Key terms:
Transpiration- Water that is lost from trees.
Solar Energy – Energy from the sun heating up water causing evapotranspiration
Gravitational potential energy – The way that water accelerates under gravity transporting it to
rivers and the sea
Water budgets – Balances between inputs and outputs in any area
Positive water balance – Plentiful supply of water
Negative water balance – Not enough water
River regime – Annual variation in discharge or flow of a river
Catchment – The area if land drained by a river and its tributaries
Watershed – The highland which divides and separates water flowing to a different river, where
two drainage basins meet
Peculation – How water falls through rocks
Through flow – Lateral transfer of water down slope through soil through natural pipes
Throughfall – water travelling through vegetation
Baseflow - Water travelling in the layer between rock and soil
Intertropical Convergence Zone (ITCZ) -A belt of low pressure around the equator
Drought – An extended period of time with a deficient rainfall relative to the average for a region
Crop Moisture Index ( CMI) – measures short term drought on a weekly scale – useful for farmers
Desertification – Land degradation in arid regions
Tipping point – When a system changes from one state to another
Positive feedback loop – A sequence of events that amplifies or increases change
Resilience – Ability of a system to bounce back and survive
Wetlands – Areas of marsh, fen, peatland or water with static or flowing water
Ground water flooding – Flooding that occurs after the ground is saturated from prolonged heavy
rainfall
Surface water flooding – Flooding that occurs when intense rainfall has sufficient time to infiltrate
soil so flows overland
Flash flooding – A flood with an exceptionally short lag time
Water scarcity – An imbalance between water demand and supply
, Water stress – A country exceeding 10% of its renewable freshwater supply
Green revolution- Use of high yield varieties od crops along with the use of agrochemical and
irrigation to increase yields and increase food supply and sercuity