Geomorphology
mehdi feyzolahpour
Abstract
Glacier cirques show the characteristics of past glaciers and climates. In this research, the analysis of 39 glacial cirques in the catchment area of Jajrud River was done. For this purpose, Arc GIS software and Google Earth images were used. The parameters of length, width, height of the top of the ...
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Glacier cirques show the characteristics of past glaciers and climates. In this research, the analysis of 39 glacial cirques in the catchment area of Jajrud River was done. For this purpose, Arc GIS software and Google Earth images were used. The parameters of length, width, height of the top of the circus, height of the floor of the cirques , area, perimeter, ratio of length to width, ratio of length to height of floor and ratio of width to height of floor were used to check the morphometry of cirques. For each of the morphometric parameters, statistical factors of coefficient of variation, standard deviation, average, maximum and minimum were calculated and estimated in Excel. Then R2 values or coefficient of determination were estimated for each of the parameters and a scatter diagram was drawn. Finally, the correlation matrix was estimated using the Pearson correlation coefficient for all factors. The highest abundance of cirques is located in the southwest direction. The maximum height of the cirques is 3800 meters and belongs to the geographical direction of the south.The highest correlations between length and width parameters were observed at the rate of 0.9936. The results show that the cirques in the north-facing slopes have a lower height. This indicates the high nutrition of these cirques and their significant volume in the Pleistocene period. Investigations showed that more developed cirques have more area, less height and less length to width ratio than less developed cirques .
Meysam Yari; Somayeh Soltani-Gerdefaramarzi; Mohsen Ghasemi; Rouhollah Taghizadeh
Volume 6, Issue 21 , March 2020, , Pages 203-225
Abstract
1-Introduction Given the growing population and the increasing need for food, water and soil conservation are of great value. In the context of conservation of soil and water resources, information on the amount of runoff production and erosion to achieve sustainable development is the basis for planning ...
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1-Introduction Given the growing population and the increasing need for food, water and soil conservation are of great value. In the context of conservation of soil and water resources, information on the amount of runoff production and erosion to achieve sustainable development is the basis for planning and decision making. Therefore, careful investigation of surface runoff and floods is an important and key step in planning and managing optimal water resources. One of the factors affecting the characteristics of surface runoff is land-use changes at different basin levels (Melesse and Shih, 2002). Land use is influenced by two components of human needs and environmental processes. Inaccurate land-use changes will disrupt the water cycle from natural equilibrium, resulting in devastating floods, including economic damage, loss of life, loss of water, and consequently reduced water resources (Jakeman et al., 2005). During the last two decades, the Qhareh-su watershed, particularly its downstream, has been experiencing rapid growth in the construction and expansion of residential structures. Human activities and changes in the basin have affected the natural arrangement of stream processes that transmit water and sediment from upstream to downstream. Human interventions are one of the major hazardous issues in this basin that causes changes in the pattern of surface currents and natural conditions of the catchments and encroachment on rivers and streams. In this regard, the present study aimed to investigate the role of land-use change on runoff in a part of Qhareh-su watershed in Ardebil province over a period of almost 20 years due to the availability of information and access to satellite images of different time periods. 2-Methodology The study area consists of a part of Qhareh-su watershed located in Ardabil province with an area of 2162.6283 km2. The minimum and maximum elevation of the mentioned watershed are 1280 and 3829 m respectively, and its average slope is 11.57%. Land use in this area often includes dry and irrigated agriculture, pasture, forest, and residential areas. The aim of the current research is to study the effect of different land uses and its changes during the years 1992-2012 on the surface runoff in a part of Qhareh-su, Ardabil watershed. At first, the maps of land use and curve number in the mentioned years were gathered and the area of each of the units was extracted. In the following, the process of land-use changes in the cases of the study period and its effect on changing the specific retention (S) and curve number were calculated and the height of runoff was estimated using the SCS method. 3-Results The results showed that during the case of the study period, area of forest, water farming, and wasteland land uses were decreased by 2.54%, 16.69%, and 1.19% respectively and the area of the rangeland, dry farming, and urban land uses were increased by 5.74%, 12.39%, 2.29% respectively. These changes have caused the increase of curve number from 78.57 to 79.77 in the years 1992 and 2012, respectively and following the decrease of the specific retention (S) from 69.28 mm in the year 1992 to 64.42 mm in the year 2012. Also, runoff height has increased from 263.4 mm in the year 1992 to 297.07 mm in the year 2012 (11.33%). Calculation of correlation coefficient between different land uses and curve number and runoff height showed that these variables have a direct relationship with rangeland, dry farming, and urban land uses while they have an inverse relationship with the forest, water farming, and wasteland. 4-Discussion and conclusion In the present study, the results of the study showed that land-use change due to its effect on the curve number of the studied basin causes a change in the surface runoff. During this 20-year period, land use has changed and this land-use change has tended to decrease from 1992 to 2012 land use including residential, pasture and dryland areas increased by 2.29%, 12.39% and 5.74% respectively, as well as forest, water and wastewater land use decreased by 2.54%, 16.69% and 1.19%, respectively. As a result, its curve number has increased, followed by a runoff height of 11.33%. This shows that in a natural ecosystem, land use and environmental changes, especially vegetation and land use affect the hydrological responses such as flooding and erosion and sedimentation rate in the area. Ultimately, it will cause severe economic and social damages. Changes in the total volume of runoff and changes in hydrological balance are the most important effects of land-use change on watershed hydrology.
Shirin Mohammad Khan; Fatemeh Moradi Pour; Anvar Moradi
Volume 5, Issue 17 , March 2019, , Pages 185-203
Abstract
Introduction
Lake Urmia in the northwest of Iran has faced a steady decline over recent decades. This has led to an increase in the level of dry lands and, consequently, has caused many environmental and social problems.There are many ecological effects on the biodiversity and growth of Artemia, the ...
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Introduction
Lake Urmia in the northwest of Iran has faced a steady decline over recent decades. This has led to an increase in the level of dry lands and, consequently, has caused many environmental and social problems.There are many ecological effects on the biodiversity and growth of Artemia, the Zooplankton, a native of Lake Urmia and major source of food for large birds. Consequently, the monitoring of coastal areas and the extract of changes in these areas in different time intervals have great importance because the nature of the coastline is dynamic. For this purpose, the remote sensing technology has a unique application in the acquisition of information about these phenomena because multi-spectral satellite images have advantages including their availability and digital interpretation.The purpose of this research was to investigate the development of the North West salt land in Lake Urmia using field data, satellite imagery, and geomorphic faces of the region.
Methodology
This research was an applied type and the data was collected through library, laboratory, and field studies. The statistical population was the water Retreat Zone of Lake Urmia Which suffered from wind erosion. This research was carried out using satellite imagery and multiple observations. Also, test sediments were obtained from this area using standard methods. Using remote sensing technology, when combined with land surveys and ground-based results, can provide better and more reliable results. For this purpose, in the present research, along with the use of remote sensing methods, field studies were also used. To carry out this research, samples of lake sediment were taken in different transects from a specific area in the northwest of the lake. The saturated extract of each sample was measured by EC meter. In the next step, using satellite imagery and field survey, the salinity, the expansion of salty and geomorphic faces were extracted. Finally, the results of the field and laboratory data, satellite imagery and geomorphic faces were compared and validated.
Results
The results showed that the surface area of the lake water was very low and spread to vast amounts of salt. Accordingly, the area of the salt land has significantly increased since 2000, especially over the past decade. According to the results of the field studies, areas with higher salt density matched the salt lines obtained from satellite imagery and geomorphic faces. The study area had 12 faces. The harvest area with a total area of 2,641 ha in the central part of the range and sandy areas with a total area of 14 ha in the northwestern part of the area had respectively the highest and lowest extent of outcrops in the studied area. Consequently, there was a close correlation between the field data and satellite imagery and salt land areas in satellite imagery and results of field studies. Due to the increase of the salinity levels in the area around the lake, local winds, and time lapse, the Agrarian lands of Azerbaijan general zone moved towards salinization and desertification. If this trend continues at the same speed, undoubtedly, in the long run, we have to wait for the enormous environmental crisis in the region.
Discussion and conclusion
The strongest indicator to extract the salt is the SI2 indicator with an accuracy of 97% and the weakest indicator is NDSI indicator with a precision of 52%. The EC value in 22 soil samples ranging from 0.9 to 78.37 indicates the high salinity variability in the region. There is the highest correlation with visible bands and infrared bands 1, 2, 3, and 4, which indicates that the saline soils in the visible and infrared areas have a higher reflection. Between 2006-2015, the range of salt land has been expanded. Altogether, with the decreasing trend of the size of Lake Urmia, in 1976 regular domain faces, in 1985 sediment removal, in 1990 harvested area, in 2000 wet area, harvested area, and salt deposits, in 2006 bar salt and salt zone, and between 2011 and 2015 salt zone were formed and expanded.
