Groundwater AIM: Where does all the water go?. Water Cycle (hydrologic cycle)

GroundwaterGroundwater

AIMAIM: Where does all the water : Where does all the water go?go?

Water Cycle (hydrologic Water Cycle (hydrologic cycle)cycle)

Water enters the Water enters the atmosphere…atmosphere…

► EvaporationEvaporation – Water – Water changes from a liquid changes from a liquid to a gas. Most water to a gas. Most water evaporates from the evaporates from the oceans. Latent heat is oceans. Latent heat is stored. Wind and high stored. Wind and high temps speed up temps speed up evaporation.evaporation.

► TranspirationTranspiration – water – water in plants evaporatesin plants evaporates

► EvapotranspirationEvapotranspiration – all – all evaporation from earth evaporation from earth and plants.and plants.

Water leaves the Water leaves the atmosphere…atmosphere…

► CondensationCondensation – – Water changes from Water changes from a gas to liquid to a gas to liquid to form clouds. Latent form clouds. Latent heat is released.heat is released.

► PrecipitationPrecipitation – any – any form of water that form of water that falls from clouds falls from clouds (rain, snow, sleet, (rain, snow, sleet, hail)hail)

►RunoffRunoff –water that –water that

flows over the ground, flows over the ground, eventually leads eventually leads back to a larger back to a larger body of waterbody of water

►AccumulationAccumulation – – when water collects when water collects into large bodies, or into large bodies, or falls directly into itfalls directly into it

Where does it Where does it go?go?

Where does it go?Where does it go?

► InfiltrationInfiltration – when – when water seeps (sinks) water seeps (sinks) into the ground to into the ground to be stored as be stored as groundwater in the groundwater in the water table.water table.

► Groundwater flowGroundwater flow – when water moves – when water moves while undergroundwhile underground

Factors that affect Factors that affect infiltrationinfiltration

► 1. Porosity: 1. Porosity: the size of the spaces between sediments in the ground or in the rocks themselves.

► 2. Permeability:2. Permeability: how fast water will pass through the soil material. The ability to pass through sediments in the ground.

Water tableWater table► The height of the water in the ground. Water near the The height of the water in the ground. Water near the

surface can evaporate, lowering the water table.surface can evaporate, lowering the water table.► Water will infiltrate the ground when it is Water will infiltrate the ground when it is unsaturated unsaturated

and permeable,and permeable, causing the water table to rise.

Infiltration – water will seep into Infiltration – water will seep into ground to the water tableground to the water table

Permeability:Permeability:

►Permeable:Permeable: water passes through water passes through fast (gravel and sand)fast (gravel and sand)

►ImpermeableImpermeable:: water passes water passes through very slowly (silt and clay)through very slowly (silt and clay)

Permeability animation

Gravel and Sand: High porosity, high permeabilityBecause there are larger spaces between the pieces of gravel and grains of sand where water can go through easily.

Silt and Clay: Low porosity, low permeabilitySilt and clay are tightly packed together and have very small spaces between them.

Why did the water pass through Why did the water pass through the gravel and sand faster?the gravel and sand faster?

What is the relationship What is the relationship between sediment size and between sediment size and

permeability?permeability?►The larger the sediment, the more The larger the sediment, the more

permeable because the spaces will be permeable because the spaces will be bigger.bigger.

►The smaller the sediment, the less The smaller the sediment, the less permeable because the spaces will be permeable because the spaces will be smaller.smaller.

http://www.brainpop.com/science/earthsystem/groundwater/

Porosity:Porosity:

►The percentage of open space in a The percentage of open space in a material compared to its total volume.material compared to its total volume. Shape –rounded particles have more Shape –rounded particles have more

porosity than angular particlesporosity than angular particles Packing-closely packed particle have Packing-closely packed particle have

lower porositylower porosity Sorting – sorted particle have higher Sorting – sorted particle have higher

porosity than unsortedporosity than unsorted

But…sorted sediments that are But…sorted sediments that are equally packed have equal equally packed have equal

porosityporosity

CapillarityCapillarity

► Small closely Small closely packed rocks packed rocks will draw will draw water up water up against the against the flow of gravityflow of gravity

Summary: Factors that affect Summary: Factors that affect runoff and infiltrationrunoff and infiltration

► Permeability of the soil- type of soil, size of Permeability of the soil- type of soil, size of sediments, sorted vs. unsortedsediments, sorted vs. unsorted

► Slope – steeper will cause more runoff, Slope – steeper will cause more runoff, shallow slope more infiltration.shallow slope more infiltration.

► Saturation of the ground – wetter ground Saturation of the ground – wetter ground will decrease permeability and cause more will decrease permeability and cause more to run off, dryer ground will allow more to run off, dryer ground will allow more infiltration, less runoffinfiltration, less runoff

►Groundcover – vegetation decreases runoff, Groundcover – vegetation decreases runoff, concrete increases runoff.concrete increases runoff.