Water §Importance and unique properties

Features §covers 71% of the Earth’s surface §regulates Earth’s climate §dilutes wastes §sculpts earth’s surface, §major habitat

Supply §97% in oceans §3% fresh water §2.997% in ice caps glaciers §.003% available to us

Watersheds - drainage basins §areas of land that drain into bodies of surface water §water flowing off land into these bodies is called surface runoff

Hydrologic Cycle §natural recycling and purification process §plenty of fresh water, if not overloaded with degradable and non-degradable material §divide world into “haves” and “have nots”

Solar powered hydrologic cycle §Evaporation §transpiration §condensation §precipitation §runoff §percolation §groundwater §water table

Surface water §precipitation that does not soak into the ground or return to the atmosphere by evaporation §streams, lakes, wetlands, reservoirs

Groundwater §precipitation infiltrates the ground and fills pores in soil and rocks §zone of saturation - all available soil and rock spaces filled by groundwater

Water Table §upper surface of zone of saturation poorly demarcated between saturated soil and rock and unsaturated soil and rock §falls in dry weather and rises in wet weather

Diagram- aquifer §Major reservoirs of groundwater §consolidated forms §solid rock with groundwater in cracks §unconsolidated forms §sand,gravel,loose earth §amount of water depends on packing

Cone of depression §withdrawal rate of aquifer exceed natural recharge rate

Use of water §mostly to irrigate crops(69%) §energy production- 23% §industrial usage highest in Europe and N.America (US)

Cause …freshwater shortages §???

Drought §at 40% of world population experience year long droughts §since 1970’s - more than 24,000 dead

Water - political issue

Water Resources in US

How do we increase water supply? §build dams and reservoirs §withdraw groundwater §increase water efficiency

Desalination §removal of dissolved salts from ocean or brackish water §7500 plants in 120 countries- 0.1% fresh water §distillation = heating salt water until it evaporates,salt left as solid §reverse osmosis - salt water pumped through thin membrane,salt left behind

Disadvantages §enormous amounts of electricity required §distribution from coastal plants expensive §dumping of concentrated brine, increases local salt concentration

Cloud Seeding §injecting large rain cloud with chemicals - silver iodide §water droplets in cloud clump around the chemical particles §forms ice §drops to earth as precipitation

Disadvantages §non availability of rain clouds §cloud seeding chemicals introduced into soil and water systems §ownership of water in clouds

Why ? §Reduce usage of waste water plants and septic systems §decrease pollution of surface water §reduce number of dams that destroy wildlife, displace people §slows depletion of aquifers

Curbing waste §evaporation, leaks, other losses

Reason for waste §artificially low water prices §external costs not included in monthly bills

Reducing irrigation losses §69% of water usage is for irrigation, §2/3 rd of this is wasted

Irrigation §3 different kinds

Gravity flow §water from aqueduct or nearby river § % efficiency §leveling of fields, surge flooding, capture and reuse runoff

Center Pivot §water pumped from underground and sprayed from mobile boom with sprinklers §70-80% efficiency

Drip irrigation §above or below ground pipes or tubes deliver water to individual plant roots § % efficiency

Less wastage - Industry §use recycled water §machines designed to save water §Japan Israel

Most Wastage - Residences §water - used to flush toilets, wash hands, baths §green lawns in arid areas

Xeriscaping §vegetation adapted to dry climate §30-80% less water used

Solutions - Appendix 5 §water meter §repair leaky pipes §low flush toilets and showerheads §gray water for irrigation

Sustainable Usage - Case study §Columbia River Basin §World’s largest hydroelectric system §more than 100 dams §electricity prices - 40% lower §interferes with salmon life cycles

Salmon ranching §artificial hatcheries §genetic inbreeding §world’s largest program for ecosystem rehabilitation §cost - $2 billion §Time - 2 decades

Florida Everglades restoration §case study

Everglades §slow moving river §50 miles wide, 6 inches deep §flows south through Everglades National Park into Estuary at Florida Bay (Fig )

World’s largest marshland § haven for 14 endangered or threatened species §(American alligator, Florida panther) §aquifer recharge, precipitation system

Problems - development - page 476 §straightening Kissimmee river §tremendous environmental impact

What can we do ? §Restore original path of Kissimmee §reclaim areas of wetlands §will cost $2 billion at the lower estimate