Abstract

Historical exploration of flash flood events and producing flash flood susceptibility maps are crucial steps for decision makers in disaster management. In this paper, classification and regression tree (CART) methodology and its ensemble models of random forest (RF), boosted regression trees (BRT), and extreme gradient boosting (XGBoost) were implemented to create a flash flood susceptibility map of the Bâsca Chiojdului River Basin, one of the areas in Romania that is constantly exposed to flash floods. The torrential areas including 962 flash flood events were delineated from orthophotomaps and field observations. Furthermore, a set of conditioning forces to explain the flash floods was constructed which included aspect, land use and land cover (LULC), hydrological soil groups lithology, slope, topographic wetness index (TWI), topographic position index (TPI), profile curvature, convergence index, and stream power index (SPI). All models indicated the slope as the most important factor triggering the flash flood occurrence. The highest area under the curve (AUC) was achieved by the RF model (AUC =0.956), followed by the BRT model (AUC =0.899), XGBoost model (AUC =0.892), and CART model (AUC =0.868), respectively. The results showed that the central part of the Bâsca Chiojdului river basin, which covers approximately 30% of the study area, is more susceptible to flash flooding.

摘要

对山洪暴发事件的历史探索和产生山洪泛滥敏感性图是决策者在灾害管理中的关键步骤。在本文中，实施了分类和回归树（CART）方法及其随机森林（RF），增强回归树（BRT）和极端梯度增强（XGBoost）的集成模型，以创建BâscaChiojdului的山洪敏感性图。流域，罗马尼亚经常遭受山洪暴发的地区之一。从正射影像图和实地观察中划定了包括962次山洪暴发事件在内的洪流区域。此外，还构造了一套解释山洪的调节力，包括坡向，土地利用和土地覆盖（LULC），水文土壤群岩性，坡度，地形湿度指数（TWI），地形位置指数（TPI），轮廓曲率，会聚指数和流功率指数（SPI）。所有模型都将坡度视为触发山洪泛滥的最重要因素。曲线下的最大面积（AUC）由RF模型（AUC = 0.956）实现，其次是BRT模型（AUC = 0.899），XGBoost模型（AUC = 0.892）和CART模型（AUC = 0.868）。 。结果表明，覆盖约30％研究区域的BáscaChiojdului流域的中部地区更容易遭受山洪泛滥的影响。899），XGBoost模型（AUC = 0.892）和CART模型（AUC = 0.868）。结果表明，覆盖研究面积约30％的BáscaChiojdului流域的中部地区更容易遭受山洪泛滥的影响。899），XGBoost模型（AUC = 0.892）和CART模型（AUC = 0.868）。结果表明，覆盖研究面积约30％的BáscaChiojdului流域的中部地区更容易遭受山洪泛滥的影响。