Transcript Hoover Dam
AIM: To explain ways in which fresh water is naturally stored as a resource and predict the effects of depletion of an aquifer. Do Now: Where do we get our water from? Where is our water stored naturally? HW: Article and Questions #3 due Friday Water can be stored two ways 1. Dams- rivers and rain runoff 2. Reservoirsrain runoff, streams, underground sources Surface Water • Water that is above the ground- does not seep into the ground – Ex: streams, lakes, ponds • Runoff – Water that does not seep into the groundflows down a slope over land. – Melting snow and glaciers, rainfall – Rills- shallow grooves that runoff carves into the ground • If deepen and connect, form larger streams that open into lakes, ponds or oceans Surface water Rills GroundwaterSome seeps into the ground between the soil and the bedrock (if porous) Runoff Water table top of the saturated layer of rocks Aquifer layer of saturated rock • Also called the zone of saturationthe saturated rock layer beneath the water table • Zone of aeration- where the water enters • Zone of discharge- where the water leaves • How the water moves depends on –amount of precipitation –porosity of rocks –slope of aquifer Overdraft • when a body of water is drained faster than it is filled • often times due to an increased demand for water. • Causes saltwater to intrude into the freshwater making unpotable water • Subsidence- removing the water weakens the bedrock causing it to sink Saltwater Intrusion Ogallala Aquifer • largest aquifer in the world • Texas, Colorado, Nebraska, Oklahoma, Kansas, Wyoming, South Dakota, and New Mexico • Large amount used for agriculture • Overdraft is occurring due to dry climate 1. What is surface water? 2. What are some sources of surface water? 3. What is runoff? 4. How does groundwater accumulate? 5. What is another name for an aquifer? 6. What determines the rate at which an aquifer moves? 7. What is overdraft? 8. What problems result from over draft? 1. Above ground in streams, lakes and ponds. 2. rainfall, melting snow, glaciers, ice sheets 3. Water that does not seep into the ground. 4. Water that does not runoff seeps through the spaces between soil particles. If the bedrock is porous or has cracks, the water seeps into the bedrock. 5. The zone of saturation. 6. Amount of precipitation, how porous the rocks are, slope of the aquifer. 7. When a body of water is depleted faster than it is refilled. 8. Weakening of the bedrock due to a drop in water pressure in the aquifer causes subsidence. A drop in pressure also causes salt water intrusion in aquifers near coastal areas.