Document Type : Research Paper
Author
Associate Professor, Department of Physical Geography, University of Sistan and Baluchestan, Zahedan, Iran
Abstract
The city of Mashhad, with a population of more than 3 million people, ranks as Iran's second-largest city. To enhance its resilience against environmental hazards, the adoption of new technologies is increasingly essential. On May 26, 1403, during a 48-minute rain due to the formation of a cumulonimbus cloud and the strengthening of its ascending conditions by a Trough on top of it, a flood occurred in the city of Mashhad led to heavy financial and human losses in different areas. This study aims to explore both natural and human factors contributing to the flood through a holistic approach. To analyze the synoptic meteorological causes, data from the ERA-5 and its maps were utilized in GrADS. Additionally, Landsat satellite imagery and digital elevation data were employed to identify waterways and canals. Google Earth and GEE software were also used to assess changes in the landscape. The results showed that in terms of intensity and duration of rainfall, the rainfall was unprecedented rainfall, and according to the threshold of 95% percentile, it is considered as extreme rainfall category (above 95% percentile). The results of this study clearly show that human encroachments, especially in urban construction and the expansion of urban roads and highways perpendicular to the seasonal and dry rivers of the city, have strongly affected the water flow pattern and increased the risk of floods. The neglect of urban geomorphology, including the destruction of natural water pathways, the construction of barriers against water flows ways like those in the Seyyedi region, and the expansion of roads perpendicular to these waterways, was intensified flooding issues in various areas in Mashhad city.
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