Environmental Management Hazards 2423-415X 7 2 2020 06 21 Preparation of flood hazards management map using a new random forest algorithm (Case study: Lavasanat watershed) (Case study: Lavasanat watershed) Preparation of flood hazards management map using a new random forest algorithm (Case study: Lavasanat watershed) (Case study: Lavasanat watershed) 181 196 78214 10.22059/jhsci.2020.307476.584 FA Leila Ebrahimi Department of Geography, Chalous Branch, Islamic Azad University, Chalous, Iran Journal Article 2020 08 02 Introduction Flood is a pervasive and global phenomenon that causes a lot of human and financial losses every year. Floods are natural hazards that do not occur spontaneously, but are caused by many factors, both natural and human. Floods are one of the three main natural hazards in Iran and it is safe to say that significant floods occur at least once a year in this part of the country. According to studies, 40 small and large floods occur annually in all parts of the country. This highlights the need to study the factors influencing the occurrence of floods. The purpose of this study is to zoning flood prone areas in the region and to determine the priority of effective factors in flood occurrence using a random forest algorithm. Materials and methods Thus, according to the studies and research background, 9 land use indicators, distance from the river, slope, height, humidity index, river flow, waterway capacity, precipitation, and land curvature were selected. After determining the variance inflation factor and tolerance coefficient, in the next step by entering the data related to the effective factors to R software, modeling was performed using random forest algorithm and the role of effective factors in flood occurrence in each sub-basin was determined. Flood risk zoning was prepared in four very dangerous, dangerous, medium and low risk zones in ARC / MAP 10.2 environment. Discus and Results Lavasan catchment area is divided into 7 sub-basins: Lavarak, Afjeh, Kand, Imameh, Fasham, Meygon and Ahar. The most important factor in the occurrence of floods in all sub-basins is rainfall. In each sub-basin, according to its natural characteristics, factors such as discharge, land use, drainage are other factors for floods. Conclusion In the northern and western basins of the Dubai River region and the slope of the next ranks have played a role in the occurrence of floods. In the northern basins of the region (Migun, Fasham and Ahar), the height of component 5 is an important factor in the occurrence of floods. In the southern basins of the region, drainage density and distance from the river after rainfall have been the most important causes of floods. Land use, especially in the southern sub-basins of the region, is an important factor in the occurrence of floods. Due to the tourist nature of this region, the process of illegal construction and land degradation has increased sharply in thi. Introduction Flood is a pervasive and global phenomenon that causes a lot of human and financial losses every year. Floods are natural hazards that do not occur spontaneously, but are caused by many factors, both natural and human. Floods are one of the three main natural hazards in Iran and it is safe to say that significant floods occur at least once a year in this part of the country. According to studies, 40 small and large floods occur annually in all parts of the country. This highlights the need to study the factors influencing the occurrence of floods. The purpose of this study is to zoning flood prone areas in the region and to determine the priority of effective factors in flood occurrence using a random forest algorithm. Materials and methods Thus, according to the studies and research background, 9 land use indicators, distance from the river, slope, height, humidity index, river flow, waterway capacity, precipitation, and land curvature were selected. After determining the variance inflation factor and tolerance coefficient, in the next step by entering the data related to the effective factors to R software, modeling was performed using random forest algorithm and the role of effective factors in flood occurrence in each sub-basin was determined. Flood risk zoning was prepared in four very dangerous, dangerous, medium and low risk zones in ARC / MAP 10.2 environment. Discus and Results Lavasan catchment area is divided into 7 sub-basins: Lavarak, Afjeh, Kand, Imameh, Fasham, Meygon and Ahar. The most important factor in the occurrence of floods in all sub-basins is rainfall. In each sub-basin, according to its natural characteristics, factors such as discharge, land use, drainage are other factors for floods. Conclusion In the northern and western basins of the Dubai River region and the slope of the next ranks have played a role in the occurrence of floods. In the northern basins of the region (Migun, Fasham and Ahar), the height of component 5 is an important factor in the occurrence of floods. In the southern basins of the region, drainage density and distance from the river after rainfall have been the most important causes of floods. Land use, especially in the southern sub-basins of the region, is an important factor in the occurrence of floods. Due to the tourist nature of this region, the process of illegal construction and land degradation has increased sharply in thi. https://jhsci.ut.ac.ir/article_78214_a23399f5fa5879c078406242d333e626.pdf