JWSS - Journal of Water and Soil Science

The evaluation of climate change impact on hydrological cycle includes uncertainty. This study aimed to evaluate the uncertainty of climate change impact on the Zayandeh-Rud Reservoir inflow during the future period of 2020-2049. The outputs of 22 GCM models were used under the three emission scenarios including RCP2.6, RCP4.5 and RCP8.5. The Bayesian Model Averaging (BMA) was used as the uncertainty analysis for weighting the 22 GCM models based on their ability to simulate the baseline 1990-2005 period. Results showed that different GCM models had different abilities in estimating climatic and hydrological variables and the application of uncertainty analysis in climate change studies could be necessary. The monthly temperature in the upstream of Zayandeh-Rud reservoir could be raised by 0.85 to 1 ◦C; also, the precipitation might be increased by 2 to 3 percent. The high flow during winter season will increase under climate change, while the spring and autumn seasons’ low flows are expected to reduce. Additionally, the annual reservoir inflow may decrease by 1 to 8 percent, showing the necessity for change in Zayandeh-Rud reservoir’s rule curve and allocation of water resources.

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.

In this study, to evaluate the rain- fed land capability in the west of Gavkhooni basin and Plasjn sub- basin, a multi- criteria evaluation method was used. First, by reviewing the literature and expert knowledge, proper data were determined. Criteria and constraint were standardized by Fuzzy and Boolean methods repeatedly and the criteria weights were determined using the analytic hierarchy process. Calculated weights showed that soil and climate criteria with 0.27 and 0.26 had the highest weights among other criteria. Criteria and constraints were combined by considering criteria weights and using the weighted linear combination method; then the rain- fed land capability model was prepared. By re- classing the prepared model, the rain- fed land capability map was produced in 6 capability classes. The results showed that 178430 hectares of the study area was related to very high and high rain- fed capability classes. To determine the rain-fed agriculture sustainability, rain- fed agriculture locations were determined in each land rain- fed capability map. The results showed that 19686 hectares of rain- fed areas were located in high and very high capability and 5999 hectares were the in lower classes.

Groundwater supplies a major portion of two basic human needs: drinking and agricultural water. Forecasting, monitoring, evaluating the performance and planning of this vital resource require modelling. The lag time of the groundwater level fluctuations against the rainfall is one of the essential data of the models. The purpose of the present study was to evaluate the piezometers behaviour by using the Pearson cross-correlation method between SPI and GRI indices in the Shiraz alluvial plain in order to determine the mentioned lag time. The results showed a similar behaviour for 86.2% of the piezometers. In 79.3% of the piezometers, groundwater level was declined one month after the rainfall event. The best correlation coefficient between the aforementioned indices was observed along the southwestern to the northeastern axis of the plain. The northern alluvial plain has a better correlation, as compared to the southern section because of the northern-southern slope of the plain. The central area of the plain had the highest correlation coefficient. The maximum correlation coefficients occurred at a time scale of 48 months. Also, since 2004, due to the decline in the atmospheric precipitation in the Shiraz plain, the SPI index has surpassed the drought level, although the trend has not been significant. However, the GRI does not follow this trend, showing a significant hydrological drought. The reason can be the disproportionate water extraction to recharge ratio in the alluvial aquifer of the plain.

This study focused on proposing a new operational perspective within main and lateral irrigation canals based on the economic value of water. To achieve this objective, the operation-economic framework offered in this study consisted of two main components of the PMP model and Operation model. The estimated economic values of water in different regions of the network were employed as the starting point for connecting the economic model with the operation model. It is worth mentioning that the technical perspective targeting adequacy of water distribution within the canals was modified in this study to be applied for the operation-economic framework since the original forms of the indicator were based on physical inherent of the water. Roodasht Irrigation District, located at Zayandeh-Rud basin, was selected as the case study, and the proposed framework was tested on the district. The obtained results revealed that in response to implementing the proposed framework in water distribution within the canal under the water shortage condition, alfalfa and safflower were the two crops those cultivation was decreased drastically in comparison with the other crops. The primary reason for the decrease was the lower values of the economic value of water for these two crops. Also ,the results of the canal operation appraisal from the adequacy of water delivery revealed that for the traditional operating system (without considering the economic perspective), the maximum values of the adequacy indicator were obtained for the upstream four canal reaches. On the other hand, the off-takes numbers of 1, 6, 5, and 12 got the maximum values of the adequacy indicator when the proposed operation-economic framework was applied for the canal system.

In general, engineering designs need to optimize the factors affecting the under-study phenomenon; however, this is often a costly and time-consuming process. In this regard, new methods have been developed to optimize with fewer tests; thus, they can make the whole process more affordable. In this study, Taguchi and Taguchi-GRA methods were used to design the geometric parameters of the protective spur dike in order to optimize their efficiency in reducing the scouring in a series of spur dikes. The results of both methods showed the optimal ratio of the length of the protective spur dike to the length of the first spur dike was 2.5 and the angle of the protective spur dike was 90 °. However, the ratio of the length of the protective spur dike to the length of the main spur dike in the Taguchi method was 0.8 and in the Taguchi-GRA method, it was 0.6. In addition, using variance analysis showed that the distance between the protective spur dike from the first spur dike, the protective spur dike angle, and the length of the protective spur dike were, respectively, the most effective on the performance of the protective spur dike. The results of this study, therefore, indicate that both methods are highly effective in optimization and, therefore, can be useful in the hydraulic engineer studies.

Today, to reduce the risks of contaminants, new remediation techniques have been focused on low-cost and environmentally friendly manners. Given the frequency of access, inexpensiveness and good physical and chemical properties, biochar has a high potential for the remediation of water pollutants. In this paper, the efficiency of chitosan engineered biochar (Bc-Ch) and pristine biochar (Bg-Bc) prepared from sugarcane bagasse biomass (Bg) in the Cd²⁺ removal in aqueous solution was investigated. To this aim, the effects of contact time, adsorbent dosage and solution pH on cadmium removal were evaluated by adsorption isotherms and Kinetic models. The results indicated that the Langmuir isotherm and the pseudo-second-order kinetic model could be well fitted with the process of cadmium biosorption. The maximum adsorption capacities of Bc-Ch, Bg-Bc and Bg ,according to Langmuir model, were found to be 32/78 mg/g, 11/57 mg/g and 2/23 mg/g, respectively. For these absorbents, the pseudo-second-order kinetic model showed the best fit to the experimental adsorption data. This study, therefore, indicated that the chitosan engineered biochar could be used as an effective, low-cost, and environmentally-friendly sorbent to remediate heavy metals contamination in the environment.

In this research, the impact of the Alagol wetland on the water treatment of Atrak River was studied. From June, 2016, to May, 2017, on the fifteenth day of the month, four samples of water were collected from the middle and the outlet of the wetland. Also, the wetland was fed only in the months of September, November and February. The parameters of acidity, electrical conductivity, phosphate, nitrate, dissolved oxygen, biochemical oxygen demand, chemical oxygen and ammonia were measured. The water pH at the entrance and exit was significantly different. EC was higher at the entrance, and its value was decreased in the middle and output. DO in the outlet of the wetland was higher than that in the middle and inlet, indicating the improved water quality and high dissolved oxygen in the wetland output. NO₃, NH₄, PO₄, BOD and COD were higher at the entrance to the wetland; also, it was decreased in the outlet and middle, and the difference was significant. Further, according to the results of September, November and February, which were fed to the wetland, water quality in the middle and outlet of the wetland was improved toward the entrance of the wetland. According to the results, Alagol wetlands could reduce the phosphorus, ammonia, BOD, COD and DO, and their concentrations were lower than the limit. However, given that the salinity at the entrance of wetland was too high, its amount in the output was higher than the standard limit and the wetland could not significantly reduce salinity. The results of this study showed that that of water pollution in the inlet, except that the dissolved oxygen parameters and the temperature were high and decreased in the middle outlet. Due to the quality of the wetland outlet, Alagol wetland water could be used for fish farming centers.

Given the various advantages of applying conservation tillage methods in the agriculture, including reducing the effects of climate change by decreasing the carbon dioxide emissions to the atmosphere caused by carbon sequestration in soil, this study was conducted with two wheat-cotton and wheat-sesame rotations at Agricultural Research Station Bakhtajerd, in Darab, the southeast of Fars Province, which had a warm and dry climate; this work was carried out in a loam soil during four years. The aim of this investigation was to compare the carbon sequestration (CS) in the soil after application of different conservation tillage methods with the conventional method. The results showed that in wheat-cotton rotation, the maximum and minimum amount of CS in the 0-20 cm depth of soil with the average 17.160 and 13.810 t/ha could be obtained by using no-till and conventional tillage, respectively. Therefore, no-till increased CS by 24.26% in wheat and cotton cultivation, as compared to the conventional tillage. The economic value of this CS increment for the environment was $2459 per hectare. In the wheat-sesame rotation, the highest and lowest CS was obtained with an average of 25.850 and 12.505 t/ha in no-till and conventional tillage, respectively. Namely, direct seeding of wheat and sesame increased the CS at the 0-20 cm depth of soil by 107%, as compared to the conventional tillage with the economic value of $9809.5 per hectare. Under similar conditions, in wheat-cotton and wheat-sesame rotations, the conventional methods could be replaced by no tillage.

Given the climatic changes and threats to food security in recent years, they have have become a major issue in agricultural climatology. The present study aimed to investigate the status of agricultural climate suitable for the cultivation of rice in the light of the influential climatic conditions in the past. Given the effect of temperature and the amount of precipitations on rice growth and the sensitivity of rice to these two variables, the study examined the predicted future temperature and rainfall and their effects on rice. Data related to the temperature and rainfalls were obtained from the Meteorological Organization. Additionally, the temperature and agricultural potential of the region were considered. By preparing the agricultural calendar for the cultivation of rice, the correlation between temperature, precipitation and rice productivity was calculated using the Spearman Correlation coefficient. By using the SDSM model, future data and temperature and precipitation return period were determined in the SMADA software. The results demonstrated that minimum spring temperature tended to be late spring. The minimum temperature had the highest impact in April, the maximum temperature had the highest impact in July and the maximum rainfall had the highest effect in both June and July. Based on the results of the prediction models, the studied region would experience an increase in temperature and rainfall by providing favorable conditions for the cultivation of rice. However, delays in the cold season and shortness of the growth period increased the risks associated with the cultivation of rice in this period.

In the last few decades, the use of porous concrete to cover the sidewalks and pavements as an interface to collect the urban runoff has been increased. This system is economically more efficient than other runoff-pollution reduction methods. To design a runoff control system and reduce its pollution, it is necessary to determine the hydraulic and dynamic properties of the porous concrete (with and without additives). In this research, the effects of cement type (2 and 5), water to cement ratio (0.35, 0.45 and 0.55), fine grains percent (0, 10 and 20%), the type of additive (pumice, industrial pumice, perlite and zeolite), and the added additive percent (5, 10, 15 and 20%) on the physical properties of the porous concrete (porosity, hydraulic conductivity and compressive strength), each with three replications,  were  investigated using robust design. Qualitek-4 software was also used to discuss the results. The results showed that to obtain the highest porosity in the mixing scheme of the porous concrete, no fine grains, cement type 2 and 15% industrial pumice should be used, and water to cement ratio should be 0.35. Also, the water to cement ratio of 0.55, 0% fine grains, type 2 cement and 15% industrial pumice resulted in the highest value of hydraulic conductivity in the porous concrete. Finally, the water to cement ratio of 0.55, 20% fine grains, type 2 cement and 5% zeolite led to the maximum compressive strength. In general, it was not possible to reach a logical conclusion in this research with the least costs without employing the robust design.

In arid and semi-arid ecosystems, isolated trees significantly influence the soil properties and can have a great impact on the soil fertility as well as the conservation and improvement of soil quality. This investigation was conducted to examine the influence of wild almond (Amygdalus arabica Olive.) trees having different ages on the physical and chemical soil properties. Soil samples were taken from the depths of 0-20, 40-60, 80-100 and 120-140 cm at two distances from the tree crown including the basal area (referred to as the rhizosphere) and the canopy edge in 3 replications for the 30, 50, and 130 year-old stands and also, in a control site, all in the Anjarak area, southeast of Baft city, Kerman Province. Soil properties including pH, EC, organic matter, calcium carbonate equivalent, available and non-exchangeable potassium and soil texture were measured in all samples. The results indicated that the measured soil properties in different depths in the study area had been influenced by the age and the canopy size of the wild almond trees. The highest and the lowest amount of pH were found in the control soil and the soils covered by 130 year-old trees, respectively. Besides, the electrical conductivity of the soil under the tree crown was more than that of the soil in the canopy edge. The accumulation of C, N, and other nutrients under the tree canopies resulted in the creation of fertility islands surrounding the trees. Furthermore, the soil physical and chemical properties were greatly improved with the increase in the tree age of Amygdalus arabica Olive. As the conclusion, wild almond trees could have very positive effects on soil properties. Therefore, it is essential to protect the trees. Otherwise, the risk of soil quality reduction would be increased and soils might become more susceptible to soil erosion.

The purpose of this study was to investigate the relationship between time and spatial features of meteorological, hydrological and agricultural droughts in Karoon 1 Dam basin. Meteorological and statistical data were accordingly selected to evaluate the drought situation between 1993 and 2016. The results showed that hydrological droughts occurred in the meteorological drought and had a very high correlation with this year's meteorological drought. The most severe droughts occurred between 2006 and 2011. Studies also showed that every three years, the basin was accompanied by a meteorological drought and then a hydrological drought. The results also showed that the highest correlation was observed with the 12-month meteorological index, with a delay of 3 months, and the 6-month meteorological and hydrological index with a delay of 3 months and a three-month hydrological drought index with a delay of two months. Therefore, it could be concluded that hydrological droughts showed a delay of almost two to three months in the entire catchment area; since this period was 4 months or more, the correlation between these two indicators was eliminated and decreased. Also, due to drought zones, during the period from 1993 to 2009, most of the droughts were caused by rainfall reduction in the southwest of the province, and this was associated with a reduction in runoff in its hydrometric stations. Of course, in 2009-2012, the runoff status had been temporarily improved, and from 2012 to 2017, the drought situation had again returned spatially to the previous routine.

The interaction of population growth, technological improvement and climate change have impacted severely on agricultural and environmental sustainability. In Iran, conventional tillage practice has resulted in soil erosion and loss of soil organic matter. In this regard, Conservation Agriculture (CA) forms part of this alternative paradigm to agricultural production systems approaches and can be regarded as a means to enhancing food productivity, reducing poverty, and mitigating the consequences of climate change in rural households. The objectives of this study were to examine the determinants and impacts of CA technology on wheat yield, poverty gap and water use. To this end, an endogenous switching regression (ESR) model was employed to estimate the impacts of CA technology on continuous variables such as wheat yield, poverty gap and water use. A sample of 260 farmers from Zarghan district was selected for interview collection of necessary farm level data. The results indicated that in the select equation of ESR model, ten coefficients (out of 12) are significant at the 5% level or higher. Knowledge of soil quality, access to credit, access to information, education, farm size, ownership of machinery, participation in agricultural extension activities and farmer’ perception have positive and significant effects on the probability of adopting CA. In contrast, variables such as the distance to shopping center and number of land parcels have negative and significant influence on adoption. Also, the results of ESR model and counterfactual analysis showed that wheat yield would increase by 1.05 tons and poverty gap and water use would decrease by 20% and 910 cubic meters per hectare respectively if farmers adopt CA technology.

The main purpose of the study is the operational simulation of main irrigation canal and evaluation of water delivery and distribution locally, regionally and overall using adequacy, efficiency, and equity indicators and “Desirability of water delivery and distribution” indicator. To achieve this goal, the hydrodynamic model of Roodasht irrigation network’s main canal was developed. The results of the calibration and validation of the hydrodynamic model showed that the two processes were satisfactory. All available scenarios including normal, water shortages and fluctuations were considered for water delivery and distribution in different conditions. In the local assessment, the adequacy varied from 7 to 85%, and the efficiency in all scenarios was 100%. The adequacy, efficiency, and equity indicators in the regional evaluation varied from 6 to 89, 91 to 100, and 13 to 46%, respectively. The overall evaluation of the canal showed that the most desirable situation is related to a harsh fluctuation increasing with the adequacy, equity and efficiency indicators equal to 82, 23 and 91%, respectively. Calculation of the “Desirability of water delivery and distribution” indicator showed poor performance in all operational scenarios except harsh fluctuation scenario with 82% of which, the canal performance was estimated in fair level.

The present study was intended to improve the chemical properties of a saline-sodic soil using the individual application of alfalfa residue and two biochars produced from sugarcane bagasse and walnut shell, at the weighting ratio of 5%; their concomitant application with gypsum, aluminum sulfate and the mixture of these two chemical amendments was considered. The experiment was conducted in three replications using the factorial experiment in a completely randomized design. After four months of incubation, the soil samples were measured for their main chemical properties. The results showed that alfalfa residues were the most effective treatment to reduce the soil pH; so the concomitant application of this organic amendment with gypsum lowered the soil pH from 9.13 in the control (untreated soil) to 7.24. It was also observed that the addition of gypsum and/or aluminum sulfate to the soil led to the increase of the soil electrolyte concentration and consequently, the increase of soil electrical conductivity to three times greater than control, through an increase of ions, like calcium and sulfate in the soil solution. Increasing the soluble sodium concentration by replacing exchangeable sodium by other similar ions showed that the studied treatments enhanced the sodium adsorption ratio (SAR), which could be regulated by washing. Concomitant application of the walnut-shell biochar with gypsum had the most increasing effect on the soil SAR, enhancing it from 22.6 in the control to 54.3. Potassium was released from organic amendments, improving the soil general conditions; addition of chemical amendments elevated soil exchangeable potassium contents; however, the elevated soil available phosphorus contents were less influenced by chemical amendments application. As the conclusion, it seems that the positive impacts of the applied chemical and organic amendments would supplement each other; as a result, the concurrent use of both treatments not only improves the bad soil chemical properties, but also enhances the soil fertility.

Today, the use of organic wastes as fertilizers to improve the physical, chemical and biological properties of soil is common. In this study, to investigate the effect of the sewage sludge on the growth and concentration of chlorophyll, nitrogen, phosphorus and potassium in quinoa plant, a factorial experiment was conducted based on a completely randomized design with three replications in a calcareous soil with electrical conductivity of 13.1 dS m^-1. Treatments included three genotypes of quinoa (Red carina, Titicaca, Q29) and three levels of sewage sludge (0, 20 and 40 t ha^-1). The results showed that the effects of the quinoa genotype, different levels of sewage sludge and the interaction of treatments on the root dry weight, shoot P concentration and chlorophyll concentration were significant. Also, the sewage sludge had a significant effect on the shoot length, shoot dry weight and shoot nitrogen concentration. By increasing the level of the sewage sludge, root length, shoot length, shoot dry weight and shoot N concentration were increased, on average, by 44.7 %, 48.8%, 42.0% and 46.6%, respectively. Also, application of 40 t ha^-1 sewage sludge significantly increased the chlorophyll concentration and shoot P concentration in Q29 and Titicaca genotypes. According to the results of this study, application of sewage sludge can increase the growth of quinoa by improving its nutrition.

In determining the allocation of water resources, the probable conditions of water resources and water demands are considered as the water allocation scenarios in the basin scale. Then, these scenarios are evaluated in the context of integrated water resources management and from the perspective of sustainable development indicators. The best scenario is selected in order to determine the water allocations. In these evaluations, there are spatial distributions and their interactions are simultaneously the key charaterictics in the decision matrix. These features are not often considered in the evaluation process. In the present study, distributed indicators and simple and integrated multi-criteria evaluation models, including ANP and CP methods, were used to evaluate the water allocation scenarios in the Aras Basin. The results showed that modeling of the spatial distribution and interactions of water allocation impacts was not possible through any of the simple multi-criteria evaluation methods. Simplifying and discarding one or two key features in the evaluation process can lead to significant uncertainties on rankings with a Spearman coefficient of -0.1. By implementing the integrated spatial decision-making approach and applying two features simultaneously, the fourth scenario was ranked first. The proposed approach was compared with the individual models, showing more accurate, with the correlation coefficients of 0.5, 0.6 and 0.7.

The scour around the bridge piers is one of the main causes of bridge failure and the extraction of aggregates may aggravate this phenomenon. The present study comprehensively investigated the scour around the groups of bridge piers in the presence of aggregate extraction pits, using different discharges. The bridge piers roughened by gravel had been compared with the simple bridge piers; so, the results showed that the roughening caused the reduction of the scour depth. Scour depth change rate led to an increase in the equilibrium time. The results also showed that the reduction of the scour depth at the downstream groups of piers was more than that in the upstream. For the lowest discharge, the aggregate extraction pits had a considerable effect on the scour depth difference for the groups of piers in the downstream and upstream. On the other hand, the effects were decreased when the rate of discharge was increased. The experimental results obtained by the rough surface models showed that as the discharge was increased, the local scour was increased too; at the same time, the bed profile was posed at the low level. Generally, the scour depth of the groups of piers in the downstream of the extraction pit was more than that in the upstream. The results of the current research, therefore, demonstrated that the surface of the bridge pier roughened by gravel reduced the scour depth.

Optimizing the water resources operation, especially in the agricultural sector, which has the largest share in the water resources operation, is extremely important. Therefore, in this research, while introducing Whale, Gray Wolf and Crow Search Optimization Algorithms, their performance in the optimum operation of Golestan single-reservoir system Dam was evaluated with the aim of providing water demand for the downstream lands based on reliability, Reversibility, and vulnerability indices. In this optimization problem, the objective function was defined as the minimization of the total deficiency during the operation period. Meanwhile, the constraints of continuity equation, overflow, storage and reservoir release volume were applied to the objective function of the problem. Then, the results were compared with the absolute optimal value based on the nonlinear programming method obtained from GAMS software; finally, a multi-criteria decision-making model was developed to rank the optimization algorithms in terms of performance. The absolute optimal response obtained by the GAMS software based on the nonlinear programming method was 19.41. The results showed that the Gray Wolf algorithm performed better than the other algorithms in optimizing the objective function, so that the average responses in Gray Wolf, Crow Search and Whale algorithms were 92, 84 and 67% of the absolute optimal response, respectively. Furthermore, the Gray Wolf optimization algorithm performs better than the Whale and Crow Search algorithms in all parameters. In addition, the coefficient of variation of the responses obtained by the Gray Wolf algorithm is 2 and 1.43 times smaller than that in the Whale and Crow Search Algorithms, respectively. Finally, the results of the multi-criteria decision-making model showed that the gray wolf algorithm had the first rank, as compared to the other two algorithms studied in solving the problem of the optimal operation of the Golestan dam reservoir.