The stage at which some sort of action is taken for a point along the river.
Deluge myths are mythical stories of a great flood sent by a deity or deities to destroy civilization as an act of divine retributionand they are featured in the mythology of many cultures. Principal types Areal Floods can happen on flat or low-lying areas when water is supplied by rainfall or snowmelt more rapidly than it can either infiltrate or run off.
The excess accumulates in place, sometimes to hazardous depths.
Surface soil can become saturated, which effectively stops infiltration, where the water table is shallow, such as a floodplainor from intense rain from one or a series of storms. Infiltration also is slow to negligible through frozen ground, rock, concretepaving, or roofs.
Areal flooding begins in flat areas like floodplains and in local depressions not connected to a stream channel, because the velocity of overland flow depends on the surface slope.
Endorheic basins may experience areal flooding during periods when precipitation exceeds evaporation. When overland River and flood occurs on tilled fields, it can result in a muddy flood where sediments are picked up by run off and carried as suspended matter or bed load.
Localized flooding may be caused or exacerbated by drainage obstructions such as landslidesicedebrisor beaver dams. Slow-rising floods most commonly occur in large rivers with large catchment areas.
The increase in flow may be the result of sustained rainfall, rapid snow melt, monsoonsor tropical cyclones. However, large rivers may have rapid flooding events in areas with dry climate, since they may have large basins but small river channels and rainfall can be very intense in smaller areas of those basins.
Rapid flooding events, including flash floodsmore often occur on smaller rivers, rivers with steep valleys, rivers that flow for much of their length over impermeable terrain, or normally-dry channels. The cause River and flood be localized convective precipitation intense thunderstorms or sudden release from an upstream impoundment created behind a damlandslide, or glacier.
In one instance, a flash flood killed eight people enjoying the water on a Sunday afternoon at a popular waterfall in a narrow canyon. Without any observed rainfall, the flow rate increased from about 50 to 1, cubic feet per second 1.
The deadly flood resulted from a thunderstorm over part of the drainage basin, where steep, bare rock slopes are common and the thin soil was already saturated. Flash floods are the most common flood type in normally-dry channels in arid zones, known as arroyos in the southwest United States and many other names elsewhere.
In that setting, the first flood water to arrive is depleted as it wets the sandy stream bed. The leading edge of the flood thus advances more slowly than later and higher flows.
As a result, the rising limb of the hydrograph becomes ever quicker as the flood moves downstream, until the flow rate is so great that the depletion by wetting soil becomes insignificant. Estuarine and coastal Flooding in estuaries is commonly caused by a combination of sea tidal surges caused by winds and low barometric pressureand they may be exacerbated by high upstream river flow.
Coastal areas may be flooded by storm events at sea, resulting in waves over-topping defenses or in severe cases by tsunami or tropical cyclones.
A storm surgefrom either a tropical cyclone or an extratropical cyclonefalls within this category. Storm surge should not be confused with storm tide, which is defined as the water level rise due to the combination of storm surge and the astronomical tide.
This rise in water level can cause extreme flooding in coastal areas particularly when storm surge coincides with normal high tide, resulting in storm tides reaching up to 20 feet or more in some cases. Although sometimes triggered by events such as flash flooding or snowmelturban flooding is a condition, characterized by its repetitive and systemic impacts on communities, that can happen regardless of whether or not affected communities are located within designated floodplains or near any body of water.
In urban areas, flood effects can be exacerbated by existing paved streets and roads, which increase the speed of flowing water. The flood flow in urbanized areas constitutes a hazard to both the population and infrastructure.
Flood flows in urban environments have been studied relatively recently despite many centuries of flood events. Examples include outburst floods and lahars. Tsunamis can cause catastrophic coastal flooding, most commonly resulting from undersea earthquakes.
Causes Flood due to Cyclone Hudhud in Visakhapatnam Upslope factors The amount, location, and timing of water reaching a drainage channel from natural precipitation and controlled or uncontrolled reservoir releases determines the flow at downstream locations.
Some precipitation evaporates, some slowly percolates through soil, some may be temporarily sequestered as snow or ice, and some may produce rapid runoff from surfaces including rock, pavement, roofs, and saturated or frozen ground. The fraction of incident precipitation promptly reaching a drainage channel has been observed from nil for light rain on dry, level ground to as high as percent for warm rain on accumulated snow.
Frequency of a precipitation threshold of interest may be determined from the number of measurements exceeding that threshold value within the total time period for which observations are available.
Individual data points are converted to intensity by dividing each measured depth by the period of time between observations. This intensity will be less than the actual peak intensity if the duration of the rainfall event was less than the fixed time interval for which measurements are reported.
Convective precipitation events thunderstorms tend to produce shorter duration storm events than orographic precipitation.KATHERINE Northern Territory nt,internet startpage information and links page for katherine region flood news & northern territory weather river camera cam rivercam webcam website.
The Truckee River Flood Management Project is a joint effort among the cities of Reno and Sparks, Washoe County, the U.S. Army Corps of Engineers and numerous other stakeholders to reduce the devastating impacts of flooding in the Truckee Meadows, Nevada.
The Red River flood along the Red River of the North in North Dakota and Minnesota in the United States and Manitoba in Canada brought record flood levels to the Fargo-Moorhead area. The flood was a result of saturated and frozen ground, Spring snowmelt exacerbated by additional rain and snow storms, and virtually flat terrain.
flood control project for more than years, headwater flooding of the pearl river has caused disruption to businesses and industry throughout the jackson, mississippi metropolitan area, putting over 5, commercial and residential structures,several hospitals and interstate highways at risk of flood damage.
7 days ago · A river flood warning is in effect for the Pee Dee River at Cheraw. This warning will continue until further notice. Major flooding is expected for this river and a number of rivers in the Pee Dee. The river rose to a record feet ( m), which was 19 feet ( m) above flood stage, and sent water over the six-month-old riverfront plaza in Evansville.