نشریه پژوهش های حفاظت آب و خاک
سال بیست و نهم شماره 4 (بهمن و اسفند 1401)

Water is a critical input for agricultural production and plays an important role in the sustainable development of the agricultural sector and the economic development of other sectors. Water shortage is one of the major challenges that most countries in the world are struggling with. The great importance of determining the optimal cropping pattern of crops and irrigation allocation planning in the water shortage conditions prevailing in Iran's watersheds is not hidden from anyone. This study aimed to optimize water allocation and determine the optimal cropping pattern of crops in five cities of the Sistan region under different management scenarios.

In this study, a model with a two-level planning approach, the Stackelberg game framework, and a genetic algorithm, was developed to optimize the water allocation between irrigated areas and crops, as well as to determine the optimal cropping area in 5 cities of Sistan region (including Hamon, Hirmand, Zahak, Nimroz and Zabol) to confront different water conditions. Selected products include wheat, barley, onion, melon, watermelon and alfalfa. The problem was solved in the form of nine scenarios, including three scenarios of irrigation efficiency, three scenarios of climatic conditions, and three scenarios of low irrigation conditions, and compared with the baseline scenario.

For water allocation among the studied regions in the baseline scenario, the most and least water was allocated to Zahak and Hirmand areas, respectively. Among the studied crops, the most water was allocated to the melon due to its low water requirement and high economic value compared to other crops, and the least amount of water was allocated to the alfalfa due to its high water requirement; also the melon with 13503.5 ha had the highest cropping area and alfalfa with 4.85 ha had the lowest cropping area in a total of five cities. The total cropping area obtained by the model was 18240.32 ha. The value of the Gini coefficient was 0.0053, which is small and close to zero, indicating that the water allocation between the regions was fair. The total interest rate obtained in the baseline scenario was 5.06 ×1013, which by applying irrigation efficiency scenarios of 50 and 70 percent, the amount of profit has increased by 12% and 34%, respectively, and the cultivated area by 27% and 47% compared to the baseline scenario. And in normal and wetyear conditions, the amount of total profit has increased by 28% and 54%, respectively, and the cultivated area by 40% and 65% compared to the baseline scenario. By applying the low irrigation scenario, the interest rate decreases compared to the baseline scenario, associated with the saving of a large volume of irrigation water, which leads to an increase in the cropping area of crops with higher economic efficiency. Therefore, by applying various scenarios, the cropping pattern moves towards crops with less water requirement and higher economic value.

According to the results, more water has been allocated to crops with higher economic value and less water requirement. Therefore, if crops with less interest rate compared to their water use and crops with high water requirement are removed from the cropping pattern and crops with higher economic efficiency and less water requirement are replaced in the cropping pattern, it can be a good solution to confront water shortage conditions. The increase in irrigation efficiency increased the total interest, thus it is recommended to save water used by plants through the improvement of irrigation technology and increase irrigation efficiency. The proposed model in this study can be employed for correct and efficient planning for agriculture and water resource management in various conditions.

Excessive extraction of groundwater has caused most of Iran's groundwater aquifers to face a drop in water level in recent years. This has subject caused the use of most of the aquifers to be prohibited, most of the Qanats have dried up and most of the permanent springs have had a significant reduction in their water supply. Therefore, the investigation of the groundwater level should be given more attention. Various methods and tools have been used to investigate this issue. Artificial intelligence models have been used in most of these studies. Among these intelligence models, Support Vector Regression (SVR) model has performed well. In order to improve the performance of these models, in recent years, the use of pre-processing tools and the formation of hybrid models have been considered. One of these tools is complementary ensemble empirical mode decomposition (CEEMD). In this research, the combination of this tool with the SVR model was used to check the groundwater level in the Aspas aquifer. Then their results were compared with the results of the Gravity recovery and climate experiment (Grace) satellite.

The Aspas subbasin with code 4321 is located northwest of the Tashk-Bakhtegan and Maharlu basin in Fars Province. To check the groundwater level in this sub-basin, the SVR model with 4 kernels include: polynomial kernels, RBF kernel, sigmoid kernel, and linear kernel (Lin) was used. Then discusses the formation of a hybrid model obtained from the combination of CEEMD with the SVR intelligence model. When an initial signal is decomposed using the CEEMD method, and the resulting sub-signals are used as inputs to the SVR intelligence model, the hybrid model of CEEMD-SVR is obtained. Satellite data was used to compare the performance of artificial intelligence models. For this purpose, Grace satellite products with 6 different algorithms were used. The parameters the coefficient of determination (R2), root mean square error (RMSE), and the Akaike information criterion (AIC), was used to examine the efficiency of the methods.

The results showed that intelligent models had better performance than Grace satellite products. Therefore, it is more appropriate to use intelligent models, especially the CEEMD-SVR model, to predict the values of the groundwater level. One of the advantages of using satellite data is that it is available up-to-date. If the satellite data values can be approximated to the observed values (in a similar statistical period) based on a suitable method, the groundwater level data can be estimated in an up-to-date manner.

In this study, the SVR model was used to evaluate the groundwater level changes in the Aspas alluvial aquifer located in the Tashk-Bakhtegan-Maharlu basin. Using observation wells in the area the aquifer groundwater hydrograph was plotted. Changes in groundwater level in the aquifer were estimated using the values of precipitation, temperature, and evaporation parameters obtained from drawing different maps, and groundwater level in the aquifer. The preprocessing tool of CEEMD was used. The results showed that the use of the CEEMD has improved by 3.08% the performance of the SVR model. The GRACE satellite products are used. The comparison of the results of processing algorithms showed that the GFZ processing algorithm had the best performance with a coefficient of determination of 0.71 and an RMSE value of 39.15. In the next step, the performance of the CEEMD-SVR model was compared with the GFZ algorithm. The results showed that the CEEMD-SVR model performed better (R2=0.77, RMSE=25.90) and has the ability to be used for modeling and predicting the groundwater level in aquifers, especially the Aspas aquifer.

protection of water and soil is the fundamental work for development natural resources in any country. Lake of available data of soil erosion is a limitation for land managers to apply soil and water conservation in the watershed scale. Over the past decades several erosion models have been invented under different environmental conditions, but, very limited numbers can be used under watershed scale that are enable to considering soil conservation measures. Among the existing methods, WEPP model, has been known as a process oriented model that can be used in different spatial scale namely: hillslope, watershed and large basin. The WEPP model requires a large amount of input data and the model efficiency is highly related into the input data. The main aim of the present investigation was the assessment of WEPP model and spatial extension of the GeoWEPP for estimating of soil erosion and sediment yield in the paired watershed.

The study area is located into the Taleghan watershed and the pair catchments of Zaidasht with area of 198.4 ha. All environmental data including: soil attributes, vegetation, climate data were extracted by field and laboratory data analysis for the five erosion plots and whole of the watershed. Model calibration was conducted based on the both infiltration and erodibility parameter through Nash- Sttcliff and R2 as well as RMSE coefficients.

After optimizing the base value of hydraulic conductivity to about 50% for runoff, the efficiency of the model using the Nash-Sutcliffe coefficient was 0.64, which means that the estimated runoff of each plot is close to the observed values. For the amount of sediment, using the basic values of the model relationships, the model did not provide the right result and the best results were obtained with an increase of 100% for rill erodibility and 150% for interrill erosion, and a decrease of 9% for shear stress and 12% for conductivity. has obtained hydraulics and the efficiency of the model using the Nash-Sutcliffe coefficient was 0.51%, the estimated values are close to the observed values of the plots. Also The results showed that in 2016 , the sediment on the submontane level was 0.2 and 0.1 ton/ha/yr for the control and the sample, respectively and In the watershed, 1.1 and 0.3 ton/ha/yr were obtained for control and sample, respectively.Therefore, the WEEP model in the study area will be effective when the parameters of erodibility and hydraulic conductivity are measured with high accuracy. On the other hand, the results of GeoWEPP were obtained in the control and sample basins, respectively, 3.3 and 2.5 ton/ha/yr.

Based on the field observations and forms of erosion, GeoWEPP spatial extension was able to present a realistic picture of the erosion situation at the basin level Considering that this extension can remove the limitation of the model implementation in terms of area, therefore it is recommended to estimate the sediment in the scale of the watershed and in a distributed manner.

In recent years, due to lack of water, using wastewater including fish effluents, for agricultural purposes has increased. Depending on water quality, irrigation method and type of crop might change. The elements present in the fish effluent interact with each other and it is possible to increase or decrease the absorption of an element through the leaves to have a negative effect on the yield and growth indicators. Therefore, the aim of this research is to provide solutions for the use of rainbow trout wastewater in the sprinkler irrigation system to provide irrigation water for potato cultivation and the effect of leaf washing with appropriate quality on yield, tuber dry matter percentage, diameter and height of stem, tuber specific weight, chlorophyll, photosynthesis, transpiration and stomatal conductance.This experiment was conducted in research farm No. 2 of Kurdistan University ,Dehgolan plain in Kurdistan province in the form of a factorial experimental format based on a completely randomized design with three replications in the summer of 2019, 2020 and 2021. The investigated factors include irrigation at two levels, A1 (irrigation with well water) and A2 (irrigation with fish farm effluent), as well as washing the leaves of the plant in four levels, B1 (Before applying fish farm effluent to the leaves, they were washed for ten minutes with fresh water), B2 (after applying fish farm effluent to the leaves, they were washed for ten minutes with fresh water), B3 (The leaves were washed with fresh water for ten minutes both before and after applying the fish farm effluent to them) , B4 (the leaves were not washed at all).Sprinkler irrigation system with micro sprinkler was used to irrigate. At the end of the growing season, the tuber yield values of different treatments were measured. Chlorophyll meter (SPAD-502-Minolta-Japan) was used in order to measure chlorophyll of leaf. The indicators related to gas exchange including photosynthesis, stomatal conductance and transpiration were measured by a portable device (ADC BioScientific LCi Analyzer Serial No. 32648). Data were analyzed with Rstudio, and mean values of the treatments were compared by the least significant difference (LSD) test at 5% and 1% significance level.The results showed that washing the leaves with fresh water significantly affected on the yield and other growth indicators. The highest amount of yield, stem diameter, specific gravity of potato, chlorophyll meter reading, photosynthesis, transpiration and stomatal conductance were 550.8 grams per pot, 9.941 mm, 1.113 g cc-1, 53.59, 22.00 (μmol m-2 s-1), 7.028 (mmol m-2 s-1), 0.4439 (mmol m-2 s-1), respectively. These amounts were results of applying B3 treatment. Also, the highest percentage of potato tuber dry matter was 13.3% and the highest figure for stem height was 35.46 cm, which were the result of applying B4 treatment.The results of this research show that compared to well water, fish effluent increased yield of potato by 16.4%, stem diameter by 4.67%, stem height by 3.72%, chlorophyll meter reading by 9.67%, and stomatal conductance by 15.40%. Also, the results showed that treatment B3 compared to B4, increased yield 64.78%, stem diameter 39.55%, tuber specific weight 48.54%, chlorophyll meter reading 41.21%, photosynthesis by 4.40%, transpiration by 25.86% and stomatal conductance by 10.13%. It is suggested to use the strategy of simultaneous use of fish effluent and fresh water in the sprinkler irrigation system to increase yield and growth indicators.

During floods, when the water velocity is high, the flow carries the pieces of tree leaves and other solid objects with them by colliding with the built bridge's piers in the direction of the water flow and accumulating upstream. This process causes a change in the procedure and maximum scour depth around the bridge pier. If the maximum scour depth exceeds the predicted values in the design of bridge piers, it can even weaken the piers and in some cases fail and overturn them. Therefore, in this research, the effect of the debris accumulation of upstream cylindrical bridge piers in two fully submerged and semi-submerged conditions on the scour profiles around the bridge pier and their maximum values are studied in a flume of Hydraulic laboratory of Babol Noshirvani University of Technology. For this purpose, all the different parameters are determined by dimensional analysis, and the efficacy of the effective parameters such as Froud densimetric number, submergence depth, and position level of debris on the longitudinal and transverse profiles around the bridge pier is investigated. Also, one equation for predicting the maximum scour depth based on experimental data is proposed and the scope of application of the parameters obtained from the dimensional analysis for use in designs is stated. Three sets of experiments were conducted, all of which were in the conditions of clear water and constant flow to investigate the effect of the debris accumulation on the scour values. The first set is the reference tests in the case of a cylindrical bridge pier with a diameter (D) equal to 3 cm, the second condition is for debris is buried debris (y0=0) and the third condition is for free debris (y0=D). The variable parameters in the experiments are the relative velocity of the flow (u/uc≥0.838) and the relative depth of the flow (y/D≥1.33). The distance of the bridge pier from the beginning of the apron is 3 meters and the median grain size of the sediment particles is 0.82 mm. In this research, while examining the time evolution of the maximum scour depth, to ensure the equilibrium of the scour hole in the tests, the time of the tests was considered 480 minutes. The results of the laboratory observations indicated that when the debris is buried, in y/D=1 to 1.67, the maximum scour depth increases by up to 10% compared to the reference condition. When the relative depth of the flow increases, the buried debris act the same as a collar, and at y/D≥2, the scour depth is reduced compared to the reference condition. In the case of free debris, in all relative depths (1.33≤y/D≤3), the maximum scour depth has increased compared to the reference condition, and its critical case is about 57% at y/D=1.33. The correlation of the proposed equation for predicting the maximum scour depth with the R2=0.96 and the RMSE=0.22 shows the appropriate accuracy of the proposed equation for the case of scour in the condition of debris accumulation. By observing the results in general, it can be found that the debris accumulation upstream of the pier, in the case that the debris is placed above the sedimentary bed, causes a significant increase in the maximum scour depth. When these objects are at the same level as the sedimentary bed, they cause an increase in scouring in shallow flow depths, and in deeper flows, they decrease the maximum scour depth compared to the case without debris. Based on the proposed equation, the densimetric Froude number parameter has the most effective, and (y-y0)/D has the least effect on results.

Water shortage is the most important factor in reducing the yield of agricultural products all over the world and this factor is more effective in arid and semi-arid regions. Iran is a country whose average rainfall is about one-third of the global average, and in terms of water resources, it is in dire straits. Therefore, it is necessary to help preserve limited water resources by optimal use, saving and increasing irrigation efficiency. This research was defined according to the consumption of the strategic product of corn and the importance of managing the country's limited renewable water resources, on top of that, the use of pressurized irrigation systems in the region and in the climatic conditions of Urmia.

In order to investigate different levels of irrigation on performance indicators and plant traits of sweet corn, under the subsurface drip irrigation system in the form of a complete randomized block design with four treatments of 20% over-irrigation, equal to the water requirement, 20 and 40% under-irrigation in four replicates in the research farm of the Engineering Department. water of Urmia University. The plant index values of stem diameter, leaf area, grain yield, number of leaves per stem, biological yield (wet), plant dry matter and cob yield during the growing season on specific dates and also on the day of harvest. was taken and evaluated.

The results showed that in general, the effects of under-irrigation and over-irrigation on biological yield, dry matter, uncoated cob yield, 300 seed weight, number of leaves and stem diameter were significant. Also, based on the results, it can be stated that with the reduction of water consumption, the cob yield decreases linearly. The highest and lowest cob yields were obtained in overwatering and 60% water requirement treatments with an average of 1.83 and 1.13 kg/m2, respectively.

In general, under-irrigation and over-irrigation have a significant effect on biological yield, dry matter, uncoated bale yield, three hundred weight, number of leaves and stem diameter. Also, based on the results, it can be stated that with the reduction of water consumption, the quantity of cobs decreases linearly. The highest and lowest cob yields were obtained in over-irrigation and 60% water requirement treatments with an average of 1.83 and 1.13 weight per square meter, respectively. According to the results of the research, with a 20% reduction in water consumption compared to full irrigation, only 5.02% of the biomass weight is reduced, apart from significance. Control (equal to water requirement) and 20% less irrigation in dry matter traits, uncoated cob yield, 300 seed weight, number of leaves and stem diameter, no significant difference was observed. The process of changes in the accumulation rate of biological yield of sweet corn initially started from 21 days after planting and after 6-9 days it entered the linear growth stage and then continued steadily. The highest weight of biological yield of sweet corn in different treatments was observed in 87 days after planting.

The canopy of woody species is one of the most important components of rangeland ecosystems. The genus Crataegus spp. is the dominant shrub covers of rangeland habitats in the north of the country. From the habitat point of view, the presence of this plant in rangeland can be seen as an almost pure canopy or mixed with other shrub species. In the current study, the effect of different land covers [i.e. Crataegus melanocarpa M. B., Berberis integerrima Bunge., Ribes Uva – crispa L. and Prunus spinosa L. (CM-BI-RU-PS); Crataegus melanocarpa M. B., Berberis integerrima Bunge and Ribes Uva – crispa L. (CM-BI-RU); Crataegus melanocarpa M. B. and Berberis integerrima Bunge (CM-BI), and pure Crataegus melanocarpa M. B. (CM)] on variability of soil characteristics and microbial respiration dynamic, in the Kinj region of Mazandaran Province, was considered. In each of the land covers, 15 soil samples (0-10 cm depth) were collected and transferred to the laboratory. The amounts of soil organic matter, bulk and particle densities, texture, aggregate stability, coarse and fine root biomass were measured. In order to determine the changes in soil moisture, temperature and microbial respiration, sampling was carried out in the middle months of each season. The highest amount of soil organic matter was observed in CM-BI-RU-PS and CM-BI-RU habitats. Pure CM habitat had the highest value of bulk density, while the lowest value of this characteristic was assigned to CM-BI-RU-PS and CM-BI-RU habitats. CM-BI-RU-PS and CM-BI-RU habitats had the highest soil porosity. The CM-BI-RU-PS shrub cover has the most aggregate stability, and with the decrease in the diversity of shrub species, their stability decreased significantly. The highest amount of sand content was assigned to the pure CM habitat and the highest amount of clay was allocated to the CM-BI-RU-PS shrub cover. The highest coarse root biomass was observed in CM-BI-RU-PS and CM-BI-RU, while the fine root biomass was the highest in CM-BI-RU-PS. The characteristics of soil moisture, temperature and microbial respiration have shown statistically significant differences in different seasons of the year and also pure and mixed Crataegus covers. The highest soil moisture values were observed in the soil of CM-BI-RU-PS and CM-BI-RU habitats and winter season, while the highest soil temperature was assigned to the summer season and pure CM habitat. Soil microbial respiration was also higher in the summer season and CM-BI-RU-PS and CM-BI-RU habitats than other seasons and land covers. According to principal component analysis (PCA), the amount of organic matter, moisture content, and soil porosity in CM-BI-RU-PS and CM-BI-RU habitats have an effective role in soil microbial respiration of this type of land cover compared to other habitats. The results of this research confirm that the presence of species diversity in land cover can lead to the protection of soil quality indicators. In this regard, it is suggested to use other native shrub species in addition to Crataegus for the restoration of degraded rangeland in the study area as well as areas with similar ecological conditions.