What or Where is the main source for the beginning of all rivers?

Question

A river has to start from somewhere and I am just curious as to where "ALL" the water originates from. For example, the Mississippi or Nile, they are enomous rivers with a lot of running water. From where does ALL that water originate from to create a large flowin stream of water

Answer 1

A river is a visble stream of water in flow. It satarts as trickle and gradually accumulates while on the run. Similar to it some other rivers form and join it. It is debatable which one of the two joins the other. Normally a smaller stream (shorter stream) joins the bigger one. While the big-small stream is already decided in the old world. Modern man in the newer lands committed mistakes. Main River Mississippi is shorter than Missouri in America; main River Murray is shorter than Darling. Before naming better to have a look at the maps.

In a region through which a significant river runs one can mark out its catchment area. This is the area in which all the precipitation runs into the river before it joins some sea. On its course if it is desired to construct a dam or put a 'weir' across the flow, some hudrological or engineering data is required. Chief among them is catchment area at that spot. It is the rain runoff as before, but running into the river before it. Suppose in the catchment area 'A', rainfall is 'x' meters over a specific period, the runoff of the river over that period is 'xA' cubic meters if losses are ignored for a while.

The catchment area on the map is generically called 'River valley' though it is not a narrow area.

Answer 2

All the water in any river can have only two sources

i) Rain

ii) Snow i.e. they are fed by Glaciers.

Huge glaciers normally melt under the sun's influence (mainly during) to produce large water bodies that mostly drain into oceans. This is a typical snowfed river. Such rivers are usually perennial as the glacier is permanent. Eg River ganges in India originates from the Gangotri glacier , one of the largest in the world.

The earth receives heaps of rainfall. Especially in higher altitudes in the equatorial regions. All this rain forms the source of millions of rivers in the world , many of them being extremely large. The examples stated by you fit in here. Say the Nile :

The Nile has two major tributaries, the White Nile and Blue Nile, the latter being the source of most of the Nile's water and fertile soil, but the former being the longer of the two, while the Blue Nile starts at Lake Tana in Ethiopia , flowing into Sudan from the southeast. The two rivers meet near the Sudanese capital Khartoum.

R.missisippi is also rain fed.  The Mississippi River is the second longest river in the United States, with a length of 2,320 mi (3,734 km) from its source in Lake Itasca in Minnesota to its mouth in The Gulf of Mexico