Majid Kazemzadeh; Zahra Nouri; Majid Rahmani; Asghar Bayat; Salma Saedi Farkoush
Volume 32, Issue 2 , July 2025, , Pages 124-139
Abstract
Background and objective: In recent years, extensive watershed management measures including biological, mechanical and biomechanical measures have been carried out with the aim of flood, erosion and sediment control and water storage in the different sections of research, study and implementation ...
Read More
Background and objective: In recent years, extensive watershed management measures including biological, mechanical and biomechanical measures have been carried out with the aim of flood, erosion and sediment control and water storage in the different sections of research, study and implementation in the country. Evaluation of watershed management plans in order to analyze the performance of implemented watershed management measures and develop basic solutions is one of the basic needs in watershed management. Therefore, the aim of this research is to quantitatively and qualitatively evaluate the effects of biological and biomechanical measures of watershed management on the vegetation cover changes in Azimieh watershed, Karaj, Alborz province.Materials and methodsIn this study, vegetation changes were determined using Landsat series 5, 7 and 8, satellite images, and NDVI index in a period of 20 years (2000-2019). Then, by using the polytrend model, the trend of linear and non-linear changes and the effect of water management measures implemented in the watershed on the vegetation cover in the Azimieh Karaj watershed, Alborz province, were investigated. Also, in order to evaluate the accuracy of the results and satellite images, field measurements were also used. Also, in order to investigate the effect of climatic factors on vegetation changes, drought index and rainfall data of Karaj station were used.ResultsResults of trend showed that 41.9% of changes were significant over 20 years. 88.3% of the significant changes in vegetation were increasing. The results of Polytrend method showed that the changes in vegetation were cubic, linear and quadratic with values of 63.4%, 27.8% and 8.8%, respectively. Evaluation of the effects of implemented measures to improving the vegetation status of the watershed showed that the percentage of canopy in the watershed was on average 28% before implementing the watershed management measures, which has increased to 34% after the implementation of watershed management measures. Of the total area of biological operations in Azimiyeh watershed (2724 hectares), in 70% of the area, changes in the vegetation status of the rangeland have been nonlinear and these changes were in projects such as seeding and tree planting and terrace. Also, the vegetation in a parts of the downstream areas of Azimiyeh watershed have been destroyed by non-linear trends due to the growth and development of residential areas and civil works such as the construction of Hemmat Highway.ConclusionThe performance evaluation of watershed management projects in Azimieh Karaj watershed showed that watershed management measures have caused a significant increase in vegetation in the region. On the other hand, development and urbanization in the downstream areas of the watershed has caused the loss and destruction of vegetation over the past years. The evaluation of watershed management plans can show the positive and negative results of the measures implemented over the years, and in this way, steps can be taken to solve their obstacles and problems.
Azad Kakehmami; Ardavan Ghorbani; Mehdi Moameri; Sahar Ghafari
Volume 28, Issue 3 , October 2021, , Pages 537-550
Abstract
By evaluating land use change and land cover, it is possible to plan and land manage to reduce the impact of alteration and degradation of exploitations. The purpose of this study was to evaluate land use changes in Ardabil province between 1987 and 2015 using Thematic Mapper (TM) sensor of Landsat 5 ...
Read More
By evaluating land use change and land cover, it is possible to plan and land manage to reduce the impact of alteration and degradation of exploitations. The purpose of this study was to evaluate land use changes in Ardabil province between 1987 and 2015 using Thematic Mapper (TM) sensor of Landsat 5 and Operational Land Imager (OLI) sensor of Landsat 8 satellite images. Firstly, the efficiency of the object-based classification method was evaluated using ground control points, error matrix, and comparing total accuracy and kappa coefficients for the resulting maps. Total accuracy and Kappa coefficients for 1987 were 82.3% and 0.70, and 2015 were 94% and 0.90, respectively. Change detection results showed that from 1987 to 2015, rangelands decreased by 4.2%, equivalent to 75039.3 hectares and forests decreased by 0.5%, equivalent to 9393.7 hectares compared to the total province area and irrigation farming increased by 3.1%, equivalent to 55276.8 hectares, residential areas increased by 0.8%, equivalent to 14989.7 hectares and dry farming increased by 0.7%, equivalent to 12632.4 hectares compared to the total province area. The most significant changes that occurred from 1987 to 2015 were the conversion of rangelands to dry farming with 13.8%, equivalent to 141794.2 hectares and irrigation farming lands with 4.8%, equivalent to 49836.9 hectares of rangelands, irrigation farming to dry farming with 7.7%, equivalent to 11464.8 hectares and forests to rangelands with 6.1%, equivalent to 1059.9 hectares which indicate that the requirement of a serious revision of the management policies.
Vahid Veisi; Mansoureh Ghavam; Omolbanin bazrafshan
Volume 26, Issue 3 , September 2019, , Pages 704-716
Abstract
Rangeland vegetation is one of the most important components of arid ecosystems and it is necessary to determine changes in rangeland vegetation under drought and wet years. The present study aimed to investigate the relationship between satellite indices and SPI index in Qom ...
Read More
Rangeland vegetation is one of the most important components of arid ecosystems and it is necessary to determine changes in rangeland vegetation under drought and wet years. The present study aimed to investigate the relationship between satellite indices and SPI index in Qom rangelands. For this purpose, the SPI index was calculated in moving averages of 1, 3, 5 and 7 years. In the next step, using Landsat images and after making the necessary adjustments to the images, the vegetation map was prepared using NDVI, MSAVI and EVI indices. Finally, correlation coefficients were used to investigate the relationship between satellite image indices and SPI index. The results showed a moderate and good correlation between MSAVI satellite indices and SPI index at peak vegetation growth months with a one month moving average of SPI index. The results of this study show that to estimate agricultural drought through remote sensing, the MSAVI index is a very suitable method and can be used for estimating drought in areas where meteorological stations are scattered (or nonexistent). Because the number of sampling points in satellite images is far greater than the number of meteorological stations.
Maryam Mombani; Mohammad Nasrollahi; kamran karimi; Hayedeh Ara
Volume 25, Issue 2 , August 2018, , Pages 248-262
Abstract
Remote sensing is the main technology to assess the expansion and rate of land cover changes. Knowledge of these changes in different parts has particular importance as the base information for different planning. The aim of the present study was the comparison of the maximum ...
Read More
Remote sensing is the main technology to assess the expansion and rate of land cover changes. Knowledge of these changes in different parts has particular importance as the base information for different planning. The aim of the present study was the comparison of the maximum likelihood and fuzzy Artmap methods to prepare land use map using Landsat satellite images. In this study, changes in land cover were evaluated over the past 24 years in Omidiyeh. Sensor images of TM Landsat 4, ETM+ Landsat 7 and OLI Landsat 8 for the years 1990, 2000 and 2014, respectively, and topographic and land cover maps of the area also were used. Images of all three periods were classified into four land uses including rangelands, agriculture, saline lands, and residential areas. The overall accuracy of the classification results showed that the fuzzy classification method with a kappa coefficient of 93% had more accuracy in comparison with the maximum likelihood algorithm with a kappa coefficient of 81%. According to the obtained results, the most dynamic land use in the region was the agricultural area, whose extent increased from 1990 to 2014, and 32703.32 hectares (32.2%) was added to this land use. An increasing trend was also obtained for the residential land use with an area about 1325.1 hectares (0.94%). On the other hand, rangelands (13.4% of the study area) showed the highest reduction in area (18857.63 hectares).
Mehdi Tazeh; Maryam Asadi; Rouhollah Taghizadeh Mehrjerdi; Saeedeh Kalantari; Majid Sadeghinia
Volume 25, Issue 1 , April 2018, , Pages 29-43
Abstract
Geomorphological map is one of the main information layers in natural resources studies. So far, various methods have been proposed for the classification and separation of various units and Geomorphological types, most of which are based on qualitative and descriptive information. In this study, the ...
Read More
Geomorphological map is one of the main information layers in natural resources studies. So far, various methods have been proposed for the classification and separation of various units and Geomorphological types, most of which are based on qualitative and descriptive information. In this study, the ability of geomorphometry parameters in separation of mountains from pediment and also separation of different types of pediments was investigated. First, ground truth map was prepared using visual interpretation of satellite data and topographic maps. Then the 1000-point sampling grid was designed randomly. Parameters including profile curvature, plan curvature, tangential curvature, cross-sectional curvature, longitudinal curvature, and general curvature were prepared from digital elevation model in the GIS software. Then, their values were extracted at all points of the sampling network. Then, artificial neural network with structure of 13_6_ 4 was used to separate the units. The results showed that the erosion pediment could be separated from epandage using artificial neural network; however, the separation of epandage pediment from covered pediment was not well. For this purpose, to improve network performance, the digital value of Landsat 7 data was added to the previous values. The resolution accuracy of mountain, erosion pediment, epandage pediment, and covered pediment was calculated to be 90, 79, 80, and 76%, respectively.
Fatemeh Hadian; Seyed Zeinolabedin Hoseini; Mansoureh Seyed Hoseini
Volume 21, Issue 4 , March 2015, , Pages 756-768
Abstract
Precipitation is one of the factors affecting vegetation. Nowadays, satellite images are broadly used for monitoring the effects of precipitation variations on the vegetation changes. The aim of this study was to investigate the relationship between vegetation dynamic and precipitation variations using ...
Read More
Precipitation is one of the factors affecting vegetation. Nowadays, satellite images are broadly used for monitoring the effects of precipitation variations on the vegetation changes. The aim of this study was to investigate the relationship between vegetation dynamic and precipitation variations using NOAA AVHRR images during the period of 1982-2006. Precipitation maps were created using the inverse distance weighting interpolation (IDW) method and time intervals of precipitation data. The study area was a forestland beside Caspian Sea, four rangeland vegetation types with grasses and shrubs, farmland areas and urban areas, located in Ardabil and Guilan provinces. To monitor the relationship between the precipitation and vegetation changes, the linear regression (NDVI, Y & Rainfall, X) method was employed. Based on the results, depending on the precipitation time, plant species, and growth form, the effect of precipitation on vegetation was different so that no significant relationship was observed between vegetation and precipitation in forestlands, farmlands, and urban areas. The highest correlation coefficient between spring precipitation and vegetation was related to the rangelands. In grassland areas, the correlation coefficient was higher than that of shrublands, whereas the reaction of grasslands to precipitation in various parts was different.
Kazem Dashtakian; Mojtaba Pak parvar; Mohammad hadi Rad
Volume 18, Issue 2 , September 2011, , Pages 292-306
Abstract
Due to the land use changes like increased acreage for agriculture, digging deep and semi-deep wells has increased rapidly in recent decades in Marvast area as these wells are the main source of water supply at the present time unlike the past which rivers and aqueducts had this role. The main purpose ...
Read More
Due to the land use changes like increased acreage for agriculture, digging deep and semi-deep wells has increased rapidly in recent decades in Marvast area as these wells are the main source of water supply at the present time unlike the past which rivers and aqueducts had this role. The main purpose of this study was to monitor land use changes on soil salinity using satellite images and GIS. Our other purpose was to investigate soil salinity changes in each land unit. With using satellite information from 1984 and 2002 years and proposed method for mapping soil salinity, land use and soil salinity maps were produced and then land use and soil salinity changes were studied. The study area had a total land area of 88980 hectares in Marvast, Yazd province. Results showed that land area of playas, deserts and rangelands respectively decreased to 7.8, 2.9 and 1.5 percent versus increase of agriculture and urban land area to 77.8 and 153 percent respectively. Also during this period, sever increase, increase and decrease of soil salinity was respectively recorded for playa, agricultural and rangelands, and deserts while no changes was detected for other regions. According to results, under ground water resources and saline waters of playas have undergone serious changes as with increase in average soil surface salinity, the ecosystem has shown negative changes.