World’s rivers

 Shape of river 

All great rivers develop the same horseshoe-shaped meanders in their lower reaches . 

Length of rivers 

Measurements of river lengths vary according to where the river is said to begin. 

Longest river of the world(America’s amazone)

 America’s Amazon is longest river of the world .The source of the Amazon was only discovered in 1971, in snowbound lakes high in the Andes. It is named Laguna McIntyre after the American who found it. If the full length of the Amazon is counted, it is 6750 km long 

2nd longest river (Africa’s Nile) 

 It is the world’s second longest river As compared with the Nile at 6670 km.The Amazon basin covers more than 7 million sq km. China’s Yangtse It is the third longest river, at 6300 km.

Seyhan River in Adana turkey

 

 

 

 

 

 

The world’s longest tributary

 The world’s longest tributary is the Madeira flowing into the Amazon. At 3380 km long it is the 18th longest river in the world. 

Ob in Russia 

The world’s longest estuary is that of the Ob in Russia, which is up to 80 km wide and 885 km long. The Ob is the biggest river to freeze solid in winter. 

Roe River in Montana 

The shortest official river is the North Fork Roe River in Montana, USA, which is just 17.7 m long. Rivers are filled with water from rainfall running directly off the land, from melting snow or ice or from a spring bubbling out water that is soaked into the ground.
 High up in mountains near their source (start), rivers are usually small. They tumble over rocks through narrow valleys which they carved out over thousands of years. Catchment area All the rivers in a certain area, called a catchment area, flow down to join each other, like branches on a tree. 

Tributaries 

 The branches of rivers are called tributaries. The bigger the river, the more tributaries it is likely to have. As rivers flow downhill, they are joined by tributaries and grow bigger. They often flow in smooth channels made not of big rocks but of fine debris washed down from higher up. 

River valleys

 River valleys are wider and gentler lower down, and the river may wind across the valley floor. In its lower reaches a river is often wide and deep. It winds back and forth in meanders across floodplains made of silt from higher up. Rivers flow fast over rapids in their upper reaches. On average, they flow as fast in the lower reaches where the channel is smoother because there is much less turbulence 

How rivers go away from their bank

 Rivers wear away their banks and beds, mainly by battering them with bits of gravel and sand and by the sheer force of the moving water. Every river carries sediment, which consists of large stones rolled along the river-bed, sand bounced along the bed and fine silt that floats in the water.

 Discharge of river

 "The discharge of a river is the amount of water flowing past a particular point each second."

 Intermittent Rivers 

 "Rivers that flow only after heavy rainstorms are ‘intermittent". 

Perennial Rivers 

 "Rivers that flow all year round are ‘perennial’ rivers." They are kept going between rains by water flowing from underground. River channels come to an end when they reach the mouth where the water flows into a larger river, lake or ocean. The river here is so wide and flat, and its bed so rough, that the water’s flow is slowed by friction. 

River channels 

 "A channel is the long trough along which a river flows. When a river’s channel winds or has a rough bed, friction slows the river down. A river flows faster through a narrow, deep channel than a wide, shallow one.

Waterfalls

 About 10 million people visit Niagara Falls each year. Waterfalls are places where a river plunges vertically. Waterfalls may form where the river flows over a band of hard rock, such as a volcanic sill. The river erodes the soft rock below but it has little effect on the hard band. Waterfalls can also form where a stream’s course has been suddenly broken, for example where it flows over a cliff into the sea, over a fault or over a hanging valley .

 The world’s highest falls

 The world’s highest falls are the Angel Falls in Venezuela, which plunge 979 m. Boulders often swirl around at the foot of a waterfall, wearing out a deep plunge pool. Angel Falls are named after American pilot Jimmy Angel who flew over them in 1935. 

Victoria falls

 Victoria Falls in Zimbabwe are known locally as Mosi oa Tunya, which means ‘the smoke that thunders’. The roar from Victoria Falls can be heard 40 km away. 

Niagra falls

Niagara Falls on the US/Canadian border developed where the Niagara River flows out of Lake Erie. Niagara Falls has two falls: Horseshoe Falls, 54 m high, and American Falls,55 m high.