Assessment of stream flood susceptibility: a cross‐analysis between model results and flood losses

Abstract

This study describes a model, which classifies the susceptibility of streams to flooding. Three flood predisposing factors are considered: average slope, accumulated flow, and average relative permeability. Multi‐criteria analysis provided results for 11 combinations of weights. Results were compared with the historical record of flood losses reported in newspapers between 1935 and 2010. Lithology appears to function as a relevant factor in differentiating the major sub‐basins. Eighty‐six percent of flood loss occurrences took place in streams identified by the model. Analysing stream flood susceptibility and flood loss data allow the identification of locations where disaster causes should be searched, apart from those explained by the predisposing factors. The assessment of streams’ flood susceptibility through this methodology is useful in (i) data‐rich contexts where additional factors may be considered and the availability of historical records helps to validate the model and (ii) data‐poor contexts where data to run the model is easily found.

Regionalization and susceptibility assessment to daily precipitation extremes in mainland Portugal

“…In addition to extreme precipitation, there are other very important conditioning factors for landslides and floods, such as: physiographic conditions of the basins, soil types, relief, slope or lithological units, in mainland Portugal (e.g. Henriques, Santos, Santos, & Fragoso, 2017;Santos & Reis, 2017;Zêzere et al, 2015).…”

Heavy Rainfall Events and Mass Movements in the Funchal Area (Madeira, Portugal): Spatial Analysis and Susceptibility Assessment

“…However, due to the existing uncertainties related to the importance of each of the selected variables in conditioning and triggering the processes under analysis, it was necessary to perform several modeling exercises, varying the relative weight assigned to each variable. It is important to emphasize that there are multiple possibilities of conjugation of weights and variables, which are affected by the subjective option adopted in this process [18,40,41]. The proposed methodology for assessing the susceptibility to the occurrence of mass movements towards and along the valley bottoms follows a workflow based on the following main steps [42]: (1) selection of sources of information about the factors considered relevant for the identification of susceptibility [43,44]; (2) calculation of the values of the selected variables per unit of land (cell); (3) integration of the variables in a multicriteria-analysis model, according to empirical functions that result from the degree of importance assigned to each factor; (4) validation of the model results based on historical and geomorphological information, satellite-derived data and field observations [30].…”

“…The methods that can be considered in the analysis of susceptibility to mass movements and flood zones can be used independently or combined and can generally be classified into three types: (a) historical method [9,10]; (b) hydrological and hydraulic models [11][12][13][14][15]; (c) empirical methods based on multi-criteria analysis [16][17][18][19]. The application of combined methods can include, for example, an integrated analysis of hydro-geomorphological processes based on field observations, on the interpretation of aerial photography and of satellite-derived data, on historical documentation analysis [20,21], and on numerical modeling of debris flow [22].…”

“…The application of combined methods can include, for example, an integrated analysis of hydro-geomorphological processes based on field observations, on the interpretation of aerial photography and of satellite-derived data, on historical documentation analysis [20,21], and on numerical modeling of debris flow [22]. Regarding the multi-criteria analysis, the estimation of areas prone to mass movements occurrence results from the integration and weighting of information of the various explanatory factors of the phenomenon studied [17,18]. Other alternative methodological approaches are based on the technique of producing scenarios (Formative Scenario Analysis) that are indicative of patterns and trajectories of flow and its probabilistic structure [23,24].…”

Urban Stormwater Modeling with Local Inertial Approximation Form of Shallow Water Equations: A Comparative Study

“…Against the background of climate change and rapid urbanization that result in more frequent extreme rainfall events and changes in the underlying surface, urban floods have become a widely distributed natural hazard worldwide (Kaspersen et al 2017). Urban floods not only impose serious security risks to human life, property, and the ecological environment, but also severely restrict the development of cities (Santos and Reis 2018).…”