San Diego Water and Soil

Seven of the eleven major watersheds lie in the city of San Diego: San Diego, Pueblo, Los Peñasquitos, Sweetwater, Otay, San Dieguito, and Tijuana. Watershed is all of the water, below and above the ground, that drains into a body of water. In San Diego this specific body of water is usually the Pacific Ocean. This can be direct or through lakes. Lake water can flow directly into the ocean or seep into the groundwater. The water inputs into the ocean through precipitation from the atmosphere or flow age from streams and groundwater. The output of the water then evaporates into the atmosphere then subduction occurs into the Lithosphere. 

The map above shows watershed paths that occurs from inner San Diego out into the Pacific Ocean, El Capitan Reservoir,  San Vincente Reservoir, Lake Murray, or Santee lakes. Map from: http://www.sdwatersheds.org/wiki/San_Diego_Watershed

When San Diego gets a large amount of rainfall it is easy for it's valleys to become flooded. An area that is prone to flooding is Mission Valley. However, management of this can prevent people from health and safety risks. A storm water conveyance system has been used to try to direct water to natural or man made features. 

This video demonstrates a case of flooding in Mission Valley, San Diego and shows how this can be very trying on people in the area. 

Video from: youtube.com

This flooding is due to high drainage density and low permeability of the soil. The water in San Diego leads to moderate expansive soils. Expansive soils are soils that expand when water is added and shrink when water is taken away. This affects people in the area in that their houses and workplaces may be ruined and need fixing. San Diego also contains many river washed soils that are eroded by water and cannot be used. 

In addition to River washed soils, San Diego has other types of poor soils as well. These Alfisol soils are lacking many minerals because it is a coastal desert. Two minerals that are lacking in the soil are Iron and Phosphorous. Also, there is too much clay and too little water in the soil sometimes making it hard for certain plants to grow. 

This picture shows a soil that has clay in it and you can see a tiny color variation from soil that does not contain clay. 

http://www.lawn-care-academy.com/clay-soil.html 

References: http://clasfaculty.ucdenver.edu/callen/1202/Battle/Destroy/Hydrology/HydrologyBasics.html, 

http://clasfaculty.ucdenver.edu/callen/1202/Battle/Destroy/Hydrology/hydrocycle.html

http://www.10news.com/weather/1207741/detail.html

http://www.ehow.com/facts_5632085_san-diego-soil-types.html

http://www.sandiego.gov/planning/genplan/pdf/peir/hydrology.pdf