Groundwater

Groundwater

Groundwater

InfiltrationSurface materialsTopographyVegetationPrecipitation

Groundwater Distribution Zone of Aeration (unsaturated

zone) Capillary Fringe Zone of saturation

Water Table

Availability of Groundwater Porosity Permeability

Groundwater Flow Hydraulic conductivity Hydraulic gradient Discharge

IV. Groundwater Flow:

A. Flow Rate dependent on:

1. Speeds: Depends on material, porosity

and hydraulic conductivity

B. Discharge: water table intersects the surface = streams, lakes, swamps, springs (confined)

Groundwater

Groundwater

V. Aquifers

Permeable body or rock/sediment that transmits and stores groundwater

Best aquifer: unconsolidated sand and gravel or

Well-sorted, poorly cemented sandstones or

Highly fractured limestones and basalts

A.Unconfined Aquifer

Impermeable layer only below permeable material

Groundwater

V. AquifersA. Unconfined Aquifer

Impermeable layer only below

Groundwater

V. Aquifers

B. Confined Aquifer

Impermeable layers above and below the aquifer

Often a deeper confined aquifer below an unconfined aquifer with an impermeable layer between the two

Water may flow hundreds of miles below ground

Below deserts in Nevada, eastern Utah, southern Arizona

Groundwater

V. Aquifers

C. Artesian Aquifer

Water will gush out of a confined aquifer when well is drilled

Occurs where the confined aquifer is tilted at an angle to the Earth’s surface

Recharge location is higher than well location, pressure from behind combats gravity

City water supplier use the same idea—tall water town on Craig’s Hill

Groundwater

V. Aquifers

C. Artesian Aquifer

Water will gush out of a confined aquifer when well is drilled

Occurs where the confined aquifer is tilted at an angle to the Earth’s surface

Recharge location is higher than well location, pressure from behind combats gravity

City water supplier use the same idea - tall water town on Craig’s Hill

Groundwater

VI. Natural Springs and Geysers

A. Natural Springs: water flows freely from the ground Water table intersects the surface Water table reaches an impermeable layer May be hot if the groundwater is near magma or if it circulates deep enough

Groundwater

VI. Natural Springs and Geysers

VI. Natural Springs & Geysers

VI. Natural Springs and Geysers

B. Geysers: intermittent emission of hot water

Water descends through fractured rock

Warmed by underlying heat source

Forced up by steam under great pressure that is heated above boiling point due to overlying pressure

Water expands

Pressure is less flashes to steam

Yellowstone: hot spot (magma)Iceland: divergent plate boundary

Groundwater

Groundwater

VI. Natural Springs and Geysers

B. Geysers: intermittent emission of hot water

VII. Threats to groundwater

Groundwater can’t meet cities’ need

If withdrawal > recharge regional lowering of the water table

Cone of depression

Aquifer is compressed land subsidence

Las Vegas 3 feet

New Orleans 7 feet

Mexico City 23 feet

Central California 26 feet(San Joaquin Valley)

Groundwater

VII. Threats to groundwater

Groundwater can’t meet cities’ need

If withdrawal > recharge regional lowering of the water table

VII. Threats to groundwater

Groundwater can’t meet cities’ need

If withdrawal > recharge regional lowering of the water table

VII. Threats to groundwater

VII. Threats to groundwater

Groundwater

VII. Threats to groundwater

Groundwater can’t meet cities’ need

If withdrawal > recharge regional lowering of the water table

Aquifer is compressed land subsidence

Venice >10 feet in 1500 years flooded (lost bottom story)

Houston ~3-7 feet since 1906 problems with ocean flooding

Saltwater intrusion into aquiferBrooklyn, NY in 1930’s turned

into saltwater - now they have to ship the water in = very high cost of water

VII. Threats to groundwater

Venice >10 feet in 1500 years flooded (lost bottom story)

Second century stone walkway beneath Venice, Italy.

Ground subsidence and rise in sea level resulted in a 13 cm rise in relative sea level/century.

Over the past century, the rise in relative sea level has reached a historical peak at 23 cm, in part due to an ill-planned industrial complex that pumped water from beneath the city from 1930 to 1970 and accelerated ground subsidence. 

VII. Threats to groundwater

Cone of depression

VII. Threats to groundwater

Groundwater

Cone of depression

VII. Threats to groundwaterGroundwater

Desalinization Plant

Groundwater Contamination

Groundwater Contamination