Showing 68 results for Rahimi
M.h. Rahimian, J. Abedi Koupaei,
Volume 25, Issue 3 (Fall 2021)
Abstract
Soil salinization is a phenomenon that threatens agricultural lands and natural areas, leading to reduced productivity, declinations of soil resources and vegetation covers, and finally, the abandonment of these areas. This study has quantified the groundwater Capillary Rise (CR) and actual Evapotranspiration (ETa) and their relationship with the soil salinity of Azadegan plain, west of Khuzestan Province. The study area has an arid climate, characterized by shallow and saline water table and a high potential evaporation rate. For this purpose, field samplings were carried out in four consecutive seasons of the year to measure salinity, soil moisture, and texture, groundwater table, and salinity at 27 scattered representative points of the study area. The CR values were estimated in different seasons of the year using UPFLOW model. Moreover, four representative Landsat satellite images were acquired to map seasonal changes of ETa through the SEBAL algorithm. Then, the effects of ETa on CR and consequent soil salinity build up were quantified in a seasonal time scale. The results showed that the average daily ETa of Azadegan plain varied from 1.55 to 7.96 mm day-1 in different seasons which caused a capillary rise of around 1.2 to 1.5 mm.day-1. This has led to the upward movement of 12 to 18.8 ton ha-1 month-1 of salts from shallow groundwater to the soil surface, which has caused surface soil salinization. Also, there was a close relationship between ETa, CR, and soil salinity parameters, which can provide insight into modeling of spatial and temporal changes of soil salinity and provision of solutions to reduce the accumulation of solutes in the soils of the study area.
R. Sadeghi Talarposhti, R K. Ebrahimi, A. Horfar,
Volume 25, Issue 4 (Winiter 2022)
Abstract
Protection of rivers’ water quality as the most accessible source of the water supply has always been considered. In this paper, self-purification and the pollution decay coefficient values of Talar River, IRAN were studied based on field measurement of DO, BOD, pH, EC, Nitrate, Phosphate, and Temperature, in four seasons of the year 2018, in tandem with the river simulation and its calibration using QUAL2Kw model and the Streeter-Phelps method. In addition to the modeling and analysis results, the measured laboratory data values of the river water samples are also presented. Based on the results, the DO variations were ranged from 5.15 in summer to 7.47 mg/l in spring and BOD variations ranged from 1.88 in fall to 7.9 mg/l in summer. Also, according to the Streeter-Phelps method the decay coefficient values varied from 1.57 (1/day) in spring to 9.63 (1/day) in fall. The values of the Talar River decay coefficient also varied from 2 in fall to 7.7 (1/day) in summer involving the QUAL2Kw model.
S. Ebrahimiyan, M. Nohtani, H. Sadeghi Mazidi, E. Soheili,
Volume 26, Issue 1 (Spring 2022)
Abstract
The basis of land management is the geomorphological zoning of the land surface, which is determined based on the same geomorphological characteristics of the zoning. Ground zoning detect land features by basic surface features such as height, slope, and slope direction. In this study, quantitative zoning of the land surface with small coefficients to the surface has been used to identify suitable areas for artificial feeding in the mountainous region of Gohar and Dasht-e Gorbayegan in Fars province. Quantitative zoning of the land surface has been performed by Evans-Shri coefficients due to the accurate determination and separation of types, faces, and surface features of the land has an important role in determining the exact land use. In this research basic models included linear, circular, and divergent models. These basic models with the dimensions of the final windows are ranked second in the MATLAB software to the level the ground is fitted to determine the fit of these models, the parameter of total squared difference has been used. In addition, the suitability of the study area for flood distribution in five different classes was determined using fuzzy logic. The most suitable areas for feeding downstream of the cones had five parameters with a maximum score of 20. The inappropriate class related to the lower plains of alluvial fans have a minimum score of five input classes in fuzzy logic, which is equal to zero.
B. Moravejalahkami, M.h. Rahimian,
Volume 26, Issue 1 (Spring 2022)
Abstract
The current research was performed to present a quick and proper method for basin irrigation infiltration equation estimation by optimization of the Manning roughness coefficient. A two-level optimization of the Manning roughness coefficient method was presented by developing a zimod simulation model and initial intake families method, USDA-NRCS, (infiltration equation based on soil characteristics), and modified intake families (infiltration equation based on soil characteristics and inflow discharge). The investigation of the results of the model based on observed advance, recession, and surface storage showed the relative error of surface storage volume estimation was decreased by 38 to 50 % by adjusting the initial intake families method. The normalized root mean square error (NRMSE) of the advance estimation was between 0.22 to 0.85 for initial intake families and this parameter was between 0.09 to 0.5 for modified intake families. NRMSE of the recession estimation was between 0.13 to 0.75 for initial intake families and this parameter was between 0.09 to 0.19 for modified intake families. The presented method based on modified intake families increases the accuracy of infiltration estimation as compared to the initial intake families method and can evaluate basin irrigation acceptably. In addition, this method needs less time for basin irrigation evaluation as compared to the complete methods of optimization of infiltration parameters and roughness coefficient.
A. Yousefi, M. Maleki-Zadeh, A.r. Nikooie, M.s. Ebrahimi,
Volume 26, Issue 4 (Winiter 2023)
Abstract
This study determines the amount of irrigation water saved as a result of the subsidy policy to adapt from flood to drip irrigation. We developed a positive mathematical programming model (PMP) to evaluate the effect of economic incentives on farmers’ decisions to choose the type of irrigation technology, cropping pattern, and "water use" and "water consumption" in rural Garkan Shomali district, which is part of the Najafabad aquifer. We collected data through farm surveys, desk research, and expert interviews. The results showed that a reduction in the financial costs of converting flood irrigation into drip irrigation can lead to farmers investing in this technology. In the current water allocation scenario, the subsidy policy increases the water consumption of drip-irrigated crops by 28%, of which 19% is non-consumed water before subsidy payment and the rest is related to the reduction of furrow-irrigated lands. Also, under non-volumetric water delivery conditions, the operating costs reduce and the net income of the farms increases because of the increase in efficiency and the development of the area under cultivation, which increases water consumption while the water use is constant. In the volumetric water delivery scenario, with the increase in subsidies, the net income of the farms will increase without developing the area under cultivation and only because of the increased yield. Therefore, subsidy policy increases irrigation efficiency at both the farm and regional levels and is an effective tool for dealing with drought conditions.
S. Bigdeli, K. Ebrahimi, A. Hoorfar, A.a. Davudirad,
Volume 26, Issue 4 (Winiter 2023)
Abstract
In this study, the accuracy of the Adaptive Network-Based Fuzzy Inference System (ANFIS) in integrating with the Gray Wolf Algorithm (ANFIS-GWO) in predicting groundwater level was evaluated for the first time using unpublished observational data from 1998 to 2018 in the Zarandieh aquifer, central Iran. Three observational wells were randomly selected for analysis. Assessment of evaluation criteria demonstrated that among the proposed scenarios using the hybrid model, the D scenario was selected as the optimal scenario with input data including the previous month's groundwater level, precipitation, temperature, and groundwater extraction. In the D scenario, parameters including MAPE, RMSE, and NASH were 0.29 m, 0.47 m, and 0.99, respectively for the first observational well. Also, C scenario with input data including the previous month's groundwater level, precipitation, and groundwater extraction for the second observational well, for the same parameters mentioned above equal to 0.20 m, 0.26 m, and 0.99. As well for the third observational well, the A scenario with input data including the previous month's groundwater level for the same parameters equal to 0.29 m, 0.41 m, and 0.99 as the optimal scenarios were selected using the ANFIS-GWO model. Based on the results, the Gray wolf algorithm in training the ANFIS model was able to reduce the average forecast error by equal to 0.03 (RMSE) and 0.02 (MAPE) meter and increased the average NASH value equal to 0.01 and increased the accuracy of predictions.
B. Ebrahimi, M. Pasandi, H. Nilforoushan,
Volume 27, Issue 4 (Winter 2023)
Abstract
The different land uses in the irrigation water area of the eleven streams of Khansar city during 1969, 1995, 2014, and 2019 have been identified and their area has been determined by analysis of the aerial photos as well as the satellite images of QuickBird, and Landsat in the Google Earth Engine (GEE) environment. Then, the net and gross areas of land under irrigation water, area of non-agricultural land uses, location and area of agricultural land uses under irrigation of the streams are separated according to the type of agricultural activity (orchard or farmland) for each stream. Aerial photos of the study area dated 1969 are the basis for the assessment of agricultural conditions before the law of Fair Water Allocation. The results showed that non-agricultural and particularly urban and residential land uses have increased since 1969. In other words, land use of part of the agricultural lands has been changed to residential and urban land uses. Despite the decreasing trend of agricultural land uses in the last 50 years, these changes have not been the same between the farm and orchard land uses and the area under orchard plantation showed an increasing trend. These changes have dramatically influenced on water demand of the streams. Land use has not significantly changed from 2014 to 2019 and no noticeable change was observed in the area of the agricultural and green agricultural lands as well as the percentage of the orchard and farming lands during these years. The results of this study confirmed the significant changes in agricultural land use and consequently water consumption in the district of the eleven streams of Khansar in recent decades. This study also highlighted the high efficiency of the combined use of aerial photos, spectral satellite images with medium spatial resolution, and visible spectral satellite data with high spectral resolution, as well as using cloud system capabilities of the Google Earth Engine to study changes in agricultural land uses during last decades.
M. Saeidi Nia, H. Mousavi, S. Rahimi Moghadam,
Volume 28, Issue 1 (Spring 2024)
Abstract
Due to the lack of water resources and excessive evaporation in the country, it is necessary to have a detailed irrigation program and a suitable management method. The present research was conducted to investigate the effect of superabsorbent and mulch in Khorramabad in July 2022 in a factorial combination with a completely randomized design in three replications. The first experimental factor was irrigation water treatment in 4 levels including irrigation that provided 100% water requirement (I100), 80% of crop water requirement (I80), 60% of crop water requirement (I60), and 40% of crop water requirement (I40). The second factor included different corrective materials including plant mulch (M), superabsorbent (S), and control treatment (I). The results showed the maximum amount of wet and dry yield and crop height was related to I100-M treatment, i.e. 100 percent water requirement and compost corrective material, which were 89.52 tons per hectare, 29.42 tons per hectare, and 2.27 meters. The maximum wet and biological productivity for I40-S was calculated as 14.24 kg of wet matter per cubic meter of water and 4.75 kg of dry matter per cubic meter of water. The lowest wet and dry yields were related to I40-M, which decreased the yield of the control treatment by 6.5 percent and 0.9 percent. The lowest productivity was related to the I100-S treatment, which was calculated as 3.13 kilograms per cubic meter of water for biological productivity and 9.14 kilograms per cubic meter of water for wet weight productivity. In general, mulch had a better performance in the treatments where the water stress was low, but when the water stress increased, the performance of the mulch treatments decreased. In the superabsorbent matter, the treatments with complete irrigation or with less stress, yield decreased, but the treatments with increased stress showed better results than most of the corrective materials and the control treatment.
