caie-as-level-geography-9696-core-physical-geography-v2 Notes | Knowt (2024)

Page 2: Hydrology and Fluvial Geomorphology

  • Drainage Basin System Outputs

    • Evapotranspiration

      • Evaporation: liquid changes into water vapor in hot, dry, and windy conditions.

      • Transpiration: water drawn by plants and released as vapor.

      • Potential Evapotranspiration: amount if unlimited water source.

    • River Discharge

      • Water flowing into the sea or channels.

      • Measured in m3/second – Cumecs.

    • Stores

      • Interception, Surface Water, Ground Water, Channel Storage, Soil Moisture.

    • Flows Above Ground

      • Throughfall, Stemflow, Overland Flow, Hortonian Flow, Channel Flow.

Page 3: Below Ground

  • Infiltration and Percolation

    • Infiltration Capacity, Percolation in different types of bedrock.

    • Throughflow, Groundwater, Phreatic zone, Baseflow.

  • Underground Water

    • Water table, Groundwater Recharge and Loss.

    • Aquifers, Springs, Water budget equation.

  • Discharge Relationships

    • Hydrograph Components, Annual and Storm Hydrograph.

    • Cumecs, Approach Segment, Rising Limb, Bank full Discharge, Peak Discharge, Lag Time, Receding Limb, Stormflow, Quickflow.

  • Drainage Basin Characteristics

    • Size and Shape, Drainage Density.

Key Concepts

  • Evapotranspiration and River Discharge

  • Storage and Flows Above/Below Ground

  • Groundwater Recharge and Discharge

  • Hydrograph Components and Drainage Basin Characteristics


  • CAIE AS Level Geography Syllabus

  • Factors affecting flood risk and discharge response:

    • Dendritic patterns have higher density

    • Impermeable surfaces lead to greater peak flows

    • Rock type influences flashiness of response

    • Steeper slopes result in higher peak flows

    • Vegetation type and land use impact flood response

  • River channel processes and landforms:

    • Bradshaw model explains changes in river characteristics

    • Erosion processes like abrasion, corrasion, solution, hydraulic action, cavitation, and attrition

    • Load transport mechanisms: traction, saltation, suspension, and solution

  • Critical erosion velocity and mean settling velocity for different particle sizes

  • Factors affecting river flow velocity: friction, bed roughness, and hydraulic radius

  • Different channel types: straight, braided, and meandering

  • Landforms like meanders, river cliffs, point bars, and oxbow lakes

  • River flow velocity influenced by friction more than gradient

  • Different channel types: straight, braided, meandering

  • Landforms like meanders, river cliffs, point bars, and oxbow lakes

  • Pools, Riffles, Waterfalls, Gorges, Potholes, Rapids, Bluffs, Floodplains, Levees, Deltas

    • Pools and Riffles: Deep sections with erosion vs. shallower sections with sediment deposition.

    • Waterfalls: Result from gradient changes, erosion, and splashback.

    • Gorges: Steep valleys from waterfall retreat.

    • Potholes: Formed by swirling pebbles eroding riverbed.

    • Rapids: Turbulent flow in upper course with rocky riverbed.

    • Bluffs: Terraces left by old floodplains, eroded by meanders.

    • Floodplains and Levees: Flat land next to river, rise during floods, levees form after floods.

    • Deltas: Sediment deposition at river's end, with different types like Arcuate, Cuspate, and Bird’s Foot.

  • Human Impact on Catchment Flow Modifications

    • Deforestation: Reduces evapotranspiration, increases surface runoff.

    • Urbanization: Impermeable surfaces increase overland flow.

    • Grazing: Ploughing reduces infiltration, leading to higher peak discharge.

    • Abstraction: Overuse causes river drying and saltwater intrusion.

    • Channelization: Alters channel characteristics, affecting flood peaks.

  • Causes and Impacts of River Floods

    • Physical Causes: Heavy rainfall, melting snow, impermeable soil, coastal surges.

    • Human Causes: Urbanization, floodplain developments, engineering obstructions.

    • Impacts: Deaths, damage, disruption, with higher tolls in LICs.

  • Flood Prediction

    • Recurrence Interval: Frequency of floods of a certain size.

    • Flood Risk Maps: Show areas prone to flooding based on severity.

  • Flood Prevention

    • Forecasting and Warning: Use of technology, emergency plans, and communication.

    • Hard Engineering: Dams, levees, channel straightening.

    • Soft Engineering: Natural processes like afforestation and flood diversion.

    • Land Use Zoning: Avoid building in flood-prone areas.

  • Diurnal Energy Budgets and Heat Transfers

    • Radiation: Incoming solar radiation, albedo, longwave radiation.

    • Cloud Effects: Cooling effect during the day, insulating effect at night.

    • Heat Transfers: Sensible heat transfer through convection, advection.

This information covers river landforms, human impacts on river systems, causes and impacts of river floods, flood prediction, prevention strategies, and aspects of diurnal energy budgets and heat transfers in the atmosphere.

Conduction and Latent Heat Transfer

  • Conduction: Heat transfer between ground and air when in contact.

    • Heat is transferred from the ground to the air.

  • Latent Heat Transfer: Occurs during evaporation or melting.

    • Heat is absorbed to change state, leaving less energy to heat the surface.

    • Latent heat of condensation enhances convection speed.

  • Evaporation: Water molecules gain energy and change to gas, cooling the surface.

  • Dew Formation: Water vapor condenses on cooler surfaces, releasing latent heat.

  • Absorbed Energy Return: Greenhouse gases absorb radiation, warming the atmosphere.

  • Surface Temperature Changes: Daytime heating by radiation, conduction, and convection. Night cooling due to lack of radiation.

Global Energy Budgets

  • Latitudinal Radiation Pattern:

    • Excess radiation in tropics, deficit at higher latitudes.

    • Horizontal transfer compensates for insolation differences.

  • Temperature Patterns:

    • Equator has little seasonal variation, while mid/high latitudes vary greatly.

    • Ground continues to lose heat after winter solstice despite resumed insolation.

Atmospheric Transfers

  • Pressure Variations:

    • Air moves from high to low pressure, affecting weather.

  • Surface Pressure and Wind Belts:

    • Low pressure in equatorial regions, high pressure in polar regions.

    • Seasonal insolation variations affect wind patterns.

  • Ocean Conveyor Belt:

    • Cold, salty water sinks and moves towards the equator.

    • Warm currents raise temperatures in polar regions.

Seasonal Variations

  • Land vs. Sea Distribution:

    • Land absorbs more radiation due to lower reflectivity.

    • Sea has high heat capacity, less absorption of radiation.

  • Altitude and Pressure Belts:

    • Air temperature decreases with altitude.

    • Pressure changes drive wind patterns.

Global Circulation Model

  • 3 Cell Model:

    • Hadley, Ferrel, and Polar cells create global circulation.

    • Rossby waves and geostrophic winds influence atmospheric patterns.

Page 10: Upper Westerlies and Jet Streams

  • Upper Westerlies:

    • Fast-moving winds due to temperature and pressure gradient.

    • Important for mixing warm and cold air.

  • Jet Streams:

    • Narrow columns of fast-moving air in Rossby waves.

    • Exist in polar and subtropical regions in each hemisphere.

    • Result from differences in air masses.

Weather Processes and Phenomena

Atmospheric Moisture Processes

  • Evaporation:

    • Occurs when vapor pressure exceeds atmospheric pressure.

    • Sped up by low humidity, heat, and strong wind.

  • Condensation:

    • Cooling below dew point or saturation turns vapor into liquid.

    • Requires hygroscopic condensation nuclei.

  • Cooling Mechanisms:

    • Conduction, radiation, expansion, freezing, melting, deposition, sublimation.

Causes of Precipitation

  • Collision Theory:

    • Droplets collide to form larger droplets.

  • Bergeron-Findeisen Theory:

    • Ice saturation before water addition.

    • Ice particles grow through sublimation.

  • Convectional, Frontal, and Orographic Precipitation:

    • Result from different air mass interactions.

  • Radiation Cooling:

    • Leads to fog and ice formation.

Types of Precipitation

  • Relative Humidity:

    • Calculation formula provided.

Weather Phenomena: Inversions

  • Frontal Inversion:

    • Colder air descends, forming warmer air above.

  • Subsidence Inversion:

    • Adiabatic cooling leads to temperature inversion.

  • Dissipation of Inversions:

    • Sun heating the ground allows warm air to rise.

The text covers upper westerlies, jet streams, atmospheric moisture processes, causes of precipitation, types of precipitation, and weather phenomena like inversions. It also explains the calculation o

caie-as-level-geography-9696-core-physical-geography-v2 Notes | Knowt (2024)
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