## 1 Introduction  
Flash floods cause some of the most profound disasters in the modern world, resulting in a diverse array of impacts [1; 2; 3], encompassing human casualties, infrastructure and property damage as well as environmental degradation, manifesting across both tangible and intangible dimensions. Particularly due to climate change, these impacts have the potential to increase, especially in the Mediterranean region. Due to their nature and the temporal and spatial scales of their occurrence [4], systematic assessment and monitoring of flash flood impacts has been difficult and impracticable. Developing a holistic understanding of the diverse direct effects of flash floods has been particularly difficult [5; 6], especially when it comes to urban areas and to extensive and destructive flood events. The discontinuous nature of flash floods, along with the diversity of their effects, makes the resulting impacts very dependent on the properties of the inundated area. This variability further complicates endeavors aimed at achieving a systematic evaluation of the breadth and intensity of these impacts. In addition, in the prevailing current practices, flash flood impacts are assessed from a single viewpoint or a single discipline [7], such as in economic terms [8; 9], or damages in agriculture [10; 11; 12] or geomorphology [13; 14], which have been explored in previous studies. Recent research acknowledges the need for a more communicable and easy-to-use system of severity characterization [15], exploiting multiple impact aspects rather than a single one [7; 16], using criteria that are consistent in multiple events [17]. This lack of systematic recording and assessment of flash flood impacts often leads to deficiencies when it comes to understanding which part of a floodplain shows higher-severity damages and what the dominant types of flood damage are in a particular area. Even in areas with repeated flood events, the identification of such patterns often remains in documentary form or relies on the perception and/or knowledge of the local emergency/risk professionals. This poor understanding of flood impacts lays the foundation for substantial challenges when it comes to the prediction of future impacts. In a previous recent study, [PERSON] et al. [18] proposed the \"Flash Flood Impact Severity Scale\" (FFISS), a method for mapping and classifying the flash flood impact severity. This approach applies in different environments, encompassing a broad spectrum of flood effects, including the built and the natural environments, infrastructure and buildings, mobile objects and population, ranking the severity of impacts by incorporating their spatial distribution. In this study, we employ the FFISS as a tool for systematically evaluating and comparing the impacts of multiple flood events within the same river basin. The primary focus of this approach is on measuring the severity of flood impacts in relation to critical factors such as the peak discharge and localized land use changes, including urban development, deforestation, or agricultural expansion. These factors are crucial as they significantly influence the behavior and consequences of floods, shaping the extent and distribution of their impacts. By comparing data from two similar flood events generated in 2009 and 2020 in the same catchment, this study aims to identify and analyze the spatial patterns in the severity of the impacts. Specifically, our objective is to explore the potential differences between the effects caused by the two events in terms of the spatial distributions and severity levels. In addition, we seek to determine whether areas with certain land use characteristics consistently experience more severe impacts, or whether the first event can influence the impact distribution in subsequent events through changes in the natural environment or community adaptation. Such patterns can provide valuable insights into the dynamics of flood events, shedding light on how future floods might unfold under similar conditions.