Evaluation of floodplains using Sentinel-1 images to locate safe points (Case study: Chabahar and Konarak counties)
Subject Areas : Applications in natural hazard and disasterzohreh salehinezhad 1 , seyed ali alhoseini almodaresi 2
1 - MSc. Remote Sensing and Geographical Information System, Faculty of Engineering, Islamic Azad University of Yazd, Yazd, Iran
2 - Professor
Keywords: Evaluation of flooded areas, Sentinel Series 1 radar images, GIS, stochastic forest algorithm, fuzzy logic, Algebraic algorithm,
Abstract :
Sistan and Baluchestan provinces, including the coastal cities of Chabahar and Konarak, have long been exposed to natural hazards, including floods. The main purpose of this study is to evaluate the flooded areas and determine the location and extent of the areas that have suffered the most flood damage in January 2017 in Chabahar and Konarak counties. Due to climate change such as heavy rainfall and using Sentinel-1 satellite images in the two time periods before and after the accident, based on the analysis and processing of images in SNAP software, the Sigma zero scattering coefficient of both images was extracted and divided into two levels of water and others. The water was separated and the threshold of 0.01 was obtained. Using the algebraic algorithm of water and non-water binary images in the form of zero and one and based on the difference between the two images, the flooded area was identified. The flooded areas were then classified using a random forest algorithm with a kappa coefficient of 0.91. Indicates the high accuracy of the classification. After preparing the map of flooded areas to locate safe points of value in Expert choice software based on the studied criteria which include (river area, structure, direction, width of communication network, and slope of the study area) and using fuzzy logic of 0.9 gammas in the environment Arc GIS10.6 software is discussed. The obtained results have determined the area of nearly 426.46 square kilometers of areas affected by floods, which have the most damage and destruction of urban and rural land use, agriculture and animal husbandry and blocking the communication routes of most villages, as well as mapping safe areas for air, sea and land services.
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