explain why the yangtze river is being dammed at the three gorges?
969400
Due to China's massive economic growth the Yantze is being dammed to provide hydro electric power
1155462
I have no idea. Technically, some people already have to walk out to a river to get water.
775597
Nile, Amazon and Yangtze in that order.
837311
Dams and levees change the course of rivers.  Farmig, forestry, and suburban development lead to erosion.  Mining can change the forms of mountains.
654079
You can get details about Yangtze River in following website.\nhttp://en.wikipedia.org/wiki/Yangtze_River
343628
figure the bottom, the top gets fed more water as it flows down river by rain, the bottom gets its water from runoff - the effect of the rain up-stream.
132862
flood (in Old English flod, a word common to Teutonic languages; compare German Flut, Dutch vloed from the same root as is seen in flow, float) is an overflow of water, an expanse of water submerging land, a deluge. In the sense of "flowing water", the word is applied to the inflow of the tide, as opposed to the outflow or "ebb". The Flood, the great Universal Deluge of myth and perhaps of history is treated at Deluge in mythology.\n\n \nFlooding in Asheville, North Carolina in July 1916In many arid regions of the world, the soil has very poor water retention characteristics, or the amount of rainfall exceeds the ground's ability to absorb water. When a rainfall does occur, it can sometimes result in a sudden flood of water filling dry streambeds known as a "flash flood".\n\nFlood from sea can cause overflow or overtopping of flood-defences like dikes as well as flattening of dunes or buffs. Land behind the coastal defence may be inundated or experience damage. Floods from sea may be caused by heavy storm (storm surge), high tide, a tsunami or a combination thereoff. As most urban communities are located near the coast, this is a major threat around the world.\n\nMany rivers that flow over relatively flat land border on broad flood plains. When heavy rainfall or melting snow causes the river's depth to increase and the river to overflow its banks, a vast expanse of shallow water can rapidly cover the adjacent flood plain. Flooding deposits silt on the flood plain, improving its fertility. Throughout history, this has attracted agriculture and other human development. In order to preserve these farms and cities, some rivers prone to flooding have had extensive and elaborate systems of dikes constructed along their shores and surrounding nearby cities. Unfortunately, by restraining flood waters, these dikes can result in much greater flooding downstream and in locations where they break. Because off the dikes the difference between water-level during flood and the surface of the inland increases and the potential devastation of the flood increases. The control of annual flooding, by dikes and by dams, also prevents the deposition of silt on the rich farmlands and can result in their eventual depletion. The annual cycle of flood and farming was of great significance to many early farming cultures, most famously to the ancient Egyptians of the Nile river and to the Mesopotamians of the Tigris and Euphrates rivers.\n\nA flood occurs when an area of land, usually low-lying, is covered with water. The worst floods usually occur when a river overflows its banks. An example of this is the January 1999 Queensland floods, which swamped south-eastern Queensland. Floods happen when soil and vegetation cannot absorb all the water ; water then runs off the land in quantities that cannot be carried in stream channels or kept in natural ponds or man-made reservoirs.\n\nPeriodic floods occur naturally on many rivers, forming an area known as the flood plain. These river floods usually result from heavy rain, sometimes combined with melting snow, which causes the rivers to overflow their banks. A flood that rises and falls rapidly with little or no advance warning is called a flash flood. Flash floods usually result from intense rainfall over a relatively small area. Coastal areas are occasionally flooded by high tides caused by severe winds on ocean surfaces, or by tidal waves caused by undersea earthquakes. There are often many causes for a flood.\n\nMonsoon rainfalls can cause disastrous flooding in some equatorial countries, such as Bangladesh, due to their extended periods of rainfall. Heavy rain caused substantial damage across eastern Europe in the summers of 2003 and 2005. Normally riverine floods occur only in winter as a result of heavy rain in combination with melting of snow and glaciers in spring.\n\nA flood can also occur when a volcanic eruption melts a large amount of ice and snow quickly. Th
783759
Most of the water resources goes towards farming.  Already the Colorado River in the US and the Yellow River in China no longer make it to the sea.  (this is what they mean when they say the Nile will run dry... we divert more and more water, taking it away from ecosystems downstream.)\n\nConservation helps, but better farming irrigation techniques and eating less meat is crucial as the world population continues to grow exponentially.  70% of all fresh water goes to farming and the majority of the produce goes to feed livestock!  The UN recently did a report on water resources and they estimated that for every 1 lb of beef it takes 7 lbs. of feed grain, which takes 7,000 lbs. of water to grow.  The water that goes to make the corn could used to feed more people with 7 lbs of vegetables and beans than 1 lb of steak.  This is not to say that we all must become vegans, but if we all ate one less meal with meat a week it would make a tremendous difference!  "Pass up one hamburger, and you'll save as much water as you save by taking 40 showers with a low-flow nozzle." \n\nHere's an article that has some good statistics about the Nile:\nhttp://www.earth-policy.org/Books/Eco/EEch2_ss6.htm\n\nIt says " Another river that is leading to sleepless nights is the Nile, because its waters must be allocated not among provinces, as in China, but among countries. Ten countries share the Nile River basin, but just three—Egypt, Sudan, and Ethiopia—dominate. Eighty-five percent of the Nile's flow originates in Ethiopia, but the lion's share is used by Egypt. Most of the rest is used in Sudan. Once the claims of these two countries are satisfied, little water is left when it enters the Mediterranean"
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The Colorado River has been dammed a lot and it's affecting the areas around it.  Is that what you mean?  Or do you mean polluted rivers?  Like, when Lake Erie caught on fire?\n\nThe Amazon is being hurt by rainforest deforestation.  Like, too much sediment running off from erosion, too much sunlight (from cutting down trees), maybe some fertilizer runoff.\n\nYeah, the Ganges is a total mess.  It's so polluted--raw sewage, industrial waste...it's disgusting.  I'd say you could find several endangered rivers in India.  \n\nTry China, too.  They probably have some endangered rivers.  Check around very industrial areas, places with stuff like nuclear plants or factories, textile or paper mills, stuff like that.
628280
the river  pushes its way down stream as it is pulled by gravity, water is a bulldozer driven by gravity.
36830
To the people of China(which I am one of), it represents their glory of achieving a great architectural wonder; a memoir of their magnificence. It was originally created to guard China against Mongols and other foes, though.
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Names\nBird's eye view of the origin of Yangtze river\nEnlarge\nBird's eye view of the origin of Yangtze river\n\nLike many rivers, the Yangtze / Chang Jiang is known by different names over different parts of its course. At its source the river is known in Chinese as the Dangqu (当曲/當曲). Downstream it is called the Tuotuo River (沱沱河) and then the Tongtian River (通天河). Where it runs through deep gorges in parallel to the Mekong and the Salween before emerging onto the plains of Sichuan it is famous as the Jinsha River (金沙江 Jīnshā-jiāng or 'Golden Sands River'). The name Yangzi was originally used by local people in the river's lower reaches. Because it was the name first heard by missionaries and traders, it was applied in English to the entire river. In Chinese Yangzi Jiang is considered a historical or poetic name for the river.\n\nThe Yangtze was earlier known to the Chinese as the Da Jiang (大江, Dà Jiāng) or 'Great River'. The Tibetan name for the river is Vbri-chu (འབྲི་ཆུ་ 'river of the female yak'). The Yangtze is sometimes referred to as the Golden Waterway.\n\nGeography\n\nThe river originates in a glacier in the Dangla mountains on the eastern part of Tibetan plateau. It then runs through the eastern part of Qinghai, turning southward down a deep valley at the border of Sichuan and Tibet to reach Yunnan. In the course of this valley, the river's elevation drops from above 5000 m to less than 1000 m. It enters the basin of Sichuan at Yibin. While in the Sichuan basin it receives several mighty tributaries, increasing its water volume significantly. The river then cuts through Mount Wushan bordering Chongqing and Hubei to create the famous Three Gorges. Eastward of the Three Gorges, Yichang is the first city on the Yangtze Plain. In Hubei, the Yangtze receives more water from thousands of lakes. The largest of these is Dongting Lake, which is mainly located in Hunan province and is the outlet for most of the rivers in Hunan. At Wuhan it receives its biggest tributary, the Han River, bringing water from its northern basin as far as Shanxi. At the northern tip of Jiangxi, another lake, Lake Boyang flows into the river. The river then runs through Anhui and Jiangsu provinces, receiving more water from smaller lakes and rivers, before finally reaching the East China Sea at Shanghai. Actually, four of China's five main freshwater lakes contribute their waters to the Yangtze River. Traditionally, the upstream part of the Yangtze River refers to the section from Yibin to Yichang; the middle part refers to the section from Yichang to Hukou, where Boyang Lake meets the river; the downstream part is from Hukou to Shanghai.\n\nCharacteristics\n\nThe Yangtze flows into the East China Sea and was navigable by ocean-going vessels up to a thousand miles from its mouth even before the Three Gorges Dam was built. As of June 2003, the Three Gorges Dam now spans the river, flooding Fengjie, the first of a number of towns affected by the massive flood control and power generation project. The project is the largest comprehensive irrigation project in the world. Proponents of the dam argue that it will free people living along the river from floods that have repeatedly threatened them in the past, and will also offer them electricity and water transport - though at the expense of permanently flooding many existing towns (including numerous ancient cultural relics) and causing large-scale changes in the local ecology.\n\nOpponents of the dam point out that there are three different kinds of floods on the Yangtze River: floods which originate in the upper reaches, floods which originate in the lower reaches, and floods along the entire length of the river. They argue that the Three Gorges dam will actually make flooding in the upper reaches of the river worse and have little or no impact on floods which originate in the lower reaches.\n\nThe river is
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Elevation is usually the reason.  Especially since water only flows downhill.\n\nI believe it may be that since the river flows into Lake Erie, the "upper" may refer to its source at Walton Lake, or any part of the river before it empties into Sandusky Bay.\n\nSame thing goes for the Nile River.  The Upper Nile is actually in the south and the lower Nile the closer you get into the Mediterranean Sea (going North).\n\nSince the Mississippi flows south, the lower Mississippi is in the southern areas, and the upper Mississippi the closer you get to the Great Lakes.
287822
There are sections of the river (in Quebec) where the tides cause the river to flow upstream.  This still happens today.
274234
It is because the water is always flowing and changing the river.  The water brings new things from up stream and washes current things down stream.  You can never count on a river to be the same as it was the last time you stepped in it.
268184
The rivers are cresting and there is a lot of standing ground water that will slowly be absorbed or drain off.
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The Yangtze River or the Chang Jiang,as it is also called,is the longest river in both China and Asia and the third longest river in the world, with a length of 6300 km. \n\nIts source is in Qinghai Province in the western part of China ,and it flows  eastwards into the East China Sea.