Q1.
Do you ever wonder how river flows?
Answer
A river flows downhill. It begins high up in the mountains, usually from melting snow, a glacier or a spring, and then runs down across the land towards lower and lower ground, until it reaches the sea.
Step by step, this is the journey:
- Rain falls, or snow and ice melt, high up on a mountain.
- The water cannot stay on the slope, so it trickles down.
- Many small trickles join and become a stream.
- Many streams join and become a river.
- The river follows the low parts of the land — it curves around hills instead of climbing them.
- Where the land is flat and low, the water spreads out and slows down. Where there is a big hollow, it collects and makes a lake.
- At the end of its journey it pours into the sea.
Why it goes downhill: Water has weight, and weight always pulls things down. So water can never flow uphill by itself. This one simple rule decides the whole path of every river in the world.
Water shapes the land too: As it rushes along, a river carries sand, mud and small stones with it. Over hundreds of years this wears away rock and cuts out valleys, and drops the mud in flat plains. So the land shapes the river, and the river slowly shapes the land.