RR5

A comprehensive set of vocabulary flashcards covering hydrological surplus, runoff processes, physical and human flood drivers, impacts, and case-study examples for A-Level Geography revision.

Hydrological Surplus

Condition where precipitation exceeds evaporation and evapotranspiration, creating excess water in a drainage basin.

Runoff

Water that flows over the land surface or in channels as an output from a catchment during surplus periods.

Groundwater Recharge

Downward movement of surplus water into aquifers, sustaining river baseflow.

Soil Saturation

Point at which soil moisture storage is full, so additional rainfall becomes surface runoff.

Baseflow

Portion of river discharge supplied by slow, continuous groundwater seepage.

Water Balance Equation

Precipitation = Evapotranspiration + Runoff + Change in Storage; expresses hydrological inputs and outputs.

Antecedent Moisture

Pre-existing soil or catchment wetness that accelerates saturation and surplus generation.

Flashy Hydrograph

Hydrograph with a steep rising limb and high peak discharge, characteristic of rapid runoff events.

Lag Time

Time interval between peak rainfall and peak river discharge on a storm hydrograph.

Interception

Rainfall temporarily stored on vegetation surfaces, reducing immediate runoff.

Dam Spillover

Intentional or accidental release of excess reservoir water that can produce downstream surplus.

Intense Rainfall

High rainfall rates over short durations, often triggering flash flooding.

Prolonged Rainfall

Long-lasting precipitation that gradually saturates catchments and raises flood risk.

Snowmelt Flooding

Rapid river rise caused by sudden thaw of accumulated snow and ice.

Storm Surge

Temporary rise in sea level driven by strong winds and low pressure during coastal storms.

Orographic Rainfall

Precipitation formed as moist air ascends a mountain barrier, cooling and condensing on windward slopes.

Catchment Size

Area of land draining to a river; small basins react quickly, large ones more slowly, to rainfall.

Vegetation Loss

Removal of plant cover (e.g., deforestation) that lowers interception and increases runoff.

Braided Channel

River with multiple intertwining channels; sediment build-up can elevate beds and heighten flood risk.

Impermeable Bedrock

Geological layer that prevents infiltration, leading to greater surface runoff.

Clay Soil

Fine-grained, low-permeability soil that saturates rapidly and generates high runoff volumes.

Soil Porosity

Proportion of void space in soil; low porosity limits water storage and boosts runoff.

Saturation-Excess Overland Flow

Surface flow produced once soil is fully saturated and cannot absorb additional rainfall.

Hydraulic Radius

Cross-sectional area divided by wetted perimeter; larger values enable faster channel flow.

Urbanisation

Expansion of impervious surfaces (roads, roofs) that accelerates runoff and flood peaks.

Peak-Flow Exaggeration

Rapid concentration of stormwater in urban drainage, sharply raising river peak discharge.

Drainage Ditches

Artificial channels on farmland that quickly remove water, increasing stream flow and flood risk.

Channelisation

Engineering practice of straightening and deepening rivers to speed flow, often shifting floods downstream.

River Dredging

Removal of sediment to increase channel capacity; can unintentionally accelerate downstream flooding.

Floodplain Development

Construction on natural overflow areas, reducing storage space and elevating flood hazard.

Levee Failure

Overtopping or breaching of embankments that releases impounded water suddenly onto land.

Reservoir Mismanagement

Inadequate release strategies that cause unexpected high flows and downstream flooding.

Gravel Extraction

Removal of river sediments that creates pits and alters flood pathways, intensifying risk.

Hydrological Threshold

Critical discharge point beyond which river levels rise rapidly, leading to flooding.

Flash Flood

Sudden, high-velocity flood occurring in small basins after intense rainfall.

Deforestation

Clearing of forests that decreases interception, increases soil erosion, and elevates flood peaks.

Agricultural Soil Compaction

Compression by livestock or machinery that reduces infiltration capacity and heightens runoff.

Impermeable Surface

Man-made cover, such as asphalt, that prevents infiltration and promotes surface runoff.

Flood Hazard

Potential threat of overflowing water bodies to people, property, and the environment.

Infrastructure Damage

Destruction of roads, bridges, utilities, and buildings resulting from flooding.

Displacement

Forced movement of people from homes due to flood inundation.

Waterborne Disease

Illnesses (e.g., cholera) spread through contaminated floodwaters.

Insurance Impact

Increase in claims and premiums, with some high-risk zones becoming uninsurable after floods.

Psychological Effects

Mental health issues—trauma, anxiety, depression—arising from flood experiences.

Ecosystem Response

Changes such as temporary wetland formation, nutrient redistribution, and altered species movement after flooding.

Secondary Hazard

Additional threats triggered by floods, including landslides, mold, and disease outbreaks.

2007 UK Summer Floods

Event caused by persistent June–July rainfall over saturated catchments; £3.2 billion damage, 48 000 homes flooded.

2010 Pakistan Floods

Severe monsoon and glacier-melt event affecting 20 million people; worsened by deforestation and weak infrastructure.

2008 Mississippi River Floods

US floods driven by snowmelt, heavy spring rain, and levee failure; spurred levee reinforcement and floodplain restoration.

Integrated Flood Management

Holistic approach combining land-use planning, early warnings, and ecosystem restoration to enhance flood resilience.

Hydrological Surplus

Condition where precipitation exceeds evaporation and evapotranspiration, creating excess water in a drainage basin.

Runoff

Water that flows over the land surface or in channels as an output from a catchment during surplus periods.

Groundwater Recharge

Downward movement of surplus water into aquifers, sustaining river baseflow.

Soil Saturation

Point at which soil moisture storage is full, so additional rainfall becomes surface runoff.

Baseflow

Portion of river discharge supplied by slow, continuous groundwater seepage.

Water Balance Equation

Precipitation = Evapotranspiration + Runoff + Change in Storage; expresses hydrological inputs and outputs.

Antecedent Moisture

Pre-existing soil or catchment wetness that accelerates saturation and surplus generation.

Flashy Hydrograph

Hydrograph with a steep rising limb and high peak discharge, characteristic of rapid runoff events.

Lag Time

Time interval between peak rainfall and peak river discharge on a storm hydrograph.

Interception

Rainfall temporarily stored on vegetation surfaces, reducing immediate runoff.

Dam Spillover

Intentional or accidental release of excess reservoir water that can produce downstream surplus.

Intense Rainfall

High rainfall rates over short durations, often triggering flash flooding.

Prolonged Rainfall

Long-lasting precipitation that gradually saturates catchments and raises flood risk.

Snowmelt Flooding

Rapid river rise caused by sudden thaw of accumulated snow and ice.

Storm Surge

Temporary rise in sea level driven by strong winds and low pressure during coastal storms.

Orographic Rainfall

Precipitation formed as moist air ascends a mountain barrier, cooling and condensing on windward slopes.

Catchment Size

Area of land draining to a river; small basins react quickly, large ones more slowly, to rainfall.

Vegetation Loss

Removal of plant cover (e.g., deforestation) that lowers interception and increases runoff.

Braided Channel

River with multiple intertwining channels; sediment build-up can elevate beds and heighten flood risk.

Impermeable Bedrock

Geological layer that prevents infiltration, leading to greater surface runoff.

Clay Soil

Fine-grained, low-permeability soil that saturates rapidly and generates high runoff volumes.

Soil Porosity

Proportion of void space in soil; low porosity limits water storage and boosts runoff.

Saturation-Excess Overland Flow

Surface flow produced once soil is fully saturated and cannot absorb additional rainfall.

Hydraulic Radius

Cross-sectional area divided by wetted perimeter; larger values enable faster channel flow.

Urbanisation

Expansion of impervious surfaces (roads, roofs) that accelerates runoff and flood peaks.

Peak-Flow Exaggeration

Rapid concentration of stormwater in urban drainage, sharply raising river peak discharge.

Drainage Ditches

Artificial channels on farmland that quickly remove water, increasing stream flow and flood risk.

Channelisation

Engineering practice of straightening and deepening rivers to speed flow, often shifting floods downstream.

River Dredging

Removal of sediment to increase channel capacity; can unintentionally accelerate downstream flooding.

Floodplain Development

Construction on natural overflow areas, reducing storage space and elevating flood hazard.

Levee Failure

Overtopping or breaching of embankments that releases impounded water suddenly onto land.

Reservoir Mismanagement

Inadequate release strategies that cause unexpected high flows and downstream flooding.

Gravel Extraction

Removal of river sediments that creates pits and alters flood pathways, intensifying risk.

Hydrological Threshold

Critical discharge point beyond which river levels rise rapidly, leading to flooding.

Flash Flood

Sudden, high-velocity flood occurring in small basins after intense rainfall.

Deforestation

Clearing of forests that decreases interception, increases soil erosion, and elevates flood peaks.

Agricultural Soil Compaction

Compression by livestock or machinery that reduces infiltration capacity and heightens runoff.

Impermeable Surface

Man-made cover, such as asphalt, that prevents infiltration and promotes surface runoff.

Flood Hazard

Potential threat of overflowing water bodies to people, property, and the environment.

Infrastructure Damage

Destruction of roads, bridges, utilities, and buildings resulting from flooding.

Displacement

Forced movement of people from homes due to flood inundation.

Waterborne Disease

Illnesses (e.g., cholera) spread through contaminated floodwaters.

Insurance Impact

Increase in claims and premiums, with some high-risk zones becoming uninsurable after floods.

Psychological Effects

Mental health issues—trauma, anxiety, depression—arising from flood experiences.

Ecosystem Response

Changes such as temporary wetland formation, nutrient redistribution, and altered species movement after flooding.

Secondary Hazard

Additional threats triggered by floods, including landslides, mold, and disease outbreaks.

2007 UK Summer Floods

Event caused by persistent June–July rainfall over saturated catchments; £3.2 billion damage, 48 000 homes flooded.

2010 Pakistan Floods

Severe monsoon and glacier-melt event affecting 20 million people; worsened by deforestation and weak infrastructure.

2008 Mississippi River Floods

US floods driven by snowmelt, heavy spring rain, and levee failure; spurred levee reinforcement and floodplain restoration.

Integrated Flood Management

Holistic approach combining land-use planning, early warnings, and ecosystem restoration to enhance flood resilience.