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Sandbag
A sandbag or dirtbag is a bag or sack made of hessian (burlap), polypropylene or other sturdy materials that is filled with sand or soil and used for such purposes as flood control, military fortification in trenches and bunkers, shielding glass windows in war zones, ballast, counterweight, and in other applications requiring mobile fortification, such as adding improvised additional protection to armored vehicles or tanks. The advantages are that the bags and sand are inexpensive. When empty, the bags are compact and lightweight for easy storage and transportation. They can be brought to a site empty and filled with local sand or soil. Disadvantages are that filling bags is labor-intensive. Without proper training, sandbag walls can be constructed improperly causing them to fail at a lower height than expected, when used in flood-control purposes. They can degrade prematurely in the sun and elements once deployed. They can also become contaminated by sewage in flood waters ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fortification
A fortification is a military construction or building designed for the defense of territories in warfare, and is also used to establish rule in a region during peacetime. The term is derived from Latin ''fortis'' ("strong") and ''facere'' ("to make"). From very early history to modern times, defensive walls have often been necessary for cities to survive in an ever-changing world of invasion and conquest. Some settlements in the Indus Valley civilization were the first small cities to be fortified. In ancient Greece, large stone walls had been built in Mycenaean Greece, such as the ancient site of Mycenae (famous for the huge stone blocks of its ' cyclopean' walls). A Greek '' phrourion'' was a fortified collection of buildings used as a military garrison, and is the equivalent of the Roman castellum or English fortress. These constructions mainly served the purpose of a watch tower, to guard certain roads, passes, and borders. Though smaller than a real fortress, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sand Boil
Sand boils or sand volcanoes occur when water under pressure wells up through a bed of sand. The water looks like it is boiling up from the bed of sand, hence the name. Sand volcano A sand volcano or sand blow is a cone of sand formed by the ejection of sand onto a surface from a central point. The sand builds up as a cone with slopes at the sand's angle of repose. A crater is commonly seen at the summit. The cone looks like a small volcanic cone and can range in size from millimetres to metres in diameter. The process is often associated with soil liquefaction and the ejection of fluidized sand that can occur in water-saturated sediments during an earthquake. The New Madrid Seismic Zone exhibited many such features during the 1811–12 New Madrid earthquakes. Adjacent sand blows aligned in a row along a linear fracture within fine-grained surface sediments are just as common, and can still be seen in the New Madrid area. In the past few years, much effort has gone into ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hessian (cloth)
Hessian (, ), burlap in the United States and Canada, or crocus in Jamaica and the wider Caribbean, is a woven fabric usually made from skin of the jute plant or sisal fibres, which may be combined with other vegetable fibres to make rope, nets, and similar products. Gunny is similar in texture and construction. Hessian, a dense woven fabric, has historically been produced as a coarse fabric, but more recently it is being used in a refined state known simply as jute as an eco-friendly material for bags, rugs and other products. The name "hessian" is attributed to the historic use of the fabric as part of the uniform of soldiers from the former Landgraviate of Hesse and its successors, including the current German state of Hesse, who were called " Hessians". Hessian cloth is available in different types of construction, form, size and color. The origin of the word ''burlap'' is unknown, though its earliest known appearance is in the late 17th century, and its etymology is spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siege Of Ninety-Six
The siege of Ninety Six was a siege in western South Carolina late in the American Revolutionary War. From May 22 to June 18, 1781, Continental Army Major General Nathanael Greene led 1,000 troops in a siege against the 550 Loyalists in the fortified village of Ninety Six, South Carolina. The 28-day siege centered on an earthen fortification known as Star Fort. Despite having more troops, Greene was unsuccessful in taking the town, and was forced to lift the siege when Lord Rawdon approached from Charleston with British troops. The area is now protected as Ninety Six National Historic Site and was designated a National Historic Landmark. Many of the surviving Loyalists were later relocated by the Crown and granted land in Nova Scotia, where they named their township Rawdon to commemorate their rescuer. Background The British Army's "southern strategy" for winning the American Revolutionary War, which had been successful in taking Charleston and winning submission of much ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Revetment
A revetment in stream restoration, river engineering or coastal engineering is a facing of impact-resistant material (such as stone, concrete, sandbags, or wooden piles) applied to a bank or wall in order to absorb the energy of incoming water and protect it from erosion. River or coastal revetments are usually built to preserve the existing uses of the shoreline and to protect the slope. In military engineering it is a sloped structure formed to secure an area from artillery, bombing, or stored explosives. Freshwater revetments Many revetments are used to line the banks of freshwater rivers, lakes, and man-made reservoirs, especially to prevent damage during periods of floods or heavy seasonal rains (see riprap). Many materials may be used: wooden piles, loose-piled boulders or concrete shapes, or more solid banks. Concrete revetments are the most common type of infrastructure used to control the Mississippi River. More than of concrete matting has been placed in rive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flood Control
Flood control methods are used to reduce or prevent the detrimental effects of flood waters."Flood Control", MSN Encarta, 2008 (see below: Further reading). Flood relief methods are used to reduce the effects of flood waters or high water levels. Flooding can be caused by a mix of both natural processes, such as extreme weather upstream, and human changes to waterbodies and runoff. Though building hard infrastructure to prevent flooding, such as flood walls, can be effective at managing flooding, increased best practice within landscape engineering is to rely more on soft infrastructure and natural systems, such as marshes and flood plains, for handling the increase in water. For flooding on coasts, coastal management practices have to not only handle changes water flow, but also natural processes like tides. Flood control and relief is a particularly important part of climate change adaptation and climate resilience, both sea level rise and changes in the weather (climat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Levee
A levee (), dike (American English), dyke (Commonwealth English), embankment, floodbank, or stop bank is a structure that is usually earthen and that often runs parallel to the course of a river in its floodplain or along low-lying coastlines. The purpose of a levee is to keep the course of rivers from changing and to protect against flooding of the area adjoining the river or coast. Levees can be naturally occurring ridge structures that form next to the bank of a river, or be an artificially constructed fill or wall that regulates water levels. Ancient civilizations in the Indus Valley, ancient Egypt, Mesopotamia and China all built levees. Today, levees can be found around the world, and failures of levees due to erosion or other causes can be major disasters. Etymology Speakers of American English (notably in the Midwest and Deep South) use the word ''levee'', from the French word (from the feminine past participle of the French verb , 'to raise'). It originat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flood
A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study of the discipline hydrology and are of significant concern in agriculture, civil engineering and public health. Human changes to the environment often increase the intensity and frequency of flooding, for example land use changes such as deforestation and removal of wetlands, changes in waterway course or flood controls such as with levees, and larger environmental issues such as climate change and sea level rise. In particular climate change's increased rainfall and extreme weather events increases the severity of other causes for flooding, resulting in more intense floods and increased flood risk. Flooding may occur as an overflow of water from water bodies, such as a river, lake, or ocean, in which the water overtops or breaks levees, resulting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buoyancy Compensator (aviation)
The static buoyancy of airships in flight is not constant. It is therefore necessary to control the altitude of an airship by controlling its buoyancy: buoyancy compensation. Changes which have an effect on buoyancy * Changes in air temperature (and thus the density of air) * Changes in lifting gas temperature (for example, the heating of the hull by the sun). * Accumulation of additional ballast (for example, precipitation or icing on the envelope) * Changes in ballast (for example, during a flight maneuver or the dropping of ballast) * Changes in weight of fuel on board, due to fuel consumption. This was a challenge especially in the large historic airships like the Zeppelins. For example, on a flight from Friedrichshafen to Lakehurst, the rigid airship LZ 126, built in 1923-24, used 23,000 kg gasoline and 1300 kg of oil (an average consumption of 290 kg/100 km). During the landing the airship had to release approximately 24,000 cubic meters of hydrogen to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barricade
Barricade (from the French ''barrique'' - 'barrel') is any object or structure that creates a barrier or obstacle to control, block passage or force the flow of traffic in the desired direction. Adopted as a military term, a barricade denotes any improvised field fortification, such as on city streets during urban warfare. Barricades also include temporary traffic barricades designed with the goal of dissuading passage into a protected or hazardous area or large slabs of cement whose goal is to prevent forcible passage by a vehicle. Stripes on barricades and panel devices slope downward in the direction traffic must travel. There are also pedestrian barricades - sometimes called bike rack barricades for their resemblance to a now obsolete form of bicycle stand, or police barriers. They originated in France approximately 50 years ago and are now produced around the world. They were first produced in the U.S. 40 years ago by Friedrichs Mfg for New Orleans's Mardi Gras p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portland Cement
Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar, stucco, and non-specialty grout. It was developed from other types of hydraulic lime in England in the early 19th century by Joseph Aspdin, and is usually made from limestone. It is a fine powder, produced by heating limestone and clay minerals in a kiln to form clinker, grinding the clinker, and adding 2 to 3 percent of gypsum. Several types of portland cement are available. The most common, called ordinary portland cement (OPC), is grey, but white Portland cement is also available. Its name is derived from its resemblance to Portland stone which was quarried on the Isle of Portland in Dorset, England. It was named by Joseph Aspdin who obtained a patent for it in 1824. His son William Aspdin is regarded as the inventor of "modern" portland cement due to his developments in the 1840s. The low cost and widespread availability of the limestone, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FEMA - 3228 - Photograph By Andrea Booher Taken On 07-09-1993
The Federal Emergency Management Agency (FEMA) is an agency of the United States Department of Homeland Security (DHS), initially created under President Jimmy Carter by Presidential Reorganization Plan No. 3 of 1978 and implemented by two Executive Orders on April 1, 1979. The agency's primary purpose is to coordinate the response to a disaster that has occurred in the United States and that overwhelms the resources of local and state authorities. The governor of the state in which the disaster occurs must declare a state of emergency and formally request from the President that FEMA and the federal government respond to the disaster. The only exception to the state's gubernatorial declaration requirement occurs when an emergency or disaster takes place on federal property or to a federal asset—for example, the 1995 bombing of the Alfred P. Murrah Federal Building in Oklahoma City, Oklahoma, or the Space Shuttle ''Columbia'' in the 2003 return-flight disaster. While on-the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
