# Distribution of Water on Earth

## Presentation on theme: "Distribution of Water on Earth"— Presentation transcript:

Distribution of Water on Earth
Chapter 1C - Hydrology Messana Science 8

8.E.1 Understand the hydrosphere and the impact of humans on local systems and the effects of the hydrosphere on humans. 8.E.1.1 Explain the structure of the hydrosphere including: • Water distribution on earth • Local river basins and water availability

THIRST VIDEO

The Hydrosphere Hydrosphere: the part of Earth that contains water
97% of Earth’s water is salt water Only 3% is fresh water: (30% groundwater, 68% frozen, 2% on surface)

Saltwater Oceans cover 71% of Earth’s surface (about ¾)
Land takes up 29% of Earth’s surface (about ¼) 2 categories of water in the Hydrosphere…based on Salinity = % salt content Saltwater: 97% of Earth’s water Oceans 35 g salt/kg of water How many oceans are currently recognized today??!!

ONLY 3% of Earth’s water is fresh
Freshwater Freshwater: < 1 g salt/kg of water ONLY 3% of Earth’s water is fresh 2/3 of that is frozen in glaciers, ice caps, & icebergs (pieces of glaciers floating in ocean) 1/3 of that is liquid & accessible in lakes, ponds, rivers, streams, or underground

Freshwater Resources Most freshwater is frozen at the polar ice caps!!
Glaciers are masses of ice and snow that move slowly over the Earth’s surface.

Where’s the water?

The Great Lakes are the largest freshwater
System on earth. They contain 84% of North America’s surface freshwater and 21% of the world’s surface fresh water supply. Only the polar ice caps contain more fresh water.

Water Cycle – Quick Review
1. Sun heats the water on the surface of Earth  2. Freshwater evaporates into atmosphere as water vapor (salt in ocean stays behind)  3. Water vapor cools & condenses on dust particles to form clouds  4. Water falls back to Earth as precipitation in the form of rain, sleet, snow, or hail  5. Precipitation that hits surface either gets absorbed into ground, stays trapped as standing water, or moves downhill as “run-off” back into lakes, ponds, rivers, streams, oceans **The amount of water on Earth stays the same!!**

Freshwater Resources 1/3 of Earth’s freshwater is groundwater!!
Groundwater forms when water moves through soils and sediment and collects in spaces underground. An aquifer is a rock layer that stores water in the spaces between the rock and allows water to flow through it.

Water Drainage Patterns
Precipitation hits the surface of Earth  1.) If Permeable/Pervious Surface = water will sink in Ex: Sand, Gravel, Dirt 2.) If Impermeable/Impervious Surface = water will not sink in, may be trapped in basin OR may run off from high  low elevation Ex: Red Clay, Cement, Asphalt

Water Drainage Patterns
Divide = high ridge of land from which water will flow in different directions Watershed/River Drainage Basin = drainage area where all water from one side of a divide flows, all water flows to one central river based on the topography (curves/elevation) of the land What River Basin do we live in?? Catawba River Wateree River Santee River  Atlantic Ocean!

Examine A Watershed

Possible Water Flow Example
Precipitation  Land  Flows Downhill  Stream  River  Larger River OR Lake  Estuary = mix of fresh & salt water in a bay  Ocean!!...all water ends up here 

Groundwater Water that seeps into the soil & is pulled down by gravity
Can move or sit under the surface if there are spaces between the rock/soil particles (permeable) Water will seep down until it hits an impermeable surface, then fill up from there (like your bathtub with the drain closed!) The region filled with ground water = Saturation Zone The top surface of this area = Water Table

Water Table & Saturation Zone

Aquifers Underground permeable rock or sediment that contains water
Particles in ground act like filter to water!!

Ogallala Aquifer – under U.S.
Huge source of freshwater for drinking & irrigation in the U.S. Depleting at alarming rate… “The average annual depletion rate between 2000 and 2007 was more than twice that during the previous fifty years!”

Groundwater to the Surface Via…
1.) Man-made Well – pipe dug into ground to extract water from aquifer 2.) Artesian Well – water flows naturally to surface because it’s under pressure 3.) Spring – water flows to surface because surface of land dips below water table 4.) Hot Spring/Geyser – water heated up by rocks, pushes up to surface due to pressure

Artesian Well & Spring

Geyser in Iceland – YouTube Clip
.com/watch%3Fv%3DW-daow- LojM&sa=U&ei=n65CT8aeApDcgge2o63lCw&ve d=0CCgQtwIwAg&usg=AFQjCNEpLlDlSzVPx4a S-Tu3nfBc1pCkKw &feature=related