Presentation on theme: "Properties of Water. Only natural substance that exists as solid, liquid, and gas in temperatures normally found on Earth –Freezing point = 0 o C (32."— Presentation transcript:
Properties of Water
Only natural substance that exists as solid, liquid, and gas in temperatures normally found on Earth –Freezing point = 0 o C (32 o F) –Boiling point = 100 o C (212 o F)
Properties of Water Expands when it freezes –More dense as a liquid than a solid –Density of water = 1 g/cm 3 –Density of ice = 0.91 g/cm 3
Properties of Water High specific heat –A lot of energy is needed to change its temperature. –Moderates air temperature
Properties of Water High surface tension –Cohesion –Adhesion
Properties of Water Universal Solvent –Dissolves many (not all) substances
The Water Cycle
Earths water supply is continuously recycled. The overall process is powered by the Suns energy.
Water Storage Ocean –Most water on Earth Glaciers –Most fresh water Lakes Ice/snow Atmosphere
How Water Enters the Atmosphere Evaporation Transpiration Sublimation
Forms of Precipitation Rain Sleet Snow Hail Freezing Rain
The Water Cycle Once water reaches Earths surface as precipitation, it can: –Evaporate –Infiltrate –Run off
The Water Cycle
Runoff Runoff is water flowing downslope along Earths surface. Runoff may –reach a stream, river, or lake –evaporate –accumulate and eventually seep into the ground (infiltrate)
Factors that affect Runoff Vegetation Rate of Precipitation Soil Compaction Slope
Surface Water Movement
Watersheds and Divides Watershed –all of the land area whose water drains into a stream system stream system –large river and all its tributaries
NC Watersheds NC has 12,200 km of rivers and streams
Moving Water Carves a Path Must have an adequate supply of water Stream begins at headwaters
Youthful Rivers Steep gradient (slope) Narrow channel (downcutting) Channel is V-shaped Fast moving Moves all sediment sizes No floodplain Rapids and waterfalls More erosion than deposition
Mature Rivers Channel is U-shaped Medium velocity Moves many sediment sizes - not boulders Small floodplain Meanders begin to form Erosion and deposition occur Carries more sediment
Old Rivers Very shallow gradient Channel is wider than deep Slow moving Moves small-sized sediments Wide floodplain Meanders are abundant Large discharge
Meandering Streams In a curve, the greatest speed is along the outside of the curve. –Erosion occurs along the outside of the curve. –Deposition occurs along the inside of the curve.
Work of Streams A streams load includes all the materials that the water in a stream carries. –solution (dissolved) –suspension (carried) –bed load (pushed)
Work of Streams Erosion –The ability of a stream to erode materials depends on its velocity. –Abrasion –Grinding –Dissolving
Lakes and Wetlands
Lakes and Freshwater Wetlands A lake is a depression that collects and holds water. Reservoirs are lakes made for storing water for a communitys use.
Origins of Lakes Natural lakes form in different ways. 1.Oxbow lakes: streams cut off meanders and leave isolated channels of water. 2.Lakes can form when stream flow becomes blocked by sediment from landslides.
Origins of Lakes Natural lakes form in different ways. 3.Cirque lakes: depressions left by valley glaciers fill with water. 4.Kettle lakes: blocks of ice left by melting glaciers melted. 5.Some lakes are formed when the ceilings of limestone caverns collapse leaving depressions that fill with water.
Lakes Undergo Change Lakes are temporary water-holding areas. Eventually lakes fill in with sediment and become part of a new landscape.
Freshwater Wetlands A wetland is a land area that is covered with water for a large part of the year. Wetlands include environments commonly known as bogs, marshes, and swamps.
Freshwater Wetlands Bogs receive their water from precipitation and tend to be rich in peat moss.
Freshwater Wetlands Marshes frequently form along the mouths of streams and in areas with extensive deltas. Marshes have tall grasses.
Freshwater Wetlands Swamps are low-lying areas often located near streams. Swamps have shrubs and trees.
Freshwater Wetlands A filtering system –Pollutants –Sediments –Pathogenic bacteria Habitats –Migratory birds –Water birds –Endangered species
Freshwater Wetlands From the late 1700s to the mid 1980s, the continental United States lost 50 percent of its wetlands.