The Science That You Want to Know
Watershed
Watershed - all the area of land drained by a river and all its tributaries springs, streams, creeks, brooks
• runoff - precipitation that flows into tributaries
• the area of the watershed delivers runoff, sediment and dissolved substances
• many areas being in mountainous or hilly areas and flow downwards
• runoff - precipitation that flows into tributaries
• the area of the watershed delivers runoff, sediment and dissolved substances
• many areas being in mountainous or hilly areas and flow downwards
Groundwater and the Hydrologic Cycle
Any precipitation reaching Earth's land surface that does not evaporate or flow into waterways percolates downward through the soil to become groundwater.
groundwater makes up 1/5th of Earth's freshwater supply and plays a key role in meeting human water needs
groundwater makes up 1/5th of Earth's freshwater supply and plays a key role in meeting human water needs
Water Pollution
Any chemical, biological, or physical change in water quality that has a harmful effect on the living organisms or that makes water unsuitable for desired uses.
Rivers and Flowing Streams
• recover rapidly from moderate levels of degradable, oxygen demanding wastes and excess heat
• this natural recovery process does not work when streams are overloaded with pollutants or from water diversion for agriculture or industry
Nutrient pollution - eutrophication
high nutrient content and low oxygen content
Groundwater
• pollution come from numerous sources that are dumped or spilled on the ground
• gasoline, oil, paint thinners and organic solvents
pollutants in drinking water is a high-risk health problem
Toxic-Chemical Pollution
Many freshwater supplies have become polluted with toxic chemicals.
Agriculture
• releases organic chemicals found in pesticides and detergents
• bacteria from livestock
• excess salt from irrigated cropland
Industrial and Manufacturing Processes
• release inorganic chemicals that include heavy metals
• mercury, arsenic and lead
All of the above substances make their way into fresh water through point or nonpoint sources.
• poison aquatic animals and plants
cause a wide array of human health problems
Rivers and Flowing Streams
• recover rapidly from moderate levels of degradable, oxygen demanding wastes and excess heat
• this natural recovery process does not work when streams are overloaded with pollutants or from water diversion for agriculture or industry
Nutrient pollution - eutrophication
high nutrient content and low oxygen content
Groundwater
• pollution come from numerous sources that are dumped or spilled on the ground
• gasoline, oil, paint thinners and organic solvents
pollutants in drinking water is a high-risk health problem
Toxic-Chemical Pollution
Many freshwater supplies have become polluted with toxic chemicals.
Agriculture
• releases organic chemicals found in pesticides and detergents
• bacteria from livestock
• excess salt from irrigated cropland
Industrial and Manufacturing Processes
• release inorganic chemicals that include heavy metals
• mercury, arsenic and lead
All of the above substances make their way into fresh water through point or nonpoint sources.
• poison aquatic animals and plants
cause a wide array of human health problems
Be sure to check out the watershed videos located in the VIDEO section!