manijeh ghohroudi tali

The coastline is one of the most rapidly changing landforms of coastal areas. It changes constantly because of the rising sea level due to natural conditions and the influence of human activities. The position of coastline usually changes following the tides. Therefore, quick and accurate measurements of dynamic coastline changes are of great significance to coastal management, sea level change research, environmental protection, and sustainable coastal development. The main purpose of this study is monitoring Caspian Sea coastline changes under the influence of sea level fluctuations during the period 1977-2017. In this regard, the Landsat satellite imageries collection, Google Earth, topographic maps and fieldworks has been used in an analytical-descriptive manner. Then, making the necessary corrections on images, combining and merging the bands with each other, the best and most appropriate band composition was selected to extraction the coastline. Then, according to the rate of changes in the region's shores, 7 littoral cells were defined in the region. In the next step, the coastline position was extracted by tracking the location of the high watermark through visual and spectral separation methods and entered the database as digital layers. The coastline changes are monitored in two time periods, from 1977-1996 and 1996-2017. The results show that during the first period, erosion was the dominant process in the region. The lowest erosion rate was about 2.46 km2 in the LC2 and the highest was about 168.80 km2 in the LC5 and only about 0.0159 km2 sedimentation occurred in the LC1. But during the second period, the predominant process in the region was sedimentation. The minimum and maximum sedimentation rates were about 1.40 km2 in the LC2 and about 72.55 km2 in the LC5, respectively. During this period, only about 0.68 square kilometers of erosion occurred in the LC1.

It seems essential to understand temporal and spatial changes in water quality of rivers as one of the most dynamic ecosystems of the world. In this research, we have analyzed temporal and spatial changes in the parameters of water quality of Aras River in the period 1999-2011 at the gauge stations of Khodaafarin, Khazangah, and Jolfa, using statistical multi-variate, factor analysis, and Principal Component Analysis. The first component with the highest explanation of variance has greatest correlation with parameters of Mg2+, Ca2+, HCO-3, EC, and TDS. The component shows the ions and suspending particles at Khodaafarin station. Among the parameters of the first component, EC has the highest factor loading (0.98) as the main parameter of the component. At the Khazangah station, the first three components explain 53.6, 17.5, and 12.9 percent of variance, respectively. The first component has the highest correlation coefficient with the parameters of Mg2+, Ca2+, SO42-, Cl-, HCO-3, EC, and TDS. In Jolfa station, the first four components with the highest eigenvalues explain 50.7, 15.8, 13.2, and 5.8 percent of the variance.

River geomorphology is one of the determining factors and an important step in mathematical modeling of landform variations. Investigating the pattern of flow in warping intervals and geomorphic units of the Aras river, the formation processes and the process of their change are important for river geomorphology studies and make river engineers better acquainted with the trend of changes. The main objective of this research is to implement fractal dimension of geomorphological changes in the Aras River route. Using the method of controlled classification and maximum probability algorithm, the layer of geomorphologic landforms of the Aras River environment for two periods was prepared in four channels of Channelform Channel, Point Bar, Flood plain, Riverside, and Coniferous; Then, the fractal models of the environment - area and cumulative number - were used to describe the mathematical behavior of these landforms. Changes in the amount of DAP (environment-area) for the landforms in the Aras River environment in the two years of 1987 and 2018 showed that the DAP values of all landforms (other than point load) in 2018 were smaller than the DAP Landforms in 1987. Therefore, the geometric pattern of the Aral River landforms in 1987 is more irregular and more complicated than in 2018. In the case of Land Point, this figure increased in 2018 than in 1987, indicating a more regular pattern of this landform. Changes in the amount of D (cumulative area - area) for the landforms studied in the Aras River environment showed that its magnitude increased in 2018 compared to 1987, which can be D, or represents small components of a large size Or more components with small size. Regarding the survey of Landsat satellite images used in this study to extract river geomorphological landforms in the Aras River in 1987 and 2018, pixel behavior of landforms is typical of the large There is a tendency to study the landforms. Of course, in the case of the river channel, it should be noted that due to the decrease in the discharge and hence the reduction of the channel width, it can be commented on the reduction of its area.