Water Cycle (Enquiry Question 2)

Agricultural drought

Where the rainfall deficiency from meteorological drought leads to deficiency of soil moisture and soil water availability

Desertification Land degradation in arid

semi-arid and dry sub-humid regions

Ecosystem services The value of ecosystems for human well-being

El Niño

A reversal of 'normal' conditions in the Pacific basin

Famine drought

A humanitarian crisis in which the widespread failure of agricultural systems leads to severe food shortages

Flash flooding

A flood with exceptionally short lag time

Flood return period

A statistical estimate of how often a flood of a certain magnitude is likely to occur

Groundwater flooding

Flooding that occurs after the ground has become saturated from prolonged heavy rain

Hydrological drought

Where reduced stream flow and groundwater levels occur because of reduced inputs of precipitation from meteorological drought

Jökulhlaup

A type of glacial outburst flood that occurs when the dam containing a glacial lake fails

Meteorological drought

Shortfalls in precipitation because of short-term variability within the longer-term average (the degree of dryness compared to 'normal' precipitation)

Negative feedback

A cyclical sequence of events that damps down or neutralises the effects of a system

Positive feedback A

cyclical sequence of events that amplifies or increases change

Resilience

The ability of a system to bounce back and survive

Surface water flooding

Flooding that occurs when intense rainfall has insufficient time to infiltrate the soil

Tipping point

When a state changes from one state to another

Urbanisation

The increase in the number of people living in towns and cities compared to the number of people living in the countryside

Wetland

An area of marsh