Groundwater Fundamentals

38% surface 62% ground 43% Public Supply 39% Agriculture 8.5% Industrial/Commercial 4.5% Recreation Irrigation 4.0% Domestic Self-supply 62% Agriculture 20% Power 8% Public Supply 6% Recreation Irrigation 4% Industrial/Commercial Reliance on Groundwater U.S. Florida

16 million people withdrawing 8 billion gallons/day Almost 30 M by 2030 Leading to an over- exploitation of ground- water resources 38% surface 62% ground 43% to Public Supply

China India Iran Israel Jordan Mexico Morocco Pakistan Saudi Arabia South Korea Spain Syria Tunisia United States Yemen Withdrawals exceed recharge creating deficits in the aquifer Over-exploitation of renewable and non-renewable aquifers Water Mining Lack of contemporary recharge

GROUNDWATER. (Mm 3 /yr) COUNTRYTotal use% Non-renewable Saudi Arabia21,00084% Libya4,28070% Yemen2,20032% Jordan48631% Egypt4,85018% Saudi Arabia and Libya, use 77% of the estimated total world extraction of non-renewable groundwater for urban supply and irrigated agriculture. The Middle East Lack of Contemporary Recharge

United States 1/3 of irrigation water comes from groundwater The 3 largest aquifers are in arid/semi-arid regions Ogallala AquiferMidwest Central Valley AquiferCalifornia Southwest Aquifer SystemArizona, Utah, Nevada

Central Valley Aquifer (California) Pumping 15% more water than is replaced Southwest Aquifer (Utah, Nevada, Arizona) Pumping 50% more water than is replaced Water storage capacity has declined by 50% High Plains Aquifer (Ogallala) ¼ gone in areas of Texas, Oklahoma, Kansas Water table declines up to 100 feet in some areas

Phoenix Arizona Growing 2 acres/hr Among the highest water users

Canal 335 miles long 44 billion gallons/yr 7% lost to evaporation Central Arizona Project

Groundwater and Aquifer Fundamentals

Freshwater Glaciers Atmosphere Groundwater Lakes Soils Rivers Wetlands 3% of total Earth water

Aquifer Water-bearing formation that can store and release usable amounts of water. Aqua – water Ferre – to carry

Aquifers/Groundwater 0.6% of total earth water. 98% of all readily available freshwater Supplies ½ of the drinking water in U.S. and more than 90% of the drinking water in FL.

Where and What is Groundwater? Water found in pore spaces, seams cracks, and fractures in geologic material or soils beneath the surface of the earth Sands Silts Gravels Muds Clays Rock Water-bearing materials

Aquifers and Aquifer Types

Unconsolidated Consolidated Confined Unconfined Aquifer Classification

Unconsolidated Aquifers

Basic Aquifer Classification Unconsolidated Aquifers Individual particles: granular sand, gravel, clays, silts Water held in pore spaces between grains of sand, gravel, clays, or rock fragments

Unconsolidated Water-Bearing Unit Generally high-yield aquifers

Unconsolidated: sand, gravel, and rock fragments saturated thickness ranges from a few feet to more than 1000 feet thick thin 174,000 mi² High Plains Aquifer Coarse, sedimentary rocks Aquifer material dates back 2 to 6 million years Erosion of the Rockies provided sediment that filled ancient channels

Consolidated Aquifers

Water held in cracks, fissures, erosion cavities and seams in solid rock formations. Consolidated Aquifers Sandstone, limestone, granite

Consolidated Rock: igneous or sedimentary Water-Bearing Unit

Rocks formed from the cooling and solidification of molten magma originating in the earth's core Igneous Rocks Extrusive rock is formed when the solidification process occurs at or near the ground surface. These rocks are generally very permeable because of the "bubbling" of gases escaping during cooling and solidification. horizontal fracturing The Columbia River Plateau covering eastern Washington and Oregon, and Idaho, averages about 500 m in thickness and is one of the largest basalt deposits in the world. Basalt aquifers are critically important water sources for the Hawaiian Islands. Consolidated Aquifers Granite

Consolidated Rock Aquifers Sandstone and Carbonate Sandstone is a cemented form of sand and gravel Carbonate formations include limestone (CaCO 3 ) and dolomite (MgCO 3 ) Exhibit mostly secondary porosity due to fracturing and dissolution openings Sedimentary sandstone limestone cavity

Consolidated Aquifers: Guaraní Aquifer Sedimented sandstones deposited during the Triassic and Jurassic periods overlaid with igneous basalt with low-permeability Slowly Recharged 37,000 km³ of water fresh drinking water for 200 years (166 km³/year) Transboundary Aquifer: Argentina, Brazil, Paraguay and Uruguay 5% of world population

Florida’s Principal Aquifer is Consolidated Limestone Calcium and Magnesium Carbonate

Extra Credit: 1.Aquifers and Ground water represent ___% of total earth water. 2. Groundwater supplies _____% of U.S. drinking water. 3. Aquifers in which water is held in pore spaces between grains of sand, gravel, clays, or rock fragments are _________ aquifers. 4. Aquifers in which water is held in cracks, fissures, erosion cavities and seams in solid rock formations are ____ aquifers. 5. Florida’s principal aquifer is composed of __________ limestone.

Confined and Unconfined Aquifers

Open to the surface, but confined at greater depth by low-permeability material Low permeability – slow water movement Unconfined Aquifers Sometimes called “surficial” aquifers

Low Permeability Geologic or Soil material Water High Permeability Unconfined Aquifer Saturated Zone Groundwater table Saturated Zone thickness dependent on rainfall

Unconfined or Surficial Aquifer Impermeable

Confined Aquifers A generally inclined, water-bearing formation located between impermeable layers of clay, rock, or shale. Impermeable, confining layer Impermeable confining layer Water Bearing Unit

Confining units (aquicludes) Water-bearing unit (consolidated or unconsolidated) Water-bearing unit is confined between two layers of material that are not permeable to water (confining units).

Confined Flow and Artesian Wells Water-bearing unit Impermeable material Recharge Flow High Pressure

Confined and Unconfined impermeable Recharge Water-bearing unit Recharge

Unconfined aquifer (surficial aquifer) Open to the surface, but confined at greater depth by low-permeability material Recharge is generally by rainfall and surface water bodies Confined aquifer Water-bearing unit is confined between two layers of material that are not permeable to water (confining units). Recharge is in areas where the upper confining unit is thin or absent Water-bearing units: sands, gravel, silts, clays, porous or fractured rock

Florida’s Principal Aquifer is Consolidated and Confined