مجله تحقیقات منابع آب ایران
سال نوزدهم شماره 5 (پیاپی 68، زمستان 1402)

Increasing water productivity is one of the mechanisms for water consumption management and economic tools such as water price are means that can lead to a reduction in consumption and an increase in productivity. Taleghan Dam is the main supplier of water for agricultural sector of Qazvin Plain the water allocation to which has decreased in recent years due to various reasons such as climate change and population growth. Meanwhile no change in the cropping pattern and the disproportionate distribution of water to the allocated water coupled with the low price of water have caused the incorrect use of water in the Qazvin Plain irrigation network. In this research first the estimation of the water cost price was done using engineering economics relationships and its effect on the income of farmers in the Qazvin plain irrigation network was evaluated. Then the cropping and water distribution pattern in case of water supply at the cost price were optimized considering the welfare of the farmers. Genetic algorithm was used for optimization and CPD and NBPD indices were employed to check water efficiency. The price of each cubic meter of water was estimated at 8,595 rials based on the costs incurred in the Qazvin Plain irrigation network. The results showed that the supply of water at this price in the current conditions reduces the welfare of the farmers. While by optimizing the pattern of cultivation and water distribution in addition to ensuring the welfare of farmers, the amount of water demand would decrease significantly and the average CPD index would increase by 69.4% compared to the current situation. Therefore, increasing the price of water without optimizing the pattern of cultivation and water distribution in the Qazvin Plain irrigation network cannot be a suitable solution for managing water resources.

In this research relative importance of different meteorological variables that affect potential evapotranspiration were analyzed. Two stations of Zanjan and Mahneshan with at least twenty years of data up to 2021 were selected for the research. The Penman-Monteith method was used to estimate ET0. In order to study the relative importance of climatic variables the factor analysis method was used. The correlation between precipitation, means of air temperature (maximum and minimum), wind velocity, relative humidity and actual sunshine hours were analyzed. Results showed that except one item with no significant correlation (wind and precipitation) all the other correlation coefficients were significant in 5 percent level. In both stations the eigenvalues of the two first factors were greater than one, however, they were negligible (close to zero) in the cases of other factors. In Zanjan the first two factors accounted for about 80.673 percent of total variance. This value was more than 82.5 percent in the case of Mahneshan station. In both stations the actual sunshine hour was the main parameter affected ET0 followed by the Tmax, Tmin and RH positioned in second to fourth ranks. Results indicated that for the selected stations the precipitation had no effect on ET0. Plotting the position of parameters on Cartesian plain showed that the position of parameters in the two stations are similar. The findings of this study are helpful in water resources management in the region.

Although rainfall-runoff modelling is not considered a big challenge recently, it is still one of the challenging issues for researchers in the basin or sub-basins without statistical data. One of the new methods in this field is the use of remote sensing techniques and the use of machine learning (artificial intelligence). In this research, to calculate the runoff in the basins without data, two basins were used including the basins for the Samian and the Amoghein hydrometric stations in Ardabil plain. The first station was chosen as the outlet of the Ardabil Plain basin for model training and calibration and the second station was used as the basin without data for verification and testing. Modelling was done using 9 input parameters including air pressure, vegetation cover index (low and high cover), soil temperature, ground surface temperature, soil water volume, runoff, evaporation potential and precipitation. Also, a parameter related to the observational data of the stations was used as an output. Modelling was done using four models of NARX, ANN-ACO, ANN-GA, ANN-PSO and the accuracy of the models were evaluated using MSE, R2, RMSE, NSE and MAE. The results showed that the NARX model is clearly superior to other models with an accuracy of 0.001, 0.86, 0.039, 0.855 and 0.015 respective to the above-mentioned measures. Remote sensing methods combined with artificial intelligence can respond to hydrologists’ challenges in data-scarce and ungauged basins around the world due to their ability to provide high-precision results.

The population is growing at an unprecedented rate, leading to a surge in food demand. This surge is coinciding with scarcity of water resources and intensifying competition among various sectors for water consumption and therefore there is an urgent need to precisely assess the water requirements of crops. Numerous studies have been conducted so far to determine water demand by considering various factors. Among these approaches, the FAO-Penman-Monteith equation has emerged as a widely recognized method. However, this equation entails extensive data requirements and involves lengthy calculations. The objective of this study was to develop a model for estimating the cumulative water requirement of common crops (wheat, barley, corn, and forage corn) on various latitudes within a specific region (the western vertical strip of Iran). Remarkably, the model only considers time as the input variable (growth period duration). Since the relationship between the cumulative water requirement of various crops and the length of the growth period follows a sigmoidal pattern, three mathematical models were employed to capture this trend; three-parameter logistic models, Gaussian functions, and third-order polynomials, all used for the purpose of modeling. The findings indicated that all three models exhibited high accuracy in estimating the cumulative water requirement for the crops during the growth period. The logistic model, in particular, demonstrated superior performance when evaluated using R2, RMSE, and NSE indices. Unlike the Gaussian and polynomial models, the logistic model preserved its original shape within the range of the growth period length, making it more appropriate for modeling the cumulative water demand from physical and biological standpoints. By utilizing this model, the water requirement for the intended product can be effortlessly estimated at any given point and within any desired time interval throughout the growth period, spanning from seconds and minutes to days, weeks, months, and beyond. As per the findings of this study, an equation with exceptional precision was introduced for each product in a homogeneous region, where the length of the growth period is consistent. This equation allows for the straightforward and precise estimation of crop water requirements.

Extreme weather events are significantly more frequent in the past decades due to global warming. While preventing these events from happening is impossible, providing accurate weather forecasts can help the society to be better prepared for them. Regional climate models have been widely applied locally as a robust forecast and monitoring tool for extreme weather events. This study assesses the performance of the Weather Research and Forecasting (WRF) model in simulating different heavy precipitation events across Isfahan province. For this, WRF parametrisation was established considering different versions of the microphysics, planetary boundary layer (PBL), short and long wavelength radiation, surface layer and convection scheme. The model was implemented in two nests of 12 and 4 km, using the GDAS-FNL reanalysis data as initial and boundary conditions for 17 extreme rainfall events in 2011-2018 and with different combinations of the schemes. The daily precipitation observational records from 77 rain gauge stations were applied to validate the WRF output. Finally, several statistical goodness-of-fit measures and spatial and temporal precipitation distributions were used to evaluate WRF performance. The result showed that the appropriate physical scheme for the parameterisation of short and long-wavelength radiation and surface layer could increase the performance of precipitation forecasts in the 4 km grid (high resolution), the microphysics was nontheless more crucial than other parameterisations. In Isfahan province, the Revised Monin-Obokhov, Dudhia, RRTMG, NSSL, TiedTKE, and BouLac schemes performed better in simulating precipitation respectively for parametrisation of surface layer, short and long wavelength radiation, microphysics, convection, and planetary boundary layer. Therefore, This optimal combination of parameterisations is suggested for further studies with the aim of precipitation forecasting and using them in flood forecast systems.

Lake Urmia has entered a period of drought, leading to the deposition of a substantial volume of salts and minerals. The sediments contain valuable minerals. The overarching objective of this research is to formulate an appropriate strategy for the retrieval of sediments in the dried bed of the lake and exploiting the valuable minerals which will indirectly contribute to reducing the adverse environmental effects of excess sediments. SWOT analysis was employed to evaluate internal and external factors related to economic exploitation. The general condition of the lake was assessed in terms of the status of minerals within the sediments through literature reviews and field surveys. Then, a panel of experts, consisting of 87 individuals, engaged in the development of strategies using open-ended questionnaires and analytical and descriptive methods based on SWOT and Delphi. The results of the research indicated that sediments contain valuable elements, such as potassium and magnesium at densities of 1.5 and 5%, respectively. The evaluation matrices of internal and external factors in the analyses yielded scores of 2.41 and 2.38, respectively, indicating a high frequency of weaknesses and threats. Defensive strategies outperformed other strategies, underscoring the need to address weaknesses and mitigate threats in the process of sediment and valuable minerals extraction. Six defensive strategies can be implemented in the current circumstances, ultimately laying the groundwork for sediment harvesting and the processing of valuable minerals. Key weaknesses include a lack of general knowledge, underdeveloped industrial units in the relevant sector, limited media coverage regarding the importance of sediment extraction, and insufficient involvement of experts.

Various mineral and chemical compounds entering into the reservoirs of the dams result in the consumption of dissolved oxygen in the water, which leads to the creation of numerous environmental problems. The aim of the present study is to evaluate the water quality changes in Aras dam reservoir in two stations representing the reservoir inlet and outlet during the study period of water year 1400-1401 (Iranian calendar). In this study, 16 water samples were taken from the inlet and outlet during eight stages and the quality parameters of the water were analyzed. The results indicated that Aras Dam acts as a sedimentation unit. According to the results, the maximum total amount of coliform, BOD5, nitrate and heavy metals including lead, arsenic and cadmium is 18000 (MPN/100ml), 9, 0.008, 0.03 and 0.01 mg/liter, respectively. Also, the average amount of EC at the inlet and outlet of the dam was estimated as 1279.3 and 1396.4 µs/cm, respectively. The increase in EC can be caused by the effect of evaporation as well as the entry of polluting currents. LSI and RSI indexes were used to evaluate the tendency of water for scaling and corrosion. According to the obtained results, scaling is the dominant phenomenon for the reservoir water.  Finally, the  index was used to determine the water quality status in Aras Dam reservoir. According to this index, the water quality status in this reservoir lies in the category of medium to relatively bad.

Strategic plans approved by the competent authorities in the form of upstream documents are a suitable indicator for expressing the policies of any country including the country's strategies related to water and food security. In this research more than 50 documents were identified in the three main areas of water, environment and agriculture to examine the mentioned issues in Iran. The documents included the upstream documents in the field of water and agriculture and were explicitly or implicitly related to food and water security. These documents were examined using quantitative analysis on frequency. First, the counted upstream documents were analyzed for 4 axes, 14 sub-axes and 36 components. Then the amount of repetition of each was evaluated in the introduced documents. The highest level of attention of the policy maker has been given to the "political-administrative-legal" axis and then the "social-economic" axis. By using the analysis of the frequency, the sections that were important from the point of view of the law and the policy maker was identified. The results obtained from these sections showed the legislator's attention and the course of strategies in time which form three time periods of (a) first 1380-1358, (b) second 1381-1390, and (c) third 1391-1400 (Iranian Calendar). This showed the changes in the level of attention each axis received from the legislative and policy making authorities over time. The results showed that the attention of politicians and legislators has changed from a specific axis (organization administrative legal) to a uniform and one-size-fits-all attention to all the examined axes, which shows a positive evolution in the policy of water resources and agriculture.

The abundance of phosphorus, nitrogen and sediment loads in the watershed affected by point and non-point pollution sources due to agricultural activities, animal breeding, urban and industrial development have led to increasing threats to surface water resources in the country. In this research, the spatiotemporal hydrological, sediment and nutrients modelling of water resources has been developed in SWAT environment for the Seymareh River-basin. The SWAT model performances in simulating the flow rate, sediment, and nutrients in different hydrometric and water quality monitoring stations have been evaluated using statistical indicators R2 (correlation coefficient) and NS (Nash-Sutcliffe). The SWAT model calibration and validation was accomplished by SWAT-CUP tool and SUFI2 technique. According to SWAT model results, the NS coefficients in various hydrometric/monitoring stations for calibration stage are more than 0.51, 0.53, 0.52, and 0.47 respectively for flow rate, sediment, total nitrogen (TN), and total phosphorus (TP). The results demonstrated that the complete removal of the phosphorus loads in 5 important point contaminant sources will reduce the average phosphorus concentration from 1.34 mg/L to 1.14 mg/L in the monitoring point (river basin outlet). Furthermore, the effects of Kermanshah City sewage on water quality degradations in the Seymareh control point are dominant in comparison to other pollution point sources. Non-point pollution sources (agriculture drainage, animal breeding, and soil erosions) have significant contribution in water quality deteriorations in the Seymareh River-basin compared to point sources

Over extraction of ground water is considered a global problem, which, in addition to the threats to countries’ water resources, has in many cases caused the lowering of the earth's surface or land subsidence. Iran has suffered land subsidence in many cases due to the dry and semi-arid climate on the one hand and the pressure on underground water resources for agricultural development on the other hand. Regarding the destructive effects of land subsidence on water and soil resources, it is a sustainability key issue to manage the phenomenon and prevent the spread of it. Since the first step in the management of this phenomenon is to identify the affected areas, in this research, for the first time, a comprehensive map of Iran's subsidence has been prepared by combining various geodetic observations, and the affected areas have been examined and analyzed in terms of their extent and height displacement rate.

Lake Urmia drying up may pose hazardous environmental and socio-economic impacts on the northwestern of Iran and change basically the legal nature of this lake as a wetland and national park. Examining the new legal status of dried Lake Urmia in terms of government’s responsibility to protect the local people and environment against the impacts of this disaster is necessary to prevent more vulnerability against these impacts and to protect the lakebed and its coastal zones. Based on legal analytical pathological method, this article investigates how Lake Urmia drought changes its legal nature and how to protect the local people and environment against the impacts of this disaster. With regard to the legal lacuna in management of drought circumstances, the legal system should take the best available urgent strategies to control and mitigate the impacts of this disaster, to avoid worsening humanitarian and environmental conditions in this region and to enhance local adaptation and to protect the lakebed and its coastal zones.

Azarshahr plain is one of the wide plains in Lake Urmia basin which has an important source of groundwater and it is at risk of nitrate pollution due to the agricultural prosperity in this plain. Therefore, it is necessary to protect these groundwater resources using the most suitable and inexpensive solutions by identifying the areas exposed to the risk of pollution. In this study, in order to investigate the inherent vulnerability and risk of contamination, geological data, hydrogeological information and geophysical data were used as well as the digital elevation map of SRTM satellite with a spatial accuracy of 30 meters. Also the concentration of nitrate contaminant sampled from 35 different sources with appropriate distribution was used for validation. The pollution risk of Azarshahr plain aquifer was investigated using "Source-Pathway- Receptor" method. In this method, after identifying the source of pollution, the aquifer vulnerability was considered as a pathway. Improved DRASTIC method by SFL, M5P and RS models were used to evaluate the aquifer vulnerability, then the vulnerability map to nitrate contaminant was obtained. Based on the highest correlation (r = 0.87) and the lowest error (RMSE = 0.06), the M5P model was selected as the best model for vulnerability assessment. Finally, the risk map of nitrate pollution was obtained by multiplying the vulnerability of the aquifer (based on the M5P model) and the velocity of the groundwater. The results showed that the pollution risk of aquifer to nitrate pollutant is high in the central part of the aquifer.

Without hydrological models the investigation and management of watersheds can be time-consuming and costly. This study aims to explore various hydrological factors including runoff, sedimentation, evaporation, and transpiration in Pasikhan watershed located in Guilan province. The study also examines the impact of these factors on the Anzali Wetland. To achieve this, the research utilizes the SWAT model. Data on flow discharge, precipitation, and sedimentation for three hydrometric station in the Pasikhan watershed from 1999 to 2020 were obtained from the regional water company of Guilan province. The necessary maps for model execution were obtained using established methods. Predictions for various factors, such as flow rate, sedimentation, surface runoff, evaporation and transpiration, deep aquifer recharge, curve number, deep infiltration, and watershed runoff, were made for the years 2040 and 2071. Discharge-sediment from 1999 to 2011 is used for calibration and for validation used the data from 2012 to 2022 is used. The study also assessed changes in hydrological components caused by climate change using the RCP8.5 scenario and land use changes. The findings demonstrate variations in multiple hydrological elements and precipitation patterns within the catchment basin. The Nash Sutcliffe criterion yielded values between 0.60 and 0.80 for both the calibration and validation phases of the model in terms of flow rate and sedimentation. This indicated that the implementation of the SWAT model is satisfactorily accurate. Results showed that the maximum surface runoff within the basin will reach 485 mm in 2055, coinciding with a rainfall of 1431 mm. Additionally, the study identified the highest levels of evaporation and transpiration as 1707 mm within the RCP8.5 scenarios in 1996. Overall, the research emphasizes the negative impact of sediment generated within the Pasikhan watershed on the Anzali Wetland, highlighting the need for effective control measures to mitigate wetland degradation

The protection of groundwater resources against pollution is an important and essential issue. One of the effective methods in the treatment of aquifers is the utilization of the injection-extraction well pair system (hydraulic fence system). In this study, the remediation system of a pair of injection and extraction wells near a stream was analytically analyzed. The potential and stream functions were analyzed together with the capture and release zones of the wells in three configurations. The base flow rate (i.e. the minimum flow rate to initiate the circulation cell between the recharge and pumping wells) was calculated and analyzed in different modes. The critical flow rate (i.e. the allowable maximum flow rate for the extraction region of the pumping well without intercepting the stream) was also specified and interpreted in the configurations for the problem. In the first configuration and when the wells were located at the dimensionless distance of 2×0.4 from each other, the critical flow rate (QCR=1.07) was more than the base flow rate (QBS=0.22). In the second configuration, equality of base and critical flow rates causes a common stream line passed through the stagnation points of the recharge and pumping wells, while the stagnation point of the pumping well was tangential to the stream. In such a situation, the dimensionless value of the distance between the injection-extraction well pair and the dimensionless value of the critical flow rate (which in this case is also equal to the base flow rate) were achieved as 2×1.04 and 0.61, respectively. In the third configuration and when the dimensionless distance between the wells was equal to 2×1.2, the critical flow rate (QCR=0.59) was less than the base flow rate (QBS=0.70). According to the results, the flow rate was determined while the remediation system captured stream’s water and the conditions of entrance of the pollution into the stream from the aquifer were created. Also, the minimum flow rate was determined for the well pair system which can has full and gapless coverage against pollution.