Chapter 12 NotesKey WordsWater Cycle – aka the hydrolic cycle, involves the movement of water from oceans, lakes, and the atmosphereDrainage Basin – an area of land that contributes water to a particular stream or riverVadose Zone – aka the unsaturated zone, includes the Earth material above the water tableWater Table – the boundary between the two zonesAquifer – earth material capable of supplying groundwater at a useful rate from a wellKarst Topography - regions of the U.S where 25% of the surface land area is underlain by limestoneWater Management – a new philosophy that states that surface water and groundwater are both subject to a natural fluxNotes- The major processes are evaporation, precipitation, transpiration, surface runoff, and subsurface groundwater flow- There is a balance between total evaporation and precipitation- The number and size of the suspended particles moved by surface waters depend on the volume and depth of the water as well as the velocity of flow- The factors that affect runoff also affect sediment erosion, transport, and deposition- The amount of surface-water runoff and sediment carried by the runoff varies significantly among drainage basins and riverso Factors that affect variation Geologic- Rock and soil type, mineralogy, degree of weathering, and structural characteristics of the soil and rock- Fine-grained, dense clay soils and exposed rock types allow little water to move downward and become part of the subsurface flow- Sandy soils and well-fractured rocks absorb more precipitation and have less surface runoff and fewer streams Topographic- Relief and slope are important because they affect the velocity of water in a stream, the rate at which water infiltrates the soil or rock, and the rate of overland flow Climatic- The type of precipitation that occurs, the intensity of theprecipitation, the duration of precipitation, and the types of storms  Vegetation- Can effect runoff ,sediment yield, and stream flow Land-use Factors- Agriculture generally increases runoff and sediment yield as land is plowed for crops- Urbanization greatly increases runoff because of the large amount of impervious pavement - Two major zones of groundwater are the vadose zone and the zone of saturationo The vadose zone is an early warning area for potential pollution to groundwater resourceso Factors that influence the rate of infiltration include: Topography Soil and rock type Amount and intensity of precipitation Vegetation Land use- A spring forms when water flowing in an aquifer intersects the Earth’s surface- The rate and direction of groundwater movement in an aquifer in part depend on both the hydraulic gradient and they type of material found in the aquifer- Nearly half the population of the US uses groundwater as a primary source of drinking water- The cost of water pumping and exploration reduces the amount of groundwater available- Only a few % of the U.S.’s total groundwater resource has been depleted- Withdrawal of groundwater by pumping from wells can reduce stream flow, lower lake level, and reduce water in wetlandso Water pollution in a stream moves through the streambed and eventually pollutes the groundwater below- Karst topography causes many problems including:o Water pollution in areas sinkholes are used for waste disposalo Cavern systems that are likely to collapse and damage buildings and roadso Drying springs- Types of water use:o Offstream use – water that is removed or diverted from its sourceo Consumptive use – type of offstream use where water isn’t returned tothe stream or groundwater resource immediately o Instream use – water that is used is not withdrawn from its source- Water use on a global basis is about 70% for agriculture, 20% for industry, and 10% for urban and rural