Chapter17

Chapter17 - Water Supply Use and Management After covering...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Water Supply, Use, and Management After covering Ch17, you should understand: Hydrologic Cycle Major H 2 O compartments (a.k.a. reservoirs) How much / where H 2 O is available to humans Types of H 2 O use Freshwater shortages & groundwater depletion How to determine a H 2 O budget Water management, conservation, & consequences Increasing H 2 O supplies Cost & pricing mechanisms that conserve H 2 O Water Resources Water covers more than 70% of Earth’s surface; most is ocean, 2.5% is fresh ( most FW is ice and glacier ) • Hydrologic cycle : movement of H 2 O among different “reservoirs” driven by energy from the sun that creates winds that facilitate evaporation and precipitation • Evaporation : when H 2 O molecules change from liquid to vapor (but not necessarily at boiling point). Allows escape of H 2 O in oceans, lakes, land & plants into the air. Only H 2 O evaporates, impurities are left behind • Transpiration : when H 2 O evaporates thru leaves; aids in drawing H 2 O up through roots • Sublimation : direct change from solid to gas; snow & ice do this VIMP ! VIMP ! 5 Reservoirs of Water on Earth Ocean Ocean Atmosphere Atmosphere aka infiltration infiltration precipitation Groundwater Groundwater Surface & soil Surface & soil Ice Ice Major Water Reservoirs • Oceans ¡ contain more than 97% of all liquid water (FW+SW) ¡ contain 90% of world’s living biomass ¡ moderate earth’s temperature ¡ average residence time of water in the ocean is about 3 - 4,000 years • Ice, Glaciers, and Snow ~2% of total water ¡ largest FW reservoir; 78% of all FW is “locked up” ¡ glaciers (mostly Antarctic), ice caps, and snowfields ¡ during most recent ice age (12K YBP), one-third of continental landmasses were covered by glaciers • Atmosphere ¡ smallest reservoir; < 0.001% of total water ¡ most rapid turnover rate (~10 days) ¡ mechanism for distributing fresh water over landmasses Major Water Reservoirs • Groundwater ¡ Second largest fresh water reservoir; but only 0.5% ! ¡ Infiltration : process of water percolating through the soil and into fractures and permeable rocks; some layers are saturated (all pores are filled w/ H 2 O) ¡ Water Table : Top of zone of water saturation ¡ Aquifer : porous layers of sand, gravel, or rock lying below the water table- Artesian Spring : place where pressurized aquifer intersects the surface; water flows without pumping ¡ Recharge Zone : area where water infiltrates into an aquifer; rate is often very slow- Presently, groundwater is being removed in many areas faster than it can be replenished Major Water Reservoirs • Surface water : Only 0.02% of FW is above ground ¡ Rivers and Streams : precipitation that does not evaporate or infiltrate into the ground runs off the surface, back toward the sea- Discharge is the term used to measure amt of water...
View Full Document

This note was uploaded on 04/22/2008 for the course BIOL 103 taught by Professor Brown during the Spring '08 term at VCU.

Page1 / 25

Chapter17 - Water Supply Use and Management After covering...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online