March 2, 2009 - Lecture Notes - Ground Water and Lakes

ISP203A Global Change Taggart 03/02/09 Last Lecture Covered on the Second Hour Exam Coverage for the Second Hour Exam begin with rock coverage Aquifers Porous and permeable and support the transport of water Water that is stored in porous rock Capacity ? ability to continuously deliver water Salt Water Intrusion ? when a well is drilled by the coast, and the fresh water is drawn out too quickly, salt water can be drawn accidentally from the well Unconfined aquifer ? Nothing to stop the water from moving down into the overlying soil or bedrock and moving into the rocks that form the aquifer Recharge time ? amount of time required to replace the water in an aquifer Confined aquifer ? water impenetrable rock on the top and bottom of the aquifer Takes a lot more time to recharge a confined aquifer than it does to recharge an unconfined aquifer Ground water contamination from a waste disposal site Water supply well has drained and lowered the water table Contamination flows through soil and bedrock and contaminates ground water supply Contaminated ground water then flows into nearby rivers or other water sources Ground water is the single biggest source of fresh water on the planet Lakes Second larges source of fresh water Big lakes are relatively rare Size can be measured by surface area or volume Caspian Sea is the largest lake in the world (measured by surface area) [436,000 km2] Water flows into the lake from surrounding watersheds and from direct rainfall No outlet Water evaporates from the lake and deposits are left behind Lake continually gets saltier Lake Superior [82,100 km2] Waterways connecting the Great Lakes to the ocean opened the way for invasive species Sea Lamprey Almost completely destroyed the Great Lakes fishery Salmon Population is artificially maintained Fishery system has been restored to the Great Lakes Requires continual input and management Native Americans retained fishing rights (unlimited) The Great Lakes are a unique treasure and someone always want to use them for something Lake Victoria (68,870 km2) Lake Tanganyika (32,600 km2) Baikal (31,500 km2) By far the deepest lake in the world Largest and oldest lake on the planet Endemic species (occur only in this lake and nowhere else in the world) Needs a huge amount of recovery from the old industrial age