The Water Planet and Hydrology Movement of Water Underground USGS.

The Water Planet and Hydrology

Movement of Water Underground

USGS

The Water Planet

Why is Earth unique?

Water Planet There is an

enormous amount of water on Earth – most of it is in the oceans.

The remainder is distributed among ice sheets and glaciers, groundwater, lakes, streams, and the atmosphere.

Water Planet There are

constant exchanges of water among the oceans, the atmosphere, and the continents.

This unending circulation of Earth’s water is called the –

Hydrologic Cycle

The Hydrologic Cycle

Water enters the atmosphere by evaporation.

Precipitation returns liquid water to the surface.

A portion soaks into the ground – infiltrates.

This is groundwater.

Runoff

Water that does not soak in will flow across surface as runoff.

Most reenters the atmosphere due to evaporation.

Some by transpiration

Winter thaw run off

Groundwater Any water that is below the surface May be in soils or porous rocks Can be tapped for wells or supply artesian

springs

Click on image to viewa groundwater animation

http://earthguide.ucsd.edu/earthguide/diagrams/groundwater/index.html

Ground water Zones

Color in accordingly

Zone of aeration: Zone where most of the interconnected pores are filled

with air. Water table: The surface below which, the ground is saturated with

water Zone of saturation: Layer of soil where pores are filled with groundwater

(below the water table) Impermeable Rock: The layer where water cannot penetrateFactors that determine whether water infiltrates:1. Slope of the land2. Porosity of surface/ground3. Permeable or not4. Gravitational pull

Physical Properties of Sediments and Water Flow –

Pore Space Unoccupied or void space between

sediment particles Can be filled with air or water Measured by packing solid in a container

to measure the total volume; water is added just to the surface filling the empty space

added water = pore spaceempty

total

% Porosity = Volume

x 100Volume

Porosity

(ability to hold groundwater) = Percentage of Pore Space

Depends on: - Shape – round is more porous than angular- Packing – loosely packed is more porous than

tightly packed- Mixture – sorted is more porous than unsorted

Physical Properties of Sediments and Water Flow –

Pore Space If particles are round and the same

size they will pack a certain way leaving a regular pore space.

If this is the case, the pore space does not depend on the particle size. The larger the particles, the larger but fewer the spaces. For smaller particles, there are more but smaller spaces.

256 cm Boulder

64 cm Cobble

2 mm Pebble Gravel

0.0062 mm Sand

0.0039 mm Silt Mud

Clay

Sediment Size Classifications

Physical Properties of Sediments and Water Flow –

Pore Space

More but smaller spaces

Larger but fewer spaces

Mixed – less empty space

http://techalive.mtu.edu/meec/module06/Packing.htm

Physical Properties of Sediments and Water Flow –

Pore Space

Larger but fewer spaces

Mixed – less empty space

Most sediments are not regular in shape and pack more tightly. This reduces the pore space even more and reducesthe connectivity of the space.

Physical Properties of Sediments and Water Flow-

Permeability To determine permeability you can

measure :flow time: time for a set amount

of water to flow through the sediment (minutes/100 mL)

orflow rate: volume of water that

flows through a given amount of sediment in a set amount of time (mL/minute)

Physical Properties of Sediments and Water Flow-

PermeabilityMeasurement

Measurement Value

Flow Time (min/100 mL)

Flow Rate(mL/min)

High Low P High P

Medium Medium P Medium P

Low High P Low P

P = relative permeability

Physical Properties of Sediments and Water Flow-

Permeability Measure of the flow of water through

ground material Depends on the size of sediment

particles because it is controlled by the connectivity of pore space and surface area

Comparison animation-play

http://techalive.mtu.edu/meec/module06/Permeability.htm

Runoff

Rainfall exceeds permeability rate of the soil

Occurs when:- slope is too steep,- temperature is below 0°C- soil is saturated

Physical Properties of Sediments and Water Flow –

Water Retention

Amount of water that is retained as water flows through sediments

Water is retained on the surface so the greater the surface area, the higher the water retention

Which will have more retention for the same volume - gravel or sand?

Physical Properties of Sediments and Water Flow –

Water Retention

For the same volume, smaller particles will have more surface area, and therefore, greater water retention.

Sand will have higher water retention.

Water Retention is due to Capillarity

Ability of a substance to draw another substance into it –

Movement of water within spaces due to properties of water:

A: adhesion = stickiness

B: cohesion = attaching itself to other water molecules

large pore space => lower capillary action small pore space => higher capillary action

Groundwater Animation for Kids

Try the animation about the importance of groundwater. It runs about 4 minutes and requires Macromedia Flash 5 (or newer version).

http://www.kingcounty.gov/environment/waterandland/groundwater/education/animation.aspx

Click on image to viewa groundwater animation