Floods and society

Abstract

Society is defined as a group of people who share versatile civilizational infrastructures. Floods are defined as the extremely high river flows or water levels of lakes, reservoirs, aquifers and estuaries. Experience demonstrates that flood dangers can be alleviated but can’t be completely eliminated. Coping with floods refers to all measures which society can undertake to alleviate impacts of floods. Three types of floods occur: natural floods, natural floods modified by humans, and floods generated by humans. Catchment size is an important parameter for floods, since unit area flow in floods of the same risk decreases with an increase of catchment area, influencing forecast, warning, response, defense and coping with floods. Three major groups of professional flood work are: obtaining information on floods and on their impacts, and coping with floods. Five groups of methods for determining flood characteristics are: frequency analysis, physically-based methods, regional methods, probable maximum flood, and historic and flood-related paleo-data methods. Assessment of flood impacts distinguishes direct and indirect flood losses. Various methods are available to calculate flood damage, leading to estimates of the average annual flood damage. Interactions between floods and society are complex, requiring sociological studies of behavior of individuals, groups and institutions. Societies in the past have acted in the following ways: defense of lives and property, decrease of losses and increase of benefits from floods, and attenuation of flood peaks by various measures. Four types of measures in coping with floods are: do nothing except education, non-structural measures, structural measures, and combination of structural and nonstructural flood mitigation measures.