Water is the most crucial factor for agricultural development. Therefore, the economic evaluation of water resources is critical. The purpose of this paper was to determine the economic value of water resources, to evaluate the financial efficiency and to decide on the price of agricultural water in Arak plain. For this purpose, the economic value of water resources for wheat, barley, alfalfa and corn was identified in 2015- 2016, using the mathematical model developed in this research. The results showed that the financial efficiency was calculated for three alternatives: free-cost water, water cost equal to the 10% of the calculated price and water cost equal to the exact calculated price.  The irrigation efficiency of 40% financial efficiency was 2.38%, 1.68% and 0.47% , respectively, for the  aformentioned methods, and  the irrigation efficiency of 70% financial efficiency was 2.07, 1.92 and 0.71, respectively. Also, the sensitivity analysis of the financial efficiency was performed, with 10% change in the farmers income and costs. The results also revealed that irrigation efficiency and financial efficiency were not aligned when farmers had free water; however, they were aligned when the farmer paid 10% of the calculated price. Financial efficiency was more sensitive to changes in the farmers income when compared to the changes in costs.

Erosion causes the reduction and degradation and the soil fertility; one of its most important consequences, endangering the food security of the inhabitants of the area. Therefore, to reduce erosion, it needs to be controlled and managed using good soil conservation methods. It is only necessary to manage and control the full impact of the factors affecting the soil first. If there is a critical state of erosion in the four watersheds, identifying the precise location of erosion will be done quickly and with less cost; thus, further erosion control and counter-operation will be feasible. In this study, geographic information system and decision making models of AHP and ANP in Bagheran region of Birjand were used to determine the erosion prone areas. First, 10 effective criteria including rain, slope, slope direction, soil, geology, permeability, vegetation, land use, distance from road and village, were determined on the erosion in the area based on the expert opinion and library studies. Next, the questionnaires were sent to experts to explore g the impact of the criteria on erosion; after completing the questionnaires based on Expert Choice and Supper Decision software, the relative importance of the criteria was obtained. The maps were then compiled and integrated according to the relative importance of the criteria. Rainfall factor had the greatest impact on the erodibility of the area in the AHP method with the relative importance of 0.21 and the   vegetation criterion with the weight of 0.158 in the ANP method had the most impact on the determination of erosion prone areas. Finally, the erodibility map of the area was obtained based on the presented models. Subsequently, the region was classified into five classes of erosion susceptibility, with areas of moderate sensitivity having the most area in both models. In the lower and upper classes, the ANP method performed better; in the middle classes the AHP method performed better.

Improper water managements and overuse of surface water and groundwater mainly for agricultural purposes in Iran have led to the drying of many rivers and groundwater. Climate change adds an extra pressure on the water resources. These changes indicate the necessity of adjustment in water management plans. This study used hydroclimatic variables including precipitation and temperature in Urmia Plain to find appropriate crops that needed the minimum irrigation water. In addition, the best time for planting each crop is determined. To find the proper crops for the region, the daily water, as required for each crop, was calculated based on climate condition, crop type, and crop growth stage. The results indicates that grape could be the best crop for the region. In addition, early planting (e.g. in spring) reduced the irrigation water needed due to more rain and soil moisture in spring than summer, which could provide crop water requirement. On the other hand, the increased temperature in spring could satisfy heat units required for the fully grown plants like barley.  

Water allocation needs to adhere to the principles of efficiency, equity, and sustainability, but, equity usually is less considered. Foumanat irrigation area with five command areas is one of the three areas of Sefidroud irrigation and drainage network that more than 90% of it is covered by paddy fields. Since water plays a key role in paddy fields, the lack of uniform distribution of water resources throughout the irrigation area during the rice cultivation period causes irrigation water scarcity and severe damage to some irrigation areas. In this study, the equity of groundwater withdrawal and the received surface water from Sefidroud irrigation and drainage canals according to the shared water resources among Foumanat’s command areas were evaluated using the Gini coefficient. Therefore, a water allocation optimization model was developed to maximize the equity in the allocation of groundwater and surface water of canals according to the minimum current economic benefit in the command areas. The results showed that in optimum conditions, the equity of groundwater and surface water resources allocation was increased by 46.3% and 43.7%, respectively. The evaluation of the optimal allocation of available water resources also showed that the amounts of groundwater withdrawal and the received surface water from canals are distributed equally among command areas.

Due to the limitation and scarcity of water supplies, it is essential to identify and reuse alternative water sources, particularly in the arid and semi-arid regions according to environmental conditions. Reuse of runoff is an adaptive management philosophy and approach to balance efforts and provide sustainable water services and manage hazards. The present study is aimed to design a suitable model of water resource management with an emphasis on crisis management. In this study, indices and dimensions of the water resources management model were determined via the Delphi method (based on Schmidt, et al.). Delphi panel members were identified and selected in three stages using random sampling. The faculty members of water resources and watershed management university specializing and passive defense experts of water organization were selected as the Delphy panel members. Initially, panel members identified the most important effective items on water resources security, based on their inference of the model. Based on the first evaluation and after eliminating duplicates, 43 items remained. Finally, 36 items remained in the analyses, when the items with low and medium significance coefficients were eliminated. The final model of water resources management was approved by the expert opinion based on the crisis management approach. According to the results, designing rainwater collection and storage systems in different parts of the city and installing tanks for roof rainwater collection in each home were selected as the best approach in the critical condition (with an average grade of 4.94), whereas the installation of the sensors in different parts of water pipe with an average grade of 2.10 was ranked in the 33rd selection. Finally, the items identified by the Delphi panel were classified into four general indices: retrofit, safety, culture, and planning. In general, it is necessary for the officials of urban water resources, as well as crisis management, must prepare for crisis conditions as well as the correct, principled, and scientific use of available water resources to extract and store rainwater and runoff to use it in crises and disrupt the general water supply system.

The effective use of rainwater is a key issue in agricultural development in arid and semi-arid regions. The tillage system as an important soil management measure can affect the rainwater retention, soil moisture content, and in consequence crop yield in rainfed lands. This study was conducted to evaluate the effects of slope gradient and tillage direction on rainwater use efficiency (RWUE) in rainfed lands in Zanjan Province. The field experiment was performed in five slope gradients (12.6, 15.3, 17, 19.4, and 22%) and two tillage directions (along slope and on contour tillage) at two replications. Mass soil water content was determined at 5-day intervals and runoff was measured after rainfalls. Wheat grain yield was determined for each plot and RWUE was computed using the proportion of wheat grain yield and precipitation. Base on the results, runoff, soil moisture, wheat grain yield, and RWUE were affected by tillage directions, so that runoff in contour line tillage decreased about 6.4 times compared to along slope tillage and in consequence increased soil moisture, wheat grain yield, and RWUE about 8.7, 24.8, and 24.8%, respectively. Increasing runoff production in contour line tillage at steeper slopes was associated with a lower capacity of cultivated furrows that strongly declined soil water retention and negatively affected wheat grain yield and RWUE in the lands. This study revealed that the efficiency of the contour tillage in water retention and RWUE decreases in steeper slopes in rainfed lands.

Snow cover is one of the important climatic elements based on which climate change may have a special effect. In general, climate change may be reflected in different climatic elements. Therefore, it is very important to study and measure changes in snow level as one of the important sources of water supply. Ardebil and Sarein cities are located at 48° 18׳ east longitude and 38° 15׳ north latitude. In this study, Sentinel-2 optical satellite was used to monitor the snow cover surface in 2018, and NDVI, S3, NWDI, NDSI, Cloud mask indices were applied to detect snow-covered surfaces using ArcGIS and Snap software. Next, to validate the snow maps extracted from the images, it was compared with the snow data in terrestrial stations using linear regression in MATLAB software and to evaluate the accuracy of the model statistical indices including RMSE, MSE, BIAS, CORR were used. The present study showed that according to Ardabil city climatic conditions, maximum-snow covered area in January with an area of 356.52 km2 and minimum snow-covered area in March with an area of 96.10 km2. The highest snow cover is observed in the high slope areas in the western slopes (Sabalan Mountain Heights) and the lowest snow cover is observed in the lower eastern slopes. The results of linear regression with generalization coefficient are 85% and the results of statistical indices of error are equal to MSE: 0.086, BASAS: 0.165, CORR: 0.924, and RMSE: 0.03. Correlation relationships between terrestrial data and estimated snow maps showed a high degree of correlation. This result is statistically significant at the 99% level. The use of optical images in estimating snow levels is very cost-effective due to the size of the areas and the high cost of installing snowmobiles. The results obtained in the present study indicated that traditional radar images with high spatial resolution and good correlation with terrestrial data can be a good alternative to snowmobiling ground stations at high altitudes or in passable areas.

Land use changes identifying to assess and monitor sensitive areas for sustainable planning and land management is essential. Remote sensing and the use of GIS technology as some of the most common methods in the world in monitoring land changes, especially, in the study of large areas. In this study, the trend of spatial land use changes in the area of Karun 3 dam was investigated. in the before and after the construction periods and dam intake using remote sensing and GIS over 27 years. In this study, the satellite imagery of Landsat 5 TM sensors from 1991 and 2008 and Landsat 8 OLI sensors in 2018 were analyzed and processed. Using object-oriented classification with land use maps for the three periods 1991, 2008, and 2018 with the overall accuracy of the Kappa index of 0.93 and 0.89 percent for 1991, 0.94, and 0.88 percent in 2008 and 0.93, respectively, and 0.86% in 2018 was prepared. The results showed that the water use of the region with an area of 37.68 square kilometers is increasing and agricultural lands and residential areas with an area of 1349.04 and 226.56, respectively, forest lands with an area of 1041.49 remained as the dominant cover of the region and rangelands by going through a decreasing trend of increase in both periods after forest use, with an area of 878.87, they had the largest area. According to the obtained results, it can be said that the construction of the Karun 3 dam has caused the flooding of agricultural lands and their conversion to another use, as a result of which the villagers were forced to migrate due to losing their jobs and abandoned residential areas become other uses.

The present study is investigated the earth dam stability during drawdown based on both numerical and experimental aspects. To validate the numerical model, a model was performed experimentally. Some soil mechanic tests were carried out through the hydraulic experiments to attain the usage factors of the numerical investigation. To investigate the effect of hydraulic conductivity on the rapid drop of water level and the use of hydraulic parameters of materials, seepage flow in the model was modeled by seep/w software. The input information to the software including hydraulic conductivity and water volume were measured by performing a constant load test and using a disc penetration meter, respectively. After validation of hydraulic conductivity with the experimental model, the results were compared with observed data. Comparison between numerical and laboratory discharge illustrated that the numerical model with laboratory model is well confirmed. In addition, saturated and unsaturated simulations demonstrated that the unsaturated model is highly consistent with the experimental model. It is assumed that due to the drawdown conditions, unsaturated models can achieve high accuracy for simulating the flow through a homogeneous earth dam.

Integrated assessment of the watershed is critical in arid and semi-arid areas due to the severe water stress in these regions. Data and information are an essential part of decision making and water governance to obtain integrated water resources management at the watershed scale. Water accounting is a helpful tool to organize information and present them as the standard indicators to achieve this goal. Therefore, the objective of this study is to implement the Water Accounting Plus framework (WA+) in the Ferizi watershed located in the Khorasan-e Razavi Province. In this study, water accounting indicators of the Ferizi watershed for a period of 28 years (1990-2017) and wet (1990-1997) and dry (1998-2009) periods were calculated using the SWAT model. The calculated indicators showed that the amount of manageable water and usefulness of consumption (transpiration) is low in the watershed and a large part of the share of irrigation in the watershed is provided by groundwater resources. Generally, the results of this study showed that the use of the SWAT model, WA+ framework, and analysis of water accounting indicators play a significant role in assessing the agricultural and hydrological conditions of the watershed. The proposed approach in this study can help managers make enlightened decisions to keep the sustainability of the watershed.

One of the significant factors affecting biochar properties is the pyrolysis temperature. This study aimed to investigate the effect of pyrolysis temperature on the properties and fractionation of Zn and Pb in biochars produced by sewage sludge. Biochars were prepared at temperatures of 300 to 700 °C and the physicochemical properties, availability, and fractionation of Zn and Pb were investigated. The results showed that pH, pHzpc, percentage of calcium carbonate, cation exchange capacity, specific surface area, and porosity in biochars were higher than in the feedstock. By increasing biochar production temperature, the mentioned properties increased. FT-IR revealed that the OH functional group is present in free form, either in the structure of C-OH and -COOH and aliphatic-CH2 groups in the sewage sludge. By converting sewage sludge to biochar, the intensity of these peaks decreased. In contrast, peaks representing complex aromatic structures appeared. The availability of Zn and Pb in biochar was reduced as compared to sewage sludge. The results of fractionation indicated that sewage sludge has bio-availability and toxicity of Pb and Zn. the amount of oxide and residual fractions of these two metals increased by converting sewage sludge to biochar at different temperatures. Therefore, it seems that biochar production from sewage sludge reduces the toxicity and bio-availability of Zn and Pb. Also, by incrementing the temperature of production, the bio-availability potential (bonding with organic matter), and non-toxicity (residual) of these metals increased.

To study the soil-landscape change in the Chaldoran region, 9 representative soil profiles were studied in 5 dominant geomorphic units of the study area including piedmont plain, mantled pediment, alluvial fan, plain, and flood plain. The results showed that the accumulation of pedogenic carbonate in some soils was concretion and light in color. In control soils in the piedmont plain (profile 5 and 7), mantled pediment (profile 6), and flood plain (profile 8) clay transferred from the surface horizons and accumulated in the lower horizon, due to relatively good rainfall in the region and distinct dry and wet seasons has led to the formation of argillic horizons along with the formation of crust on the surfaces of aggregates and building units and has formed the Alfisoils order. Mineralogical results showed the presence of chlorite, illite, kaolinite, and smectite minerals. According to the evidence, illite, chlorite, and kaolinite minerals were inherited and smectite minerals were formed due to weathering and evolution of illite, chlorite, or palygorskite minerals. Also, the results of the CIA index in the region indicated that the soils of the region are in the stage of weak to moderate weathering. In general, the results indicated the critical role of drainage, land use, and parent materials in the soils of the study area.

Surface runoff is one of the most significant components of the water cycle, which increases soil erosion and sediment transportation in rivers and decreases the water quality of rivers. Therefore, accurate prediction of hydrological response of watersheds is one of the important steps in regional planning and management plans. In this regard, the rainfall-runoff modeling helps hydrological researchers, especially in water engineering sciences.  The present study was conducted to analyze the rainfall-runoff simulation in the Gorganrood watershed located in northeastern Iran using AWBM, Sacramento, SimHyd, SMAR, and Tank models. Daily rainfall, daily evapotranspiration, and daily runoff of seven hydrometric stations in the period of 1970-2010 and 2011-2015 were used for calibration and validation, respectively. The automated calibration process was performed using genetic evolutionary search algorithms and SCE-UA methods, using Nash Sutcliffe Efficiency (NSE) and root mean of square error (RMSE) evaluation criteria. The results indicated that the SimHyd model with NSE of 0.66, TANK model using Genetic Algorithm and SCE-UA methods with NSE of 0.67 and 0.66, and Sacramento model using genetic algorithm and SCE-UA methods with NSE of 0.52 and 0.55 have the best performance in the validation period.

The existence of silty sand in the infrastructure under concrete constructions, hydraulic structures, and irrigation systems has always caused challenges. Improving this kind of soil is always a challenging approach to increase compressive strength and shear stress. There is a conception that adding some extra material such as concrete can increase the stability of this soil against contributed forces. The present study investigated the effects of curing time (3, 7, 14, 21, and 28 days) and different percentages of various additives (3%, 5%, and 7%) on the strength of the silty sand soils. A series of laboratory tests were carried out to measure the Uniaxial Compressive Strength (UCS) and California Bearing Ratio (CBR) by evaluating the effect of additives on the strength parameters of silty sand soil. In total, 299 experimental tests have been conducted in the soil mechanics laboratory of SRBIAU. Results indicated that adding additives such as concrete to silty sand soil improved significantly the compressive strength and shear strength. The comparisons among the experimental test illustrate that due to increasing the curing time, the aforementioned parameters were increased significantly; however, Confix and Bentonite aggregates did not have a marginal effect on the compressive strength and shear strength. Also, after the 21^st day of the curing time, the rate of increment of the UCS and CBR reached slightly and then attained a constant value. Also, after this duration, the curing time is an independent factor in the variation of the UCS and CBR tests. Furthermore, the addition of 5% Pozzolana cement and 7% Portland cement with 28 days of curing had the highest CBR number and UCS resistance of 176.26 and 17.58 kg/cm², respectively. Also, the sketch of the different failure patterns was shown during the curing time. Finally, by increasing the curing time, the behavior of specimens from semi-brittle to brittle made them harder.