Showing 19 results for Sar
F. Tajik, H. Rahimi, E. Pazira,
Volume 6, Issue 3 (10-2002)
Abstract
The general characteristics of salt-affected soils and soil structure degradation process are partially known, but the effects of saline and sodic conditions on mechanical properties of soils are not well recognized. In this study, the effects of electrical conductivity (EC) and sodium adsorption ratio (SAR) on tensile strength of soils with different organic carbon contents were assessed under laboratory conditions. The soil samples were collected from Dasht-E-Naz, at Sari region in the North of Iran. The samples had the same clay mineral (Illitic) and the main difference between them was the organic carbon content, subjected to different cropping systems. The tensile strength was determined on soil samples which had been treated by solutions having defined EC (0.5 and 4 dS/m) and SAR (0, 5, 15).
The tensile strength was positively related to organic carbon content, but negatively to SAR. With increasing SAR, tensile strength decreased, and at a given SAR, the treatments with higher EC showed higher tensile strength. The analysis of variance showed significant differences (at 0.01) between soil samples (four levels), soil sampling depth (two levels), EC (two levels), and SAR (three levels) for all variables under investigation. For soil factor, the order of averages were: Virgin soil > Permanent pasture (Festuca) > Intensive cropping > Permanent pasture (Agropyron).
A. Kheiri, A. Borhani, S. M. Okhovvat, H. Eshtiaghi,
Volume 7, Issue 3 (10-2003)
Abstract
In an etiological study on stunted, nursery grown maple seedlings, a species of root-lesion nematode (Pratylenchus vulnus) and two species of fusarium (Fusarium oxysporum and F. solani) were isolated from the infected roots. Interactions between the nematode and the two fungi in a complete randomized design with six treatments and four replications were carried out under greenhouse conditions. Nematodes were surface sterilized and reared on sterilized carrot discs. Then the maple seedlings at two-leaf stage were inoculated with a population density of 40 nematodes/100 gr soil in pots. The results indicated singnificant differences between the treatments. Seven months after inoculation, the treatments with nematode alone showed a high mortality rate of about 75% along with a severe increase in population up to about 11.2 and 1266 nematodes/gr of soil and roots, respectively. In treatments with nematode and each of the two-fungus species, the deleterious effects of fungi on nematodes were observed through decrease of nematode population. It was also shown that F. oxysporum was more effective than F. solani in nematode control.
B. Sharifnabi, G. Saeidi,
Volume 8, Issue 3 (10-2004)
Abstract
Safflower (Carthamus tinctorius L.) is one of the multi-purpose oilseed crops which has a high adaptation to different conditions such as resistance to drought and it is suited to be grown in arid and semi-arid regions such as Isfahan province. Root rot disease is an important soil-borne disease of safflower in Isfahan, which can be caused by different pathogens. The objective of this study was to determine the causal agent of safflower root rot and to evaluate different genotypes for tolerance to the disease. Different species of Fusarium were isolated from sample collections. Laboratory and greenhouse inoculations indicated that F. solani was the only pathogenic species. In this experiment, 60 genotypes of safflower including breeding lines selected from various Iranian local populations and foreign cultivars were evaluated for reaction to the disease in a randomized complete block design with three replications in greenhouse. Artificial inoculation via injection of spore suspension of F. solani (106 spores/ml) was conducted on 8-week plants and then development of necrosis and death percentage were recorded. The results showed that there were significant differences among the genotypes in terms of reaction to the disease. The most resistant and susceptible genotypes were breeding lines of IUTE14310 and IUTC121 with mean necrosis of 9.67 and 28.33 mm, and death percentage of 32 and 74, respectively. Based on the means of necrosis and death percentage, the genotypes were significantly classified in 5 distinct groups including resistant (7 genotypes), moderately resistant (19 genotypes), tolerant (29 genotypes), moderately susceptible (3 genotypes), and susceptible (2 genotypes). The commercial foreign cultivars of AC Sunset, AC Sterling belonged to tolerant and moderately susceptible groups, respectively. However, Saffire was classified as a tolerant genotype. The local landrace of Kooseh which is widely grown in Isfahan province was classified as susceptible genotype. Phenotypic and genetic coefficients of variation (23.85 and 18.32 %, respectively) and a relatively high broad-sense heritability (59%) for necrosis and also the phenotypic and genetic coefficients of variation (25 and 21 %, respectively) and a high broad-sense heritability (73%) for death plants indicated that there was sufficient genetic variation for resistance and selection can be effective for producing resistant genotypes to Fusarium root rot disease.
M. J. Soleimani,
Volume 9, Issue 2 (7-2005)
Abstract
Some of the field crops are severely affected by the Fusarium foot and root-rot in the west of Iran, Hamadan. Pathogenic Fusarium species are potentially severe destructive diseases and could be a major limiting factor for the cereals and potato production in this province. The purpose of this study was to determine the possible effect of soil solarization on the population dynamics of Fusarium spp. The propagules under Hamadan climatic conditions. Pre-tarping irrigation to achieve the field capacity was carried out prior to the various treatments including the black and transparent polyethylene plastic sheets. The experiment was performed in a completely randomized block design with three replicates, in a naturally infested soil. After three, five and eight weeks, soil samples were collected from different soil depths in appropriate plots. The propagule numbers of Fusaria were counted through dilution plate method using selective Nash & Synder and PDA media. The results indicated that the propagules of Fusarium in treated soils (five and eight weeks treatments) were significantly decreased as compared with the three week treated and untreated control plots. Better results obtained with the transparent sheets after eight weeks, followed by treatments with five weeks of mulching. Accordingly, the hydrothermal control of the Fusarium foot and the root-rot disease seem to be effective under the cool and temperate area of Hamadan.
A. Mazaheri, B. Hatami, J. Khajehali, S. E. Sadeghi,
Volume 11, Issue 41 (10-2007)
Abstract
Sarta longhorned beetle, Aeolesthes sarta, is one of the most destructive wood borer pests of fruit and shade trees in Iran. In this research, the reproductive parameters were studied under laboratory conditions. Fifteen pairs of newly developed adults (1-2 days after emergence from overwintering sites) were caged separately on 15 logs of Ulmus carpinifolia and fertility table was made using this data. The results showed that 3.9±0.2 days after emergence, females began to oviposit for 16.6±0.6 days, as oviposition period. Mean number of laid eggs was 122.6±17.5 per female. The mean longevity of male and female was 26±0.6 and 29.4±0.4 days, respectively. Females had no mortality during oviposition period, so gross reproductive rate (GRR) and net reproductive rate (R0) (famale/female/generation) were equal (61.6±8.7). Intrinsic rate of increase (rm), mean generation time (T) and doubling time of the population (t) were 0.0067±0.24-5 famale/female/day, 612.5±0.4 and 102.7±3.6 days, respectively. The finite rate of increase (λ) (female/female/day) was 1.006±0.24-5. Intrinsic rate of increase (rm) was very low (0.00672), because of longer lifetime of females (mean 602 days), low longevity during reproductive period (maximum 22 days) and long mean generation time (612.5 days).
A. Hosseinzadeh Colagar, A. Mostafaie, M. Motallebi, M.r. Zamani,
Volume 11, Issue 41 (10-2007)
Abstract
Plant pathogenic microorganisms produce a variety of enzymes capable of degrading different polysaccharides of the plant cell walls. Pathogens use these enzymes to penetrate and colonize host cells. Polygalacturonases are thought to be the first cell wall-degrading enzymes secreted by pathogens when they grow on plant cell walls. Oligogalacturonic acids with the polymerization degrees of 10 to 13 are intermediate products of pectin degradation by the action of polygalacturonases and are known to activate plant defense responses. PG- inhibiting proteins (PGIPs) present in the cell wall of many plants increase the stability of oligogalacturonic acids in the tissues by modulating fungal PG activities. These glycoproteins of the plant cell extracellular matrix retard the advancement of fungal hyphae, reduce tissue maceration, and prevent colonization of pathogen. In this study, Phaseolus vulgaris PGIPs were extracted from hypocotyle of Derakhshan and Naz bean cultivars. PvPGIPs were purified by afinity chromatography and analyzed by SDS-PAGE. Three major bands in the range of 47-55 kDa were detected. Average yield of The affinity-purified PGIPs was 1.68 mg per 100 gram of fresh bean hypocotyle. The inhibitory effect of PGIP was assayed on the PG activities of highly virulent isolates of Fusarium oxysporum (F15) and Ascochyta rabiei (IK04). The inhibitory activity of crude PGIP from Naz and Derakhshan cultivars on polygalacturonase activity of F. oxysporum was 18 and 28 units, respectively. These inhibitory activities increased to 40 units after purification. The inhibitory effect of crude PGIPs from both these two cultivars on PG activity of A. rabiei was 9 units, while purified PGIPs inhibited this PG activity to 18 and 29 units, respectively.
N. Sahebani , J. Zad , A. Sharifi-Tehrani , A. Kheiri ,
Volume 12, Issue 43 (4-2008)
Abstract
Polyphenol oxidase (PPO) activities were measured spectrophotometrically in tomato(Roma VF: resistant to Fusarium oxysporum f.sp. lycopersici and susceptible to Meloidogyne javanica) roots inoculated with nematode and fungi in four biological life stages of nematode. PPO specific activity showed a significant decrease in treatments (nematode + fungi) as compared with control plants. Results showed that nematode is able to change or suppress induction of this enzyme in spite of fungal induction. Nematode in all biological stages suppressed the induction of PPO activity in tomato roots but in young adult formation stage the suppression was higher than other life stages including giant cell formation, egg-laying and penetration. Native polyacrylamide gel revealed the presence of five isozymes of PPO with Rm values of 0.26, 0.31, 0.44, 0.50 and 0.63. Isoforms with Rm values of 0.26, 0.44, 0.50 and 0.53 showed significant changes in nematode + fungus inoculated tomato plants compared to plants inoculated with fungus alone. Based on the results obtained in this study, nematode infection resulted in suppression of tomato defenses against the fungi (as secondary pathogen) and intensified the fungal disease. Five PPO isoforms with Rm values of 0.26, 0.31, 0.44, 0.50 and 0.63 were shown in native polyacrylamide gel among which the isoform with Rm value of 0.31 had a thicker band in tomato plants inoculated with nematode or fungus alone. Two isoforms with Rm values of 0.44 and 0.53 in nematode-inoculated plants were similar to the corresponding bands in the healthy control. Isoforms with Rm values of 0.26, 0.44, 0.50 and 0.53 in nematode-fungus-inoculated tomato plants showed significant changes compared to plants inoculated with the fungus alone. Nematode infection of root tissue caused suppression of PPO specific activity and induced changes in PPO isoforms with Rm values of 0.26, 0.44, 0.50 and 0.63 more significantly than isoform 0.31.
N. Sahebani, N. Hadavi,
Volume 12, Issue 43 (4-2008)
Abstract
This research was conducted to study the effect of nematode (Meloidogyne javanica) on severity of tomato Fusarium wilt (Fusarium oxysporum f.sp. lycopersici race 1) and changes in Phenylalanine ammonia lyase (PAL) activity in split-root assays to show the possibility of systemic induced susceptibility caused by nematode to the fungus by local nematode infection. The results showed that the activity of nematode in one part of root confered susceptibility to Fusarium wilt in other part of the plant root and subsequently disease symptoms increased significantly in comparison to the control (without nematode inoculation). PAL specific activity showed a significant decrease in one half of split-root inoculated with fungus when the other half was inoculated with nematode as compared with the control (without nematode inoculation). Based on the results obtained in this study, nematode infection in one part of tomato plant root resulted in suppression of tomato defenses in all parts of the root, reduced tolerance or resistance to the fungus (as secondary pathogen) and intensified the fungal disease.
A.h Hosseinzadeh, I Bernousi, M Mardi, M Bihamta, S Omidi, B Yazdi Samadi,
Volume 13, Issue 47 (4-2009)
Abstract
Fusarium head blight (FHB) is one of the most destructive diseases of wheat causing significant reduction in grain yield and quality. Development of resistant varieties is an effective, economical and enviromentally safe way to control FHB disease. A major QTL (quantitative trait locus) for Fusarium head blight resistance, Qfhs.ndsu-3BS, derived from cv. Sumai 3, has been identified and verified by several research groups via molecular marker analysis. The resistant cv. Sumai 3 was crossed to susceptible cv. Falat, then three backcrosses were followed by one self-fertilization. Three simple sequence repeat (SSR) markers, Xgwm 389, Xgwm493, Xgwm533, were used for marker assisted selection (MAS) in BC1 and BC2 generations.The probability of linkage between markers and Qfhs.ndsu-3BS was calculated using a binomial probability function based on the assumption that a molecular marker at a specific distance from Qfhs.ndsu-3BS in the population would carry the donor-parent allel as a function of the distance between marker and QTL and the number of backcrosses/selfs used in deriving the population. Microsatelite locus Xgwm 493 was significantly associated with Qfhs.ndsu-3BS.
Zh Osamny, A Siosemardeh,
Volume 13, Issue 47 (4-2009)
Abstract
Studying genetic diversity is important because a decrease in genetic variability might result in a reduction of the plasticity of the crops to respond to changes in climate, pathogen populations, or agricultural practices. In this study, 72 Sardari wheat (Triticum aestivum L.) ecotypes were analyzed by AFLP markers and 17 phenotypic characters. Three pairs of EcoRI/MseI primer combinations produced 1582 polymorphic bands (with mean percentage of polymorphic 73.92%). Cluster analysis using Jaccard coefficient and the entire AFLP data divided all ecotypes into eight major groups. Mean, coefficient of variation, phenotypic, genotypic and environment variance were calculated in each quantitative character. Cluster analysis using Euclidian distance through the quantitative characters divided all ecotypes into six major groups. Comparison of genetic distances obtained from AFLP and agronomic data showed low correlation between the two diversity measurements (0.02). The results showed a high degree of genetic diversity between the Sardari ecotypes, suggesting that Sardari is not a single cultivar, but it is the mass of ecotypes and could be introduced in the gene bank.
H. Kedri Gharibvand, G. A. Dianati Tilaki, P. Tahmasebi, M. Mesdaghi, M. Sardari,
Volume 17, Issue 64 (9-2013)
Abstract
The aim of this research was to determine the effects of Camphorosma monspeliaca species on soil variables in its habitat. Ecological positive or negative effects of new species on environment must carefully be examined before allowing their plantation in vast areas on the other hand these species with their special characteristics have special effects on their surrounding environment that should be considered. Camphorosma monspeliaca is one of the non-native and adapted species in Chaharmahal va Bakhtiari Province that its unique habitat has 3500 ha area. Effect of this species on new environment requires more studies on their several different aspects. Here we studied effect of this species on soil in order to assess ecological effects of this species on environment. This species distributed in all of the landscape but most distribution of species located at southern and northern aspects and land with flat topography.This species can establish in non saline soil, loam and clay loam texture with different value of organic matter, lime and gypsum. The research was carried out at four stages of information and background collection, field sampling, soil test and statistics analysis. The research method was based on comparison among adjacent stand and stands of this species. Soil variables in two surface (0-10 cm) and depth (10-30 cm) were measured. Result showed that there was significant difference among adjacent stand and stands of this species in terms of SAR, OM and Sand in stands of this species were greater than the adjacent stands. This species increased content of organic matter and amounts of SAR, OM and Sand. From the results obtained on three topography position, despite of negative effect of Camphorosma monspeliaca on under soil with increase of SAR, it can be concluded that Camphorosma monspeliaca had a positive effect on soil organic matter and soil texture
N. Shafiee, H. Shirani,
Volume 17, Issue 66 (2-2014)
Abstract
Copper is considered as one of the most important nutrient elements for plants. If its contents are concentrated higher than the standard value it can be considered as a pollutant element. The content of absorbable copper in the area around Sarcheshmeh copper mine can be significantly high. In this study, samples of soil were collected in summer through a particular sampling method with chimneys of Sarcheshmeh plant as the center of sampling area within a radius of 6km, in three different directions (Rafsanjan, Sarcheshmeh City and Sarcheshmeh mine) and. The total concentration of absorbable copper and some chemical properties of soil (i.e. pH and EC) were measured for 122 surface samples (depth of 0 to 35 cm). There was a significant negative regression between pH and total absorbable copper content, and a significant negative regression was observed between EC and total absorbable copper content. The best fitted model was spherical model, and Ordinary Kriging was applied to map the absorbable copper content. Results showed that most concentration of copper occurred in the Rafsanjan direction. Also, regarding wind orientation which blows towards Rafsanjan, the chimneys probably have a significant effect on increasing copper content in Rafsanjan moreover, the copper content is substantially higher around chimneys than other areas. Also, transition of copper elements from chimneys by wind can be significant up to 4 km from Sarcheshmeh plant.
M. Sarmast, M. H. Farpoor, M. Sarcheshmehpoor, M. Karimian Eghbal,
Volume 18, Issue 68 (9-2014)
Abstract
Biocalcite infilling and bridging in a sandy soil was studied in the present research. Effects of 2 bacterial species (Sporosarcina pasteurii and Sporosarcina ureae), 3 reactant concentrations (0.5, 1.0, and 1.5 M of urea and CaCl2 mixture), and 6 reaction times (12, 24, 48, 96, 192, and 288 hr) on saturated hydraulic conductivity and mechanical strength of a sandy soil were studied as a factorial experiment. Soil samples were selected from sand dunes of Joopar area, Kerman Province. Bacterial inoculums and reactant solutions were daily added to soil columns. Results of the study showed that S. pasteuriihad had a higher effect on decreasing hydraulic conductivity of the treated samples (11.57 cm/h) compared to the blank (41.61 cm/h) than S. ureae. Increasing reaction times (from 12 to 288 hrs) and reactant concentrations (from 0.5 to 1.5 M) decreased hydraulic conductivity by 49 and 16 %, respectively. S. pasteurii increased strength of treated samples up to 2.6 Mpa pressure compared to S. ureae. Reactant concentrations and reaction times increased soil strength significantly (2.13 and 4.1 Mpa, respectively). Micromorphological observation showed calcite crystals bridging soil particles and filling pore spaces.
H. Nazaripour, Z. Karimi, M. Sedaghat,
Volume 20, Issue 75 (5-2016)
Abstract
Drought is a climatic anomaly that associates with a significant decrease (lack) of precipitation and water resources availability, which spreads on vast temporal and spatial scales, and significantly affects various aspects of life and environment. One of the most common methods of drought assessing and monitoring is calculating drought indices (DIs). Drought areal and temporal extent and its severity are determined by these indices. In this study, an aggregate drought index (Hydro-Meteorological) has been developed for the assessment of hydrological and meteorological droughts in Sarbaz river basin located in southeastern of Iran. The Aggregate Drought Index (ADI) comprehensively considers all physical forms of drought (meteorological, hydrological, and agricultural) through selection of variables that are related to each drought type. In this case, monthly values of Stream flow Drought Index (SDI) and Standardized Precipitation Index (SPI) indicators were used for four similar reference periods with principle component analysis and aggregate hydro-meteorological index was defined based on its first component. The study time span was set between 1981-82 to 2010-11, which begins of October in Iran. Results based on the aggregate drought index (ADI) revealed that a long period of hydro-meteorological drought occurred from 1999-2000 to 2005/06 in southeast of Iran, in which, 2003/04 water year has been extremely a drought year. The ADI methodology provides a clear, objective approach for describing the intensity of drought. This index is appropriately able to represent the behavior of Hydro-Meteorological droughts and recommended as an integrated index for assessing and monitoring of regional droughts. Finally, different states of hydro-meteorological drought have been extracted based on conventional regional thresholds, and have been modeled by Markov chain. This made the estimation of drought state transition frequency possible, and made the prediction of next drought state time more real. State transition frequency matrices, are the main instruments for predicting drought states in real time. Results of validation tests and conforming the predicted results with real data indicate that predicting hydrological drought state transitions in the study area using Markov chain method is valid.
K. Shirani,
Volume 22, Issue 3 (11-2018)
Abstract
The persistent scattering interferometry (PSI) technique is a valuable tool in displacements' monitoring of earth's surface. The persistent scattering interferometry (PSI) based on persistent scatterrer (PSInSAR) is one of the techniques used to reduce constraints (temporal and spatial incoherency). It is based on persistent scatterer and monitor displacement of only the pixels with timely-constant properties of scatterer. In order to detect and monitor landslides, two time series SAR data sets including PALSAR ascending images from 2007 to 2010 and ASAR images from 2003 to 2010 with C-band and L-band wavelength were applied, respectively. Also, the PSI technique was implemented in a landslide near Noghol village, Padena, Semirom of Isfahan province. The results revealed that both PALSAR and ASAR data set were efficient in identifying Noghol landslide. The results obtained from ASAR and PALSAR images processing (with the values of 1253 mm and 1578 mm in two stages of time 4 and 7 years, respctively) were compared. The obtained vertical displacement's rate of the landslide by using ASAR data was more suitable because of its descending orbit. However, PALSAR images that indetified more persistent scatterrer points were better in the detection of the landslide area. The results of GPS and PSInSAR techniques revealed that landslide displacement values and aspect were the same, confirming 135 centimeters of displacement to the west aspect. Finally, a combination of radar data in two different passes provided the possibility of monitoring the mechanism of landslide and its movement direction.
H. Ghorbani, A. Vali, H. Zarepour,
Volume 23, Issue 4 (2-2020)
Abstract
Drought as a natural hazard is a gradual phenomenon, slowly affecting an area; it may last for many years and can have devastating effects on the natural environment and in human lives. Although drought forecasting plays an important role in the planning and management of water resource systems, the random nature of contributing factors contributing to the occurrence of and severity of droughts causes some difficulties in determination of the time when a drought begins or ends. The present research was planned to evaluate the capability of linear stochastic models, known as multiplicative Seasonal Autoregressive Integrated Moving Average (SARIMA) model, in the quantitative forecasting of drought in Isfahan province based on the Standardized Precipitation Index (SPI). To this end, the best SARIMA models were chosen for modelling the monthly rainfall data from 1990 to 2017 for every 10 synoptic stations in Isfahan province to forecast their monthly rainfall up to five years. The monthly time scale SPI values based on these predictions were used to assess the drought severity of different stations for the 2018- 2022 time period. The station results indicated a weak drought at the 2019- 2022 period for Isfahan, Kashan and Naeen, a severe drought in 2019 for Ardestan and Golpaygan, and a weak one in 2019 for the East of Isfahan, KabootarAbad and Shahreza stations. All other stations, except Golpayegan, Isfahan, Kashan and Naeen, faced a severe drought in 2018.
K. Shirani, M. Pasandi, B. Ebrahimi,
Volume 25, Issue 1 (5-2021)
Abstract
Land subsidence as a hydrogeomorphology event is currently occurring dangerously in many plains of the country due to uncontrolled groundwater extraction from water bearing layers, and accordingly monitoring and studying this phenomenon seems to be necessary. In this study, land subsidence rate of the Najafabad aquifer was determined through the Differential Radar Interferometry (DInSAR) processing of the ASAR and PALSAR radar data and the results were validated by comparying with the differential leveling and groundwater level drowdown data. Processing of the ASAR sensor data estimates the land subsidence in the Najafabad plain at an average annual subsidence rate of 6.7 cm and a total of 41 cm during 6 years period and processing of the PALSAR data suggests an annual rate of 7.7 cm and total subsidence of 30 cm during 4 years period. Most of the occured displacements are related to the Tiranchi, Koushk, Ghahderijan, Goldasht and Falavarjan cities. The simultaneous groundwater level data with acquisition date of the radar satellite images between 2002 and 2014 shows a drawdown ranging from 0.5 to 46.5 meters in the south and east to north of the Najafabad city consistent with the estimated land subsidence areas.The DInSAR processing of the PALSAR data has led to a more accurate results with higher spatial resolution. Results of the radar data processing can be employed for the hazard zonation directly utilized for management and planning of control and preventive measures.
S. Asghari Saraskanrood, R. Modirzadeh,
Volume 25, Issue 3 (12-2021)
Abstract
Snow cover is one of the important climatic elements based on which climate change may have a special effect. In general, climate change may be reflected in different climatic elements. Therefore, it is very important to study and measure changes in snow level as one of the important sources of water supply. Ardebil and Sarein cities are located at 48° 18׳ east longitude and 38° 15׳ north latitude. In this study, Sentinel-2 optical satellite was used to monitor the snow cover surface in 2018, and NDVI, S3, NWDI, NDSI, Cloud mask indices were applied to detect snow-covered surfaces using ArcGIS and Snap software. Next, to validate the snow maps extracted from the images, it was compared with the snow data in terrestrial stations using linear regression in MATLAB software and to evaluate the accuracy of the model statistical indices including RMSE, MSE, BIAS, CORR were used. The present study showed that according to Ardabil city climatic conditions, maximum-snow covered area in January with an area of 356.52 km2 and minimum snow-covered area in March with an area of 96.10 km2. The highest snow cover is observed in the high slope areas in the western slopes (Sabalan Mountain Heights) and the lowest snow cover is observed in the lower eastern slopes. The results of linear regression with generalization coefficient are 85% and the results of statistical indices of error are equal to MSE: 0.086, BASAS: 0.165, CORR: 0.924, and RMSE: 0.03. Correlation relationships between terrestrial data and estimated snow maps showed a high degree of correlation. This result is statistically significant at the 99% level. The use of optical images in estimating snow levels is very cost-effective due to the size of the areas and the high cost of installing snowmobiles. The results obtained in the present study indicated that traditional radar images with high spatial resolution and good correlation with terrestrial data can be a good alternative to snowmobiling ground stations at high altitudes or in passable areas.
B. Ebrahimi, M. Pasandi, H. Nilforoushan,
Volume 27, Issue 4 (12-2023)
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.
