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Freshwater and Groundwater

Freshwater and Groundwater. THE MOST IMPORTANT RESOURCE OF ALL!!!!! John Solder Andrew McCauley. Natural State. Globally 111,000 km 3 / yr of water precipitates onto the earth’s surface. 65,500 km 3 / yr evaporate and transpire directly back to the atmosphere.

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Freshwater and Groundwater

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  1. Freshwater andGroundwater THE MOST IMPORTANT RESOURCE OF ALL!!!!! John Solder Andrew McCauley

  2. Natural State • Globally 111,000 km3/yr of water precipitates onto the earth’s surface. • 65,500 km3/yr evaporate and transpire directly back to the atmosphere. • Humans use approx. 3800 km3/yr, only about 10% of the available freshwater discharge. • 30% of ET is attributed to crops and rangelands, while 90% of water consumed goes to agriculture. Units in thousands of Km3 (Jackson et al. 2001, fig. 2)

  3. Natural Variation • Freshwater availability is a direct result of global climate variability. • 50% of total annual discharge occurs through flooding, largely due to seasonal precipitation variability.

  4. Aquifer Use and Depletion • Many areas depend on groundwater as major resource. • Groundwater is seen as an infinite reservoir and use is commonly greater than the rate of recharge.

  5. Groundwater Overuse • Subsidence • Drying up of current wells, drilling deeper for water. • Reduction of local discharge. • Salt water intrusion. • Salinization • Partly saltwater intrusion affects the salinity of water in the aquifer. • Largely is the concentration of dissolved minerals from irrigation. • Chemical Alteration • Lowering of water table affects oxidation reactions in sub-surface. • Sulphate soils become acidic. • Release of arsenic. • Release of stored carbon in peat bogs.

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