Core Physical Flashcards
Water Table
level at which pore spaces and fractures in ground become saturated.
Above = unsaturated
Below = saturated
Groundwater recharge
recharged by precipitation & surface water bodies seeping into groundwater stores. Storm events less effective
Field Capacity
no more water can infiltrate the soil
Formation of springs
1) Permeable rock meets impermeable rock, causing infiltrated water to build up and escape as a spring
2) Water table meets surface, causing discharge of groundwater
Influences on Hydrographs - CLIMATE
Climate - Precipitation, Temperature, antecedent moisture
Influences on Hydrographs - TOPOGRAPHY AND RELIEF
Rough & Jagged - ↓ velocity
Steeper slope - ↑ velocity, less time to infiltrate = ↑overland flow
Types of Erosion
Corrasion: Scraping and Grinding along river channel
Solution: Water dissolving parts of rock/soil
Hydraulic Action: Force of water causes rocks to fragment
Cavitation: water enters small cracks, increases pressure and widens cracks
Transportation
Traction: Rolling of large rocks
Saltation: pebbles bounced along bed
Suspension: small pebbles carried
Solution: Soluble materials carried within water
Hjülstrom Curve
Graph shows how velocity affects rivers material
Riffle-pool sequences
alternating patterns of shallow and deeper water in a river channel
Prevention: Forecasts and warnings
Forecasting: precipitation forecasts - estimate level of flood risk in an area, allowing for warnings to be issued as soon as possible
UK warnings: Met Office issues flood alerts (🟠) flood warnings and severe flood warnings (🔴)
Predicting flood risk
floods modelled to show different factors that effect likelihood of flood e.g. slope, topography
River Don Case study
84mm rainfall in south yorkshire
groundwater flooding: late november, major incident declared
IMPACTS: 6 severe flood warnings issued, thousands of properties evacuated, 1,000 properties flooded
Flood defences: Put in place 2007, EA said these significantly reduced damage in 2019, sandbags on side of rivers at towns
shortwave radiation
incoming directly from sun
longwave radiation
energy received by earth stored as heat energy. when ground warms it is re-radiated as longwave radiation
Latent heat transfer
occurs when water evaporates, moving heat from surface to atmosphere
sensible heat transfer
transfer of parcels of air from point at which budget is assesed
Wind belts
wind patterns that cover the planet. Changes in air pressure make winds blow from high to low
3 main types: Polar easterlies, Prevailing westerlies, tropical easterlies
Jet streams
strong, regular winds which blow in upper atmosphere, 10km above surface as part of rossby waves. 2 each hemisphere, 100-300km/h
types of jet stream
30-50 Polar Jet, 20-20 Sub Tropical Jet