0.0001, 2.46 (mm/day), 0.34 and 16.98%, respectively. The result of performance of drainage equations revealed that Hooghoudt and Ernst equation were as the equations with the highest and lowest accuracy in predicting drainage rate, respectively. Also from the newly developed equations, the Yousfi et al equation was found with relatively well accuracy to predict the drainage rate. This equation was placed in second rank after Hooghoudt equation and other equations showed poor performance. Thus, with selection of the appropriate drainage rate, the Hooghoudt equation is suggested for designing of drain spacing in medium to heavy textured soils such as sugarcane agro-industrial.

Limited information is available on the effect of residues rates and slope direction on dryland wheat
(Triticum aestivum L.) yield.  This study was carried out to determine the effects of residues rates and tillage direction on grain yield and yield components of the Sardary wheat in a dryland region in Zanjan. Five wheat residues rates (0, 25, 50, 75 and 100% surface cover) were applied and incorporated into soil in two slope directions (along the slope and on contour lines) using the randomized complete blocks design with three replications in a land with 10% slope steepness. Overall, thirty plots with 2m × 5 m dimensions were installed in the field and wheat grain yield and yield components were determined for growth period from 2015-2016. Results indicated that grain yield and yield components were significantly affected by the residues rates and slope direction and their interaction. In contour tilled plots, wheat grain yield (1.78 to per hectare), thousand grain weight (42.26 kg) and wheat height (55.11 cm) were 5.32, 5.01, 16.19 and 1.36 percent more than the plots tilled along the slope. The highest grain yield was found in 75% of residue (2.45 ton per hectare) under contour line direction which was about 53% bigger than control treatment (0% straw mulch) under along the slope. This study indicated that the application of straw mulch before cultivation and incorporating into soil using contour line tillage are proper soil management methods to obtain higher wheat yield in this dryland region.

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.

One of the important elements in mechanized irrigation is to know the relation between suction force (matric force) and soil moisture, which is referred to as moisture curve. The shape and coefficients of this curve are influenced by the texture and structure of the soil and can change with soil structure modification.  The most important goals of this study were to evaluate the effect of using zeolite on water holding capacity and coefficients of moisture curve patterns of two sandy and loamy soil texture, the effect of using zeolite on the shape and soil moisture curve coefficients based on various models, some of them so far in Iran, zeolite was added to soils at levels of consumption (2, 5 and 10%). The moisture content of each soil was determined at various points in 12 points using a Dicagon machine.  Soil moisture curve coefficients using software and fittings of six Brooks and Corey models, Kosugi, Durner, Fredlund and Xing,  VanGenuchten and Seki. The results indicate that in all models, the parameter value increases with the use of zeolite and increase the level of use. Water storage capacity also increases with the use of zeolite.  Other results showed that the best model for estimating the moisture curve of laryngeal and sandy soils of the Darren model is weakest and the weakest models in the lush soils of the broccoli model and Kasughi model and in the sandy soil of the Brooksouli model Blindness and model-gnuchten Shand.

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.

Creation and conservation of urban parks is challenging in arid environments where daily thermal extremes, water scarcity, air pollution and shortage of natural green spaces are more conspicuous. Water scarcity in the arid regions of Iran is major challenge for water managers. Accurate estimation of urban landscape evapotranspiration is therefore critically important for cities located in naturally dry environments, to appropriately manage irrigation practices. This study investigated two factor-based approaches, Water Use Classifications of Landscape Species (WUCOLS) and Landscape Irrigation Management Program (LIMP), to measure the water demand in a botanic garden. The irrigation water volume applied was compared with the gross water demand for the period from 2011 to 2013. On average, WUCOLS estimated an average annual irrigation need of 1164 mm which is 15% less than the applied value of 1366 mm while the LIMP estimate of 1239 mm was 9% less than the applied value. Comparison of estimated and applied irrigation showed that a water saving of 9% can be made by the LIMP method. The outcomes of this research stressed the need to modify the irrigation requirements based on effective rainfall throughout the year, rather relying on long-term average data.

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 aim of this study was the effect of raw water quality on the efficiency of domestic reverse osmosis apparatus in Khuzestan province. The results showed that the purified water quality was related to the quality of entrance raw water. With increasing in salt concentrations (EC) or TDS, purification efficiency was decreased. The cation and anions content of refinery water was related to TDS and EC. The Ca/Na and Mg/Na were decreased due to refinery. The ability of these apparatus to reduction of two valence cations were more than mono valence. As same as this trend was observed for anions. Also, the comparison of the EC of raw water and refinery from these apparatuses had different EC from different raw water entrance. This means of these apparatuses had different efficiency with changes of raw water quality. Generally, domestic water purification systems have better performance in Karun river water treatment than in Kheiryrabad and Karkheh rivers.

Soil water content is the most effective factor associated with the hydrophobic and hydrophilic changes in a soil. Water repellency in soils, is not a permanent feature; it can be reached in the dry season and reduced or eliminated in the wet season It can be said that in terms of moisture, there is a critical region that is defined as the threshold moisture content, where in lower moisture, the soil is repellent and in higher moisture, the soil is wet able. The purpose of this study was to investigate soil moisture variations on degree of hydrophobicity and determine the amount of threshold water content in soil samples of wetland around Shahr-e-Kord. In this study, some samples of Shahr- e-Kord wetland were investigated. After determining the initial moisture content of the soil, the soil hydrophobicity conditions were determined by determining the time of water droplet penetration (WDPT). Soil moisture variations were carried out using soil wetting and drying method, and in each step the soil hydrophobicity conditions were tested. Reducing water content in soil samples, led to a change in the degree of hydrophobicity in hydrophobic samples, in one soil hydrophilic soil sample, Reducing water content changed hydrophilic soil to hydrophobic soil. The threshold water content was also observed up to a maximum of 54% volumetric water content at a given point. Based on this, the higher moisture content of the threshold at this point indicates the higher soil potential for runoff generation. Soil analysis showed that soil organic matter had a positive correlation with threshold water content.

Nowadays, water supply for the sectors of household consumption, agriculture, green spaces and industry is currently one of the most important challenges for governments in many parts of the world, especially in arid and semi-arid climate regions such as Iran. The aim of this study was to simulate the amount of run-off from the daily precipitation for Sarpol-e Zahab city, for the purpose of estimating the required amount of water for the irrigation of the green spaces of the city. In this study. After providing information and using the Digital Elevation Model (DEM) map of city, all individual sub-basins of the basin were produced. All data related to creating and overlaying hydrologic, climatologic and physiographic layers were used according to the HEC-HMS hydrologic model. The run-off depth and flood volume of each sub-basin were obtained through the SCS method. Then the required amount of water for the green areas of Sarpol-e Zahab city was calculated. The efficient rainfall was estimated using four methods including SCS, 80 percentage, reliability, and USDA for each month, separately. Finally, the amount of needed water for the green area was obtained using these four mentioned methods. The results indicated that the role of curve number in the infiltration rate was more than other variants. Impermeability of urban basins and changes was created due to the growth and development of the city such as removal of vegetation, soil compaction, creation of the water collection and leading surface waters, decreasing the amount of water penetrating to soil significantly. The amount of surface water for sub-basins was estimated to be 266000 cubic meters. Besides, the results showed the amount of required water for 5 months of the year (from early May to September late) using four methods of SCS, 80percentage, reliability  and USDA was  equal to 243525, 238062, 267865 and 236458 cubic meters, respectively. The amount of the estimated runoff volume was 266,000 cubic meters. Regarding the area of green spaces in Sarpol-e Zahab city and its daily need of water, this volume of water could  supply the required amount of water to irrigate the green area of the city for five months (From May to September).

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%).

This research tried to provide a sustainable solution for the allocation of water resources of Zayandehrood basin in a way ensuring minimal conflicts and tension between the stakeholders in use of the water resources, four main decision makers of the basis, comprising Regional Water Company, conflicts among Agricultural Jahad Organization, and Department of Environment of Isfahan Province and Chaharmahal and Bakhtiari Province, were reviewed and 128 possible cased  according to 7 scenarios were constructed and applied in the  GMCR model. According to the GMCR approach, 6 balanced sustainable scenarios in different climatic periods of the basin were presented. Finally, the results were generalized for choosing the best mode in the form of a scenario within the WEAP model; also, the results obtained from these scenarios were presented using the criteria of system performance assessment. On the basis of the findings, Scenario II was developed, comprising the application of new simultaneous management of demand and supply, restrictions in drawing water from water tables, new prioritization in stakeholder allocation and new water portion plans in the basin as the best scenario with 81.4% sustainability index.

Flood is a natural disaster making the heavy humanistic and economic damages each year in most parts of Iran. In this research, the SWAT model performance in flood prediction and sub-basin priority was investigated in terms of flooding in Araz-Kose watershed in Golestan province. To calibrate the model, SUFI2 was applied. The calibration and validation were done for the 1991-1998 period based on the data of 2001-2009. After validation, the indices (R2, bR2, and NS) were estimated. They were equal to 0.81, 0.81 and 0.73 for calibration and 081, 0.78 and 0.64 for validation, respectively. The sensitivity analysis results showed 13 effective parameters. The curve number (CN2) was determined as the most effective parameter. For studying the flooding in a watershed, the Araz-Kose watershed was divided into six parts. Based on the obtained results from the SWAT model with different CN and F indexes (with/without considering the sub-watershed), the sixth sub-basin with 22.4% decrease in discharge was chosen as the most effective region in flooding. Meanwhile, the other sub-basins including 4, 1, 3, 5 and 2 had more flood potential, respectively.

Sloping farmlands are the major sources of soil, water and nutrient losses in arid and semi-arid regions. Information about the impacts of different tillage practices on soil erosion, nutrient loss and crop nutrient uptake on the sloping farmland of semi- arid soil is, however, limited. This study was carried out to investigate the effects of tillage direction on soil, water, nitrogen and phosphorous losses and their uptake by plant in a rainfed wheat land. Field experiments were conducted in two tillage directions: downslope tillage and contour line tillage with four fertilization treatments: control, urea, triple superphosphate, and urea + triple superphosphate at the field plots with 1.75 m ´ 8 m in dimensions by using the randomized completely block design at three replications in Zanjan Township during 2014-2015. According to the results, Significant differences were found between the two tillage practices in soil loss (P < 0.001), water loss (P < 0.001), nitrogen loss soil loss (P < 0.001), and nitrogen uptake by wheat grain (P < 0.001), while phosphorous loss and its uptake did not show any statistically significant difference. Soil and water loss in the downslope tilled plots was 1.65 and 2.50 times higher than the contour line tillage, respectively. Nitrogen loss in the downslope tilled plots was 1.29 times more than that in the contour line tilled plots. Nitrogen loss in the plots was attributed to soil and water loss, so significant relationships were observed between nitrogen loss and soil loss (R² = 0.59)
and water loss (R² = 0.55). This study, therefore, revealed that the tillage direction is an important factor controlling runoff, soil loss, and nitrogen loss and its uptake by wheat in the rainfed lands of semi-arid regions. Application of the contour tillage is, therefore, the first step to conserve soil and water and to improve soil productivity in these regions.

Localized irrigation methods can be used to manage low water holding capacity in the sandy soils. In this research, the effects of different irrigation systems including pot, tape and drip irrigation with gravity pressures of 0.5, 1.5 and 3 meters on the sandy soil moisture distribution under watermelon cultivation were compared with the furrow irrigation as the control treatment. The moisture content of the soil at different depths and at the distance of 5 and 20 cm from the plant was measured using the TDR device. Water distribution study showed that in the pot irrigation method, the moisture content of different depths of soil was kept constant by 16% during the irrigation interval, but the highest moisture content was observed in gravitional drip irrigation treatment at the depths of 40, 50 and 60 cm; in contrast, the lowest amount of moisture was observed in the pot irrigation treatment. In tape and gravitional drip irrigation system with gravity pressure, in addition to the adjustment soil moisture up to 15 to 22% within the wetting front, soil moisture can be kept almost constant by pulsed irrigation technique. Therefore, while providing the use of drip irrigation system with minimum water pressure available in most of the agricultural land (0.5 m), using pot irrigation can ensure sandy soil moisture retention and soil for the cultivation of fruits such as watermelon plants.

Water resources management depends on the precise assessment of water storage and access in each region, as well as environmental interactions of these resources. The man objective of this study was to delineate the potential zones of groundwater storage using FAHP. Mapping and assessment of it required maps of geomorphology, drainage, density, lineament density, slope and vegetation, which were initially prepared as the input layers in FAHP; the appropriate weights were attributed to them based on FAHP. Potential zones of ground water were classified into five classes of poor, average, good, very good and excellent. The number and density of available wells and springs in the study area dealt with the potential of the region for groundwater storage. So, ROC was used to assess the validation of results, considering spring points as signs of water resources. According to the results, classes of very good, good, average, weak, and very weak were ranked as the first to the last in terms of privilege order with an area of 37.7, 55, 40, 107, and 98.4 square kilometers, respectively.