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38-975: Coordinates : 32°50′N 119°20′E  /  32.833°N 119.333°E  / 32.833; 119.333 Lake in China Gaoyou Lake [REDACTED] [REDACTED] [REDACTED] Gaoyou Lake Coordinates 32°50′N 119°20′E  /  32.833°N 119.333°E  / 32.833; 119.333 Basin  countries China Max. length 39 km (24 mi) Max. width 30 km (19 mi) Surface area 674.7 km (300 sq mi) Average depth 1.44 m (5 ft) Max. depth 2.4 m (8 ft) Water volume 971.6 × 10 ^  m (34.31 × 10 ^  cu ft) Surface elevation 5.7 m (19 ft) Settlements Gaoyou Gaoyou Lake ( Chinese : 高邮湖 ; pinyin : Gāoyòu Hú )

76-532: A prime meridian at the westernmost known land, designated the Fortunate Isles , off the coast of western Africa around the Canary or Cape Verde Islands , and measured north or south of the island of Rhodes off Asia Minor . Ptolemy credited him with the full adoption of longitude and latitude, rather than measuring latitude in terms of the length of the midsummer day. Ptolemy's 2nd-century Geography used

114-646: A little before 1300; the text was translated into Latin at Florence by Jacopo d'Angelo around 1407. In 1884, the United States hosted the International Meridian Conference , attended by representatives from twenty-five nations. Twenty-two of them agreed to adopt the longitude of the Royal Observatory in Greenwich , England as the zero-reference line. The Dominican Republic voted against

152-416: A location often facetiously called Null Island . In order to use the theoretical definitions of latitude, longitude, and height to precisely measure actual locations on the physical earth, a geodetic datum must be used. A horizonal datum is used to precisely measure latitude and longitude, while a vertical datum is used to measure elevation or altitude. Both types of datum bind a mathematical model of

190-535: A longitudinal degree is 111.3 km. At 30° a longitudinal second is 26.76 m, at Greenwich (51°28′38″N) 19.22 m, and at 60° it is 15.42 m. On the WGS   84 spheroid, the length in meters of a degree of latitude at latitude ϕ (that is, the number of meters you would have to travel along a north–south line to move 1 degree in latitude, when at latitude ϕ ), is about The returned measure of meters per degree latitude varies continuously with latitude. Similarly,

228-670: A national cartographical organization include the North American Datum , the European ED50 , and the British OSGB36 . Given a location, the datum provides the latitude ϕ {\displaystyle \phi } and longitude λ {\displaystyle \lambda } . In the United Kingdom there are three common latitude, longitude, and height systems in use. WGS   84 differs at Greenwich from

266-841: A simple translation may be sufficient. Datums may be global, meaning that they represent the whole Earth, or they may be local, meaning that they represent an ellipsoid best-fit to only a portion of the Earth. Examples of global datums include World Geodetic System (WGS   84, also known as EPSG:4326 ), the default datum used for the Global Positioning System , and the International Terrestrial Reference System and Frame (ITRF), used for estimating continental drift and crustal deformation . The distance to Earth's center can be used both for very deep positions and for positions in space. Local datums chosen by

304-500: A year, or 10 m in a century. A weather system high-pressure area can cause a sinking of 5 mm . Scandinavia is rising by 1 cm a year as a result of the melting of the ice sheets of the last ice age , but neighboring Scotland is rising by only 0.2 cm . These changes are insignificant if a local datum is used, but are statistically significant if a global datum is used. On the GRS   80 or WGS   84 spheroid at sea level at

342-583: Is where Earth's equatorial radius a {\displaystyle a} equals 6,378,137 m and tan ⁡ β = b a tan ⁡ ϕ {\displaystyle \textstyle {\tan \beta ={\frac {b}{a}}\tan \phi }\,\!} ; for the GRS   80 and WGS   84 spheroids, b a = 0.99664719 {\textstyle {\tfrac {b}{a}}=0.99664719} . ( β {\displaystyle \textstyle {\beta }\,\!}

380-418: Is a spherical or geodetic coordinate system for measuring and communicating positions directly on Earth as latitude and longitude . It is the simplest, oldest and most widely used of the various spatial reference systems that are in use, and forms the basis for most others. Although latitude and longitude form a coordinate tuple like a cartesian coordinate system , the geographic coordinate system

418-571: Is expected to cause devastating effects on the remaining porpoises. Due to the Three Gorges Dam upriver on the Yangtze river, Poyang Lake can seasonally shrink and dry up. In 2012, the lake nearly dried up completely. 200 square kilometers (77 sq mi) of land was underwater in October, while the lake is normally 3,500 square kilometers (1,400 sq mi) in area when full. In addition to

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456-756: Is known as the reduced (or parametric) latitude ). Aside from rounding, this is the exact distance along a parallel of latitude; getting the distance along the shortest route will be more work, but those two distances are always within 0.6 m of each other if the two points are one degree of longitude apart. Like any series of multiple-digit numbers, latitude-longitude pairs can be challenging to communicate and remember. Therefore, alternative schemes have been developed for encoding GCS coordinates into alphanumeric strings or words: These are not distinct coordinate systems, only alternative methods for expressing latitude and longitude measurements. Poyang Lake Poyang Lake , also known by its Chinese name as Poyang Hu ,

494-540: Is not cartesian because the measurements are angles and are not on a planar surface. A full GCS specification, such as those listed in the EPSG and ISO 19111 standards, also includes a choice of geodetic datum (including an Earth ellipsoid ), as different datums will yield different latitude and longitude values for the same location. The invention of a geographic coordinate system is generally credited to Eratosthenes of Cyrene , who composed his now-lost Geography at

532-731: Is the angle east or west of a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses (often called great circles ), which converge at the North and South Poles. The meridian of the British Royal Observatory in Greenwich , in southeast London, England, is the international prime meridian , although some organizations—such as the French Institut national de l'information géographique et forestière —continue to use other meridians for internal purposes. The prime meridian determines

570-665: Is the largest freshwater lake in China . Located within Jiujiang Prefecture in Jiangxi Province , it is fed by the Gan , Xin, and Xiu rivers and flows northward into the Yangtze River through a channel. The area of Poyang Lake fluctuates dramatically between the wet and dry seasons, but in recent years the size of the lake has been decreasing overall. In a normal year the area of

608-504: Is the sixth largest freshwater lake in China , it is located between Anhui Province and Jiangsu Province . In a sense Gaoyou Lake is a manmade lake, and its creation is part of a long story about flood control and hydraulic engineering in ancient China. Gaoyou Lake is now part of the Huai River system as the Huai River flows south through Gaoyou Lake on its way to the Yangtze River and

646-405: Is ultimately calculated from latitude and longitude, it is crucial that they clearly state the datum on which they are based. For example, a UTM coordinate based on WGS84 will be different than a UTM coordinate based on NAD27 for the same location. Converting coordinates from one datum to another requires a datum transformation such as a Helmert transformation , although in certain situations

684-489: The Library of Alexandria in the 3rd century BC. A century later, Hipparchus of Nicaea improved on this system by determining latitude from stellar measurements rather than solar altitude and determining longitude by timings of lunar eclipses , rather than dead reckoning . In the 1st or 2nd century, Marinus of Tyre compiled an extensive gazetteer and mathematically plotted world map using coordinates measured east from

722-4155: The Pacific . It is about 39 kilometres (24 mi) long and 30 kilometres (19 mi) wide, covering approximately 674.7 square kilometres (300 sq mi). See also [ edit ] 1931 China floods Gaoyou Grand Canal (China) Notes [ edit ] ^ "www.aboutgaoyou.com" . Archived from the original on 2018-07-25 . Retrieved 2011-11-04 . ^ Sumin, Wang; Hongshen, Dou (1998). Lakes in China . Beijing: Science Press. p. 279. ISBN   7-03-006706-1 . v t e Lakes of China Five Great Lakes Poyang Dongting Chao Tai Hongze [REDACTED] Notable freshwater lakes Xingkai Poyang Dongting Tai Hulun Hongze Nansi Bosten Chao Gaoyou Ngoring Gyaring Sayram Baiyangdian Honghu Longgan Liangzi Dianchi Manasarovar Ulansuhai Luoma Erhai Junshan Fuxian Shiju Wabu Nanyi Dongping Ge Yangcheng Chenghai Dianshan Yangzong Xingyun Qilu Yilong Ayding Buir Chagan Daming Diexi Dongqian Heaven (Changbai Tianchi) Baihua Karakul Kunming Lugu Ruyi South Tangjiashan Baiyun Xuanwu Yueya Kanas Dushu Notable salt lakes Qinghai Namtso Siling Zhari Namco Tangra Yumco Ulungur Yamdrok Pangong Rakshastal (La-Ang Tso) Aibi National Parks Jingpo Wudalianchi Tai West (Hangzhou) East Lake (Wuhan) Tianshan Tianchi Songhua Jingyue Slim West Dongting Hongfeng Dianchi Jin Crescent Qinghai Chao Fairy West (Huizhou) Qiong Bosten Feiyun Huguang Rock Bailong Sayram Huating Zhelin Protected wetlands Dongting Poyang Hulun South Dongting West Dongting Xingkai Bita Napa Lashi Nygoring Gyaring Nature Reserves Hengshui Xingkai Wudalianchi Yinglong Caiyun Shengjin Poyang Dongting Erhai Serling West (Dunhuang) Gahai Qinghai Caohai Hulun Kanas Hongze Haba Major urban lakes West (Hangzhou) East (Wuhan) Tangxun Lake Kunming Jinji Yuyuantan West (Huizhou) Slim West Taiye Dianchi Daming Yueya Ruyi South Xuanwu Qujiangchi Lotus Pond Baiyun Yinglong Caiyun Moon Reservoirs Three Gorges Longtan Longyangxia Danjiangkou Supung Thousand Islands Xinfengjiang Liujiaxia Changshou Yantan Jiangkou Guanting Miyun Yuqiao Beidagang See also: List of dams and reservoirs in China [REDACTED] Lakes portal [REDACTED] China portal Retrieved from " https://en.wikipedia.org/w/index.php?title=Gaoyou_Lake&oldid=1170914864 " Categories : Lakes of Jiangsu Lakes of Anhui Huai River Hidden categories: Pages using gadget WikiMiniAtlas Articles with short description Short description matches Wikidata Coordinates on Wikidata Articles using infobox body of water without alt Articles using infobox body of water without pushpin map alt Articles using infobox body of water without image bathymetry Articles containing simplified Chinese-language text Geographic coordinate system A geographic coordinate system ( GCS )

760-508: The jiangzhu ("river pig"), a native of the lake along with other waters such as Dongting Lake , might follow the baiji , the Yangtze river dolphin, into extinction. Calls have been made for action to be taken to save the porpoise, of which there are about 1,400 left, with between 700 and 900 in the Yangtze, and another about 500 in Poyang and Dongting Lakes. 2007 population levels are less than half

798-412: The 1997 levels, and the population is dropping at a rate of 7.3 percent per year. Sand dredging has become a mainstay of local economic development in the last few years, and is an important source of revenue in the region that borders Poyang Lake. But at the same time, high-density dredging projects have been the principal cause of the death of the local wildlife population. Dredging makes the waters of

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836-502: The Equator, one latitudinal second measures 30.715 m , one latitudinal minute is 1843 m and one latitudinal degree is 110.6 km. The circles of longitude, meridians, meet at the geographical poles, with the west–east width of a second naturally decreasing as latitude increases. On the Equator at sea level, one longitudinal second measures 30.92 m, a longitudinal minute is 1855 m and

874-548: The Three Gorges Dam, which must store water in its reservoir to be usable in winter, a drought was also blamed for the shrinkage. The Jiangxi local government has proposed to build the Poyang Lake Dam to maintain water levels in the lake, building a sluice wall across the connection between the lake and the Yangtze river. An environmental impact assessment is pending. Scientists, as well as environmental groups such as

912-642: The Yangtze River switched again, causing the Gan River to further back up and form Lake Poyang. The lake was named for Poyang County , which it flooded along with Haihun County , forcing a mass migration to Wucheng Township in what is now Yongxiu County . Wucheng thus became one of the great ancient townships of Jiangxi Province . This migration gave birth to the Chinese idiom , "Drowning Haihun County gives rise to Wucheng Township" ( Chinese : 淹了海昏縣，出了吳城鎭 ). Poyang

950-460: The far western Aleutian Islands . The combination of these two components specifies the position of any location on the surface of Earth, without consideration of altitude or depth. The visual grid on a map formed by lines of latitude and longitude is known as a graticule . The origin/zero point of this system is located in the Gulf of Guinea about 625 km (390 mi) south of Tema , Ghana ,

988-463: The lake averages 3,500 square kilometers (1,400 sq mi). In early 2012, drought, sand quarrying, and the practice of storing water at the Three Gorges Dam lowered the area of the lake to about 200 square kilometers (77 sq mi). The lake provides a habitat for half a million migratory birds and is a favorite destination for birding . During the winter, the lake becomes home to many migrating Siberian cranes , up to 90% of which spend

1026-432: The lake muddier, and the porpoises cannot see as far as they once could, and have to rely on their highly developed sonar systems to avoid obstacles and look for food. Large ships enter and leave the lake at the rate of two per minute and such a high density of shipping means the porpoises have difficulty hearing their food, and also cannot swim freely from one bank to the other. Furthermore, construction of Poyang Lake Dam

1064-415: The length in meters of a degree of longitude can be calculated as (Those coefficients can be improved, but as they stand the distance they give is correct within a centimeter.) The formulae both return units of meters per degree. An alternative method to estimate the length of a longitudinal degree at latitude ϕ {\displaystyle \phi } is to assume a spherical Earth (to get

1102-473: The motion, while France and Brazil abstained. France adopted Greenwich Mean Time in place of local determinations by the Paris Observatory in 1911. The latitude ϕ of a point on Earth's surface is the angle between the equatorial plane and the straight line that passes through that point and through (or close to) the center of the Earth. Lines joining points of the same latitude trace circles on

1140-516: The one used on published maps OSGB36 by approximately 112   m. The military system ED50 , used by NATO , differs from about 120   m to 180   m. Points on the Earth's surface move relative to each other due to continental plate motion, subsidence, and diurnal Earth tidal movement caused by the Moon and the Sun. This daily movement can be as much as a meter. Continental movement can be up to 10 cm

1178-520: The proper Eastern and Western Hemispheres , although maps often divide these hemispheres further west in order to keep the Old World on a single side. The antipodal meridian of Greenwich is both 180°W and 180°E. This is not to be conflated with the International Date Line , which diverges from it in several places for political and convenience reasons, including between far eastern Russia and

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1216-430: The same datum will obtain the same location measurement for the same physical location. However, two different datums will usually yield different location measurements for the same physical location, which may appear to differ by as much as several hundred meters; this not because the location has moved, but because the reference system used to measure it has shifted. Because any spatial reference system or map projection

1254-646: The same prime meridian but measured latitude from the Equator instead. After their work was translated into Arabic in the 9th century, Al-Khwārizmī 's Book of the Description of the Earth corrected Marinus' and Ptolemy's errors regarding the length of the Mediterranean Sea , causing medieval Arabic cartography to use a prime meridian around 10° east of Ptolemy's line. Mathematical cartography resumed in Europe following Maximus Planudes ' recovery of Ptolemy's text

1292-486: The shape of the earth (usually a reference ellipsoid for a horizontal datum, and a more precise geoid for a vertical datum) to the earth. Traditionally, this binding was created by a network of control points , surveyed locations at which monuments are installed, and were only accurate for a region of the surface of the Earth. Some newer datums are bound to the center of mass of the Earth. This combination of mathematical model and physical binding mean that anyone using

1330-458: The surface of Earth called parallels , as they are parallel to the Equator and to each other. The North Pole is 90° N; the South Pole is 90° S. The 0° parallel of latitude is designated the Equator , the fundamental plane of all geographic coordinate systems. The Equator divides the globe into Northern and Southern Hemispheres . The longitude λ of a point on Earth's surface

1368-445: The width per minute and second, divide by 60 and 3600, respectively): where Earth's average meridional radius M r {\displaystyle \textstyle {M_{r}}\,\!} is 6,367,449 m . Since the Earth is an oblate spheroid , not spherical, that result can be off by several tenths of a percent; a better approximation of a longitudinal degree at latitude ϕ {\displaystyle \phi }

1406-496: The winter there. Poyang Lake has also been called Pengli Lake ( 彭蠡澤 ) historically, but they are not the same. Before the Han dynasty , the Yangtze followed a more northerly course through what is now Longgan Lake whilst Pengli Marsh formed the lower reaches of the Gan River . The area that is now Poyang Lake was a plain along the Gan River. Around AD 400, the new more southerly course of

1444-629: Was named for the earlier Po County of the Qin dynasty , in turn named for the city of Poyi ( 番邑 ) in the state of Chu . Lake Poyang reached its greatest size during the Tang dynasty , when its area reached 6,000 square kilometers (2,300 sq mi). A fishing ban has been in place since 2002. In January 2020, China imposed a 10-year fishing moratorium on 332 sites along the Yangtze, including Poyang Lake to protect marine biodiversity. In 2007 fears were expressed that China's finless porpoise , locally known as

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