1.Chapter 14 Water

2. Hydrosphere All the water on and above the earth 100 % of earths water existed since formation of the planet 97.5 % seawater 2.5 % fresh 1.7% locked in glaciers and ice caps 0.78% in Groundwater including soil moisture and swamp water 0.02% in rivers and lakes 3. Properties of Water Adhesion ability to stick to other things Cohesion ability to stick to itself Surface Tension through hydrogen bonding water forms a skin on its surface Capillarity ability of water to be drawn up Universal Solvent ability to dissolve a wide range of substances 4. Properties of Water Exists in 3 forms solid, liquid, gas Changes temperature slowly stores large quantities of heat Takes a lot of heat to evaporate water due to strong attractive forces Universal solvent Water can ionize Surface can contract due to strong cohesive forces Expands when freezes 5. 12.1 Water supply and demand Domestic water use 10% Flushing, bathing, drinking Industrial 49% goes to cooling of electrical power plants to all other industry Agriculture 41% Irrigation feeds most of the world 6. Fig. 12.4, p.298 7. Hydrologic Cycle Where does the energy for the hydrologic cycle come from?? 8. Aquifer Vocab Zone of aeration area of an aquifer where there is air between particles Zone of saturation area of an aquifer where there is water between particles Recharge zone area where an aquifer receives water from the surface Confined aquifer an aquifer that has an impermeable layer above and below it Unconfined aquifer an aquifer that has an impermeable layer below it but is open above 9. 11.2 Streams Flowing water in a channel River: large stream fed by tributaries Stream flow & velocity Gradient steepness Discharge volume of water flowing/unit time Channel characteristics Bank bed 10. 11.2 Streams Stream erosion and transport Competence how big Capacity how much Dissolved load i.e.; like salt Suspended load portion that remains suspended Bed load load that rolls, skips or bounces along the bottom 11. 11.2 Streams Drainage basins (ie watershed) All the land drained by a body of water Separated by mountains, ridges, or plateaus E.g.; Mississippi Embayment Drains 2/3 of the U.S. land area between the Appalachians and the Rockies Smaller drainage basins exist within these larger basins North Carolina has 13 major basins Cape Fear & Yadkin Pee Dee are the two closest 12. US Watersheds Mississippi is the largest river basin in the US covering almost 2/3 of the continental land mass. The river itself is the 14th longest in the world at 2350 miles 13. Fig. 11.12, p.270 14. World Watersheds The Nile (N. Africa) 4160 miles The Yangtze (China) 3964 miles The Congo (C. Afri - 2718 miles Amazon Brazil S. America - 4000 miles 15. Stress on the Worlds River Basins Comparison of the amount of water available with the amount used by humans. Figure 14-6 16. TOO LITTLE FRESHWATER Cities are outbidding farmers for water supplies from rivers and aquifers. Countries are importing grain as a way to reduce their water use. More crops are being used to produce biofuels. Our water options are: Get more water from aquifers and rivers, desalinate ocean water, waste less water. 17. Water Resources in US Eastern US Flooding Urban shortages Pollution Western Arid Regions Low precipitation High evaporation Recurring prolonged drought These conditions result in water scarcity: 1) Dry climate 2) Drought 3) Desiccation 4) Water stress 18. WITHDRAWING GROUNDWATER TO INCREASE SUPPLIES Most aquifers are renewable resources unless water is removed faster than it is replenished or if they are contaminated. Groundwater depletion is a growing problem mostly from irrigation. At least one-fourth of the farms in India are being irrigated from overpumped aquifers. 19. Fig. 14-7, p. 313 Trade-Offs Withdrawing Groundwater Advantages Disadvantages Useful for drinking and irrigation Aquifer depletion from overpumping Available year- round Sinking of land (subsidence) from overpumping Exists almost everywhere Polluted aquifers for decades or centuries Renewable if not overpumped or contaminated Saltwater intrusion into drinking water supplies near coastal areas Reduced water flows into surface waters No evaporation losses Cheaper to extract than most surface waters Increased cost and contamination from deeper wells 20. Groundwater Depletion: A Growing Problem The Ogallala, the worlds largest aquifer, is most of the red area in the center (Midwest). Areas of greatest aquifer depletion from groundwater overdraft in the continental U.S. Figure 14-8 21. Fig. 12.17b, p.306 22. Fig. 12.15, p.304 23. Fig. 12.16, p.305 24. Other Effects of Groundwater Overpumping Groundwater overpumping can cause land to sink, and contaminate freshwater aquifers near coastal areas with saltwater. Figure 14-11 25. Other Effects of Groundwater Overpumping Sinkholes form when the roof of an underground cavern collapses after being drained of groundwater. Figure 14-10 26. Fig. 12.18, p.306 Subsidence a sinking of the Earths surface caused by loss of aquifer porosity The land in this San Joquin Valley region has subsisted by 30 feet in 50 years. 27. Fig. 14-12, p. 316 Solutions Groundwater Depletion Prevention Control Waste less water Raise price of water to discourage waste Subsidize water conservation Ban new wells in aquifers near surface waters Tax water pumped from wells near surface waters Buy and retire groundwater withdrawal rights in critical areas Do not grow water- intensive crops in dry areas Set and enforce minimum stream flow levels