Geography 5 Week 9 Lecture 15 Ground Water and Aquifer Depletion Aquifers are Underground reservoirs in which the groundwater is stored Saltwater intrusions The movement of seawater into a freshwater aquifer near the coast Saltwater intrusions occur along coastal areas when groundwater is depleted faster than it recharges Ogallala aquifer The largest groundwater deposit in the world which lies under 8 Midwestern states extensive portions in Kansa Texas and Nebraska Farmers in the High Plains rely on water from the Ogallala aquifer Water in the O A takes hundreds or even thousands of years to renew after it is withdrawn to grow crops and raise cattle South to North Water Transfer Project China Big investment Channelization and the Environment Deepening Widening Clearing Lining existing stream channels Purposes flood control improve drainage control erosion improve navigation Channelization is widespread in Urban Areas o ex Los Angeles River Negative Impacts of Channelization o Habitat Changes Pools Rapids Sediment o Loss of Shading More severe temperature fluctuations Loss of Wetlands Increased Flooding o During Precipitations o Downstream of channelization o Common in LA Aesthetic Degradation Effect of Urbanization on Stormflow Timing Biological Diversity Biogeography and Conservation Biodiversity has become a measurement for the success failure of conservation efforts Genetic Diversity the Raw Material needed for adaptation evolution Interconnected The loss of one species in a community may affect other species and the working of that community Patterns of Biodiversity Global Scale Plant Biodiversity greatest in the Tropics Low Latitudes o Why Greater solar energy which will create more biodiversity greater primary productivity in the tropics Biodiversity Hot Spots Global Hot Spots Across the global Tend to see them in the tropics because of greater primary productivity CA is higher in animal biodiversity Factors that tend to Promote Biodiversity A physically diverse habitat o Many niches e g Multiple Canopies in Tropical Rainforests Altitudinal Diversity e g Southwest China o hot spots river areas b c as you move from West to East there are mountain ranges and river basins o Each river basin has its own unique biodiversity Moderate amounts of Disturbance o Temperature Moisture etc o Changes in the ecosystem via human activity etc o Disturbances are bad for the ecosystem E g Fire Ecology o Crown Fires vs Ground Fires o Problems with Fire Suppression Adaptations to Moderate Fire Disturbance o e g Serotinous Cones o After a fire the Seritinous cones have survived Fire is necessary for certain communities to reproduce ex High diversity at one Trophic Level can stimulate High Diversity in another o helps stimulate biodiversity in another level Factors that tend to reduce biodiversity Extreme Environments Places may be aesthetically beautiful but there biodiversity may not be great Limitations of a Crucial Resource Introduction of Exotic Species South East Asia California Habitat Fragmentation Several impacts The Edge Effect o increase the amount of edge and decrease amount of poor habitats o Helps reduce biodiversity Exotic species can get in there and change the environment Ex The Cowbird thrives in agricultural regions o Led to a decline in native bird species as the Cowbirds multiply Biodiversity and Extinction Background or Normal Extinction Rates versus Catastrophic or Mass Extinction Extinction is happening all the time and it is a natural process Humans causing the 6th Catastrophic Extinction 29 05 2012 20 27 00 29 05 2012 20 27 00