Water Resources and Groundwater Management

Water Resources and Water Use

• Water is vital for life, but only a small percentage is accessible for human use
• Most fresh water is frozen in glaciers and ice caps, not readily available.

Groundwater

• Groundwater is water found underground; crucial for human needs
• Aquifer: A permeable layer of rock or sediment holding groundwater
  • Unconfined aquifer: Groundwater flows freely through soil and porous rock above.
  • Confined aquifer: Groundwater is trapped below an impermeable layer, causing potential pressure for wells.
• Water table: The upper level where groundwater saturates the soil
• Groundwater recharge: The process where water seeps into aquifers via precipitation
• Spring: Natural outflow of groundwater to the surface
• Artesian well: A well tapping into a confined aquifer, with groundwater naturally rising.
• Cone of depression: When groundwater is pumped too quickly, creating a dip in the water table near a well.
• Saltwater intrusion: Saltwater can intrude into freshwater aquifers due to lowered pressure from excessive well pumping.

Ogallala Aquifer

• The Ogallala Aquifer is the largest in the U.S., supporting vital agricultural activity
• Extensive groundwater withdrawals for irrigation have depleted the aquifer significantly since 1950, causing a decline in water levels by several meters.

Surface Water

• Surface water includes streams, rivers, ponds, and wetlands, forming aquatic biomes.
• Early human civilizations typically established settlements along major rivers for the readily available water source.
• Floodplain: Land adjacent to a river, prone to flooding when the river overflows.

Atmospheric Water and Precipitation

• Atmospheric water is essential to global water distribution.
• Impermeable surfaces (pavement, buildings) prevent water from seeping into the ground, reducing recharging of groundwater.
• This is a crucial factor for water availability in urban areas.

Human Alteration of Water Availability

• Levees and Dikes: Structures constructed to prevent flooding along rivers and coastlines
• Dams: Barriers restricting river flow, creating reservoirs, but altering ecosystems downstream
• Aqueducts: Channels conveying water from one place to another for human needs, but can have negative impacts on ecosystems.
• Desalination: The process of removing salt from saltwater to produce freshwater
  • Distillation: Using heat to convert water to steam, then condensing it into freshwater
  • Reverse Osmosis: Pumping freshwater through a membrane to filter out salt.

Water Use

• Water use in agriculture, industry & households varies significantly by region.

• Irrigation techniques include furrow, flood, spray & drip, with hydroponic being an alternative approach for higher efficiency

• Industrial water use includes generating electricity, cooling machinery and refining metals.

• Household water use accounts for a portion of total water use but varies by nation and can often be reduced with conservation strategies.

• Water footprint: Total daily per capita use of freshwater globally, used to track water consumption.

Water Conservation

• Water conservation strategies are needed, including water-pricing systems, xeriscaping and removing water-demanding sources, for future water sustainability.
• Gray water and contaminated water are reused in some areas.