Population density is a measurement of population per unit area or unit volume. It is applied to living organisms, most of the time to humans, it is a key geographical term. In simple terms population density refers to the number of people living in an area per kilometer square. Population density is population divided by total land water volume, as appropriate. Low densities may lead to further reduced fertility; this is called the Allee effect after the scientist. Examples of the causes in low population densities include: Increased problems with locating sexual mates Increased inbreeding For humans, population density is the number of people per unit of area quoted per square kilometer or square mile; this may be calculated for a county, country, another territory or the entire world. The world's population is around 7,500,000,000 and Earth's total area is 510,000,000 square kilometers. Therefore, the worldwide human population density is around 7,500,000,000 ÷ 510,000,000 = 14.7 per km2. If only the Earth's land area of 150,000,000 km2 is taken into account human population density is 50 per km2.
This includes all continental and island land area, including Antarctica. If Antarctica is excluded population density rises to over 55 people per km2. However, over half of the Earth's land mass consists of areas inhospitable to human habitation, such as deserts and high mountains, population tends to cluster around seaports and fresh-water sources. Thus, this number by itself does not give any helpful measurement of human population density. Several of the most densely populated territories in the world are city-states and dependencies; these territories have a small area and a high urbanization level, with an economically specialized city population drawing on rural resources outside the area, illustrating the difference between high population density and overpopulation The potential to maintain the agricultural aspects of deserts is limited as there is not enough precipitation to support a sustainable land. The population in these areas are low. Therefore, cities in the Middle East, such as Dubai, have been increasing in population and infrastructure growth at a fast pace.
Cities with high population densities are, by some, considered to be overpopulated, though this will depend on factors like quality of housing and infrastructure and access to resources. Most of the most densely populated cities are in Southeast Asia, though Cairo and Lagos in Africa fall into this category. City population and area are, however dependent on the definition of "urban area" used: densities are invariably higher for the central city area than when suburban settlements and the intervening rural areas are included, as in the areas of agglomeration or metropolitan area, the latter sometimes including neighboring cities. For instance, Milwaukee has a greater population density when just the inner city is measured, the surrounding suburbs excluded. In comparison, based on a world population of seven billion, the world's inhabitants, as a loose crowd taking up ten square feet per person, would occupy a space a little larger than Delaware's land area; the Gaza Strip has a population density of 5,046 pop/km.
Although arithmetic density is the most common way of measuring population density, several other methods have been developed to provide a more accurate measure of population density over a specific area. Arithmetic density: The total number of people / area of land Physiological density: The total population / area of arable land Agricultural density: The total rural population / area of arable land Residential density: The number of people living in an urban area / area of residential land Urban density: The number of people inhabiting an urban area / total area of urban land Ecological optimum: The density of population that can be supported by the natural resources Demography Human geography Idealized population Optimum population Population genetics Population health Population momentum Population pyramid Rural transport problem Small population size Distance sampling List of population concern organizations List of countries by population density List of cities by population density List of city districts by population density List of English districts by population density List of European cities proper by population density List of United States cities by population density List of islands by population density List of U.
S. states by population density List of Australian suburbs by population density Selected Current and Historic City, Ward & Neighborhood Density Duncan Smith / UCL Centre for Advanced Spatial Analysis. "World Population Density". Exploratory map shows data from the Global Human Settlement Layer produced by the European Commission JRC and the CIESIN Columbia University
A floodplain or flood plain is an area of land adjacent to a stream or river which stretches from the banks of its channel to the base of the enclosing valley walls, which experiences flooding during periods of high discharge. The soils consist of levees and sands deposited during floods. Levees are the heaviest materials and they are deposited first. Floodplains are formed; when a river breaks its banks, it leaves behind layers of alluvium. These build up to create the floor of the plain. Floodplains contain unconsolidated sediments extending below the bed of the stream; these are accumulations of sand, loam, and/or clay, are important aquifers, the water drawn from them being pre-filtered compared to the water in the river. Geologically ancient floodplains are represented in the landscape by fluvial terraces; these are old floodplains that remain high above the present floodplain and indicate former courses of a stream. Sections of the Missouri River floodplain taken by the United States Geological Survey show a great variety of material of varying coarseness, the stream bed having been scoured at one place and filled at another by currents and floods of varying swiftness, so that sometimes the deposits are of coarse gravel, sometimes of fine sand or of fine silt.
It is probable that any section of such an alluvial plain would show deposits of a similar character. The floodplain during its formation is marked by meandering or anastomotic streams, oxbow lakes and bayous, marshes or stagnant pools, is completely covered with water; when the drainage system has ceased to act or is diverted for any reason, the floodplain may become a level area of great fertility, similar in appearance to the floor of an old lake. The floodplain differs, because it is not altogether flat, it has a gentle slope downstream, for a distance, from the side towards the center. The floodplain is the natural place for a river to dissipate its energy. Meanders form over the floodplain to slow down the flow of water and when the channel is at capacity the water spills over the floodplain where it is temporarily stored. In terms of flood management the upper part of the floodplain is crucial as this is where the flood water control starts. Artificial canalisation of the river here will have a major impact on wider flooding.
This is the basis of sustainable flood management. Floodplains can support rich ecosystems, both in quantity and diversity. Tugay forests form an ecosystem associated with floodplains in Central Asia, they are a category of riparian systems. A floodplain can contain 100 or 1,000 times as many species as a river. Wetting of the floodplain soil releases an immediate surge of nutrients: those left over from the last flood, those that result from the rapid decomposition of organic matter that has accumulated since then. Microscopic organisms thrive and larger species enter a rapid breeding cycle. Opportunistic feeders move in to take advantage; the production of nutrients falls away quickly. This makes floodplains valuable for agriculture. River flow rates are undergoing change following suit with climate change; this change is a threat to other floodplain forests. These forests have over time synced their seedling deposits after the spring peaks in flow to best take advantage of the nutrient rich soil generated by peak flow.
Many towns have been built on floodplains, where they are susceptible to flooding, for a number of reasons: access to fresh water. The worst of these, the worst natural disaster were the 1931 China floods, estimated to have killed millions; this had been preceded by the 1887 Yellow River flood, which killed around one million people, is the second-worst natural disaster in history. The extent of floodplain inundation depends in part on the flood magnitude, defined by the return period. In the United States the Federal Emergency Management Agency manages the National Flood Insurance Program; the NFIP offers insurance to properties located within a flood prone area, as defined by the Flood Insurance Rate Map, which depicts various flood risks for a community. The FIRM focuses on delineation of the 100-year flood inundation area known within the NFIP as the Special Flood Hazard Area. Where a detailed study of a waterway has been done, the 100-year floodplain will include the floodway, the critical portion of the floodplain which includes the stream channel and any adjacent areas that must be kept free of encroachments that might block flood flows or restrict storage of flood waters.
Another encountered term is the Special Flood Hazard Area, any area subject to inundation by the 100-year flood. A problem is that any alteration of the watershed upstream of the point in question can affect the ability of the watershed to handle water, thus affects the levels of the periodic floods. A large shopping center and parking lot, for example, may raise the levels of the 5-year, 100-year, other floods, but the maps are adjusted, are rendered
Marriage called matrimony or wedlock, is a or ritually recognised union between spouses that establishes rights and obligations between those spouses, as well as between them and any resulting biological or adopted children and affinity. The definition of marriage varies around the world not only between cultures and between religions, but throughout the history of any given culture and religion, evolving to both expand and constrict in who and what is encompassed, but it is principally an institution in which interpersonal relationships sexual, are acknowledged or sanctioned. In some cultures, marriage is recommended or considered to be compulsory before pursuing any sexual activity; when defined broadly, marriage is considered a cultural universal. A marriage ceremony is known as a wedding. Individuals may marry for several reasons, including legal, libidinal, financial and religious purposes. Whom they marry may be influenced by gender determined rules of incest, prescriptive marriage rules, parental choice and individual desire.
In some areas of the world, arranged marriage, child marriage and sometimes forced marriage, may be practiced as a cultural tradition. Conversely, such practices may be outlawed and penalized in parts of the world out of concerns of the infringement of women's rights, or the infringement of children's rights, because of international law. Around the world in developed democracies, there has been a general trend towards ensuring equal rights within marriage for women and recognizing the marriages of interfaith and same-sex couples; these trends coincide with the broader human rights movement. Marriage can be recognized by a state, an organization, a religious authority, a tribal group, a local community, or peers, it is viewed as a contract. When a marriage is performed and carried out by a government institution in accordance with the marriage laws of the jurisdiction, without religious content, it is a civil marriage. Civil marriage recognizes and creates the rights and obligations intrinsic to matrimony before the state.
When a marriage is performed with religious content under the auspices of a religious institution it is a religious marriage. Religious marriage recognizes and creates the rights and obligations intrinsic to matrimony before that religion. Religious marriage is known variously as sacramental marriage in Catholicism, nikah in Islam, nissuin in Judaism, various other names in other faith traditions, each with their own constraints as to what constitutes, who can enter into, a valid religious marriage; some countries do not recognize locally performed religious marriage on its own, require a separate civil marriage for official purposes. Conversely, civil marriage does not exist in some countries governed by a religious legal system, such as Saudi Arabia, where marriages contracted abroad might not be recognized if they were contracted contrary to Saudi interpretations of Islamic religious law. In countries governed by a mixed secular-religious legal system, such as in Lebanon and Israel, locally performed civil marriage does not exist within the country, preventing interfaith and various other marriages contradicting religious laws from being entered into in the country, civil marriages performed abroad are recognized by the state if they conflict with religious laws.
The act of marriage creates normative or legal obligations between the individuals involved, any offspring they may produce or adopt. In terms of legal recognition, most sovereign states and other jurisdictions limit marriage to opposite-sex couples and a diminishing number of these permit polygyny, child marriages, forced marriages. In modern times, a growing number of countries developed democracies, have lifted bans on and have established legal recognition for the marriages of interfaith and same-sex couples; some cultures allow the dissolution of marriage through annulment. In some areas, child marriages and polygamy may occur in spite of national laws against the practice. Since the late twentieth century, major social changes in Western countries have led to changes in the demographics of marriage, with the age of first marriage increasing, fewer people marrying, more couples choosing to cohabit rather than marry. For example, the number of marriages in Europe decreased by 30% from 1975 to 2005.
In most cultures, married women had few rights of their own, being considered, along with the family's children, the property of the husband. In Europe, the United States, other places in the developed world, beginning in the late 19th century and lasting through the 21st century, marriage has undergone gradual legal changes, aimed at improving the rights of the wife; these changes included giving wives legal identities of their own, abolishing the right of husbands to physically discipline their wives, giving wives property rights, liberalizing divorce laws, providing wives with reproductive rights of their own, requiring a wife's consent when sexual relations occur. These changes have occurred in Western countries. In the 21st century, there continue to be controversies regarding the legal status of married women, legal acceptance of or leniency towards violence within marriage, traditional marriage customs such as dowry and bride price, for
Per capita income
Per capita income or average income measures the average income earned per person in a given area in a specified year. It is calculated by dividing the area's total income by its total population. Per capita income is national income divided by population size. Per capita income is used to measure an area's average income and compare the wealth of different populations. Per capita income is used to measure a country's standard of living, it is expressed in terms of a used international currency such as the euro or United States dollar, is useful because it is known, is calculable from available gross domestic product and population estimates, produces a useful statistic for comparison of wealth between sovereign territories. This helps to ascertain a country's development status, it is one of the three measures for calculating the Human Development Index of a country. In the United States, it is defined by the U. S. Census Bureau as the following: "Per capita income is the mean money income received in the past 12 months computed for every man and child in a geographic area."
Critics claim that per capita income has several weaknesses in measuring prosperity: Comparisons of per capita income over time need to consider inflation. Without adjusting for inflation, figures tend to overstate the effects of economic growth. International comparisons can be distorted by cost of living differences not reflected in exchange rates. Where the objective is to compare living standards between countries, adjusting for differences in purchasing power parity will more reflect what people are able to buy with their money, it does not reflect income distribution. If a country's income distribution is skewed, a small wealthy class can increase per capita income while the majority of the population has no change in income. In this respect, median income is more useful when measuring of prosperity than per capita income, as it is less influenced by outliers. Non-monetary activity, such as barter or services provided within the family, is not counted; the importance of these services varies among economies.
Per capita income does not consider whether income is invested in factors to improve the area's development, such as health, education, or infrastructure. List of countries by average wage List of countries by GDP per capita—GDP at market or government official exchange rates per inhabitant List of countries by GDP per capita—GDP calculated at purchasing power parity exchange per inhabitant List of countries by GNI per capita List of countries by GNI per capita List of countries by income equality Total personal income
Crawfordsville Crawfordville, is a city in Crittenden County, United States. The population was 479 at the 2010 census; the late Johnnie Taylor, an important figure in both late 1960s and early 1970s Memphis-based soul as well as more recent blues, was born in Crawfordsville. Fred Smith, a former basketball player for the Harlem Globetrotters and the only Green Party member of the Arkansas House of Representatives, serving from District 50, is a Crawfordsville native and a graduate of Crawfordsville High School. Dan Young, an attorney at Rose Law Firm, is from Crawfordsville. Crawfordsville is located near the center of Crittenden County at 35°13′33″N 90°19′35″W. U. S. Route 64 passes just north of the town, leading east 8 miles to Marion and 19 miles to Memphis and west 9 miles to Earle. According to the United States Census Bureau, Crawfordsville has a total area of 0.58 square miles, all land. As of the census of 2000, there were 514 people, 202 households, 142 families residing in the town.
The population density was 451.0/km². There were 222 housing units at an average density of 194.8/km². The racial makeup of the town was 49.81% White, 49.42% Black or African American, 0.19% Asian, 0.58% from two or more races. 1.17% of the population were Hispanic or Latino of any race. There were 202 households out of which 29.7% had children under the age of 18 living with them, 42.1% were married couples living together, 22.3% had a female householder with no husband present, 29.7% were non-families. 27.7% of all households were made up of individuals and 13.4% had someone living alone, 65 years of age or older. The average household size was 2.54 and the average family size was 3.12. In the town, the population was spread out with 27.0% under the age of 18, 8.8% from 18 to 24, 27.0% from 25 to 44, 23.9% from 45 to 64, 13.2% who were 65 years of age or older. The median age was 37 years. For every 100 females, there were 89.7 males. For every 100 females age 18 and over, there were 91.3 males.
The median income for a household in the town was $26,518, the median income for a family was $31,667. Males had a median income of $31,250 versus $19,205 for females; the per capita income for the town was $12,176. About 19.4% of families and 21.1% of the population were below the poverty line, including 27.9% of those under age 18 and 16.4% of those age 65 or over. Marion School District, including Marion High School, serves Crawfordsville. On July 1, 2004 the Crawfordsville School District consolidated into the Marion School District. Crittenden County website
Crittenden County, Arkansas
Crittenden County is a county located in the U. S. state of Arkansas. As of the 2010 census, the population was 50,902; the county seat is Marion, the largest city is West Memphis. Crittenden County is Arkansas's twelfth county, formed October 22, 1825, named for Robert Crittenden, the first Secretary of the Arkansas Territory. Crittenden County is part of TN-MS-AR Metropolitan Statistical Area. Most of the county's media comes from Memphis, although some Little Rock TV is imported by Comcast Cable, it lies within Arkansas's 1st congressional district. According to the U. S. Census Bureau, the county has a total area of 636 square miles, of which 610 square miles is land and 27 square miles is water. Wapanocca National Wildlife Refuge As of the 2010 census, there were 50,902 people residing in the county. 51.2% were Black or African American, 46.1% White, 0.6% Asian, 0.3% Native American, 0.8% of some other race and 1.1% of two or more races. 2.0% were Hispanic or Latino. As of the 2000 census, there were 50,866 people, 18,471 households, 13,373 families residing in the county.
The population density was 83 people per square mile. There were 20,507 housing units at an average density of 34 per square mile; the racial makeup of the county was 50.91% White, 47.05% Black or African American, 0.24% Native American, 0.47% Asian, 0.02% Pacific Islander, 0.66% from other races, 0.64% from two or more races. 1.42% of the population were Hispanic or Latino of any race. There were 18,471 households out of which 37.40% had children under the age of 18 living with them, 45.80% were married couples living together, 21.30% had a female householder with no husband present, 27.60% were non-families. 23.70% of all households were made up of individuals and 8.00% had someone living alone, 65 years of age or older. The average household size was 2.72 and the average family size was 3.23. In the county, the population was spread out with 31.10% under the age of 18, 9.40% from 18 to 24, 29.10% from 25 to 44, 20.50% from 45 to 64, 9.90% who were 65 years of age or older. The median age was 32 years.
For every 100 females there were 91.00 males. For every 100 females age 18 and over, there were 85.00 males. The median income for a household in the county was $30,109, the median income for a family was $34,982. Males had a median income of $31,299 versus $21,783 for females; the per capita income for the county was $14,424. About 21.00% of families and 25.30% of the population were below the poverty line, including 35.30% of those under age 18 and 23.70% of those age 65 or over. Public education for elementary and secondary school students is available from Earle School District, which leads to graduation from Earle High School; the Old Earle High School is listed on the National Register of Historic Places. Is available in West Memphis and Marion. Crittenden County is served by Arkansas State University Mid-South in West Memphis; the college offers bachelor's and master's degree programs in conjunction with Arkansas State University, The University of Arkansas, The University of Central Arkansas, Arkansas Tech University and Franklin University.
Crittenden County was served by 152 Bed Crittenden Regional Hospital in West Memphis until late August 2014. The hospital operated a number of outpatient clinics in Marion and West Memphis and a Pediatric Dental Clinic in cooperation with the UT Dental School. Crittenden Regional Hospital has closed the ER and will permanently close on 7 September 2014; the nearest hospitals are located in Tennessee. The Arkansas Department of Health operates a clinic in West Memphis. A number of private clinics operate in Marion and West Memphis. Crittenden County in the nineteenth century was dominated by black Republicans, who carried the county in most elections from Reconstruction until the “Redeemers” disfranchised all blacks in Arkansas between 1900 and 1960. From 1910 until 1944 it was overwhelmingly Democratic as only whites voted, when faced with a national Civil Rights plank Crittenden was one of three Arkansas counties to vote for Strom Thurmond over Harry S. Truman in 1948. Since the re-enfranchisement of black residents began in the 1950s, Crittenden has been Democratic-voting, despite a large-scale shift of white residents to the GOP, reversing the nineteenth century party alignment.
The last Republican to win the county was George Bush senior in 1988. Crittenden County is served by the West Memphis Municipal Airport, a General Aviation facility with a Control Tower and Instrument Landing capabilities. General DeWitt Spain Airport is a civil aviation airport just north of downtown Memphis; the Memphis International Airport is nearby and provides commercial aviation through numerous carriers and is the international cargo hub for FedEx. Union Pacific operates a 600 Acre intermodal facility west of Arkansas. BNSF Railway operates a yard in Marion. Limited Passenger Rail is available on Amtrak at Memphis Central Station in nearby Memphis; the City of New Orleans runs twice daily on a North-South route from Chicago to New Orleans. Crittenden County and West Memphis jointly operate a port on the Mississippi River; the International Port of Memphis lies just across the Mississippi River via Interstate 55. The International Port of Memphis is the 4th largest inland port in the United States.
Crawfordsville Earle Marion Turrell West Memphis Townships in Arkansas are the divisions of a county. Each township includes unincorporated areas. Arkansas townships have limited purposes in modern times. However, the United States Census does list Arkansas populat
A meander is one of a series of regular sinuous curves, loops, turns, or windings in the channel of a river, stream, or other watercourse. It is produced by a stream or river swinging from side to side as it flows across its floodplain or shifts its channel within a valley. A meander is produced by a stream or river as it erodes the sediments comprising an outer, concave bank and deposits this and other sediment downstream on an inner, convex bank, a point bar; the result of sediments being eroded from the outside concave bank and their deposition on an inside convex bank is the formation of a sinuous course as a channel migrates back and forth across the down-valley axis of a floodplain. The zone within which a meandering stream shifts its channel across either its floodplain or valley floor from time to time is known as a meander belt, it ranges from 15 to 18 times the width of the channel. Over time, meanders migrate downstream, sometimes in such a short time as to create civil engineering problems for local municipalities attempting to maintain stable roads and bridges.
The degree of meandering of the channel of a river, stream, or other watercourse is measured by its sinuosity. The sinuosity of a watercourse is the ratio of the length of the channel to the straight line down-valley distance. Streams or rivers with a single channel and sinuosities of 1.5 or more are defined as meandering streams or rivers. The term derives from the Meander River located in present-day Turkey and known to the Ancient Greeks as Μαίανδρος Maiandros, characterised by a convoluted path along the lower reach; as a result in Classical Greece the name of the river had become a common noun meaning anything convoluted and winding, such as decorative patterns or speech and ideas, as well as the geomorphological feature. Strabo said: ‘…its course is so exceedingly winding that everything winding is called meandering.’The Meander River is south of Izmir, east of the ancient Greek town of Miletus, now Milet, Turkey. It flows through a graben in the Menderes Massif, but has a flood plain much wider than the meander zone in its lower reach.
Its modern Turkish name is the Büyük Menderes River. When a fluid is introduced to an straight channel which bends, the sidewalls induce a pressure gradient that causes the fluid to alter course and follow the bend. From here, two opposing processes occur: secondary flow. For a river to meander, secondary flow must dominate. Irrotational flow: From Bernoulli's equations, high pressure results in low velocity. Therefore, in the absence of secondary flow we would expect low fluid velocity at the outside bend and high fluid velocity at the inside bend; this classic fluid mechanics result is irrotational vortex flow. In the context of meandering rivers, its effects are dominated by those of secondary flow. Secondary flow: A force balance exists between pressure forces pointing to the inside bend of the river and centrifugal forces pointing to the outside bend of the river. In the context of meandering rivers, a boundary layer exists within the thin layer of fluid that interacts with the river bed. Inside that layer and following standard boundary-layer theory, the velocity of the fluid is zero.
Centrifugal force, which depends on velocity, is therefore zero. Pressure force, remains unaffected by the boundary layer. Therefore, within the boundary layer, pressure force dominates and fluid moves along the bottom of the river from the outside bend to the inside bend; this initiates helicoidal flow: Along the river bed, fluid follows the curve of the channel but is forced toward the inside bend. The downstream velocity of the fluid is convectively transported to the outside bend, resulting in higher velocities at the outside bend; this secondary flow effect dominates over that of irrotational flow: In real meandering rivers, we observe higher downstream fluid velocities at the outside bends. The higher velocities at the outside bend result in higher shear stresses and therefore results in erosion, thus meander bends erode at the outside bend, causing the river to becoming sinuous. Deposition at the inside bend occur such that for most natural meandering rivers, the river width remains nearly constant as the river evolves.
Where the is not forced to bend by a natural obstacle, Coriolis force of the earth can cause a small imbalance in velocity distribution such that velocity on one bank is higher than on the other. This can trigger deposition of sediment on the other; the technical description of a meandering watercourse is termed meander geometry or meander planform geometry. It is characterized as an irregular waveform. Ideal waveforms, such as a sine wave, are one line thick, but in the case of a stream the width must be taken into consideration; the bankfull width is the distance across the bed at an average cross-section at the full-stream level estimated by the line of lowest vegetation. As a waveform the meandering stream follows the down-valley axis, a straight line fitted to the curve such that the sum of all the amplitudes measured from it is zero; this axis represents the overall direction of the stream. At any cross-section the flow is following the centerline of the bed. Two consecutive crossing points of sinuous and down-valley axes define a meander loop.
The meander is two consecutive loops pointing in opposite transverse directions. The distance of one meander alo