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Freshwater and Groundwater

Freshwater and groundwater are essential resources for humanity, with about 111,000 km³ of water precipitating yearly. While humans utilize approximately 3,800 km³, this is just about 10% of the available freshwater discharge. Agriculture consumes a staggering 90% of water, highlighting the critical relationship between freshwater availability and agricultural practices. The overuse of groundwater, often seen as an infinite resource, leads to issues such as subsidence, well drying, and salinization. Addressing these challenges is vital for sustainable resource management.

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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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