Geography Rivers and Landforms

Harder rock remains above softer eroded rock, forming an overhang.

Falling water erodes riverbed to create a deep basin.

Overhang collapse leads to a steep-sided, narrow valley.

Deep, narrow, steep-sided valley carved by river erosion.

Sections of a river with a steep gradient, causing fast-flowing water over rocks.

Shallow riverbed with exposed rocks, whitewater appearance.

Cylindrical holes eroded in the riverbed due to swirling eddies and trapped pebbles.

Typically found in upper course rivers due to high turbulence.

Floodplains are formed as rivers deposit sediment during floods, building up flat areas on either side of their channels.

Levees are natural embankments along a river, created by the deposition of heavy sediment during floods.

Deltas are landmasses formed at the mouth of a river where it enters a lake or ocean, as sediment is deposited.

Deltas can have various shapes, including arcuate (triangle-shaped), cuspate (V-shaped), and bird's foot (extending into the water).

An arcuate delta, like the Nile Delta, is a triangle-shaped delta formed by a river flowing into a sea with alternating currents.

A cuspate delta, like the Ebro Delta, has a V-shape with curved sides, formed by waves hitting the river head-on.

A bird's foot delta, like the Mississippi Delta, has a long, branching shape formed when the river's current is stronger than the sea's waves.

A distributary is a smaller river or stream that branches off from the main river in a delta.

A meander is formed when a river flows through a low-gradient area, causing the water to flow faster on the outer bend and slower on the inner bend. This leads to erosion on the outer bend and deposition on the inner bend, creating a winding curve.

Oxbow lakes form when the outer banks of a meander erode, narrowing the neck of the bend. Eventually, the river cuts through the neck, forming a straighter channel, leaving the old bend isolated as a lake.

Levees are naturally formed banks along the sides of a river channel in its lower course. They are formed by deposition of sediment during floods.

A flood plain is a flat area adjacent to a river that is prone to flooding. It is formed by deposition of sediment during floods.

Deltas are landforms created at the mouth of a river where it enters a larger body of water. They are formed by the deposition of sediment as the river's speed decreases.

Estuaries are partially enclosed coastal bodies of water where freshwater from a river mixes with saltwater from the sea. They are also areas of deposition.

Alluvial fans are cone-shaped deposits of sediment created by flowing water, typically at the base of mountains.

Rivers erode their bed through processes like hydraulic action (force of water), abrasion (rocks grinding), and attrition (rocks colliding). The effectiveness of erosion depends on the hardness of the riverbed and the force of the water.

Floodplains are fertile due to alluvial deposits, making them ideal for farming.

High discharge leading to overflowing water causing damage to property and infrastructure, affecting livelihoods and potentially resulting in loss of life.

Floods lead to a range of negative impacts including property damage, disease outbreaks, food shortages, and disrupted infrastructure.

Water flow wears down the riverbed and banks, damaging roads, houses, and other infrastructure.

Rivers provide water for drinking, agriculture, and industry, supporting human life and economic activities.

Rivers provide a source of food, such as fish, sustaining communities and contributing to local economies.

Rivers can be used for transportation, connecting people and goods, potentially leading to trade and economic development.

Methods used to reduce the impact of river flooding, such as building dams, levees, and flood walls.

Building dams across rivers to control water flow and reduce the risk of flooding downstream.

Raised banks built along river channels to contain floodwaters and protect surrounding land.

Increased global temperatures contribute to flooding by accelerating ice melt in mountains and causing more extreme rainfall.

Floods can cause damage to property, infrastructure, and human lives, as well as disrupt ecosystems and spread disease.

Using scientific methods to forecast the likelihood and severity of floods, allowing for better preparation.

Measures taken to lessen the negative effects of floods, such as relocating buildings or strengthening infrastructure.

A comprehensive strategy involving prediction, mitigation, and construction activities to control and manage flood risks.

When precipitation enters a circular basin, it reaches the river at roughly the same time due to equal distances. This causes a rapid increase in river discharge, potentially leading to flash floods.

If a basin's soil is impermeable, precipitation cannot soak into the ground. This excess water flows directly into the river, increasing discharge and raising the risk of flooding.

Dense vegetation cover intercepts precipitation and stores it, reducing the amount of water reaching the river. Sparse vegetation leads to less interception and increased flooding risk.

In basins with steep slopes, water flows rapidly into the river, increasing discharge and flood likelihood. Gentle slopes allow water to infiltrate more slowly.

Rivers with many tributaries tend to flood more easily as they receive contributions from numerous sources. Combined discharge increases rapidly after heavy rainfall.

Urban areas are prone to flooding due to impermeable surfaces like concrete and asphalt, which increase surface runoff and river discharge.

Deforestation reduces vegetation cover, leading to decreased infiltration and increased surface runoff into rivers, making flooding more likely.

Dams hold back large amounts of water, reducing river flow downstream. However, dam failure can cause catastrophic flooding.