وحید فیضی

Introduction: According to the flood records in Mazandaran province, this region is regarded as one of the flood-prone regions of the country, and due to the floods, it has suffered many casualties and financial losses. Therefore, this study aimed to investigate the settlements at risk of flooding as one of the main goals of this research. Methods: This descriptive-analytical study was conducted based on extensive and exploratory research approaches. The required data were collected from monthly discharge and the maximum instantaneous discharge in the stations of Mazandaran province along with the population statistics of the provincial cities, as well as the statistics of the Natural Resources and Watershed Management Organization concerning the floods. Accordingly, the statistics of hydrometric stations from 1971 to 2021 of Iran's water resources management main company, the population statistics of the province based on the census of 2015, and the statistics of floods that occurred from the beginning to 2021 have been used in this study. Flood return periods were obtained in the study stations in different statistical distributions using Hyfa software. Finally, Arc GIS software (version 10.3) was used to zone floods in Mazandaran province. Findings: Based on the results, about 1013 square kilometers of the province's surface accounting for 4.25% of its total area is located in the boundaries of large floods that have a return period of 50 to 100 years. Moreover, due to the high altitude, rainy-snowy events, and the significant amount of precipitation in Sarab (Dali Chai and Lar basins) and Payab, Haraz basin has a significant runoff rate discharge so that about 500 to 600 liters of water flow from this basin annually per square meter. Conclusion: According to the obtained results, strategies have been proposed to increase resilience against flood risk using different methods.

INTRODUCTION: Identification of the settlements located in high-risk zones in terms of natural hazards is one of the first steps in risk management and development planning. This study aimed to identify villages exposed to earthquakes and floods in South Khorasan province. METHODS: The present study used the Analytic Hierarchy Process method to evaluate the validity and reliability of measuring instruments through exploratory factor analysis. Since the value of the KMO index was 0.879, the number of samples was sufficient for analysis. Moreover, the significance of the Bartlett test was less than 5% and Cronbach's alpha coefficient was obtained at 0.856; accordingly, the questionnaire was reliable. FINDINGS: Based on the spatial analysis of the seismic vulnerability, 214 and 502 villages were in the zone of very high and high vulnerability, respectively. Moreover, the results of flood vulnerability showed that the southern and northwestern parts of South Khorasan province had the lowest vulnerability. The number of villages located in the very high vulnerable zone was very limited and included only seven villages of Chenesht, Kalateh Abbas, Takti Ti, Tangel Behdan, Ebru, Khankuk, and Ostan Siah, which are located in the east of the province. CONCLUSION: Based on the integrated results of two hazards (i.e., earthquakes and floods), it is observed that 523 rural settlements are in a very high-risk zone, which accounts for 14.7% of the total settlements in the South Khorasan province, compared to the total rural settlements. Furthermore, the highest dispersion frequency of rural settlements is in the zone of moderate vulnerability. This zone with 1,344 settlements includes about 37.7% of the total settlements in the province