Coastal Squeeze Of Salt Marshes Environmental Sciences Essay

Coastal Squeeze Of Salt Marshes Environmental Sciences Essay Coastal squeeze of salt marshes refers to any situation in which the coastal margin, which is the area buffering land and sea is squeezed between the fixed boundary of the land, and the rising sea level. Numerous studies regarding rising sea level exist, though there is only a select few that directly address the problem of coastal squeeze on tidal marshes. Past 200 years has seen an accelerated and unprecedented loss of natural wetlands due to direct and indirect human activity. A reported 50% or salt marshes are lost or degraded worldwide (MEA 2005, UNEP 2006). Despite ongoing restoration efforts around the world, the overall demands for more housing and associated development activities will lead to more loss of active wetlands. An increasing population, coupled with agricultural development and advances in technology have an ever greater impact on wetlands. Humans have been utilizing wetlands and their resources since the onset of organized civilization. Documented use of salt marshes for ecosystem services date back to the Neolithic in some areas (Knotterus 2005), and the origin of civilization is said to be the Mesopotamian tidal marshes, or the Fertile Crescent. (Sanlaville 2002) Nevertheless, wetlands have been undergoing mass degradation worldwide, with losses in the United States beginning with the arrival of early settlers in the late 16th century. Studies show that the United States has lost 54% of its original 87 million hectares of wetland, and that number is continually dwindling. (Tiner 1984) This loss of wetlands can only be expected to get worse with rising sea level which will drown and squeeze out many coastal marshes. Current predictions expect sea level to rise by 40cm by 2080, producing massive impacts on coastal wetland. Human Use The enclosure of coastal land, namely salt marshes, has been a way of artificially creating productive land for many centuries. Beginning with the colonization of the United States by Dutch and English settlers in the late 17th century, salt marshes were used by humans for a variety of uses, their primary use being grazing of livestock, and harvesting of salt hay to be used as livestock feed and fodder. Salt marshes during this period of time were often artificially diked, filled, planted and tilled to create an alterable and ideal landscape for agricultural use. This widespread drainage was most prevalent in the southern colonies of the United States. As the industrial revolution began in the 19th century, agriculture began to move across the US via Westward Expansion, and an increasing immigrant population and the need for urban expansion yielded a new population which had little connection to the land. In this time period, salt marshes were increasingly converted to usable space, such as housing and industrial factories. (Bromberg- Gedan Sillman 2009) The public perception of salt marshes shifted from that of a fertile agricultural land, to a menace to health and life, a trackless wasteland that must be converted to a usable landscape. In this time period, a large portion of the United States salt marshes were converted into other types of environments, often urbanized. It was not until the late 1960s that the value of salt marshes was recognized again by the United States public and governmental population, and these concerns have deepend over time as repeated environmental and economic disasters validate the predictions of the 60s and 70s. Scientific perspectives towards wetland science are shifting to contain: a wider recognition of the consequences of wetland degradation, opportunities for wetlands to deliver improvements through integrated development, a focus through the conservation movement, and more recognition of ecosystem services within policy frameworks. (Maltby, 2009) The concept of wise use of wetlands, enacted through the Ramsar Convention of 1970, was a major leap forward in the preservation of coastal wetlands, with its regulations and goals still being used in coastal policy today. (Maltby 2009) Though human society has made leaps and bounds in the preservation of salt marshes, the current rate of loss is estimated at 1-2% per year worldwide. (Butler, 2010) The diked coastal floodplain of the US is about 50,000 km in size, much of which would have been coastal wetlands, and while restoration efforts are in place, it is not enough to counteract the loss worldwide. Models suggest that future coastal wetland loss through sea level rise will reach 5-20% of current wetlands by 2080, while urban development will continue to pressure wetlands. The global biodiversity outlook suggests that this coastal squeeze may cause coastal wetland systems to be reduced to narrow fringes by 2100, or lost entirely. (Figure 1) http://www.beachapedia.org/images/d/db/Global_warming_graphic3.gif Figure 1: Anticipated future changes to salt marshes as sea level rises. (Titus 1991) The Importance of salt marshes To stand at the edge of the sea, to sense the ebb and flow of the tides, to feel the breath of a mist moving over a great salt marsh, to watch the flight of shore birds that have swept up and down the surf lines of the continents for untold thousands of years, to see the running of the old eels and the young shad to sea, is to have the knowledge of things that are nearly eternal as any earthly life can be.- Rachel Carson, Under the Sea Wind, 1941 National academy of Sciences defines wetlands as: ecosystems that depend on constant or recurrent, shallow inundation or saturation at or near the surface of the substrate. The minimum essential characteristics of a wetland are recurrent, sustained inundation or saturated at or near the surface and the presence of physical, chemical, and biological features reflective of recurrent, sustained inundation or saturation. Common diagnostic features of wetlands are hydric soils, and hydrophytic vegetation. These features will not be present where specific physio-chemical, biotic, or anthropogenic factors have removed them or prevented their development. (Natural Resource Council, 1995) Technically, wetlands can occur in any area in which precipitation is larger than losses from evaporation and drainage, but are dependent on how humans choose to use them. Since the colonization of the United States, wetlands have been steadily decreasing. Wetland occur over a wide range of environments, from the arctic to the tropics, from coastal areas to secluded intercontinental areas. The total wetland area on earth has been estimated to be approximately 6% of its total land surface at a minimum, as many countries do not have comprehensive inventories of identified wetlands. (Mitsch and Gosselink, 2000) In North America, specifically the USA and Canada, there is an estimated 14.2 million hectares of wetlands (Scott and Jones 1995). The wetlands of the United States span the entire east coast, and are also incredibly extensive along the Gulf of Mexico, but less common on the steeper, rockier Pacific coast. This paper will focus on the salt marshes of the Eastern United States, namely New England. Complex interactions take place within these ecosystems, in which the biotic and abiotic world are fully linked. The interactions that take place within these environments provide the basis for the delivery of goods and services from these ecosystems. The provision of these services, however, is reliant on the maintenance and protection of these ecosystems. Benefits from ecological processes that occur in wetlands are not always obvious, and for this reason, they tend to be ignored by humans when decisions are made to alter wetlands. As stated in The Wetlands Handbook, Wetland functions are the result of ecological processes that are necessary for the self-maintenance of the ecosystems, and occur without human intervention. (Maltby 2009) Wetlands protect and maintain water quality by providing a filter for sediments and excess nutrients, essentially purifying water in connected water resources, such as oceans, lakes, and rivers, which are used by humans for recreational activities, and drinking water. Nutrients, toxins, and sediments enter the wetland environment via runoff, which in urban areas can contain very high levels of toxic materials which could contaminate the water supply, if not for filtration via marshes and wetlands. Scientists have estimated that wetlands may remove between 70% and 90% of the worlds entering nitrogen (Reilly 1991, Gilliam 1994), in addition to the removal of pathogens, toxic metals such as lead and copper, surface water pollutants, and other nutrients such as phosphorus. Salt marshes alone sequester more carbon in their soils than any other temperate biome partially due to the unique microbes that live in these environments, sequestering roughly 771 Billion tons, the same amount that i s currently in our atmosphere. In addition to this, they contribute 1% or more to the annual global loss of fixed nitrogen via microbially mediated denitrification. (Schuster Watson 2007) The hydrology of a particular wetland environment controls every factor of the ecosystem, including nutrient cycling, biogeochemical processes, species biodiversity, and filtration. (Maltby 2009) Coastal Wetlands are not only an interface between land and sea, but also an interface between groundwater, surface water, and atmospheric moisture. Wetlands process key ecosystem elements such as nitrogen, carbon, and phosphorus, and thus are the basis of ecosystem functioning and balance. It is this balance that maintains the supply of wetland products and service that are valuable to humans and other species alike. However, like many environments, this balance is fragile, and the removal or addition of one key element could alter the way the entire ecosystem functions. Salt marshes provide many valuable ecosystem services which must be preserved. (Table 1) Salt marshes act as natural filters that purify water entering the estuary (Mitsch and Gosselink 2008). As water passes through marshes, it slows due to friction of grasses. Suspended sediments are then deposited on the marsh surface, facilitating nutrient uptake, and filtering the water. This filtration is very valuable to human drinking water, as displayed In Louisiana, where treatment of wastewater attained capitalized cost savings of $785 to $15,000/acre compared to municipal treatment. (Breaux 1995) Marshes are an important storm buffer, and provide many resources such as fish, sand, gravel, hay, and shellfish to humans. Table 1 Values of ecosystem services of tidal marshes Ecosystem service Examples of human benefits Average value (Adj. 2007 $a haà ¢Ã‹â€ Ã¢â‚¬â„¢1 yearà ¢Ã‹â€ Ã¢â‚¬â„¢1) Disturbance regulation Storm protection and shoreline protection $2824 Waste treatment Nutrient removal and transformation $9565 Habitat/refugia Fish and shrimp nurseries $280 Food production Fishing, hunting, gathering, aquaculture $421 aw materials Fur trapping $136 Recreation Hunting, fishing, birdwatching $1171 TOTAL $14,397 Table 1: Estimated monetary value of ecosystem services marshes provide on an annual basis (Gedan Bromwell, 2009) Dollar values were adjusted for inflation from original data, presented in 1994 dollars (Costanza et al. 1997). The adjustment was done with the U.S. Department of Labor Inflation Calculator, which uses the Consumer Price Index to correct values through time. Please see Costanza et al. (1997) for valuation methods and note that this valuation method is not universally accepted by economists, see Bockstael et al. (2000) Coastal Squeeze in Marshes Coastal squeeze, as defined by the Environment Agency of England is The reduction of intertidal (mean low water spring tide to mean high water spring tide) habitat as a consequence of sea level rise and the action of flood defenses. If sea levels rise without flood defenses in place, the inter-tidal area is able to gradually move inland over time and there is no net loss of habitat. With defenses or other constraints present, the movement inland of the high water line is impeded, but the low waterline moves shoreward, which leads to a loss of the inter-tidal delta. (Figure 2) (Black and Veatch, 2006) It occurs when landward conversion is not able to take place. Landward conversion takes place when the lower limits of salt marsh habitats are eroded, and the eroded sediments are re-deposited further landwards. This process is often referred to as habitat rollover. http://www.eloisegroup.org/themes/climatechange/images/coastal_squeeze.jpg Figure 2: Illustration of the process of coastal squeeze due to seawalls. (Pontee 2011) Causes of Coastal Squeeze There are many different driving factors of coastal squeeze, including sea level rise, waves, storm activity, sediment supply, and sediment mobility. Coastal erosion is the main factor in coastal squeeze, as it would not be able to occur if it were not for sea level rise and the resulting need for a migration of the salt marsh landscape. Natural causes of coastal squeeze are loss of the total wetland area by coastal erosion and inundation, change in forest or beach structure via natural disasters or erosion, migration rather than overall loss, and the accretion of new beach or land. There are also a number of anthropogenic causes of erosion, which tend to be more localized than natural causes. Oftentimes, the erosion is caused by sand and gravel extraction from beaches, the construction of piers or breakwaters, which interrupt sediment transport, and the construction of floodwalls and ditches, which prevent coastal retreat. (Pontee 2011) . Examples of anthropogenic coastal defenses i nclude seawalls, which are large concrete structures, bulkheads, which are retaining walls made of wood (not only do they block landward migration, but also often release toxins into the water), and revetment, which is a sloping structure of rocks which decreases the shallow water refuge of an intertidal zone. (Butler 2007) While the width of coastal environments varies natural on an annual, or even a month to month basis, the result of anthropogenic coastal squeeze are typically long term, if restoration actions are not taken. Relation to Climate Change Climate change can affect salt marshes in a number of different ways, namely through sea level rise, particularly when sea walls prevent marsh vegetation from moving upward and inland. With predicted rates of sea level rise, coastal accretion may very well fail to keep pace with this accelerated rise if a critical threshold is crossed, and marsh vegetation is drowned. (Kirwan and Guntenspergen 2009) However, sea level rise does not always lead to the loss of marsh areas, because some marshes experience a process called vertical accretion, in which sediments accumulate vertically, helping the marsh to maintain their elevation with the respect to sea-level where the supply of sediment is sufficient. This is only possible, however, in areas in which the sediment is available. In areas where the sediment supply is more limited, marshes are more susceptible to coastal squeeze, which may lead to their eventual drowning. Vertical Accretion is not always good, however, because after a certai n height, marshes will no longer be regularly inundated by the tide, and this accretion will form a natural barrier. (Temmerman et al 2004) Rising levels of Co2 may affect salt marsh plants and limit their response to coastal squeeze, and temperature change could potentially alter the geographical distribution of salt marshes in temperate and arctic latitudes. (Chapman 1977) However, temperature may change too quickly for many marshes to migrate and adjust. Recent evidence suggests that hurricane intensity and frequency is also anticipated to increase with climate change, causing higher rates of erosion in tidal marshes, increasing the rate of coastal squeeze. (IPCC 2007) Case Studies Abbots hall: Abbots hall Farm is located within the Blackwater Estuary of Essex, England. It consists of farmland, dry grassland, salt tolerant grassland, and existing marsh areas. The main factor in the increasing problem of coastal squeeze in this area was the 3.8km of sea wall along the north bank of the Salcott Channel, a main marsh creek. The saltmarsh was on the seaward side of this wall, thus subjecting it to coastal squeeze by limiting it migration landwards. However, the Coastal Realignment project breached the wall in many areas, so as to provide area for new saltmarsh to form inland. While wall still remains at the ends of the farm as property markers, the resulting intermittent, unrestricted areas of marsh now have the potential to remain healthy and viable in the future. While this is an improvement, the Essex coastline still contains over 400 miles of sea wall, built to enclose saltings to improve grazing. Though these are not expected to be taken down in the near futur e, the loss of wetlands may prompt a dire need to do just so. (Figure 3) Figure 3: Rising seas causing a narrowing shoreline on the Blackwater Estuary, Essex (Doody, 2004) The Gulf coast Region of the United States, which includes vast marshes such as the Florida Everglades, is experiencing some of the highest wetland loss rates in the United States, largely because of human interference. The Everglades region of Florida contains a wide array of wetland environments, including sawgrass prairies, salt marshes, tree islands, and mangrove forests. The Southern Florida Project for Flood Control and Other Purposes of 1948 created many canals, floodgates, and levees to reduce flood risks to agriculture, transportation, and urban development. However, they interfered with natural hydrological processes in the area, and in return, actually reduced their natural capacity to mitigate flooding. (Robert Twilley 2007) Future Expectations and Conclusions Global climate change is expected to affect can and atmospheric circulation, sea level rise, the intensity of hurricanes, the magnitude of precipitation, and sea surface and air temperatures. (IPCC 2007) Under normal conditions, salt marshes adjust to these conditions, but under the increased pressures of population rise and urbanization, combined with the ever quickening rate of climate change, salt marshes may not be able to adapt fast enough to the changes occurring around them. The future hydrology of salt marshes will all depend on these factors. In the case of a widespread depletion of salt marshes, we can anticipate the effects to worsen globally.

The Importance of External Factors in Influencing the Conducting

The Importance of External Factors In Influencing The Conducting Of US Foreign Policy To answer the essay question, external factors are indeed important in influencing the conducting of American foreign policy, as they are for all countries. They are important because they determine the direction American foreign policy takes, and with it, can drastically alter the futures of entire countries (Iraq & Afghanistan post 9/11).This essay will devote itself to exploring and explaining how each external factor is important and influential, and proceed to back it up by providing historic and modern examples detailing its effect on US foreign policy, and the end results. These external factors that will be explored are (sequentially) strategic interests of other nations, geographically-based vulnerabilities of the USA in relation to economic and military interests and finally the successes of grass roots revolution in the Arab Spring in upending both long-standing allies and enemies, and it s effect on traditional US foreign policy stances.The first external factor is the strategic interests of both allies and enemies across the world. Due to the USA’s current position as a hyper-power with a global presence, its influence and interests often collide with those interests or spheres of influence of other nations, ranging from allies such as the United Kingdom, Israel and Poland, to long-time rivals such as the Russian Federation and the People’s Republic of China or find itself involved in a conflict between two different nations (such as the Falklands issue or the current Israel-Iran crisis).In such situations where the USA must interact with other involved nation-states, the USA has either attempted to compromise with the other parties involved in an attempt to reach an amicable solution or fully backed a local ally/pursued its own objectives to the detriment of local nation-states.One of the more notable examples of the first is in the long-running nego tiations with North Korea, where six-country negotiations (featuring Russia, America, China, Japan and both Koreas) have been ongoing since 2003, primarily concerning North Korea’s nuclear program but also the normalization of trade, demilitarization and normalization of diplomatic relations.In no less than six different rounds of negotiations (with a seventh one starting in 2012), the United States has sat down for talks with the isolationist North Koreans, attempting to reach an agreement to the satisfaction of all the regional powers involved, an agreement that would see international concerns over North Korea’s nuclear program addressed, as well as pave a way towards future reunification.While talks have continually broken down or bore little fruit, this is more so due to unrealistic North Korean demands and various violations than the USA negotiating under false pretenses or seeking personal advancement. The North Korean talks in particular stand as a specific cas e where the USA has and continues to work alongside regional powers for the benefit of all involved. The second approach taken by the USA is that of fully favoring one side or party in a conflict or situation (usually a long-term ally or one of more relevance) over the other side, sometimes to its own eventual detriment.A prime example of this would be the Israel-Palestine situation in the Middle East today. While the United States has several allies among the Arab nations (Jordan, the Gulf states, Saudi Arabia, Yemen, formerly Egypt†¦), it has always prioritized Israel as its main ally in the region, providing it with billions of dollars yearly in grants, equipping it with some of the most advanced military technology in the world and sharing intelligence since the 1950s.As a result of these incredibly close ties to the Jewish state, the United States is often viewed as responsible or linked to Israel’s actions, while at the same benefiting from its use as a local proxy . So mutually linked however are the two nation-states, that it has directly anchored the USA into the morass of the Israeli-Palestine situation, an action that has often invited Arab rage against the Americans, most infamously concerning Al Qaeda and the 9/11 attack.While pure political/strategic matters are a critical and pervasive external factor in US foreign policy, there is also a backdrop of geography-based concerns that are particularly dangerous to the US’s foreign policy aims. The first element of geographic factor is an economic concern relating the international shipping lanes such as those of the Persian Gulf, while the second element is a military one, involving the supplying of NATO military forces in the land-locked status of Afghanistan.The first element is the more globally threatening one, as shipping lanes such as those of the Panama Canal (Central America), the Horn of Africa (East Africa) and the Hormuz Straits (Persian Gulf) are economic chokepoints, im portant to not only a hyper-power as the USA but the entire world economy. They are important because they are integral waterways in the world economy, shipping massive amounts of Persian Gulf oil daily across the world to countries such as India, China and the USA (nearly 46% of the world’s seaborne petroleum is shipped through both areas together).For the US specifically however, the Persian Gulf is a life-line that cannot be severed, even for a brief period. In 2006 for example, U. S. gross oil imports from the Persian Gulf were 2. 2 million barrels per day, accounting for 17 percent of the US total net oil imports. As such, oil-client states such as India, China, America, and Britain among others have warships detailed to the regions to protect and ensure safe shipping, as well as dealing with piracy.The USA specifically maintains its 5th Fleet in the area, being responsible for the Red Sea, the Persian Gulf, the Arabian Sea and the Gulfs of Aden & Oman. The second elemen t, the military one is far more US-centric, however. Ever since the invasion of Afghanistan in 2001, NATO forces in the country have been reliant on supply routes going through Pakistan in order to continue operating. As reported by CJ Radin, the supply route starts at the Pakistani port of Karachi, where ships dock and offload their supplies onto trucks.The trucks then drive through Pakistan and enter Afghanistan through either the Khyber Pass near Peshawar or through the Chaman crossing near Quetta. However, due to multiple incidents (the OBL Abbottabad raid, drone airstrikes killing Pakistani citizens, various cross-border raids, Pakistani covert support to Taliban cells, Taliban ambushes of supply convoys from the Pakistani border, etc†¦), the relationship between Pakistan and the USA has grown strained, first limiting and then stopping the supplies landing from Karachi.As a whole, the Pakistani route was quite crucial to the NATO military effort, being the closest and most developed friendly port/road network into Afghanistan. Without supplies, NAO faced a struggle to continue their operations against resilient Taliban cells, a struggle that was slowly relieved by the slow build up of a northern network over the course of the last four years through Russia, Turkey and various Baltic, Caucasian & Central Asian states.This network has two different routes, one starting at a Baltic port, then by rail through Russia, Kazakhstan, and then to Uzbekistan before reaching NATO, while the other brings supplies by ship or rail to a Georgian port on the Black Sea, then by rail through Georgia and Azerbaijan, by ferry across the Caspian Sea, and by rail again through Kazakhstan and Uzbekistan, though it is reportedly by far the most limited.Overall, nearly 35% of US supplies in April 2010, 50% in April 2011, and 55%-65% in July-Sept 2011 came from the new northern network, while other NATO forces received roughly 40% the northern network. These instances both ind icate the striking lengths that the USA is affected by such vulnerabilities, as well as how strongly they are tied to American economic and military instances. In discussing American interests in regions such as Central Asia and the Middle East, one cannot ignore the effects of the Arab Spring.While much ink has devoted to this subject since 2011, here in this essay I will only focus on its affect on traditional US foreign policy stances. To put it simply, since the Cold War, the United States has gained a habit of often backing authoritarian or despotic regimes, monarchies such as Saudi Arabia and Iran (prior to the Islamic Revolution) or strongman republics such as Yemen and Pakistan.These countries repressed their citizenry, yet as long as they were American allies, they were celebrated, or even praised as loyal and as champions of stability and good, while other authoritarian regimes received lambasting and sanctions and other punishments. While Iraq received democracy and liber ation from Saddam, while Condoleezza Rice spoke of the violence wrecked upon Hamas-ruled Gaza and Hezballoh-influenced Lebanon as the â€Å"birth pangs of a new Middle East†, it was the Arab Spring that brought forth a new Middle East.Over a dozen homegrown instances of civil resistance, of rebellion, of revolution, successful or otherwise, all attempted and/or achieved without US prompting. In Libya, in Egypt, in Tunisia, Yemen, long-standing regimes have fallen. Authentic democracies are starting to develop, democracies with no inherent ties or links to the United States, with no reason to reach out to them directly. If I can quote Noam Chomsky on one thing, it’s that the USA cannot count on these new governments to be as friendly or welcoming as their predecessors.It can’t treat these new governments as their predecessors, it can’t control their opinions on Israel or Iran, it can’t easily buy their loyalties, not as things are still unfolding. I n effect, the United States now has to come up with new policies, new strategies to deal with these countries, to decide on continuing pre-existing deals or renegotiate new ones. In conclusion, there are several very important external factors that influence how American foreign policy is conducted, and they are truly important.Learning to how to recognize and compromise in order to accept the strategic interests of other nations, how to handle the geographic limitations and vulnerabilities that often define or control the options available in a situation, and how to adapt to dealing with lesser, developing nations that while democratic are not favorable to you or your interests. Bibliography CJ Radin, 2011, Focus ‘Analysis: The US-Pakistan relationship and the critical factor of supply’ [online] 4 December. Available: Daily Mail Reporter, 2011, Focus: ‘Pakistan gives US two week ultimatum’ [online] 8 November. Available: http://www. dailymail. co. uk/news /article-2066488/Pakistan-gives-US-2-week-ultimatum-abandon-secret-airbase-closes-border. html Cox, M. and Stoke, D. , 2008, US Foreign Policy, Oxford: Oxford University Press Lansford, T. , 2003, A Bitter Harvest: US Foreign Policy & Afghanistan, Ashgate Holsti, O. , 2006, Making American Foreign Policy, Routledge DeAlkatine, N. , 2012, American Diplomacy: Interpreting the Arab Spring, Journal, Range 1996, Available from UWE Library

Dams and Reservoirs

A dam is any barrier that holds back water; dams are primarily used to save, manage, and/or prevent the flow of excess water into specific regions. In addition, some dams are used to generate hydropower. This article examines man-made dams but dams can also be created by natural causes like mass wasting events or even animals like the beaver. Another term often used when discussing dams is reservoir. A reservoir is a man-made lake that is primarily used for storing water. They can also be defined as the specific bodies of water formed by the construction of a dam. For example, the Hetch Hetchy Reservoir in California’s Yosemite National Park is the body of water created and held back by the O’Shaughnessy Dam. Types of Dams One of the most common types of major dams is the arch dam. These masonry or concrete dams are ideal for narrow and/or rocky locations because their curved shape easily holds back water via gravity without the need for a lot of construction materials. Arch dams can have one large single arch or they can have multiple small arches separated by concrete buttresses. The Hoover Dam which is on the border of the U.S. states of Arizona and Nevada is an arch dam. Another type of dam is the buttress dam. These can have multiple arches, but unlike a traditional arch dam, they can be flat as well. Normally buttress dams are made of concrete and feature a series braces called buttresses along the downstream side of the dam to prevent the natural flow of water. The Daniel-Johnson Dam in Quebec, Canada is a multiple arch buttress dam. In the U.S., the most common type of dam is the embankment dam. These are large dams made out of soil and rock which use their weight to hold back water. To prevent water from moving through them, embankment dams also have a thick waterproof core. The Tarbela Dam in Pakistan is the world’s largest embankment dam. Finally, gravity dams are huge dams that are constructed to hold back water using only their own weight. To do this, they are constructed using extensive amounts of concrete, making them difficult and expensive to build. The Grand Coulee Dam in the U.S. state of Washington is a gravity dam. Types of Reservoirs and Construction The first and usually largest type of reservoir is called a valley dammed reservoir. These are reservoirs that are located in narrow valley areas where tremendous amounts of water can be held in by the valley’s sides and a dam. The best location for a dam in these types of reservoirs is where it can be built into the valley wall most effectively to form a water tight seal. To construct a valley dammed reservoir, the river must be diverted, usually through a tunnel, at the start of work. The first step in creating this type of reservoir is the pouring of a strong foundation for the dam, after which construction on the dam itself can begin. These steps can take months to years to complete, depending on the size and complexity of the project. Once finished, the diversion is removed and the river is able to flow freely toward the dam until it gradually fills the reservoir. Dam Controversy In addition, the creation of a reservoir requires the flooding of large areas of land, at the expense of the natural environment and sometimes villages, towns and small cities. The construction of China’s Three Gorges Dam, for example, required the relocation of over one million people and flooded many different archaeological and cultural sites. Main Uses of Dams and Reservoirs Another major use of dams is power generation as hydroelectric power is one of the world’s major sources of electricity. Hydropower is generated when the potential energy of the water on the dam drives a water turbine which in then turns a generator and creates electricity. To best make use of the water’s power, a common type of hydroelectric dam uses reservoirs with different levels to adjust the amount of energy generated as it is needed. When demand is low for instance, water is held in an upper reservoir and as demand increases, the water is released into a lower reservoir where it spins a turbine. Some other important uses of dams and reservoirs include a stabilization of water flow and irrigation, flood prevention, water diversion and recreation. To learn more about dams and reservoirs visit PBSs Dams Site. Rogun - 1,099 feet (335 m) in TajikistanNurek - 984 feet (300 m) in TajikistanGrande Dixence - 932 feet (284 m) in SwitzerlandInguri - 892 feet (272 m) in GeorgiaBoruca - 876 feet (267 m) in Costa RicaVaiont - 860 feet (262 m) in ItalyChicoasà ©n - 856 feet (261 m) in MexicoTehri - 855 feet (260 m) in Indiaà lvaro Abregà ³n - 853 feet (260 m) in MexicoMauvoisin - 820 feet (250 m) in SwitzerlandLake Kariba - 43 cubic miles (180 km ³) in Zambia and ZimbabweKuybyshev Reservoir - 14 cubic miles (58 km ³) in Russia

DRNC Scenario Free Essay Example, 1000 words

It should be noted that U. S. law enforcement agencies have always experienced a struggle in terms of challenges experienced when policing mass demonstrations as well as when crowd control is required. As the PARC (2014) portal portrays, failures in overall incorporation of best practices as well as model policies in terms of preparation for, and subsequent responses to mass demonstrations are responsible for eventual injuries and deaths witnessed. Such injuries or deaths are experienced on both sides where protestors and police officers being prone in addition to non-participatory party entities caught in such situations (PARC, 2014). Apart from physical and psychological negative effects, such contexts often result in a variety of civil legal challenges that may eventually cost the policing agencies huge amounts of money. As Reynardus (2004) alludes, this may be because of civil settlements and awards paid out to plaintiffs, who successfully present alleged utility of policing tactics and policies that are unconstitutional in a given court of law. Thus, in the prior planning of anticipated mass demonstrations by city officials and police leaders amongst other critical stakeholders, there are basic issues to consider. We will write a custom essay sample on DRNC Scenario or any topic specifically for you Only $17.96 $11.86/pageorder now These pertain to aspects regarding intelligence, training, strategic planning, inter-agency coordination, supervision, appropriate tactics, communication strategies, dispersal announcement procedures, appropriate uses-of-force guidance plans, proper officer identification, mass arrests planning, and the adequate preparation of humane and sufficient detention sites (Reynardus, 2004). DRNC special event in Miami-Dade: Strategies, Preparation and Policy Measures Due to the various issues that are expected to arise because of such situational contexts, the U. S. Department of Justice Office of Community Oriented Policing Services (COPS) provides strategic policy input, provisions and pertinent standard measures. As directed by the Consolidated Appropriations Act (2004), submission of ‘best practices’ is thus a critical part of policy procedure. Accordingly, this pertains to action plans aimed at enhancing overall security, peace and order during special events of local, national and/ or regional importance. Thus, various state entities in the U. S. do draw from amalgamation of all provided ‘best practices’ as encapsulated within the Planning and Managing Security for Major Special Events: Guidelines for Law Enforcement National Report, as their baseline of operational procedures (U. S. DRNC Scenario Free Essay Example, 1000 words As Reynardus (2004) alludes, this may be because of civil settlements and awards paid out to plaintiffs, who successfully present alleged utility of policing tactics and policies that are unconstitutional in a given court of law. Thus, in the prior planning of anticipated mass demonstrations by city officials and police leaders amongst other critical stakeholders, there are basic issues to consider. These pertain to aspects regarding intelligence, training, strategic planning, inter-agency coordination, supervision, appropriate tactics, communication strategies, dispersal announcement procedures, appropriate uses-of-force guidance plans, proper officer identification, mass arrests planning, and the adequate preparation of humane and sufficient detention sites (Reynardus, 2004). DRNC special event in Miami-Dade: Strategies, Preparation and Policy Measures Due to the various issues that are expected to arise because of such situational contexts, the U. S. Department of Justice Office of Community Oriented Policing Services (COPS) provides strategic policy input, provisions and pertinent standard measures. As directed by the Consolidated Appropriations Act (2004), submission of ‘best practices’ is thus a critical part of policy procedure. Accordingly, this pertains to action plans aimed at enhancing overall security, peace and order during special events of local, national and/ or regional importance. We will write a custom essay sample on DRNC Scenario or any topic specifically for you Only $17.96 $11.86/pageorder now Thus, various state entities in the U. S. do draw from amalgamation of all provided ‘best practices’ as encapsulated within the Planning and Managing Security for Major Special Events: Guidelines for Law Enforcement National Report, as their baseline of operational procedures (U. S. Department of Justice Community Relations Service (U. S. DJCRS), 2000). As Captain Barry Jackson, co-chair of the Mass Arrest/ Casualty Subcommittee (Miami-Dade Police Department), I would tactfully implement the provisions availed in the aforementioned National Report. This would be through adaptation of such ‘best practices’, to the prevailing and potential contexts within our region of jurisdiction. In these regard, the consideration and subsequent identification of key issues associated with possible mass arrests and/ or casualties during the DRNC special event can be adequately derived from the FTAA Miami IRP Report. The Independent Review Panel, an external apparatus for fact-finding and subsequent dispute resolution found a variety of issues that affected the overall effectiveness and efficiency with which the MDPD was able to cater for the security needs of society during the FTAA Miami 2003 conference (Reynardus, 2004).