فصلنامه حفاظت منابع آب و خاک
سال سیزدهم شماره 1 (پیاپی 49، پاییز 1402)

Different factors are effective in increasing wheat production, one of the most important of which is water. Determining the actual consumed water of wheat in arid and semi-arid regions is of particular importance and the economic use of water is a serious and very important issue for farmers and researchers who cultivate and produce wheat under irrigation. The season of wheat cultivation has a direct effect on its water requirement due to the change in the energy pattern affecting evapotranspiration, and it will definitely have a lower water requirement in winter than in spring and summer. Therefore, the present study was conducted in order to investigate the water requirement system in determining the actual amount of irrigation water and wheat plant yield based on the inverse solution of the production function under water stress conditions for Alvand variety wheat in Qazvin province.

The research was conducted in 2017-2019 crop years in Qazvin province on a land of 600 square meters in Esmailabad research station (49º 52' N, 36º 15' E, 1285 MSL). The experimental design was in the form of split plots and in the form of a randomized complete block design with three replications. So that the main factor of irrigation management includes providing water requirements of 20 (I1), 40 (I2), 60 (I3), 80 (I4) and 100 percent (I5) and secondary treatment includes irrigation until the end of the flowering stage (S1) and The pulping of the seed was (S2). The country's using NIAZAB system was provided by the Soil and Water Research Institute (SWRI). This system is designed to determine the water requirement of farmland and Orchard products, which has the ability to estimate and determine the water requirement, Consumed water and plants irrigation planning at the level of the region, city, catchment and plain. One of the prominent points of this system is its location-based nature, and the user can extract their regional needs by referring to the system and can allocate the water used for the cultivation pattern under different usage options to the beneficiaries of the agricultural water stakeholder with the ability to provide an update.

The results showed that the root mean square error in Tafteh, Pasquale and Raes methods was 122, 83 and 126 mm per day, respectively, and Pasquale method had a better estimation than other methods. In Pasquale's method, the best normalized root mean square error was observed with 0.18%. The index of agreement or consistency in Tafteh, Pasquale and Raes methods was 0.95, 0.98 and 0.95%, respectively, and the Coefficient of Efficiency of the model was 0.77, 0.91 and 0.73, respectively. The results of the statistical analysis showed that the measured and simulated values are close to the 1:1 line and have a good relationship, and the coefficient of determination values in the studied years showed 0.98. The results of estimation the amount of wheat plant evapotranspiration in the using NIAZAB system in the Qazvin plain with the methods of Tafteh et al. (2013), Pasquale et al. (2017) and Raes et al. (R2=0.98) were high and the root mean square error in Tafteh, Pasquale and Raes methods was 120, 83 and 126 mm per day, respectively, in which Pasquale's method had a better estimation than other methods.

In general and according to the statistical results, a good approximation was observed between the real data and the using NIAZAB system in determining the amount of irrigation water under water stress conditions, which indicates the appropriate evaluation of the water requirement system and the ability to simulate the wheat yield function in relation to different treatments. It was irrigation and this system can be used as a suitable tool in estimating water needs to improve water management in wheat.

The deficit irrigation method with the aim of saving water consumption can be presented as a useful strategy in low water conditions and with the proper use of the amount of water consumption. Optimum use of water and proper use of fertilizer, in addition to increasing plant yield, increases the water productivity and fertilizer. Nitrogen is one of the main elements in plant nutrition, because of its importance in the plant's vital processes; its deficiency reduces performance more than other elements. The present research was conducted with the aim of investigating the effect of water stress and different levels of nitrogen fertilizer on the yield and productivity of Williams cultivar soybeans in Hormozgan province.

This experiment was conducted in the form of split plots in the form of randomized complete blocks in three replications in Hajiabad city (Hormozgan province) in two crop years 2021 and 2022. The main factor was irrigation in 6 levels without irrigation and providing 40, 60, 80, 100 and 120% of water requirement and the secondary factor was the amounts of nitrogen fertilizer (urea source) in four levels including zero, 50, 100, 150 and 200 kg/ha. Each experimental unit had dimensions of 5×20 m2 and had 10 cultivation rows.

The interaction effect of irrigation and nitrogen fertilizer on biological, pod and seed yields, harvest index, thousand seed weight, number of seeds per plant, pod length, water consumption efficiency in biological, pod and seed were significant at 1% level. The interaction effect of irrigation and fertilizer showed that the highest amount of biological, pod and seed yields in the conditions of 100% water requirement and 150 kg N/ha consumption were 6051, 4941 and 3049 kg/ha respectively. The maximum harvest index due to the interaction effect of irrigation and nitrogen fertilizer was in the conditions of 100% water requirement and with 100 and 150 kgN/ha fertilizer with an average of 0.43%. The interaction effect of irrigation and nitrogen fertilizer showed that the maximum thousand seed weight was with 120.8 g in the condition of 100 percent water requirement and fertilizer consumption of 200 kg/ha. The highest efficiency of water consumption based on biological, pod and seed yields were observed in conditions without irrigation and 150 kg N/ha in the amount of 5.61, 3.71 and 2.28 kg/m3 respectively.

According to the results, the availability of water and sufficient nitrogen are two very important factors that affect the growth and yield of soybean. Therefore, in addition to the lack of water, the lack of nitrogen also causes stress on the growth and yield of soybean. With the upward trend of nitrogen fertilizer consumption, the yield decreased and if there is not enough water, the increase in nitrogen fertilizer consumption aggravates the effect of moisture stress and as a result the yield of the plant decreases, therefore, in water shortage conditions, Excessive use of nitrogen fertilizer is not recommended. According to the results, full irrigation and nitrogen consumption up to 150 kg/ha are suggested for the studied area.

The analysis of hydrological events is one of the important components of the management of water resources and consumption. The amount of water consumption directly depends on the climatic phenomena in a region. Rainfall is one of the important indicators of climate change, which has been considered by researchers in the probabilistic analysis of hydrological phenomena. This research has been conducted with the aim of evaluating trend analysis and estimation of rainfall return period in water resources management of Lorestan province using modified Mann-Kendall method and bivariate probabilistic modeling.

The study area is Lorestan province located in the western part of Iran. Based on the conceptual framework of the study, time series of rainfall data were collected for the statistical period of 35 years from 1365 to 1400. In order to analyze the trend of precipitation in the province, the modified Mann-Kendall non-parametric test was used. Furthermore, Archimedean joint functions were used to determine the return period of two variables, duration and height of precipitation.

The results showed that in most parts of Lorestan province, the height of rainfall in the 10-year return period was less than 50 mm per day. This amount of rainfall will provide between 100 and 200 million cubic meters of agricultural water for eight cities. Noorabad and Aleshtar respectively have the highest and lowest predicted amounts of water in the next 10 years. Moreover, the comparison of precipitation trends showed that there was no significant decreasing or increasing trend at the 5% confidence level.

The results showed that although a significant decreasing or increasing trend was not detected using the Man-Kendall method in the cities of Lorestan province, the return period of rainfall indicates a decrease in available water resources for agriculture. Planning based on bivariate distribution functions showed that the duration of rainfall can play a decisive role in calculating the return period.

The use of hydrological models in watersheds has always been of interest to water resources researchers. Hydrological simulation models are valuable tools for investigating challenging issues related to watershed management, such as the effect of climate change on water resources and the effect of urbanization on floods and droughts. Spatial distribution hydrological model WetSpa is used to simulate river flow at basin scale. The model uses the observed topography, land use, soil map, and daily meteorological time series (rainfall, evaporation and temperature) to predict hydrographs and distributional-spatial hydrological parameters of the basin. In this article, the object-oriented, modular and process-oriented model of WetSpa, which is prepared based on the flexible modeling approach, is applied to simulate the daily hydrograph in Khorramabad basin.

The inputs of the model include digital elevation maps, soil type, land use, and time series of precipitation, temperature, and potential evaporation and transpiration, which are from the statistics of 6 meteorological stations in a ten-year period (water year 84-85 until 93-94) is used. After preparing the inputs of the model, at first the maps of the distribution parameters are automatically generated in the map format by the GIS pre-processing component of the model. After that, the model is calibrated using a 5-year statistical period (water year 84-85 to 89-88) of precipitation, temperature, and potential evaporation and transpiration data. The model uses Thiessen polygons to apply precipitation, temperature, and evaporation data. For this purpose, the daily discharges of Jam Anjir hydrometric station located at the outlet of the studied watershed are used. Model calibration is done manually by determining the values of 11 global (general) parameters of the model, so that the best match between simulation and observational hydrograph is obtained. And finally, the validation of the model is carried out based on a 5-year statistical period (water year 89-88 to 94-93) and the values of the global parameters obtained in the calibration stage.

The maps of distributed parameters are produced, which after preparing the inputs of Mashdand's production model showed that the average potential runoff coefficient of the area is 63% and the concentration time of the area is 17 hours. In the following, according to the 11 global parameters, which symbol and range of changes are specified in table (3), the model global (general) parameters values  are obtained in the calibration stage. Comparing the simulated hydrograph by the model and the observed hydrograph in the calibration stage shows that the best match between the observed and simulated data is established with a correlation coefficient of 0.39. Validation of the model is also based on a 5-year statistical period (water year 89-88 to 94-93) and the values of global parameters. The output files of the model illustrate that 26.15% of the precipitation becomes runoff during the calibration period. During the validation period, the share of total runoff from precipitation is 26.42%. Moreover, the simulation results of the model demonstrate the ratio of evaporation to precipitation in the calibration and validation periods is 57.18 and 69.20%, respectively. Additionally, the results of the evaluation of the model based on the Kling-Gupta index (KGE) present the value of 0.68 for the calibration period and 0.74 for the validation period.

In this article, the effectiveness of WetSpa model is investigated in order to simulate the daily flow of Khorram Abad River at Cham Anjir hydrometric station. According to the results obtained from this research, it can be said that the Wetspa spatial distribution model has the ability to simulate the hydrological behavior of the basin with acceptable accuracy. The graphical comparison of the calculated and observed hydrographs for the calibration and evaluation period also shows a relatively good match between the two hydrographs. Examining the results of calculating of the water balance components by the model demonstrates that the outflow in the calibration and validation period accounted for 26.15 and 26.42% of the total precipitation respectively, seems logical considering the major land use of mountains and pastures in the irrigation basin.

Drought is a global phenomenon that can occur anywhere and cause significant damage to humans and natural ecosystems. Therefore, the issue of hydrological drought and reduction of river flow in Ardabil province is also an important issue that requires a comprehensive study.

In this study, hydrological drought characteristics are using Severity-Duration-Frequency (SDF) curves considering four different threshold levels (constant, annual average, seasonal, and environmental flow) in 33 hydrometric stations in Ardabil province. The severities of drought events are calculated using Easy-Fit software in different return periods. In this regard, drought magnitude-duration-frequency curves are calculated and based on that, the values of drought events in different return periods are calculated and analyzed.

The highest drought event is determined for constant, seasonal, yearly, E-flow threshold levels in Samina, Mashiran, Booran, and Samian stations, respectively.  Also, the lowest occurrence of drought is associated with the Vildaragh station. The majority of drought events in all four aforementioned thresholds are mostly observed in shorter durations, especially within one-month periods. The Jonson_SB and General Extreme Value distributions were the most suitable statistical distributions. The highest intensity of drought increases with longer return periods associated with the average annual threshold level, and the lowest intensity of hydrological drought is linked to the threshold of environmental flow. The SDF curves for all stations demonstrate an increasing trend, indicating that with prolonged hydrological drought duration in all studied thresholds, the severity of hydrological drought occurrences also increases. The greatest intensity of hydrological drought is sequentially related to the annual threshold, followed by the seasonal threshold and the fixed threshold, with the threshold of environmental flow being the lowest and least. Consequently, for shorter return periods, the fixed threshold indicates greater intensity or magnitude compared to the seasonal threshold in all four stations, and for longer return periods, the seasonal threshold demonstrates higher intensity of drought events compared to the fixed threshold.

Furthermore, it can be concluded that the magnitude of hydrological drought at a fixed threshold shows less variability in all four selected stations compared to the other thresholds. It should be noted that in defining drought based on fixed, annual, and seasonal thresholds, events will have a higher number and greater intensity compared to the environmental flow threshold. The spatial changes in drought intensity are depicted on the map, indicating that most droughts have occurred in stations located in the northern and north-western regions (Borran and Dostbiglou). Separating the effects of human and climatic factors in drought assessment is a suggestion from this study that could be considered in future research.

Today, the dependency between energy consumption and water use has become an important issue in pressurized irrigation networks. In addition to the problem of water scarcity, rising energy costs are also a challenge for the agricultural sector. The objective of this study was to investigate different strategies to reduce energy consumption in the pressurized irrigation network of Saleh Abad.

For this purpose, firstly, minor changes affecting energy consumption including change in diameter of lateral pipe were evaluated. In this level, evaluated scenarios were lateral pipe diameters in mm 63 and 75. Hydraulic analysis of irrigation network was calculated using WaterGems software and energy consumption in different pumping stations was calculated using energy audit. In the second level of evaluation, four scenarios were defined to reduce energy consumption in the irrigation networks by structural changes in the irrigation network based on energy audit strategies, critical point control, network sectoring and pumping station management. The scenarios were (i) network sectoring without changing the main canal line, (ii) change of main canal line to pipe line, (iii) implementation a new first pipe line for a part of the network that is irrigated by gravity water, and (iv) elimination of the secondary pumping station by increasing the primary pumping station head. In the scenarios i, ii and iii, the part of the irrigation network lands was determined that could be irrigated without the need for a secondary pumping station. In this scenarios, the energy saving was calculated in a new condition by varying the type or number of pumps in secondary pumping stations to provide upstream discharge and head requirements.

The results showed that according to the topographic conditions of the network, changing the diameter of the laterals had no effect on saving energy. Also, the results showed that by network sectoring and applying scenarios(i), (ii), and (iv), the irrigated area without the need for a secondary pumping station were 610.8, 1591.5 and 1621.8 hectares, the energy saving in secondary pumping station were 14.6, 46.1 and 47.4% and the total energy consumed in network were 3.9, 12.4 and 12.7%, respectively. In the scenario iv, the primary pumping station was optimized. The result indicated that if the pumps type of the primary pumping station were changed and the water reservoir was implemented in higher level, it would be possible to eliminate the secondary pumping stations. In this case, the total area network (2820 ha) was irrigated without the secondary pump station and the energy saving was 8.46%.

The results of this study showed that changing the diameter of the lateral pipe had no significant effect on the energy consumption of the network. Also, the results showed that network sectoring and changes in main pipeline, it is possible to save up to 3121 MWh in the annual energy consumption of the network. Therefore, it is suggested that, network sectoring based on the input pressure of hydrants and the use of gravity, in the design of irrigation and drainage networks, considered as an effective solution to reduce energy consumption.

Cooling towers are an important and vital part of industrial units that are used for water cooling that is used in the cooling processes of systems in power plants, refineries and other industrial units. One of the important components of towers is the relaxation pool, the main role of which is to collect water for transfer to the system, the number of suction pools is usually designed according to the number of each pump. One of the important tasks of the relaxation pool structure in this structure is energy dissipation. In this regard, usually in this pond, the hydraulic structure of the hydraulic jump is used for energy dissipation. In the hydraulic jump process, the current changes from supercritical to subcritical. This causes a loss of flow energy. In cooling ponds, downstream slope is usually used to control the hydraulic jump. In cooling ponds, downstream slope is usually used to control the hydraulic jump. Various studies have shown that using stairs instead of ramps can greatly increase energy loss in the relaxation pool. In this study, by replacing the stepped surface with a sloping surface, the effects of this process on flow lines as well as its effects on cavitation are investigated.

In this research, the Fluent numerical model is used to numerically model the flow around the structure of the cooling tower calm pond. In this regard, the dimensions of the relaxation pool in the concrete cooling tower are very important from an engineering point of view and should be designed in such a way that the operating conditions of the pumps are safe. Existence of high velocities and pressure drop in the dischargers causes serious problems related to the occurrence of cavitation phenomenon. Since modeling a physical model usually requires a lot of time and money, a numerical model calibrated with laboratory data was used to follow this research. In this study, due to the recognition of destructive eddy currents created around the lower valve when the valve is opened, hydraulic optimization of the relaxation pool and the appropriate width of the relaxation pool in refineries is one of the objectives of this study.

The study of increasing the flow in numerical modeling showed that with increasing the flow due to the increase in energy loss due to the stepping of the end threshold, the water height in the calm pool decreases significantly. This drop is estimated at an average of about 67%. Also, the results of water level profiles showed that the threshold of the end of the pond in a stepped manner, has a greater drop than the sloping conditions. Also, in exchange for higher discharges, this drop will move to higher values. Therefore, in the numerical model, the flow conditions on the stairs were analyzed at minimum and maximum flow. Regarding the study of pressure drop in the relaxation pool, it can be stated that the development of flow in the pool section based on increasing the width and height of the duct increases the amount of velocity during the discharge, which has led to pressure drop.

The results of the study of cavitation number along the pond indicate that for the ratio of water depth to the width of the pond less than 1.82, the possibility of cavitation during the pond will be reduced. Also, depleting blocks in the pond have a positive effect on improving hydraulic performance, which leads to increased energy dissipation and jump stabilization, reduced speed, length, height of hydraulic jump and also reduces the risk of cation compared to the case without depleting blocks.

The occurrence of frequent floods in Iran necessitates a flood forecasting and warning system with a suitable lead time. The use of numerical rainfall forecasting models in flood forecasting and warning is one of the important measures taken by researchers in most parts of the world. The TIGGE database includes mid-term precipitation forecasts simulated by global forecast centers. The purpose of this research is to evaluate the efficiency and the degree of uncertainty caused by the rainfall forecasts of four numerical models of the TIGGE database (including CPTEC, ECCC, ECMWF, and KMA) for simulating floods with the HEC-HMS hydrological model.

In this research, the precipitation data of seven meteorological stations were used to evaluate the uncertainty of discharge from TIGGE database precipitation prediction models in the Poldokhtar watershed. Also, three flood events on March 24, 2017, April 6, 2018, and April 15, 2018, were studied. At first, precipitation forecasts were extracted from four centers CPTEC, ECCC, ECMWF, and KMA. Due to the existence of systematic error in the forecasts, a bias correction was done on them, and to correct the bias, the Delta method was used. Processed and raw forecasts of four rainfall forecasting models were entered into the HEC-HMS model for flood forecasting, and in the next step, the flow uncertainty assessment of the HEC-HMS model was performed in all members of the four rainfall forecasting models. In this research, 5 factors P, R, S, T, and RD were used for uncertainty analysis.

The results indicate the significant superiority of the ECMWF model in predicting precipitation events. The use of all 4 rainfall sources led to an acceptable simulation of the flood peak flow in three different events. Also, the predicted peak discharge time had little difference from the observed data. According to the results of the uncertainty analysis, the ECMWF model was considered the best model based on P, R, S, T, and RD factors. The KMA model performed well in severe and very severe floods. The group prediction system of TIGGE models also had an acceptable performance in all events. Also, the hydrological-meteorological prediction model predicted the time of flood occurrence and the probability of occurrence well.

The intended research investigates flood forecasting and warning in the Poldokhtar watershed using the meteorological-hydrological system, based on meteorological forecasts of the TIGGE database and flood simulation using the HEC-HMS hydrological model. The final product of this system is probable discharge and flood forecast. The results reveal the success of the TIGGE database in flood forecasting. The ECMWF model excelled in predicting peak discharge. The upper and lower band calculation method was used to determine the uncertainty, which showed the uncertainty well. This system displayed the time of peak discharge well and with a small time delay, which indicates its good performance. The predicted rainfall from the four centers used in this study (ECMWF, ECCC, CPTEC, and KMA) have significant differences. To reduce these differences, we used a multi-model group forecasting system that had encouraging results.

One of the consequences of climate change is the occurrence of extreme events such as drought, which is important to identify, monitor, evaluate, and inform about the occurrence conditions. In this study, the effects of climate change on the drought situation in the near future (2021-2040), mid-term (2041-2060), and long-term (2061-2080) have been discussed using the Aridity Index estimated by the Copernicus Climate Change Database with the use of GFDL-ESM2M climate model output under RCP4.5 and RCP8.5 scenarios.

In the current research, climate data simulated by the Copernicus database is used to calculate the Aridity Index of different parts in various time horizons. Mann-Kendall's test is applied to investigate the changes of drought indices in different time horizons. Also, the aridity index is used to determine the climatic condition of different parts of Iran in several time periods and its changes are analyzed and investigated.

The results illustrate that in the near future and based on the RCP4.5 scenario, the average annual dryness index has an increasing trend in most parts of the country, and these climate changes lead to a change in the climate of some parts of the north of the country from humid to semi-arid and semi-humid, and parts of the center and the southeast become dry to semi-arid. According to the RCP8.5 scenario, there is a downward trend in parts of the east and the center of the country, and an upward trend in parts of West Azerbaijan, East Azerbaijan, Chaharmahal Bakhtiari, and a part of Kermanshah, and climate change rises the spatial extent of dry climates in the country. Also, in the mid-term and based on the RCP4.5 scenario, a downward trend can be seen in most parts of the country, and climate change will increase the area of dry climate lands in the central and southeastern parts, while according to the RCP8.5 scenario, there is an upward trend in most of the country, and climate change causes a soar in semi-arid and dry climates in parts of the northwest, northeast, and parts of the center and south of the country. Finally, in the long-term and based on the RCP4.5 scenario, the mentioned trends will be almost true and climate change will lead to the expansion of areas with arid and semi-arid climates.

The results obtained in the this research showed that the average drought index in the near future, mid-term and long-term according to the RCP4.5 scenario are 0.5, 2.2 and, 2.3%, respectively and according to the RCP8.5 scenario,  2, 4.2 and, 4.1% have risen compared to the primary period, respectively, and it rises by 1.4 percent compared to the base period, and it is a good indication that the reduction in rainfall and the increase in the temperature of the earth's surface will lead to a soaring in the dryness of different parts of the country. In addition to changing the climate of the region, this issue will have irreparable effects on the condition of water resources, agriculture, environment and urbanization. Therefore, in order to reduce the aforementioned effects, it is recommended that managers and officials consider appropriate measures, correspond to each clime region, to control the amount of water consumption in different parts of the country.

The Hargreaves equation is one of the simplest methods for estimation of reference crop potential evapotranspiration which has two constant coefficients of 17.8 and 0.0023. The Hargreaves equation has been calibrated in many studies around world based on lysimeter data or the Penman-Monteith method. The main objective of this study was the calibration and validation of Hargreaves equation with three conditions based on the Penman-Monteith equation in Shiraz and Zarghan synoptic stations in Fars province. 

In this study, the Hargreaves equation has been calibrated and evaluated with three different conditions based on the Penman-Monteith method in Shiraz and Zarghan synoptic stations in Fars province. In the first condition (H1), the monthly effective temperature was used instead of monthly mean temperature, and also the constant coefficients of 17.8 and 0.0023 were calibrated. The monthly effective temperature is the function of minimum and maximum monthly temperature and a constant coefficient that must be determined in calibration stage. In the second condition (H2), the constant coefficients of 17.8 and 0.0023 were calibrated, and in the third condition (H3) only the constant coefficient of 0.0023 was calibrated. For this study, 25 years (1988-2012) of monthly weather data of Shiraz and Zarghan synoptic stations in Fars province were used to calibrate the three mentioned conditions, and the coefficients of each condition for each month and each station were determined separately by using the Solver menu of Excel software. Then, 10 years (2013-2022) of monthly data of mentioned stations were used to evaluate the obtained results. Also, Root Mean Square Error (RMSE), Normalized Root Mean Square Error (NRMSE), Mean Bias Error (MBE) and model Efficiency Factor (EF) were employed to compare the results in calibration and evaluation stages.

The results in calibration and evaluation stages for both stations showed that the H3 condition for estimating evapotranspiration was better than the other conditions, and only determining a coefficient instead of 0.0023is needed. The value of this coefficient was changed between 0.0022 to 0.0027 in both stations.

The results indicated that similar to many previous studies in the world, it is better to calibrate the coefficients of the Hargreaves equation for estimating reference crop potential evapotranspiration for study region. On the other hand, the results showed that using monthly effective temperature for estimating reference crop potential evapotranspiration in Hargreaves equation didn’t lead to the improvement of evapotranspiration estimation.