Inundation is both the act of intentionally flooding land that would otherwise remain dry, for military, agricultural, or river-management purposes, and the result of such an act.
Definition
The noun "inundation" refers to both the act of inundating; an overflow; a flood; a rising and spreading of water over grounds; and to the state of being inundated; flooding. It should therefore be distinguished from other types of flooding, not caused by man. It should also be recognised that this type of flooding would not take place without the intentional human act. So e.g. tidal flooding of areas that fall dry at ebb tide, and periodical river floods are not inundations in the sense intended here. The latter condition implies that in most topographies the act usually applies to causing an overflow of a river or stream by damming it. This is also the only method foreseen in the 1888 British military textbook that discusses the technique correctly under "military obstacles". However, in areas that have been reclaimed from the sea, marches or lakes, and are artificially protected from the waters, as in e.g. the artificial hydrological entities, known as Polders, may be inundated by simply giving the water source access again. In the latter perspective inundation may simply be a form of hydraulic engineering. Before we limit the concept to military uses, it should be recognised that there are at least two other possible uses of inundation as a human act:
agricultural uses, as in preparing paddy fields for the growing of semi-aquatic rice in many countries;
river management, in the form of diverting flood waters in a river at flood stage upstream from areas that are considered more valuable than the areas that are sacrificed in this way.This may be done ad hoc as in the 2011 intentional breach of levees by the United States Army Corps of Engineers in Missouri or permanently, as in the so-called overlaten, an intentionally lowered segment in Dutch riparian levees, like the Beerse Overlaat in the left levee of the Meuse between the villages of Gassel and Linden, North Brabant.
Military inundation
Military inundation creates an obstacle in the field that is intended to impede the movement of the enemy. This may be done both for offensive and defensive purposes. Furthermore, in so far as the methods used are a form of hydraulic engineering, it may be useful to differentiate between controlled inundations and uncontrolled ones. To count as controlled, a military inundation has to take the interests of the civilian population into account, by allowing them a timely evacuation, by making the inundation reversible, and by making an attempt to minimize the adverse ecological impact of the inundation. As Vandenbohed discusses, that impact may also be adverse in a hydrogeological sense if the inundation lasts a long time. From a legal point of view, a military inundation should therefore be seen as a government "taking" of private property under the constitutional protection of private property in many countries. In the Netherlands, this was the subject of art. 152 of the Dutch constitution of 1887.
