جستجوی مقالات مرتبط با کلیدواژه "water demand" در نشریات گروه "آب و خاک"

Evapotranspiration is considered as the water requirement for plants. Therefore, its measurement is necessary for all agricultural and irrigation projects. Evapotranspiration is one of the main components of the hydrological cycle associated with agricultural systems. Usually, evapotranspiration can be obtained using reference evapotranspiration (ET0). Accurate estimation and prediction of ET0 is essential in managing water resources, planning irrigation, and determining the water requirement of plants. Prediction of the ET0 by providing information about the future state in different time scales can help to make appropriate decisions, plan, and apply water resources management methods. Also, assessing agricultural drought conditions by well-known indices such as the Standardized Precipitation-Evaporation Index (SPEI) and Palmer Drought Severity Index (PDSI) directly requires ET0 of the region. The sharp decrease in the level of Lake Urmia and the threat to the region's ecosystem have also made the need for accurate calculation of ET0 more significant than in the past. One of the solutions to calculate ET0 is to use the FAO-56 Penman-Mantis equation (FAO-56 PM), an acceptable alternative for the scarce lysimeter data. However, the Penman-Mantis equation is highly dependent on the wind speed parameter, so a small error in the wind speed measurement causes a significant error. Therefore, this study aims to provide an innovative and reliable model for estimating ET0 without the need for wind speed parameters in Tabriz and Urmia stations.

In this study, to predict daily ET0 different intelligent models including multi-layer perceptron neural network (ANN-MLP), support vector regression (SVR), and support vector regression combined with firefly algorithm (SVR-FFA) were used in Urmia and Tabriz stations during 2002-2022 period. The input parameters of the models included minimum relative humidity (RHmin), maximum relative humidity (RHmax), average relative humidity (RHavg), sunshine hours (SSH), minimum temperature (Tmin), maximum temperature (Tmax), average temperature (Tavg), and average soil temperature (Tsoil) which were obtained from Iran Meteorological Organization (IRIMO). Also, four different scenarios were used to run the models. The selection of different input combinations was based on the correlation coefficient, so the first combination had the lowest correlation and the last combination had the highest correlation concerning ET0. Also, data from 2002-2015 for 14 years were considered for model training and from 2016-2022 for 6 years for model testing. Correlation coefficient (R), mean absolute error (MAE), root mean square error (RMSE), and normalized root mean square error (NRMSE) indices were used to evaluate the used models.

The comparison and evaluation of the models used in Tabriz station showed that the SVR-FFA-4 model was chosen as the best model in this station with the root mean square error of 1.23 mm day-1. Among the SVR models, the SVR-4 model showed a good performance with the root mean square error of 1.95 mm day-1 after the combined model. Finally, the ANN-4 model also obtained an acceptable accuracy compared to other ANN combinations by having the root mean square error of 1.99 mm day-1. Finally, the evaluation of the results used for the Urmia station shows that the SVR-FFA-3 model has made the best predictions compared to other models with a root mean square error of 1.16mm day-1. The SVR-3 and SVR-4 models had a higher accuracy than other SVR combinations with a root mean square error of 1.78 mm day-1, but the third scenario was chosen as the appropriate model in the SVR model due to having less input. Among the ANN combinations, the ANN-3 model has a good performance compared to the other combinations of this model with the root mean square error of 1.81 mm day-1.

The results of this study showed that in both studied stations, the hybrid model showed higher accuracy than the individual models. So, in Tabriz station, the SVR-FFA-4 model had the best performance with an error rate of 1.23 mm day-1. In the Urmia station, the SVR-FFA-3 model showed good accuracy with an error rate of 1.16 mm day-1. Finally, it is suggested to use the hybrid model to predict the daily reference evapotranspiration in the northwest of the country. One of the limitations of this research is the lack of access to the parameters of dew point temperature and solar radiation. Therefore, it is suggested to use these parameters in the subsequent studies.

Effective approaches and policies including identifying priorities and optimal water allocation techniques, especially in basins with different users are considered essential for sustainable development in each region. With 1100 m3 of renewable water per person per year, Iran is considered to be the most critical region in the world in terms of water resources. Unfortunately, most plans in the water sector of such countries are based on local economic growth, and no attention is paid to the amount of available water resources. Considering the issue of a water crisis and the droughts of the last few years, the issue of water resources management has gained high importance. To overcome the mentioned problems, it is inevitably essential to use newly developed water management techniques based on advanced approaches. Although optimization techniques are well-known tools in these issues, the simulation method is utilized as a helpful approach. To simulate water management in the basin, there are various available models. RIBASIM, MIKE BASIN, WEAP, and MODSIM models are famous and user-friendly ones in this collection. WEAP software is a comprehensive and advanced water resource system simulation tool widely used in watershed management and can consider physical and hydrological processes. The scenarios that can be investigated with this software include population growth, economic development, changing the policy of operating reservoirs, extracting more from underground water resources, saving water, allocating ecosystem needs, integrated use of surface and underground water, reuse of water, etc.

This study was conducted in the Nahand catchment area which is located in East Azerbaijan province. Nahand river is the main draining course of this catchment, on which a dam has been built to supply a part of Tabriz's drinking water. To control the performance indicators of the reservoir, several management and exploitation scenarios were developed and evaluated in the WEAP model. The WEAP model was presented in 1990 by the Stockholm Environment Institute (SEI). It is a comprehensive and advanced model for simulating water resource systems, which is extensively used in the management of water resources in watersheds. This model has provided a practical tool for water resource planning and policy analysis to put all the issues related to water resources and uses in a single environment. The WEAP model is capable of simulating issues related to consumption such as water consumption patterns, water reuse strategies, costs, and water allocation patterns, as well as issues related to resources such as river flow, groundwater resources, reservoirs, and water transmission lines. The inputs of the WEAP model include data on the population of Tabriz City, per capita consumption of drinking water per person, the amount of water wastage in the distribution network, the inlet discharge of the Nahand reservoir, the information of the Nahand dam, the amount of cultivated area, etc., and to evaluate the model R^2, RMSE, and MAE statistical indicators were used in two periods of calibration and validation. Then, various operating conditions were investigated by compiling the Reference (continuation of the status quo), SC1 (increase of input flow by 10%), and SC2 (decrease of input flow by 10%) scenarios. Besides, Reservoir performance indicators are used to measure its performance under different operating circumstances.

The simulation results of the studied area indicated that the WEAP model with evaluation criteria including R2, RMSE, and MAE in the calibration stage was 0.89, 1.16, and 1.01 MCM, respectively, and in the validation stage were 0.88, 6.22, and 6.01 MCM, respectively. The results also showed that the amount of water demand for the near future period (2021-2040) will increase due to the increase in population, and therefore, the resources in the basin will not be able to meet all assumed needs. The findings showed that the studied system for the near future period (2021-2040) under the reference (continuation of the status quo), SC1 (increase in flow by 10 %) and SC2 (decrease in flow by 10 %) scenarios from the drinking water supply point of view, will result in a shortage of 28.1, 7.3 and 44.3%, respectively, and from the supply of agricultural needs point of view will result in 31.4, 18.3 and 44.4%, respectively. Also, by evaluating the reservoir's performance indicators, it was found that under all assumed scenarios, the system will fail under the condition of supplying 100% and 80% of the needs, whereas the reservoir will be more sustainable by applying the SC1 scenario in comparison with the other two scenarios.

To choose the best management and exploitation scenarios, due to existing circumstances and limitations such as time limitation, cost, possible risks to the environment, etc., it is not possible to apply all scenarios in the basins and, thence, it is logical to choose the most suitable scenario. Therefore, software tools can help experts to make decisions by considering all limitations. By examining the results of the reservoir performance indicators, it can be seen that the reservoir will encounter failure in supplying 100 and 80% of the needs in the future period under all scenarios and the sustainability index of the reservoir (remedial stability) in supplying 100%. The needs under the Reference, SC1, and SC2 scenarios will reach 31, 49, and 22%, respectively, and in meeting 80% of the needs, the sustainability index will be slightly higher.

In recent decades, the use of groundwater for irrigation, drinking, and industry has increased in developing countries such as Iran. This increase, in turn, improves food security and reduces poverty in these areas. However, reducing the level of the water table and sustainable development are concerns. These concerns have increased, especially regarding the alluvial aquifer of the Ajabshir plain, which plays a significant role in providing water in the area. Considering the growth of the population and the water needed, it is very important to study the water quantity and quality for the future and the well deepening. There are several methods to determine the maximum depth of deepening. However, this study emphasizes the fluctuations of the groundwater level as a result of them instead of the relatively complex studies of modeling and water balance. For this purpose, after collecting the data, the maps of the groundwater isodepth, isolevel, fluctuations, and aquifer bedrock were drawn in the GIS software. Then, the unit hydrograph of the plain was prepared to determine the amount of groundwater level drop. Population growth and water demand were determined for the horizon of 1420. The findings of this research indicate that the overexploitation of groundwater resources will have consequences such as a drop in the groundwater level (equivalent to 6 m), a decrease in the quality of the groundwater, and subsequent land subsidence. The minimum level for well deepening in the Ajabshir aquifer varies between 1250 meters and 1290 meters.

Optimal cultivation patterns are necessary for the sustainable development of agriculture and the protection of land and water resources, and the need for it has deepened. In the context of sustainable agricultural development, the optimization of the cultivation pattern, in addition to the economic benefits, should also follow the subsequent environmental effects. Due to the limitation of water resources in different regions of the world, joint use of surface and groundwater has become very important. Optimizing the joint use of surface and groundwater has become a necessary contribution to sustainable irrigation methods, and due to this, there is a need to improve methods of joint use of surface and underground water. The purpose of this research is to use a new comprehensive structure of multi-objective simulator-optimizer in order to simultaneously formulate the optimal cultivation pattern and the optimal allocation of surface and groundwater resources for the integrated management of the water resources system and solving complex water resources problems.  

The study area in this research is Shahriar Plain in Tehran Province, Iran. Shahriar Plain is located on the western outskirts of Tehran city. In this study, a multi-objective simulator-optimizer modeling pattern was prepared and for this purpose, it was first simulated using the groundwater modeling system (GMS) of the groundwater level. Then six scenarios including a 50 % increase in artificial recharge, 50 % increase in artificial recharge and 30 % reduction in consumption from exploitation wells, 50 % increase in artificial recharge and 40 % reduction in consumption from exploitation wells, 30 % reduction in consumption from exploitation wells, 40 % The reduction of consumption from exploitation wells, elimination of drinking and industrial exploitation wells and its impact on the aquifer was defined based on the groundwater level in order to optimally exploit the aquifer of the study area. After this step, the groundwater level was estimated using the artificial neural network (ANN) model. Finally, the two objective functions of income to cost and groundwater level changes were estimated based on the constraints related to the conditions of the desired area by a multi-objective genetic algorithm (NSGA-II).

The GMS model in a steady state was calibrated. The RMSE error was 0.71 meters and the maximum and minimum differences between observed and calculated values were calculated as 1.73 and 0.001 meters, respectively. The maximum amount of yield water in the calibration stage of the unstable state is 0.0976 and related to the northern regions of the area and due to the coarseness of the alluvial formations in these areas, and its minimum value is 0.0003 and related to the southern regions of the area. The results obtained from the model showed the RMSE error at this stage and the verification mode equal to 0.72 and 0.98 meters, respectively. Also, the budget resulting from the third scenario of the GMS was estimated to be 203 (MCM), which has increased by 313 (MCM) compared to the budget resulting from this model in the water year 95, and has caused an increase of the groundwater level by 13 meters. Therefore, the model has adequately simulated the groundwater flow in the aquifer. Also, the results of the optimization model showed the highest amount of optimal irrigation demand for Eslamshahr district at 66%, then Shahriyar at 20%, and finally Robat Karim at 14%. Optimal water demand volume and area under cultivation in the total state, have decreased by 36%, and the volume of groundwater consumption by 74 percent compared to the current conditions. The amount of optimal water consumption (surface water and groundwater) of agricultural products also shows the values of 36, 39, and 25% respectively in Shahriar, Eslamshahr, and Robat Karim districts, which according to this issue, water consumption in the agricultural sector is in optimal conditions compared to the current situation has decreased by 44 %. The highest parameter of the ratio of income to cost obtained is related to Shahriar district, then Robat Karim district and finally Eslamshahr district. The results of the simulator models show the groundwater level changes resulting from the third scenario compared to the neural network model by 11 m. Finally, Optimal cultivation pattern planning and exploitation of water resources compared to the third scenario of the model and the neural network model, was chosen as the pattern of optimal water planning.   

Products such as vegetables, alfalfa, onions, grapes, pears, and pomegranates can be used more in the study areas, because the amount of income to cost and volume of water consumed have been suitable, and these factors have been very effective in increasing the net profit and changes in the groundwater level, and prevent the occurrence of crime and water complex problems. Also, optimal cultivation pattern planning and exploitation of water resources compared to the third scenario of the GMS and the neural network model, was evaluated as the selected optimal planning pattern of water resources. Therefore, by applying the desired research policies and optimal management and control of the cultivation pattern of agricultural products and available water resources, in addition to preventing the occurrence of crisis in water issues, environmental and economic problems can also be reduced.

The increase in demand for water resources due to population growth and economic development along with water wastage and a decrease in rainfall, on the other hand, has made it significant to pay attention to water demand and make sound policies. Our country is facing the risk of a water crisis in the coming years, mainly due to its location in a dry and semi-arid climate, as well as the ever-increasing growth of water consumption. To alleviate the water crisis, international trade in agricultural products can play a significant role in redistributing water resources because traded goods contain a large amount of virtual water. Water restriction in Iran is an undeniable fact, for this purpose, trading based on virtual water can be a solution to reduce the effects of water restriction. Due to being located in a dry and semi-arid climate, Iran is facing the risk of a water crisis in the coming years. Therefore, in order to deal with it, it is necessary to be more sensitive to the types of water consumption. Among these uses is virtual water. The water used in the production process of goods is called virtual water, a part of which is kept in the product. Virtual water trade occurs when goods are imported into global markets. Virtual water trading is expected to reduce water consumption at the national and international levels due to more efficient and specialized use of water. Today, the concept of virtual water is one of the most critical issues in water resources management. Today, the problem of water shortage has become a serious concern due to climate changes and uneven distribution of rainfall in most regions and countries, including Iran, and is considered the most important obstacle to the economic development of these countries. Trade as a tool to prevent the unnecessary withdrawal of water resources, focusing on the strategy of virtual water trade, can play an essential role in achieving the economic development of countries.

The study area of the research is the Shiblo-Poldasht plain in the northwest of Iran. This area is located in the east of the Poldasht study area and in the north of the Qara Ziauddin study area. The aim of this research was to investigate the statistical status of the cultivated area, the production performance, and the evaluation of the productivity and virtual water of agricultural crops in the Poldasht plain. The time frame of the research is from 2011 to 2021 in an 11-years period. Accurate calculation and determination of water requirement (m3 ha-1). The amount of water required by a plant for its proper growth, taking into account the loss of evaporation and transpiration of the plant, is called the water requirement of the plant. Therefore, the water requirement of the plant depends on the amount of evaporation and transpiration of the plant. It is worth noting that due to different climates and weather conditions, plant growth conditions and as a result, the amount of water needed by plants are also different. In the present research, the various productivity indicators and virtual water of the crops of Dasht-Poldasht have been examined. Moreover, according to the objectives of the research, the physical and financial indicators of water productivity, including the performance index per unit of water volume (CDP), income per unit of water volume (BPD), and net return per unit of water volume (NBPD) have been calculated.

In this research, the amount of virtual water and the productivity index as well as the net and gross economic value of the major crops grown in Poldasht city in West Azarbaijan province were investigated. In this regard, first, data and information related to crops were collected through relevant organizations and institutions, and NETWAT, CROPWAT, and CLIMWAT programs and Excel programs were used to draw graphs and graphical results. Then the yield of crops was calculated by dividing the amount of crops produced by the area of ​​planting crops and the productivity index and virtual water. The results of this research show that the watermelon crop with a harvesting area of ​​5789 ha and a production rate of 237951000 kg and a production yield of 41103.99 kg ha-1 with a water requirement of 2760 m3 ha-1 has a productivity of 14.89 kg m-3 and has The highest level of productivity is also the results show that the alfalfa product is the lowest level of productivity. It is worth noting that despite the fact that the watermelon product has high production and productivity at a very low harvest level, it is also a very water-loving product that has a relatively high water requirement, and generally experts are looking for an alternative product due to the lack of water resources. Finally, it is suggested that traditional (submerged) irrigation methods should be replaced by modern pressurized irrigation methods so that in addition to increasing efficiency and productivity, we can see a reduction in water consumption and its wastage. It is also suggested that the water requirements of agricultural crops be compared with each other using the data of the Agricultural Jihad Organization and the aforementioned programs, and its effect on the amount of water consumed and its savings, as well as the net and gross values ​​of the production of crops, and the final results It is compared with the national water document to fully verify the amount of water needed.

Despite the fact that the watermelon product has high production and productivity at a very low harvest level, it is also a very water consuming product possessing a relatively high water requirement, and generally experts are looking for an alternative product, due to the lack of water resources. Finally, it is suggested that traditional flood irrigation methods should be replaced by modern pressurized irrigation methods, so that in addition to increasing efficiency and productivity, we can encounter with a reduction in water consumption and its wastage. It is also suggested that the water requirement of agricultural crops should be compared with each other using the data of the Agricultural Jihad Organization and the aforementioned programs, and its effect on the amount of water consumed and its saving, as well as the net and gross values of crop production, should be evaluated. Finally, the results have been compared with the national water document so that the amount of water needed can be fully verified.

As countries seek higher per capita incomes and economic development, hence water consumption in the agricultural, industrial and domestic sectors is increasing. Due to the water crises, it is important to study the factors that increase water demand. In this regard, the present paper employs the Logarithmic Mean Divisia Index (LMDI) method to analyze the factors affecting changes in the water demand of Iran’s industries. According to this method, changes in water demand (at a two-digit ISIC level) are divided into three factors economic growth, technical coefficient (inverse productivity), and structure of the industry. In the following, demand decomposition with the variable base year (1997-2001, 2001-2007, 2007-2011, 2011-2017) showed that  industrial production has the largest share in increasing water demand and its share has increased from 43% to 80%. On the other hand, the share of water productivity has decreased from 45% to 7%, and the effect is reversed. Changing the structure of the industry also has a somewhat constant share of around 10%. In general, it can be concluded that the increase in industrial production has been the main driving force of the water demand in the industrial sector in Iran. While improving productivity and increasing the share of lower water-intensive industries have not been able to neutralize it, and even their impact has diminished in recent decades. Therefore, a self-sufficient strategy has not been sustainable in terms of water. The current path will lead to an escalation of the water crisis and even a choice between the survival of the industry or the reduction of water stress.

Hashtgerd plain has 56percent of Area of Alborz province and consumes more than 84% of surface water resources and more than 90% of groundwater. It is recognized as one of the most significant agricultural zones that experiences critical crises such as subsidence because of excessive withdrawal of these resources. Consequently, it will be inevitable to manage water resources optimally that establishing the water market as an economic instrument will play a significant role in allocating water resources optimally. The economic value of water input and its demand function was estimated in these areas. The equilibrium price of water input in plain was calculated and compared with the results achieved by valuation calculations using the results of estimating the demand functions and the amount of water supply in this study to examine the probability of developing a water market in Hashtgerd using the positive mathematical planning method and SWAP approach and also the optimal cultivation pattern of the region was estimated, which includes 3divisions.As the result, if there is the required physical infrastructure and the related laws, it will be possible to create a water market among regions in conditions that Nazarabad is the purchaser and Taleghan and Savojbolagh are the sellers of their surplus water resources. The results of examining the possibility of forming an intra-regional water market also show that considering that the enthusiasm to pay in people who have limited resources is more than the obtained equilibrium price and the willingness to receive is lower in people who sell their surplus water resources than the equilibrium price; it will be possible to form a water market among farmers in each city with an equilibrium price equal to 3394 Rials per cubic meter. In this situation, both customers (due to purchasing water cheaper than enthusiasm to pay) and sellers (selling water more expensive than enthusiasm/willing to receive) will benefit from creating the market. However, due to the higher equilibrium price of the economic value of water in the cities of Taleghan and Savojbolagh, there is a possibility of failure of the water market and the transfer of water to other sectors.

Growing population of the cities along with the desire for better welfare and health has increased the water demand. On the other hand, many cities are located in the arid and semi-arid regions with the low rainfall and renewable water resources. Therefore it causes the water crisis. Shiraz is one of the metropolises that is facing this problem and in the warm seasons of the year experiences the drop in water pressure and water outages. Increasing the water supply, regardless of demand management, will exacerbate the crisis. Water pricing has been also one of the most important concerns of policymakers in demand management. Given the importance of this issue and also the role of social interactions among the consumers and the neighboring community network on the water consumption behavior, the present study concentrates on providing an agent-based framework for examining the water demand and changes in consumption behavior (diffusion process). The model has been calibrated for domestic water consumption in Shiraz for the years 2005-2019. Price increase scenarios (for all or only part of the consumers) as well as granting free branches have been simulated for the years 2020-2032. The results show that small increases in water prices do not have significant effect on consumption and cooperative behavior trend. Also, giving free branching to some consumers will intensify non-cooperative behavior among other consumers and increase the consumption sharply.

One of the most important inputs in all economic sectors of Iran is water. The solution to the shortage of water resources in Iran is not more water supply, but an effective solution to adopt policies and measures that change the economic structure and pattern of water consumption. In this study, the income elasticity and price elasticity of Kermanshah urban water demand and the estimation of daily consumption of each person during the period 1392-1397 have been estimated. For this purpose, at first, the general form of water demand function was calculated by maximizing an Aston Gray utility function and was estimated using the VAR model, based on the Johansen method of Kermanshah urban water demand function. According to the results, urban water demand is inversely related to water prices and directly related to income. Price elasticity indicates a negative relationship between price changes and water demand. If the price of water increases by 10%, the demand for it will decrease by 4.3%. On the other hand, the absolute value of price elasticity and revenue elasticity of water is less than one. Also in this research, ARDL model has been used to investigate the long-term, short-term relationship, error correction test and tensile tests as a complementary and comparative method with VAR model of ARDL model. In both models, the price elasticity is less than one, ie with a 10% increase in price, consumption decreases by less than 10%. The non-zero price elasticity of water indicates that increasing tariffs can be used as a way to reduce water consumption, at least in the short term. The results showed that according to the criterion of the usefulness function of acetone, the minimum water consumption for each subscriber in Kermanshah is about 8.21 cubic meters (8210 liters) per month. According to the model, this amount is about 273 liters per day. That's about 273 liters a day, according to model estimates.

During the last two decades, there have been numerous challenges in the field of urban water supply in Yazd province, such as lack of supply resources on the one hand and increased per capita consumption, as well as high migration rates on the other hand, which analyze the current and future status of supply and demand. Therefore, in this study, we first use linear expenditure models to account for factors such as household income, weather conditions, population and non-price controls such as building materials type and seasonal variation using generalized least squares method and integrated data. 3081 urban households in Yazd province were estimated per capita water consumption. Then, in three ideal scenarios, desirable and available, in both migration and non-migration, the urban water demand of Yazd province for the 25-year horizon (1400-1425) was predicted and the supply shortage was calculated compared to the current situation. The results showed that water supply in the five demand scenarios will face a deficit, which is the case in four critical and severe scenarios. According to the three patterns, this deficit will reach between 3 to 72 million cubic meters in the 25-year horizon in no migration mode and between 14 and 112 million cubic meters in migration mode. According to the results obtained, in order to overcome the main challenge of supply deficit, demand-side policies such as migration control, consumption pattern and quota reform, and supply-side policies such as water transfer should be adopted.

One of the most important tools for water demand management is water and energy tariff changes. The aim of this effort was to study the level of groundwater in Mehran plain using the system dynamics method under different scenarios of energy carriers price changing. the conceptual model was designed, dynamic hypotheses were explained and simulation was performed. After calibration and verifying the model, the research purpose was evaluated in terms of applying 12 scenarios combining energy tariff increases and water tariff increases. According to the results the effect of changing energy tariffs on changes in aquifer volume and groundwater level was more than the change of water tariff. The results also indicated that the increase of water and energy tariffs could reduce harvest from the groundwater, and in all scenarios an increase in energy tariffs of 80 percent of the current tariff and increasing the surface water tariff  of 50 percent of the current price and Performance of the Right to Supervision would have the greatest impact on the stopping of the decline in groundwater levels and its significant increase

Groundwater resources in the world are experiencing significant reductions due to climate change and drought. Therefore, in order to make appropriate decisions by managers and planners, forecasting and studying the economic effects of drought is essential. Thus, the purpose of this study was to investigate the welfare effects of drought on groundwater beneficiaries. Accordingly, the present study investigated the economic effects of drought and its impact on the cultivation pattern of the southern Mahyar Plain and changes in social welfare in the 2016-2017 crop years, using the groundwater market approach. For this purpose, three approaches of regression estimation, positive mathematical programming, and dynamic programming were used. The results showed that in drought conditions, the area under barley and wheat cultivation increased and the area under corn decreased. Other results showed that the reduction of water supply due to drought would reduce the social welfare by 1020 million Rials (based on 2016 prices). Therefore, it is suggested that the amount of welfare lost by farmers due to water shortages should be a criterion for determining the amount of compensatory payments.

Water as a vital resource is one of the most important factors for growth and development in human societies. Mashhad plain is one of the critical plains of Iran that the drought of the past years has caused the level of aquifers to drop. This study aims to investigate the factors affecting water demand in the Mashhad plain. Necessary statistics and information for this purpose were collected by the Ministry of Jihad for Agriculture and the Meteorological Department of Khorasan Razavi Province for the dominant crops in the region's cultivation pattern, including wheat, barley, tomatoes, alfalfa, cucumbers and potatoes. In order to determine the amount of water required by the products, the net water demand index, which is a function of evaporation, humidity, rainfall and wind speed, and NETWAT software were used. The factors affecting the net water requirement of these products were investigated using the Sur panel pattern. The net estimated need for the model was used as the amount of water demand. The spatial panel pattern was used to investigate the factors affecting this index. The meaningful of the Neighborhood Variable (Rho) indicates that the pattern under study is spatial and that the use of classical patterns is difficult. The results of the data analysis show that as the price of water, the cost of irrigation, the cost of chemical fertilizers and the cost of renting land increase, the amount of demand for irrigation water decreases and the excessive consumption of water is prevented.

Water as the most scare input in the production of agricultural products is not only a limiting factor for agricultural activities, but also is obstacle to other economic and social activities. Water supply of different sectors faces a lot of constraints with increasing population and development in different dimensions and rising standards of living. Therefore, appropriate policies should be used to manage water demand. One of these policies is the pricing of water resources in different ways in the agricultural sector. Investigation of internal studies on water valuation shows that there is a great difference between the economic value of water and paying farmers for water. Water pricing policies based on the economic value of water can be effective in allocation and optimal use of water. Therefore, it is necessary to do various studies in order to apply appropriate policies to the climatic conditions of different regions. Pricing policies in different parts of the country in most cases are used only by area pricing. Due to the problem of water crisis, the growing demand, and the gap between water supply and demand, area-based pricing method does not provide sufficient incentives for optimal use of agricultural water. Therefore, this study examines the different methods of water pricing such as area pricing, volumetric pricing and combination of both. Therefore, this study examines the optimal consumption of water resources for the purpose of water and soil conservation in Gonbad-e-Kavous County, Golestan province. This syudy considered the volumetric pricing and composition of volumetric with area-based methods in addition to area-based pricing method that is the innovation of this study. Since different agricultural policies can not be investigated and analyzed in the laboratory environment, so the potential effects of these policies should be investigated by appropriate instruments of policy before, during and after the implementing of policy. Therefore, due to the importance of the subject, in this study, the Positive Mathematical Programming (PMP) model is used to simulate farmers' behavior in the downstream lands of Golestan Dam (1) in Gonbad-e-Kavous County, in the implementation of various water pricing methods such as Area-based, volumetric and mi combined of them. In this study, data were collected using random sampling method and 20 scenarios were investigated. The GAMS software package is also used to analyze the information in this study.The results of this study show that water demand in all three methods (area-based, volumetric and combined) will decrease from 22.6 to 48.8% as water price rises in different scenarios. The highest and lowest water demand reduction is related to the area-based and combined water pricing method, respectively.Applying appropriate water pricing methods makes water be distributed optimally between users based on the value of marginal product and provides incentives to save and prevent loss. Therefore, based on the results of this study, it is recommended to use a volumetric and area-based pricing method in combination.

The water requirement of the urban district of Zahedan City in Iran is met by the transfer of water from Sistan Chah-Nimeh reservoirs that are themselves suffering from severe water crisis. So, the prediction of the urban demand for drinking water can greatly help managers and users of urban water systems to use sound management practices. The present paper uses the artificial neural networks of GMDH and RBF, as two vigorous tools for the analysis and modeling of nonlinear relationship, to estimate monthly demand for drinking water in Zahedan in 2017. The selected parameters include mean monthly temperature, relative humidity percentage, mean precipitation, sunny hours, and previous-month consumption rate. The results of comparing MSE and MAE indicators show that after studying different structures with various number of neurons and hidden layers, the GMDH neural network with three hidden layers that has one neuron in layer 1, three neurons in hidden layer 2, and three neurons in hidden layer 3 yields the best results for the predication of short-term demand for drinking water. The comparison of linear and nonlinear activity functions reveals that in output layer of GMDH and RBF neural models, the nonlinear functions outperform linear functions. As well, among the GMDH model, the models with nonlinear output show better performance than those with linear output. Also, it is shown that the expansion of the network structure cannot improve the results considerably.

Supplying the tap water in Mashhad city is going to face serious challenges and threats in the future. The population of this city is more than 3 million and its pilgrim is estimated at 25 million per year. Urbanization in Mashhad city and around it is growing. The range of this study is including Mashhad city along with Golbahar, Chenaran, and Ghuchan. The excessive development of these cities leads Mashhad city to physical water scarcity in long term. For this purpose, the effective factors on water demand in Mashhad city have been identified. For this purpose the most desirable urban water demand function has been extracted, by using the Stone Gary method. It is worth mentioning that in order to investigate economic and social uncertainties in the model, the results of previous researches and the opinion of experts have been used; then, the effective uncertainties on the elements are determined by using the fuzzy linear regression model. Finally, urban water demand function of the Mashhad city for 2010-2017 is calibrated and used to estimate water demand from 2018 to 2070. The results show that the demand function of Mashhad city is strongly influenced by the time between receipt of the bill and the household composition. So these two factors can be considered for demand management. At the end, the model accuracy is based on the R^2 that is equivalent to 0.921 which indicates the proper performance of this model in predicting urban water demand.

cropping pattern changes and increasing energy tariffs helps groundwater resources management. The aim of this investigation was to study the effect of crop pattern on groundwater level in Mehranplain using the system dynamics approach under different scenarios of energy price changes. To develop the model, a conceptual framwok was designed and the dynamic hypotheses were formulated. The calibration and validation of the model were performed for a period of 8 and 6 years, respectively, and the model simulated in a 25-year period until 1420 in nine scenarios. The results showed that changing the crop pattern from alfalfa to conola with increasing 100 percent in energy tariff would have the most positive impact on aquifer is equivalent to an increase of about 55 million cubic meters of aquifer water volume, and an increase of about 8 meters in the groundwater level. Also changing the crop pattern from alfalfa to corn with increasing 50 percent in energy tariff lead to groundwater level stability.

Existing water governance systems suggest a lot of inefficiencies in managing water scarcity, creating potentially severe risks for many aspects of societies and economies.Water markets are a relatively new and increasingly popular tool for coping with water challenges. They allow the voluntary exchange of water between buyers and sellers. This paper, with the review-analytical approach, introduces the new water management paradigm- demand-driven management - focuses on market-based water demand management, its implications and features, and outlines the potential of this approach to address the challenges of water scarcity. Strengthening and stimulating water saving; increasing access to water; improving community resilience; improving water and allocation efficiency; restoring water to nature; and improving accounting for water usage and availability,are the promises and benefits of a market approach to manage water demand and cope with the scarcity challenges.

The globally growing demand for water has shown the need for its efficient and judicial utilization, and particularly in agriculture being single largest consumer of water. Crop evapotranspiration represents crop water demand and governed by weather and crop conditions and most of the current water demand models are non-spatial models, they use point data. Global scale satellite images can solve these problems. According to the high performance of satellite indices, it is necessary to estimate crop coefficient using combination of reflectance and thermal bands. The aim of this research was to estimate the effective crop coefficient of potato using vegetation indices and principle component analysis.
Principle component analysis (PCA) was used for effective crop coefficient estimation. Modeling of associations between vegetation indices and crop coefficient were conducted using artificial neural network. In the present study, NDVI, RI, EVI, SAVI, MSAVI, NVSWI, TVX, TVI, mNDVI and mTVI were the used as vegetation indices. PCA is designed to transform the original variables into new and uncorrelated variables (axes), namely the principal components, which are linear combinations of the original variables. The new axes lie along the directions of maximum variance. PCA provides an objective procedure of finding indices and information on the most meaningful parameters, which describes a whole data set affording data reduction with minimum loss of original information. Artificial neural networks are a computational model which is based on a large collection of simple neural units, loosely analogous to the observed behavior of a biological brain's axons. RMSE, MAE and MARE were the statistics used for investigating the performance of crop coefficient of vegetation indices with FAO crop coefficient.
Eleven MODIS vegetation indices are derived in the period of 2013 to 2016 for potato over the limited area between Tabriz and Bostanabad. The last year was considered as the validation period. According to the FAO-56 paper, the lengths of initial stage, crop development stage, mid-season stage, late season stage were considered to be 25, 30, 45, 30 days, respectively. The vegetation indices were derived using MODIS sensor with 2×2 pixels. The PCA showed that with increasing the number of components, the eigenvalues decreased. The analysis indicated that the three first components accounted for the 85.45 % of the total variance of data and the eigenvalues of them were greater than 1, the three first components were thus selected. NDVI, RI, TVI, MSAVI and NVSWI in the first component, mNDVI in the second component and LST in the third component had the highest coefficients. NDVI in the first component with high coefficient indicted the importance of index in the crop coefficient determination. The coefficients of SAVI and MSAVI were higher than NDVI. From the three investigations on the kind of principle component, the first investigation led to a 55.75 % decrease in RMSE relative to the second and third investigations. The first and second components together had less error rather than third component. The average of MAE for first, second and third investigations was, respectively, 0.17, 0.22 and 0.2. Therefore, component with exact values of particular vectors resulted in a reduced error. The sensitivity of artificial neural network led to an increase in the simulation accuracy (for example the RMSE decreased from epoch 100 to 50 was 48.27%). Crop coefficient estimation using vegetation indices of principle component analysis was underestimated about 1% in the validation period. Overestimation and underestimation were found in the initial and crop development stages, respectively.
The quantities of statistics showed the improvement of artificial neural network performance with combination of vegetation indices using principle component analysis. The vegetation indices with reflectance bands performed well. The combination of thermal and reflectance bands enhanced the vegetation indices efficiency. In addition to NDVI index for crop coefficient estimation, improvement of indices according to the study area condition increased the indices performance. The kind of mathematical equations of indices can increase the indices performance which using the same bands with different equations have different results. The selected component of principle component analysis has important role in increasing the simulation accuracy. The error reduction of simulated crop coefficients can increase the precision of irrigation consumption and agricultural planning which the principle component analysis has more important role.

Serious attention to agricultural water supply management is inevitable due to an increase in demand for this most precious resource. Water demand management is a strategy that reduces the demand for, increases its use efficiency of, and prevents the waste of its resources. Various laws, pertaining to the prudent water management, have been passed; however, many of them have never been enforced. Therefore, the existing structure was investigated by polling a group of water- related experts. The questionnaire, which was employed for this research, was answered by38 eminent water experts. The calculated Cronbach's alpha coefficient of the polling was 0.701 that pointed to the strong reliability of the questionnaire. Those water experts were in agreement with reorganization of the water resources management and maintained that a “lack of coordination among relevant agencies” and the “legal difficulties in reforming the consumption patterns” have greatly affected the emergence of the existing water crisis. Therefore, a countrywide organizational chart, consisting of five levels, was proposed: 1. Providing a framework and adapting a firm policy on logical water management in coordination with the judiciary bodies; 2. Enabling the managers of large watersheds to adapt their own policies; 3. Enabling the managers of sub-watersheds to adapt their own policies; 4. Implementing the confirmed policies employing the existing hardware and software and looking for the new methods; 5. Implementing the adapted policies at the local scale. We strongly recommend an assessment of this chart by the concerned water authorities.