When rain falls on the continental divide.
It begin to change when they first got settled the indus valley river
River systems begin to form by heavy rain showers and storms. The system is begun by the puddle of water trickling from the source joining with another river beginning a small stream and so on.
A continuous source of water, such as precipitation or melting snow, is necessary for a river system to form. This water needs to flow downhill, carving a path through the landscape, which creates channels that eventually form a river system.
That part of the river system is known as a maturelandscape.
Because that is where the Blue Nile and White Niles merge to form the River Nile
The nervous system begins to form during the third week of embryonic development.
Gravity.
Mississipi-Missouri
In many cases rivers begin at a source that has snow fall. The run off from melting snow can be the beginning of a river. Small streams built upon the items mentioned above can combine with other small streams and thus become the beginning of a river.
The Murray River of Australia is the longest river in Oceania.Many websites will incorrectly state that the longest river is the Murray-Darling but this is not a river. These are two separate rivers (the Murray and the Darling) which form part of a vast river system known as the Murray-Darling river system.
The nervous system begins to form in the early stages of embryonic development, around the third week after conception.
river systema river system.