River environments Flashcards
What is the hydrological cycle?
The continuous circulation of water in the Earth-atmosphere system
What type of cycle is the hydrological cycle?
A closed cycle
What are the 3 main water stores?
The atmosphere, the land and the sea
What is evaporation?
Water goes from liquid to gas due to the heat of the sun
What is transpiration?
Plants take up water from the soil and ‘breathe’ it into the air
What is evapotranspiration?
Loss of moisture from the ground by direct evaporation
What is condensation?
When water vapour cools and becomes liquid
What is precipitation?
Transfer of water from atmosphere to earth
What is overland flow/runoff?
Precipitation that fell to the floor moves due to gravity
What is groundwater flow?
Underground water movements to rivers, lakes and the sea
What is infiltration and percolation?
Water moves downwards into the aquifer
What is throughflow?
Water moves slowly through the soil until it reaches a stream or river. This happens between surface and aquifer
What is the aquifer?
Groundwater
What are drainage basins?
Areas of land where water from rain or snowmelts drains downhill into a large body of water
Name the 3 broad types of drainage basins.
-They deliver water directly to the sea
-They’re part of a larger system of drainage basins
-They don’t lead to the sea but to ‘inland’ seas
Name inputs of a drainage basin
energy from the sun, precipitation, possibly water from tributory drainage basins
Name outputs of a drainage basin
River discharge, evaporation and transpiration from the water in the basin
What is a watershed?
Area or ridge of land that separates waters flowing to different rivers/seas
Define mouth of a river
Where a river enters a larger river, lake or ocean
Define discharge
The volume of water flowing through a river channel at a given time
Define source
A place where a river begins
Define confluence
When 2 or more flowing bodies of water join to form a single channel
Define tributary stream
Freshwater stream that feeds into a larger stream, river or body of water
Define channel
A wide waterway between two landmasses close to each other
What is discharged measured in?
Cumes (m3 of water per second)
Define river regime
The changes in a river’s discharge over the course of a year
What is a hydrograph?
A graph showing how a river responds to a specific rainfall event
What is a storm hydrograph?
Records changing discharge of a river after a rainstorm
Name 3 factors affecting river regimes
Rock type, t° and rain
Explain Bradshaw’s model
States that river characteristics, its long profile, change downstream. For example width, depth and velocity increase.
What is physical weathering?
Breakdown of rocks by changes in t° and water freezing in the cracks
What is chemical weathering?
Causes rocks to decay and disintegrate. Slightly acidic rain seeping into porous rocks
What is biological weathering?
The roots of plants gradually growing in the cracks in rocks
Define mass movement
Weathered material moving down the river slope because of gravity.
What are the two main types of mass movements in river valleys?
Slumping and soil creep
Explain slumping
When the bottom of a valley side slope is cut away by the river flowing at its base. It makes the slope unstable and weathered material slumps down.
Explain soil creep
Weathered material moves slowly down the slope because of gravity. It collects at the bottom of the valley side and is eroded by the river.
What are the three processes at work in shaping landforms?
Erosion, transport and deposition
Name the 3 types of erosion
Hydraulic action, abrasion and corrosion
What are interlocking spurs?
When a river swings side to side. Think S shape.
Explain hydraulic action
Water hits the river bank with such force that material is dislodged and carried away.
Explain abrasion
Material carried by the river is rubbed against the sides and floor of the channel. ‘Sandpaper’ action.
Explain how corrosion works
Minerals in the rocks on the sides of the river channel are dissolved by the water flowing past them.
How is a waterfall formed?
When a band of hard rock is more resistant to erosion than the rock below
What is a gorge?
A narrow valley with steep, rocky walls located between hills or mountains
What is a delta?
Wetlands that form as rivers empty into another body of water
What is an estuary?
A partially enclosed, coastal water body where freshwater from rivers mixes with saltwater from the ocean
In which 4 main ways can water be used?
Domestic, industrial, agricultural and leisure
Why has water demand increased greatly in the last 50 years?
Improved standards of living, rise in agricultural productivity and industrialisation
Explain water surplus and water deficit
Water surplus: more supply than demand
Water deficit: more demand than supply
Give 3 examples of agricultural water pollution
liquid from farm silage and slurry enters rivers, fertilisers and pesticides seep into groundwater, deforestation (runoff carries soil and slit into rivers)
Give 3 examples of domestic water pollution
discharge of untreated sewage, use of rivers for washing and bathing, emptying chlorinated water from swimming pools
Give 3 examples of industrial water pollution
Taking water from an ecosystem and returning it at higher t°, spillages from industrial plants, metallic minerals and toxic substances ending up in rivers
What are the 3 stages of managing the clean water supply?
Collection, treatment and delivery
How can clean water be delivered?
Pipes, wells, bottled water
Why is water treated?
To remove minerals, algae, bacteria, fungi, etc.
Give three examples of water treatment
Disinfection to kill bacteria, filtration to remove sediments and sedimentation to remove suspended soil
What are the purposes of dams and reservoirs?
Good supply of clean water, generating electricity, flood control
Name three strategies to increase water supply
Dams and reservoirs, water transfers and desalination
When does flooding occur?
When the amount of water in the river exceeds the capacity of the river’s channel.
Name three physical factors of flooding
Soil type, weather and rock type
Name three human factors of flooding
Deforestation, burning fossil fuels and urbanisation
What are some effects of flooding on the environment?
Loss of wildlife habitats, soil erosion, destroyed vegetation, landslides, destruction of settlements and soil contamination by sewage
What are some effects of flooding on people?
Disease and stress, death and injury, loss of belongings, damage to property, insurance claims, crops and animals lost, disruption to transport, contamination of water supply
What can be done to control and manage floods?
Construction of hard-engineering structures, adjustment by building soft-engineering structures and prediction
What is hard engineering?
Building structures to manage floods like dams, flood embankments or relief channels
What is soft engineering?
Building on the natural structure of the area to minimise and prevent flood damage
Name 4 case studies on increasing the water supply
Ebro project, Spain
Tagus-Segura project, Spain
3 Gorges project, China
North South water transport project, China
