Rivers

River Components

  • River Source: The beginning point of a river.

  • course: The route a river takes to sea.

  • Drainage basin: the area of land drained by the river.

  • Watershed: The region or area of land that separates waters flowing to different rivers, basins, or seas.

  • Tributary: Smaller river that feeds into the main river.

  • Confluence: Point where tributary meets the main river.

  • Estuary: Tidal area of the river.

  • River Mouth: Where the river meets the sea.

Stages of a River

1. Youthful Stage

  • steep

  • fast flowing

  • low volume of water

  • erosion

2. Mature Stage

  • gently sloping

  • starts to slow down

  • higher volume of water

  • erosion and deposition

3. Old Age Stage

  • leveling off

  • slow moving

  • large volume of water

  • deposition

Processes of Erosion

  • Hydraulic Action: Force of moving water eroding riverbeds and banks.

  • Abrasion: Rocks carried by the river scrape the bed, deepening it.

  • Attrition: River's load collides and breaks into smaller pieces.

  • Solution: Chemicals in the river dissolve rock on the riverbed.

Processes of river transportation

  • Rolling(traction): Heavy stones moved along the bottom.

  • Bouncing(saltation): Smaller stones bouncing along the riverbed.

  • Suspension: Small stones and pebbles floating in the water.

  • Solution: Tiny dissolved bits.

Features of Rivers

Youthful River Features

  • Interlocking Spurs: Streams flow around hills unable to erode.

  • V-Shaped Valley: Caused by vertical erosion; steep valley sides.

  • Waterfall: Formed when a river flows over hard rock, eroding softer rock below.

Mature River Features

  • Meanders: Bends and curves in the river due to flatter land.

    • Erosion on the outer bend, deposition on the inner bend.

Old Age River Features

  • Oxbow Lakes: Horseshoe-shaped lakes formed from meanders cut off due to deposition during floods.

  • Levees: Ridges of alluvium formed by the deposition of floodwaters.

Human Interaction with Rivers

  • Case Study: Dam Building in Ireland (e.g., Arda Crussia on River Shannon).

    • Hydroelectric power plants create artificial lakes.

    • Benefits: Free electricity.

    • Disadvantages: Flooding of fertile farmland.