Geomorphology and Flooding

Abstract

The shape and size of landforms are the results of the interaction of exogenic or geomorphic processes, such as weathering and erosion, governed by climatic conditions, and of endogenic processes, given by diastrophism, including folding, uplift, and depressions of crustal blocks, and by volcanism. An overview is here given of the different types of exogenic or geomorphic processes, which directly or indirectly may affect flooding processes. Geomorphology, the discipline that studies landforms and their causes, explains, among other things, whether a river is likely to flood and change its course. The primary erosion agent is the liquid water, which carves Earth’s surface areas with different intensities, sizes, and shapes, depending on local climatic, geological, hydrological conditions, and land use. Erosion acts selectively, namely engraving and scouring away debris from weaker rock zones, so that depressions, named catchments, drained by stream channels form. Erosion is controlled by the general base level, represented by the medium sea level of the moment, where all continental waters flow, and local base level, determined by the geostructural characteristics of the catchment. The higher the amount and intensity of rainfall, the larger the extension of the catchment and runoff discharge, including the load given by the material transported by abrasion, grinding, impact, and solution, particularly high in case of floods. Devastating flood energy may be sensibly decreased by reducing its load. Geomorphological investigations should focus on catchment erodible areas, define their characteristics, and suggest the best solutions.

Topics & Concepts