Change Detection and Prediction of Urmia Lake and its Surrounding Environment During the Past 60 Years Applying Geobased Remote Sensing Analysis

摘要

The gradual depletion of Urmia lake has been a challenge in both national and international scale during recent years. In recent decades the imprudent industrial development accompanied by continuous use of groundwater aquifers has been one of the most pivotal reasons for this crisis. Water level monitoring and detection of its changes within Urmia lake as well as the surrounding environment in the past 60 years integrating GIS, Remote sensing and photogrammetric methods is the main goal for this study. In order to accomplish this, Aerial Photogrammetry images and derived topographic maps from them for the year 1955, Digital Elevation data, quantitative and qualitative information regarding water wells and lake Urmia respectively and finally remotely sensed images of Landsat TM, ETM+ and OLI sensors were used. The temporal range for the study was set to 60 from the year 1955 to 2014. Scrutinizing 12 images relating to different periods, vast changes in both area and perimeter of the lake were detected. Based on the results, the lake area has decreased from 451800 hectares in 1955 to 89730 in recent years due to various causative factors. It is also found that the highest water recession, which caused increasing coastal salty areas, has been occurred in the southern parts of the lake. While the receding water level of the lake has a deep correlation with the increasing agricultural activities around the lake, it has a reverse relation with the lake water EC. These fluctuations can be detrimental to the environment, economy and society. Looking at the changes in lake Urmia, if the current situation keeps on and no drastic measures are taken, turning into a salt land, the Lake would be completely disappeared till 2033.