Presentation on theme: "Distribution of Water on Earth"— Presentation transcript:
1Distribution of Water on Earth Chapter 1C - HydrologyMessanaScience 8
28.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
4The Hydrosphere Hydrosphere: the part of Earth that contains water 97% of Earth’s water is salt waterOnly 3% is fresh water: (30% groundwater, 68% frozen, 2% on surface)
5Saltwater 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 contentSaltwater:97% of Earth’s waterOceans35 g salt/kg of waterHow many oceans are currently recognized today??!!
6ONLY 3% of Earth’s water is fresh FreshwaterFreshwater:< 1 g salt/kg of waterONLY 3% of Earth’s water is fresh2/3 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
7Freshwater 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.
10The Great Lakes are the largest freshwater System on earth. They contain 84% ofNorth America’s surface freshwater and21% of the world’s surface fresh watersupply. Only the polar ice caps containmore fresh water.
11Water 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!!**
12Freshwater 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.
13Water Drainage Patterns Precipitation hits the surface of Earth 1.) If Permeable/Pervious Surface = water will sink in Ex: Sand, Gravel, Dirt2.) If Impermeable/Impervious Surface = water will not sink in, may be trapped in basin OR may run off from high low elevationEx: Red Clay, Cement, Asphalt
14Water Drainage Patterns Divide = high ridge of land from which water will flow in different directionsWatershed/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 landWhat River Basin do we live in??Catawba River Wateree River Santee River Atlantic Ocean!
16Possible 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
17Groundwater 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 ZoneThe top surface of this area = Water Table
19Aquifers Underground permeable rock or sediment that contains water Particles in ground act like filter to water!!
20Ogallala 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!”
21Groundwater to the Surface Via… 1.) Man-made Well – pipe dug into ground to extract water from aquifer2.) Artesian Well – water flows naturally to surface because it’s under pressure3.) Spring – water flows to surface because surface of land dips below water table4.) Hot Spring/Geyser – water heated up by rocks, pushes up to surface due to pressure