The Great Lakes are 1.383 km long from east to west and 1.654 38+0.25 km wide from north to south, with a total area of 245,000 square kilometers, almost as big as that of Britain. It is the largest freshwater lake group in the world. The westernmost Lake Superior is the largest freshwater lake in the world, ranking second only to the Caspian Sea. The area and capacity of the other four lakes are also among the highest in the world 15. The average depth of the Great Lakes is nearly 100 meter, surpassing the North Sea and the Baltic Sea, with the deepest depth of 406 meters. The total storage capacity is 24,458 cubic kilometers, accounting for 1/5 of the global fresh water, about 40 times of the annual runoff of the Mississippi River, the largest river in North America, and about 90% of the total fresh water supplied by lakes and reservoirs in the United States. The total basin area is 753,950 square kilometers.
The Great Lakes are called "Mediterranean Sea of North America" or "Freshwater Sea" because of their vast waters and huge amount of water, and they are located in the middle of the North American continent.
The lake level difference of the Great Lakes is divided into three levels: Lake Superior flows into Lake Michigan and Lake Huron via Sartre Saint-Maastricht Beach (length 1200m, height difference 6m); From Lake Huron to Lake Erie via saint clair river-St. Clare Lake-Detroit River, the height difference of this connecting waterway is only 2 ~ 3 meters, and the water potential is gentle; The height difference between Lake Erie and Lake Ontario is 99 meters, and there is the world-famous Niagara Falls. The waterfall, with a drop of about 49 meters and a width of 1240 meters, is a famous scenic spot in North America with surging water potential and magnificent scenery. The lake finally empties into the Atlantic Ocean through the St Lawrence River.
The Great Lakes join some nearby rivers and small lakes, forming a unique water network in North America. Very few rivers are injected. The lake is mainly replenished by rain and snow, and the water level is stable. The annual fluctuation of water level is only 30-60 cm. The water level is mainly rain and snow, and the lowest in winter. Lake banks and rivers began to freeze in 65438+ 10, and thawed in late March and early April. The water level is the highest in June and July, but the height difference between lakes is only about 0.5 meters ... The Great Lakes have an obvious regulating effect on the climate near the coast. Compared with neighboring areas, the lake area is cool in summer and warm in winter, with more precipitation.
How did such a large lake group form its huge lake basin? Where do the vast lakes come from?
In geological history, the Great Lakes region once belonged to the upper reaches of rivers. In the Quaternary, a vast area in the northern part of the North American continent was invaded by continental glaciers. The Great Lakes region is close to the center of two continental glaciers, Labrador and Kivadin, and was covered by glaciers during several major ice ages. At that time, the area covered by glaciers was roughly north of Ohio River-St. Louis-Kansas-Missouri River and Calgary, Canada, accounting for about half of North America. The ice sheet is 2400 meters thick, which has a strong planing effect, so that the loose sediments and soft rocks in the original low-lying valley are taken away by glaciers, making the valley wider and deeper. To the south of the Great Lakes is the southern margin of glaciers, where sediments and large and small stones are constantly accumulating to form the last moraine, thus forming the huge lake basin of the Great Lakes at present. When the climate became warmer, the continental glaciers began to recede, and the melted ice water was blocked by the last moraine and accumulated in the glacial depressions, forming five great lakes. The Great Lakes have a history of about 6.5438+200,000 years since their formation.
The specific situation in the Great Lakes region is as follows:
Lake Superior, one of the five great lakes in North America, is the largest freshwater lake in the world, with an area of 824 10 square kilometers, which is much larger than Lake Victoria, the second largest freshwater lake in the world (68,000 square kilometers). 2.6 times that of Lake Baikal (3 1.500 square kilometers), the largest freshwater lake in Asia; 4.6 times that of Lake Ladoga, the largest freshwater lake in Europe (1800 square kilometers); Lake Titicaca (8330 square kilometers), the largest freshwater lake in South America, is 10 times. The lake is owned by the United States and Canada, with the United States accounting for 2/3 and Canada accounting for13, covering an area of about 28,000 square kilometers. The lake is 6 16 km long from east to west, 257 km wide from north to south, 3000 km long in coastline, 183 m above sea level, 148 m in average depth, 406 m in maximum depth and12,240 cubic km in storage capacity, which is the highest among the five lakes and the deepest in the lake basin. The climate in the lake area is cool in Leng Xia in winter, foggy, windy and full of waves. The seasonal fluctuation range of water surface is 40 ~ 60 cm, and the water level is lower in winter and higher in summer. The water temperature is low, the water surface temperature generally does not exceed 4℃ in midsummer, the lakeshore is frozen in winter, and the navigation period is generally about 6 ~ 7 months. This lake is relatively pure. The largest island in the lake is Royal Island, which has been designated as a national park by the United States. The coastline on the north shore is tortuous, with many lakes and bays, backed by high cliffs and rock walls; How low is the beach on the south bank? It accepts about 200 small tributaries, such as Nipigon River and St. Louis River, mostly from the north and west banks, with a drainage area of127,700 square kilometers (excluding the lake area). Lake water flows into Lake Michigan through the St. Mary River. The difference between the two lakes is about 6 meters, and the current is swift. The Su Saint Mary Canal was built to bypass the rapids and smooth the shipping between the two lakes.
Lake Michigan is one of the five great lakes in North America and the only lake in the United States. It extends 517km from north to south, and is about190km wide from east to west, covering an area of 58,000 square kilometers. It is the largest freshwater lake in America. The lakeshore line is 2100km long. The depth of the lake gradually decreases from north to south, with an average depth of 84 meters, the deepest point of 282 meters and the storage capacity of 4875 cubic kilometers. The lake is about 177 meters above sea level. The current is slow and counterclockwise. From mid-February to mid-April of the following year, the lakeshore zone was frozen, which affected shipping. The south bank is straight, sand dunes are widely distributed, and artificial ports are built; The north shore is winding, with many lakes and natural harbors. The main lake bay is Green Bay. Beaver Island, Fox, Manitou and other islands. It is injected by Fox and other small rivers, with a drainage area of110.8 million square kilometers (excluding the lake area). The northeast end is connected with Lake Huron through Mackinac Waterway. At the southern end, it pours into the original Chicago River. In order to treat the sewage from Chicago, its flow direction was artificially changed at the beginning of the 20th century, and it was injected into the Illinois River through the Chicago Canal. Lakes have an obvious regulating effect on climate. The prevailing west wind makes the east coast warm in winter and cool in summer, and it is not frozen in early autumn and late spring.
Lake Huron is one of the Great Lakes in North America, which is owned by the United States and Canada. It is 330 kilometers long, 295 kilometers at its widest point and covers an area of 59,600 square kilometers. The lakeshore line is 2700 kilometers long. The average water depth is 60 meters and the deepest point is 229 meters. The water storage capacity is 3540 cubic kilometers. The elevation of the lake is177m. The lake has good water quality and rich fish. It freezes along the lake shore in winter, and the shipping season is limited to the beginning of April to the end of June 1 1. The island and peninsula meet obliquely, dividing the lake area into two parts, the east is also called George Bay. Manitulin Island in the lake is 130 kilometers long and covers an area of 2,766 square kilometers. The island is extremely irregular in shape and is the largest island in the world's freshwater lakes. There are many lakes and swamps on the island, covering an area of 100 square kilometers. Manitulin Lake is the largest lake in the world. The word Manitulin, which means "elf" in Indian, may be that the indigenous people think that there is an island in the lake, and there is a lake on the island, which is the hiding place of the "elf". There are beaches, gravel beaches and cliffs on the shore of the lake with beautiful scenery, which is a resort for rest and entertainment. Many small rivers are injected, with a drainage area of133,900 square kilometers (excluding the lake area). St Mary's River is connected to Lake Superior in the west, Mackinac Waterway is connected to Lake Michigan in the southwest, and saint clair river-St Clare-Detroit River flows into Lake Erie in the south.
Lake Erie is one of the Great Lakes in North America, which is owned by the United States and Canada. Extending from southwest to northeast, it is 388 kilometers long, 92 kilometers wide and covers an area of 25,700 square kilometers. Length of lakeshore line 1200 km. The average depth is 18m, and the deepest point is 64m, which is the shallowest among the Great Lakes. The water storage capacity is 455 cubic kilometers. The elevation of the lake is174m, which is 99m higher than that of Lake Ontario. How strong the storm is, it often causes the lake to fluctuate, and the water is shallow, which has a certain impact on shipping. From early February to early April in 65438, the lake was frozen and the navigation period was 8 months. It accepts tributaries such as Lake Huron, Racine and Momi, with a drainage area of 58,800 square kilometers (excluding the lake area). Water from Lake Superior, Lake Michigan and Lake Huron flows into saint clair river through the Detroit River in the west, and niagara river in the east flows into Lake Ontario. It is connected with Lake Ontario and Hudson River respectively through Welland Canal and Bucky Canal in New York State, and also connected with Ohio River through the canal.
Lake Ontario, one of the five great lakes in North America, is located between the United States and Canada, extending slightly from east to west, with a length of 3 1 1km, a width of 85 km from north to south and an area of 19500 square km. Length of lakeshore line1380km. The average depth is 85 meters and the deepest point is 236 meters. The water storage capacity is 1688 cubic kilometers. The lake is 75 meters above sea level, 99 meters lower than Lake Erie. Surface water flows from west to east, with an average daily velocity of about 13 km. From February 65438 to mid-April of the following year, the coastal zone was frozen, and the annual navigation period generally reached 8 months. The north shore is a vast plain; Niagara Cliff on the south bank crosses niagara river and flows into the rivers such as Genesee River, Oswego River and Braque River, with a drainage area of about 70,000 square kilometers (excluding the lake area). In the southwest, it receives water from four upstream lakes through the niagara river and flows into the Atlantic Ocean through the St. Lawrence River. There are many canals connected with the surrounding lakes and rivers. For example, the southwest is connected to Lake Erie through the Welland Canal (avoiding Niagara Falls); The Oswego Canal in the east longitude is connected with the Baji Canal, the Hudson River and the Atlantic Ocean in new york. The northwest is connected with George Bay of Lake Huron by Trent Canal; The northeast is connected with the Ottawa River by the Lido Canal. With the completion of 1959 St. Lawrence deepwater channel, its shipping position is more important. The lake area is densely populated.