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 (as in most historic inundations in the Netherlands under the Dutch Republic and its successor states in that area and exemplified in the two Hollandic Water Lines, the Stelling van Amsterdam, the Frisian Water Line, the IJssel Line, the Peel-Raam Line, and the Grebbe line in that country) and uncontrolled ones (as in the second Siege of Leiden during the first part of the Eighty Years War, and the Inundation of Walcheren, and the Inundation of the Wieringermeer during the Second World War). 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. That impact may also be adverse in a hydrogeological sense if the inundation lasts a long time. Effects
Floods can also be a huge destructive power. When water flows, it has the ability to demolish all kinds of buildings and objects, such as  bridges, structures, houses, trees, cars...  For example, in Bangladesh in 2007, a flood was responsible for the destruction of more than one million houses.
Peripheral cyanosis may be due to the following causes:
All common causes of central cyanosis
Reduced cardiac output (e.g. heart failure or hypovolemia)
Cold exposure
Chronic obstructive pulmonary disease (COPD)
Arterial obstruction (e.g. peripheral vascular disease, Raynaud phenomenon)
Venous obstruction (e.g. deep vein thrombosis)

Differential cyanosis
Differential cyanosis is the bluish coloration of the lower but not the upper extremity and the head. This is seen in patients with a patent ductus arteriosus. Patients with a large ductus develop progressive pulmonary vascular disease, and pressure overload of the right ventricle occurs. As soon as pulmonary pressure exceeds aortic pressure, shunt reversal (right-to-left shunt) occurs. The upper extremity remains pink because deoxygenated blood flows through the patent duct and directly into the descending aorta while sparing the brachiocephalic trunk, left common carotid, and left subclavian arteries. Evaluation
A detailed history and physical examination (particularly focusing on the cardiopulmonary system) can guide further management and help determine the choice of testing to be performed. Tests that can be performed include pulse oximetry, arterial blood gas, complete blood count, methemoglobin level,  electrocardiogram, echocardiogram, X-Ray, CT scan, cardiac catheterization, and hemoglobin electrophoresis. In newborns, peripheral cyanosis typically presents in the distal extremities, circumoral, and periorbital areas. Of note, mucous membranes remain pink in peripheral cyanosis as compared to central cyanosis where the mucous membranes are cyanotic. It is important to note that skin pigmentation and hemoglobin concentration can affect the evaluation of cyanosis. Cyanosis may be more difficult to detect on people with darker skin pigmentation.