River Environments

Hydrosphere

All the water stored on the Earth’s surface and in the atmosphere

Hydrological cycle

The sum total of all processes in which water moves from the land and ocean surface to the atmosphere and back in the form precipitation

Evaporation

When liquid water is converted to water vapour due to heat

Condensation

When water vapour cools and turns back into liquid water

Precipitation

When water stored in clouds fall to earth as rain, snow, hail or sleet

Transpiration

When water is evaporated from leaves of plants and trees

Surface Water

Water stored on Earth’s surfaces eg. in lakes or ponds

Groundwater

Water stored in the ground eg. aquifers (rocks that store water)

Infiltration

When water soaks into the ground

Percolation

Water flowing downwards through soil and rock

Levee

An embankment made up by deposited material during a river flood, occurring in the lower course of a river to prevent flooding by increasing the height of riverbanks.

River Mouth

The point where a river flows into a larger body of water, leading to sediment deposition due to reduced current speed.

Estuary

The area where a river meets the sea, characterized by tidal river flow and silt deposition forming mudflats.

Deltas

Landforms at river mouths where sediment deposition forms due to reduced water velocity, found at the mouth of large rivers like the Mississippi.

Water Cycle

A closed system involving water sources like rivers and lakes, crucial for global water distribution.

Reservoirs

Artificial lakes created by damming valleys to store water for various uses.

Aquifers & Wells

Underground porous rock formations storing freshwater, accessed through drilling wells for water extraction.

Water Demand

The need for water for various purposes, reflecting the level of consumption.

Water Supply

Meeting water demand by tapping into sources like groundwater, lakes, and rivers.

Water Balance

Comparing water demand and supply in a region to assess water availability.

Water Scarcity

A lack of water supply, defined as falling below 1000 cubic meters per person per year.

Water Stress

When water supply falls below 1700 cubic meters per person per year, indicating water scarcity.

Water Surplus

Areas where water supply exceeds demand, ensuring water availability.

Global Water Crisis

A situation where a significant portion of the world's population lacks access to safe drinking water, leading to various health and social issues.

Floodplain Development

The increase in housing and economic activities on floodplains, leading to a higher percentage of people at risk of flooding.

Human-induced Climate Change

The impact of warmer atmosphere holding more moisture, resulting in increased precipitation and more frequent extreme weather events like hurricanes.

Groundwater Flooding

Flooding caused by intense precipitation raising the water table to the surface, leading to significant agricultural losses and affecting low-lying areas.

Dam

A hard-engineering structure that restricts water flow, creates reservoirs to suppress floods, and provides water for various activities like irrigation.

Afforestation and Reforestation

Soft engineering approaches involving planting trees to increase interception, slow down water flow, and reduce erosion and landslides.

Embankment/Artificial Levees

Hard engineering structures that increase a river's carrying capacity by raising riverbanks and deepening the channel.

Hazard Resistant Building Design

Adjusting buildings to reduce losses during floods, considered a hard engineering approach to flood management.

Dredging/Channel Digging

Soft engineering method involving the removal of silt from riverbeds to increase river capacity and reduce flood risks.

Straighten the River Channel

Soft engineering technique to speed up water flow and decrease flooding probability in an area.

Land-Use Zoning

Soft engineering strategy that restricts construction in flood-prone areas to prevent damage and reduce flood risks.

Attrition

Pieces of bed load (material carried by a river or seawater) are hit against one another. This causes them to break apart and become smaller and more rounded.

Abrasion

Pieces of rock are picked up by the river or seawater and hit against the bed or the banks. This wears them away.

Hydraulic action

The sheer force of river water removing loose material from the bed & banks of the river

Attrition

In swirling water, rocks and stones collide with each other and with the bed and banks. Over time the sharp edges of the rock and stones become smooth and the rocks and stones become smaller in size.

Solution

Some rocks such as limestone which is soluble in slightly acidic water, dissolve slowly in river water

Lateral Erosion (sideways)

Takes place in the middle & lower course and widens the valley

Vertical Erosion (downward)

Upper course near source cuts down into its bed deepening valley

Traction

Stones rolled along the riverbed (needs the most energy)

Saltation

Sand-sized particles ‘bounce’ along the riverbed

Suspension

Small slit and clay sized particles are held within the water and carried by the river’s flow

Solution

Some minerals dissolves in the water (needs the least energy)

Deposition

When a material in a river falls out of transportation because of a lack of energy to carry the material