Floods occurring in alluvial fans are very peculiar and hazardous, due to the mobility of the channel in the regions. Such mobility increases the uncertainty of the course to be occupied by the water or the debris flow, which makes hazard mapping more complex. Since the flow in alluvial fans is three-dimensional, the flood mapping in these regions without hydrological data can be unfeasible. Then, at first the present study applied to the Upper Mampituba river basin characterized with three main alluvial fans (Molha Coco and Malacara Fans (MCMFs) and Boi Fan), southern Brazil, three models: Hydrological Engineering Center – River Analysis System 2D (HEC-RAS), FAN Model and Height Above The Nearest Drainage (HAND). The FAN and HAND models are considered geomorphological models and comparatively simpler. Then the combination between these two models was applied to generate flood hazard maps. The proposed combination model presented results more coherent with alluvial fan feature, representing satisfactorily the flood extent of the most recent event occurred in the study area (showing good performance metrics: statistical F (%) 72.65, General Accuracy (%) 79.82, FIT(%) 38.44 and False Alarm Rate (%) 20.50).

由于河道在该地区的流动性，冲积扇中发生的洪水非常特殊且危险。这种流动性增加了水或泥石流所占据的航道的不确定性，这使得危害图的绘制更加复杂。由于冲积扇中的水流是三维的，因此在没有水文数据的地区进行洪水制图是不可行的。然后，首先，本研究应用于巴西南部南部具有三个主要冲积扇（Molha Coco和Malacara Fans（MCMFs）和Boi Fan）的Mampituba上游流域，这三个模型是：水文工程中心–河流分析系统2D（HEC） -RAS），风扇模型和最近排水上方的高度（HAND）。FAN和HAND模型被认为是地貌模型，相对而言较为简单。然后，将这两个模型之间的组合应用于生成洪水灾害图。拟议的组合模型显示的结果与冲积扇特征更加一致，令人满意地表示了研究区域最近发生的洪水泛滥程度（显示了良好的性能指标：统计F（％）72.65，一般精度（％）79.82，FIT（ ％）38.44和误报警率（％）20.50）。