*3.1. Flash Flood Inventory*

Accurate mapping of the past flash flood events has a great impact on the accuracy of developed flash flood susceptibility maps. In order to predict the future flash flood events in a region, it is necessary to have records of the past flash flood events of the area [45]. These events depend on many factors including topography (terrain gradient), meteorology (antecedent rainfall), soil type, vegetative cover, and anthropogenic activities. These factors are considered as important parameters for the preparation of flash flood inventory and for the prediction of future flash flood events. In this research, in total, 320 past flash flood locations (represented on the maps by points) were obtained from the regional water organization of Markazi province (Figures 1 and 2). These flash flood points were divided randomly into 70% data points for training and 30% for validation purposes. In addition, 320 nonflooding points randomly selected from the high-altitude areas with low probability of flooding which were also used to combine with flash flood data for generating the training and testing datasets.

**Figure 2.** Flash flooding in Tafresh city.
