1 - Changes in the Water Cycle Flashcards
What natural processes cause change in the water cycle?
Seasonal changes, storm events, El Niño and La Niña and cryospheric processes.
Explain seasonal change as a natural process that causes change in the water cycle.
SUMMER: Less precipitation and more evapotranspiration due to higher temperatures and deciduous trees having their leaves.
WINTER: Reduced flows due to water being stored as ice. Reduced interception as deciduous trees loose their leaves.
Change is not long-term…only seasonal and on a regional scale
Explain storm events as a natural process that causes change in the water cycle.
Cause sudden increase in rainfall -> flooding -> replenishment of some water stores.
Unlikely to cause long-term change as storm events are temporary and on a regional scale.
Explain El Niño and La Niña as a natural process that causes change in the water cycle.
El Niño - every 2-7 years, causes warm temperatures in a predictable way.
La Niña - every 2-7 years, causes cooler temperatures in a predictable way.
It is likely that climate change will increase the probability of more El Niño’s in the future.
Explain cryospheric processes as natural processes that causes change in the water cycle.
As we move from glacial to interglacial periods, the amount of water stored as ice changes.
Interglacial - ablation occurs…ice melts and more water is stored as a liquid
Glacial - accumulation occurs…water freezes and more water is stored as ice
Ablation is causing sea levels to rise. If all the worlds glaciers and ice caps were to melt, sea levels would rise by 60m! For the UK, this would mean SE England would disappear.
What human impacts cause change in the water cycle?
Farming practices, land use change and water abstraction.
Explain farming practices as a human impact that causes change in the water cycle.
Ploughing breaks up the surface and increases infiltration.
Arable (crops) farming can increase interception and evapotranspiration.
Pastoral (animal) farming compacts soil, reducing infiltration and increasing runoff.
Explain land use change (deforestation) as a human impact that causes change in the water cycle.
Reduces interception and evapotranspiration.
Explain land use change (urbanisation) as a human impact that causes change in the water cycle.
Reduces infiltration and evapotranspiration.
Increases runoff.
Explain water abstraction as a human impact that causes change in the water cycle.
Reduces the volume of water in surface stores e.g. lakes.
Increases during dry seasons…water is needed for irrigation.
Human demand for water from aquifers is often greater than the inputs into aquifers, leading to a decline in global long-term water stores.
