The hydrological cycle Flashcards
The hydrological cycle is…
continuous circulation of water between the atmosphere, lithosphere and biosphere.
Interception is the precipitation…
that lands on trees and other vegetation.
Infiltration-surface water…
soaks into the soil.
Throughflow-water flows…
through soil.
Percolation-water moves…
downwards through permeable rocks. In Chalk it is fast.
Groundwater flow is very slow…
movement of water into the river.
Hortonian overland flow is any…
surface runoff as a result of higher rainfall intensity than infiltration capacity.
Saturated overland flow caused when…
the soil has reached its maximum soil moisture capacity and infiltration is 0.
Condensation-water vapour…
cools down and clouds are formed.
Evaporation-water heated by…
sun becomes water vapour(latent heat)
Groundwater is water…
stored in porous rocks.
The water table is…
the top of the saturated zone in permeable rock. It may rise or fall depending on inputs and outputs of the hydrological cycle.
Drainage cycle is…
open as water can be transferred to other areas,
Stem flow is any precipitation…
that has been intercepted by vegetation, then passes down the branches and stems of vegetation.
How to calculate discharge?
- cross-sectional area and velocity are required
- discharge requires the multiplication of CSA and velocity
- recorded as cumecs-cubic meters per second
Potential evapotranspiration is…
the water loss that would occur if there was an unlimited supply of water for vegetation. E.g. Egypt has annual precipitation less than 250mm, but potential EVP is 2000mm.
Discharge is…
the movement of water in channels.
Soil water or soil…
moisture is the subsurface water in the soil above the water table.
Field capacity refers to…
amount of water held in the soil after excess water drains out.
Soil moisture deficit is the degree to which…
soil moisture falls below field capacity.
Soil moisture recharge occurs when…
precipitation exceeds potential evapotranspiration.
Soil moisture surplus is the period when…
soil is saturated and water cannot enter, so flows over the surface.
Soil moisture utilisation is the process by which…
water is drawn to the surface through capillary action.
The amount of fresh water in groundwater stores is…
97%.
Surface water stores:
- lakes
- small puddles following a storm
- wetlands, swamps
- snow, ice
The phreatic zone is…
permanently saturated zone within solid rocks and sediment.
Aquifers are rocks that…
contain significant quantities of water, provide a reservoir. Rocks such as limestone or sandstone.
Recharge of groundwater:
- infiltration
- seepage(through banks and bed of rivers, lakes)
- artificial recharge from irrigation
Losses of groundwater:
- evapotranspiration
- natural discharge(spring)
- artifical abstraction (Saudi Arabia resrve decreased by 42% since 1985)
Aeration zone is between…
water table and the surface. Also called the unsaturated zone.
Aquitard is a band of…
rock with low permeability.
