SWES 210 1st Edition Lecture 7Outline of Last Lecture I. Current human populationa. Whats the problemII. Exponential population growtha. Defining exponential growthb. J-shaped curveIII. Carrying capacitya. Defining carrying capacityb. S-shaped curveIV. Human population so farV. Population growth ratea. Natural rate of population growth (formula)b. Population growth rate (formula)VI. Example problems of human population growth Outline of Current Lecture II. Where are the sources of water?a. Ice caps and glaciersb. Defining freshwaterIII. Human impact on groundwatera. Defining the water tableb. Defining the vadose zoneIV. The water cyclea. Human impacts on the water cycleV. Ogalla aquiferVI. Water conservationa. Dams in the Us and Dams worldwideCurrent Lecture- What percentage of the global water supply is fresh water?o 2.5%- Most of the freshwater is in___?o Ice caps and glaciers- Where is water?o Water may seem abundant, but drinkable water is rare Freshwater= relatively pure, with few dissolved slats. Most is tied up in glaciers, ice caps, and aquifersThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- What is groundwater?o Water found underground beneath layers of soil- Human impact on groundwatero Surface water disconnection from groundwater due to water table lowering=no rivero Water table= the upper limit of groundwater in an aquifer. Water may be ancient, thousands of years old)o Groundwater becomes exposed to air when the water table reaches the surface. exposed water runs off to the ocean or evaporates.o Vadose zone= unsaturated zone with porous soilo We have pumped more groundwater than is recharged naturally-this resource is being depleted in some places= decreasing watertables- The water cycleo Water vapor exits plant leaves during transpiration through many tiny openings called stomatao Water loss from plant leave during transpiration is caused in part by the sun’s heat energy in a process similar to the way we lose water we perspire.- Human impacts on the hydrologic cycle (water cycle)o Overdrawing groundwater for drinking, irrigation, and industrial useo Irrigating agriculture fields= depelets rivers, lakes, streams, and groundwater and increases evaporationo Damming rivers increases evaporation and infiltrationo Emitting pollutants changes acidity of precipitation (acid rain)o Removing forests and vegetation increases runoff= erosion. This reduces transpiration and lowers water tables- The ogalla aquifero World’s largest known aquifero Underlies the great plains of the USo Irrigation with this groundwater has created a very bountiful grain-producing region- Water conservationo 1922- 7 states agree to “Colorado river compact” (7 states in agreement)o 50% water in upper basin, 50% water in lower basino about 80% of the water in this basin- how many dams are there in the US?o 75,000o of those, 8100 are ‘major’ dams- how many major dams in the world?o 45,000 worldwideo 22,000 of these dams are in china (three gorges dam on the Yangtze river) this dam is 8 times the size of the hoover dam and is the worlds largest power