Water-Overview of SurfaceWater (dams, water cycle, etc)

WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL  Water keeps us alive, moderates climate, sculpts the land, removes and dilutes wastes and pollutants, and moves continually through the hydrologic cycle.  It is renewable if kept “clean”.

Fig. 14-3, p. 308 Unconfined Aquifer Recharge Area Precipitation Evaporation and transpirationEvaporation Confined Recharge Area Runoff Flowing artesian well Recharge Unconfined Aquifer Stream Well requiring a pump Infiltration Water table Lake Infiltration Unconfined aquifer Confined aquifer Confining impermeable rock layer Less permeable material such as clay

Where is the water?  97% of the water on earth is saltwater.  Only about 0.02% of the earth’s water supply is available to us as liquid freshwater

Water Usage  47% Agricultural  44% Industrial  9% Residential  Wisconsin—100 gallons per person daily

Types of Surface Water 1.Lentic- non-flowing a.Lake-larger, more diverse, often more oxygen b.Pond-smaller, less diverse, less oxygen. Light penetrates entire body of water 2.Lotic- flowing a.River- larger, more volume b.Stream- smaller, less volume COLD vs WARM Water and Oxygen (cold holds more oxygen!)

Cont. 3.Wetlands- terrestrial areas saturated part of the time with water. Can be fresh or saltwater. Wetland Services a.Biodiversity b.Water Trap (flood control) c.Carbon Dioxide Trap d.Pollutant Trap

WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL  Some precipitation infiltrates the ground and is stored in soil and rock (groundwater).  Water that does not sink into the ground or evaporate into the air runs off (surface runoff) into bodies of water.  The land from which the surface water drains into a body of water is called its watershed or drainage basin. (Mississippi—30 states)

WATER POLLUTION: SOURCES, TYPES, AND EFFECTS  Water pollution is any chemical, biological, or physical change in water quality that has a harmful effect on living organisms or makes water unsuitable for desired uses. –Point source: specific location (drain pipes, ditches, sewer lines). –Nonpoint source: cannot be traced to a single site of discharge (atmospheric deposition, agricultural / industrial / residential runoff)

Dangers to Surface Water  Eutrophication-decrease in oxygen in a body of water. –Can be caused by algal blooms due to increased levels of nitrates and phosphates in water. –Nitrates and phosphates come from sewage, farm runoff (animal wastes), and fertilizers that enter surface water.

POLLUTION OF FRESHWATER STREAMS  Most developed countries have sharply reduced point-source pollution but toxic chemicals and pollution from nonpoint sources are still a problem.  Stream pollution from discharges of untreated sewage and industrial wastes is a major problem in developing countries.

Global Outlook: Stream Pollution in Developing Countries  Water in many of central China's rivers are greenish black from uncontrolled pollution by thousands of factories. Figure 21-5

PREVENTING AND REDUCING SURFACE WATER POLLUTION  Most developed countries use laws to set water pollution standards, but such laws rarely exist in developing countries. –The U.S. Clean Water Act sets standards fro allowed levels of key water pollutants and requires polluters to get permits. –EPA is experimenting with a discharge trading policy similar to that for air pollution control.

Reducing Water Pollution through Sewage Treatmentn (Septic)  Septic tanks and various levels of sewage treatment can reduce point-source water pollution. Figure 21-15

Reducing Water Pollution through Sewage Treatment  Raw sewage reaching a municipal sewage treatment plant typically undergoes: –Primary sewage treatment: a physical process that uses screens and a grit tank to remove large floating objects and allows settling. –Secondary sewage treatment: a biological process in which aerobic bacteria remove as much as 90% of dissolved and biodegradable, oxygen demanding organic wastes.

Reducing Water Pollution through Sewage Treatment  Primary and Secondary sewage treatment. Figure 21-16

Reducing Water Pollution through Sewage Treatment  Advanced or tertiary sewage treatment: –Uses series of chemical and physical processes to remove specific pollutants left (especially nitrates and phosphates).  Water is chlorinated to remove coloration and to kill disease-carrying bacteria and some viruses (disinfect).