هانیه نیل فروشان

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.

Planning the cultivation pattern and water rights allocation in the irrigated lands by the Khansar Sarcheshmeh springs requires knowledge of the discharge of the springs, estimated based on the Standard Precipitation Index (SPI) in this research. The relationship between the SPI index, precipitation, and discharges of Khansar Sarchesmeh springs has been evaluated over three different periods to estimate the groundwater resources and inflow to the streams. In a year with normal or near-normal climatic conditions and average annual rainfall between 295 to 494 mm, the average annual discharge of Sarcheshmeh springs is expected to be between 12.8 and 24.3 million cubic meters (average of 18.1 million cubic meters) with 67.5% probability and a frequency of 1.5 years based on the extreme value distribution. For a year with average dry climatic conditions (270 mm average annual rainfall), the predicted average annual discharge of Sarcheshmeh springs is 11.9 million cubic meters with a 9% probability and a frequency of 11 years. In extremely dry climatic years (with an occurrence frequency of 28 years), the discharge of Sarcheshmeh springs is expected to decrease to less than 10.1 million cubic meters per year. In normal and close to normal conditions, with average rainfall in the range of 236 to 326 mm in the first six months, the average annual (water year) discharge of Sarcheshmeh springs is expected to be 18.5 million cubic meters (ranging from 15.3 to 21.8 million cubic meters with a 67.5% probability based on the extreme value distribution). According to the results of this research, rainfall of less than 168 mm occurred in the first half of the water year is a warning of the occurrence of a moderate to extremely dry drought with an annual discharge of less than 11.6 million cubic meters that can be distributed in the streams. Precipitations of more than 394 mm during the first half of the water year also indicate the likelihood of a moderate to extremely wet year, with an annual rainfall of more than 28 million cubic meters. Results of the research indicate that less than 168 mm of rainfall in the first half of the water year signals the potential for a moderate to extremely dry drought, with an annual discharge of less than 11.6 million cubic meters that can be distributed in the streams, while more than 394 mm of precipitation during the same period suggests the possibility of a moderate to extremely wet year with an annual rainfall of more than 28 million cubic meters.

Glaciers influenced by climatic factors and therefore as an important indicator in the study of climate change are studied. Although morphometric analyzes of glaciers based on the analysis of optical satellite data can provide an opportunity to measure ice outcrops, but the identification and determination of the buried glaciers underneath the Supraglacial moraines (accumulated debris on top of the glacial ice) and, consequently, the determination of the actual glacial body and their parameters, including the level and volume of the glaciers, are not possible based on optical satellite imagery. On the other hand, the existence of an ice cooling source underneath the glacial debris, which leads to a significant reduction in the surface temperature of the glacial debris, is a distinguishing feature for the separation of covered glaciers.
The over 2000 km long NW-SE trending Zagros Mountain belt extends from eastern Turkey to the Makran Mountains, forming a morphological boundary between the Iranian plateau and the Mesopotamian and Persian Gulf basins. The Zardkuh Mountain lies along the central Zagros Mountain Range (32°14'-32°38' N; 49°50'-50°15' E) in Chahar-Mahal and Bakhtiari province, Iran. The highest summit of this mountain chain is 4220 m a.s.l altitude. Small glaciers (mostly cirque glaciers) were first reported on the northern slopes of Zardkuh during August 1933. Other research has pointed to some glacial cirques on Zardkuh which have altitude about 3000m and located in small valleys on the N faces of the Zardkuh. Some new researches on the active glaciers of Zardkuh show the greatest glacier concentration around 1) Joft-zarde and Shahe Shahidan (Zarkuh) summits 2) around Sirdan summit and 3) Haft-tanan (Iluk) region. Based on the latest study, the current size of Zardkuh’s glaciers have estimated about 7.1 km2.
In this research, the expansion of natural glaciers of Zardkuh Mountain has been determined by the combined analysis of thermal (Thermal Infrared Sensor (TIRS) of Landsat 8), optical data (Operational Land Imager (OLI) of Landsat 8 and Quickbird image) and digital elevation data, based on Split Window Algorithm. For this purpose, the following steps are carried out: 1) Preparation of Landsat 8 TIRS and OLI images, Quickbird image and Digital Elevation Model with 10 m resolution 2) Radiometric correction and rectification of images to WGS-1984-UTM-Zone_39N 3) Detection of exposed ice of active glaciers using by short wavelength infrared and green spectral bands of Landsat and optical images 4) Creation of 3D model of active glacier by combination of DEM and Quickbird images / Landsat images 5) Estimation of Land Surface Temperature (LST) using by Normalized Difference Vegetation Index (NDVI) and Land Surface Emissivity (LSE) based on the Single Window Algorithm. The NDVI is calculated as a ratio between measured reflectivity in the red and near infrared portions of the electromagnetic spectrum. The land surface emissivity (LSE (𝜀)) is calculated based on the Proportion of vegetation (Pv) and NDVI. 6) Supervised classification of LST layer based on the sampling of ice and supraglacial deposits temperatures for each glacier (the presence of ice under sediments has already been confirmed in field visits) 7) Area calculation of ​​the glaciers based on the classified LST layer.
In this study, Land Surface Temperature (LST) layer were calculated for Zardkuh Mountain based on the single method algorithm. Furthermore, Land Surface Emissivity (LSE), Proportion of vegetation (Pv) and normalised difference vegetation index (NDVI) layers were calculated for the study area. The surface area of exposed ice of Zardkuh glaciers is detected by using the short wavelength infrared and green spectral bands by making RGB753 color composite which its spatial resolution has improved with Panchromatic band to 15 m and 3D model of glaciers. Based on the results of this study, the area of the exposed ice of glaciers were 123 hectares. The surface area of exposed ice and buried glaciers underneath the Supraglacial moraines of Zardkuh glaciers based on the described methodology, were measured about 201 hectares in August 2017. The area of ​​the Haftanan, Joftzarde, Kuhrang3 and Khersan glaciers has decreased and reached to 32, 31, 30 and 29 hectares, respectively.
In this paper, potential of remote sensing to study the actual extent of Zardkuh glaciers in Zagrous Mountains in Iran by estimating LST distribution with the help of Landsat 8 OLI and TIRS sensor bands provided. Remote Sensing technology data such as Landsat 8 TIRS proved as an efficient one to estimate LST. Single window algorithm methods are applied to calculate the LST from TIRS data. Based on the results of this study, the area of the glaciers (surface and buried ice) in comparison with previous studies, shows a significant decrease in the past decade.