goglpubli.blogg.se - Rive definition

It can usually be drunk safely by people unless it is too dirty because of mud or human pollution. The water in rivers is "fresh water" that has come from rain, snow and from underground streams. The River Styx runs out of the Mammoth Cave in Kentucky, US There are deltas on the Nile River, the Amazon River, the Mekong River, the Mississippi River and the Danube River.

Deltas are often made into wildlife reserves. Deltas are often places that are not good for towns or farms but are very good for birds and other wildlife and fishing. When this happens, it is called the delta of the river. The main stream of the river gets broken into many parts that spread out into a triangle shape like the Greek letter delta. Where a river flows out to the sea, it sometimes flows very slowly through sandy or muddy land, making lots of little islands as it flows. Many of the world's largest cities and harbours are at estuaries. Many kinds of fish, clams, molluscs and other sealife live at estuaries. The fresh water of the river mixes slowly with the salt water, becoming brackish water – somewhat salty water. An estuary is a wide, funnel-like mouth of the river.

If there is a strong tide where the river meets the sea, the river forms an estuary. The shape of the mouth depends on the conditions of the sea where it flows. Corn, rice, fruit, cotton, hay, tobacco and sugar are some of the crops that are grown near old rivers. Old rivers are the most useful type of river for growing crops. An old river often meanders (twists and turns), and sometimes, after a flood, it leaves lakes behind which are called ox-bows or billabongs. An old river slowly builds up its banks on either side the high banks are called levees. An old river often floods across the land after there is lots of rain at the headwaters. A wide slow river is called an 'old river'. As it flows over the flat land the river becomes wider and slower. The place where the river flows out into a bigger body of water is called the 'mouth' of the river.Īs a river flows towards its mouth, the countryside around the river often changes from hilly to flat. The last part of a river Ī river usually ends by flowing into an ocean, a lake or a bigger river. The city of Florence was built beside the Arno River.

Some rivers only flow after there has been rain near the head water.

Some rivers flow from hills where there is no snow, but lots of rain.

As more little streams run in, the main stream gets bigger, until it forms a river. The melting snow runs together to form a small stream that runs down the mountain.

A river may begin in mountains where there is snow.

The source of a river may be a lake where lots of water from small streams gathers when it rains or snows.

A spring is water that flows out from under the ground.

The source of a river may be a spring, often on a hill, mountain, glacier, or another high place.

As the rivers travel downhill they begin to erode the ground taking small bits of soft rock and soil. Young rivers often have lots of small waterfalls and rapids. A young river is often in a V-shaped river bed, and flows quickly downhill over stones, and around big rocks. The part of the river that is near the source is called a 'young' river. The start of a river is called the source or head water.