water_resource_management_chapter_4es.ppt
- 1. Freshwater Resources and Water Pollution
- 2. Properties of Water Molecules of water: H2O – 2 Hydrogen atoms – 1 Oxygen atom Polar molecule – One end slightly positive – One end slightly negative
- 3. Properties of Water Hydrogen bonds that result from water’s polarity responsible for many of water’s properties – High heat capacity (Moderates climate) – Universal solvent
- 4. The Importance of Water All living things need water Composes majority of the body of organisms Habitat for many organisms Helps regulate climate Shapes earth’s surface Dilutes & degrades wastes
- 5. Water on Earth About 97% Earth’s water is salty–less than 1% of the planet’s water is available fresh H2O Fresh water is distributed unevenly 2025: 1/3 human population will live in areas lacking fresh water
- 6. Water, water, everywhere? (NOT) Comparison of population sizes and shares of the world’s freshwater among the continents. (Only 7 countries account for 60% of global water availability)
- 7. Water Wars Many countries in the Middle East, which has one of the world’s highest population growth rates, face water shortages.
- 8. Water wars cont… Most water in this dry region comes from the Nile, Jordan or Tigris rivers. Countries are in disagreement as to who has water rights. Currently, there are no cooperative agreements for use of 158 of the world’s 263 water basins that are shared by two or more countries.
- 10. Surface Water Streams, rivers, lakes, ponds, reservoirs, wetlands Runoff replenishes surface water Watershed Area of land drained by a single river What watershed do we live in?
- 11. Groundwater Supply of fresh water found under Earth’s surface--recharged when water at surface infiltrates into the ground Stored in under ground aquifers Discharged into rivers, springs, etc…
- 12. Infiltration - Process of water percolating through the soil and into cracks and permeable rocks. Zone of Aeration - Upper soil layers that hold both air and water. Zone of Saturation Lower soil layers where all spaces are filled with water. Water Table - Top of zone of saturation
- 13. •Recharge Zone - Area where water infiltrates into an aquifer. -Recharge rate is often very slow. -Presently, groundwater is being removed faster than it can be replenished. Evaporation and transpiration Evaporation Infiltration Unconfined aquifer Confined aquifer Well requiring a pump Flowing artesian well Runoff Precipitation Confined Recharge Area Less permeable material such as clay Confining permeable rock layer Unconfined Aquifer Recharge Area Water table
- 14. Aquifers - Porous layers of sand, gravel, or rock lying below the water table.
- 15. Water Resource Problems Too much water Too little water Poor-quality water
- 16. Changes in Surface Runoff Prior to 1970 about 10% of stormwater became runoff Now 55% of stormwater is transported as runoff as development exceeds 75% of the permeable soil area
- 17. Stormwater Runoff (greatest contributor to nonpoint source pollution) contains: Nutrients* Metals* Suspended solids* Pesticides Hydrocarbons Microorganisms *Present in nearly 100% of stormwater samples
- 18. Too Much Water Heavy rainfall, rapid snowmelt, removal of vegetation, and destruction of wetlands cause flooding. Floodplains, which usually include highly productive wetlands, help provide natural flood and erosion control, maintain high water quality, and recharge groundwater. To minimize floods, rivers have been narrowed with levees and walls, and dammed to store water.
- 19. Human activities have contributed to flood deaths and damages
- 20. Too Little Water Arid & semiarid lands (growing in extent -- desertification) Irrigation required to produce food Greatest use of water (71%)
- 21. Aquifer Depletion Removing groundwater faster than it is replenished Lowers water table Land subsidence Saltwater intrusion Salt water seeps into fresh water Occurring in South Florida
- 22. Overdrawing Surface Waters Damaging to ecosystems Wetlands dry up (Everglades) Estuaries become too salty (FL Bay) Worldwide, the demand for water is growing as the human population and indvidual consumption continue to grow exponentially Water wars Arial Sea
- 23. Water Management Goal: sustainable supply of high quality water How do we supply water? Building dams (ex: Columbia River) Diversion (ex: Colorado River) Desalination (ex: FL Keys) - very expensive to build & operate plants
- 24. Water Conservation: Agriculture Single largest user of water worldwide Much lost to evaporation or seepage Solution: drip irrigation Perforated pipes distribute water Goes straight to plants Reduces water use 40-60%
- 25. Water Conservation: Municipal Solutions: Use gray water Education: modify habits Water-saving fixtures & Appliances Repair leaks Cisterns & rain barrels Water gardens
- 26. Water Pollution Physical or chemical change in water that adversely affects the health of humans or other organisms Global problem
- 27. Eutrophication Build up of nutrients in a body of water Naturally occurs slowly Humans cause imbalances by creating pulses of nutrients due to over- fertilizing crops & lawns and raising animals in confined areas Nutrients include nitrogen and phosphorus-containing compounds that are essential to life in small quantities but harmful in excess.
- 28. Sources of Water Pollution Nonpoint source Enters over a large area Runoff (agriculture or, urban lawns) or atmospheric deposition Point source: specific spot
- 30. Controlling Water Pollution 1. Source Reduction (Pollution Prevention) Cheapest and most effective way to reduce pollution is to avoid producing it or releasing it into the environment. Design products that do not pollute Soil Conservation 2.Ban release of pollutants 3.Reward purchasing environmentally preferable products (e.g. rebates)
- 31. The End