final report for hydrology 1

8/7/2019 final report for hydrology 1

1/31

GROUNDWATERGROUNDWATER


2/31

GROUNDWATER AND THEGROUNDWATER AND THE

WATER CYCLEWATER CYCLE Now that you have learned about the exciting world ofNow that you have learned about the exciting world ofgroundwatergroundwater, it is time to see how it fits into that endless watery, it is time to see how it fits into that endless wateryprocess called the water cycle, also know as the hydrologic cycle.process called the water cycle, also know as the hydrologic cycle.

the water cycle, when water from the earths soil, plants, andthe water cycle, when water from the earths soil, plants, and

water bodies turns into water vapor through the process ofwater bodies turns into water vapor through the process ofevaporation.evaporation. This invisible vapor, most of which comes from the worldsThis invisible vapor, most of which comes from the worlds

oceans, travels up into the atmosphere and condenses, formingoceans, travels up into the atmosphere and condenses, formingclouds. This is calledclouds. This is called condensation.condensation.

The vapors in the clouds condense more and more until theyThe vapors in the clouds condense more and more until theyform water droplets.form water droplets.

More and more water vapor combines with the water dropletMore and more water vapor combines with the water dropletuntil it is too heavy to stay in the sky any longer. The water fallsuntil it is too heavy to stay in the sky any longer. The water fallsto the earth far below asto the earth far below as precipitation.precipitation.

Examples of precipitation include rain, hail, sleet, and snow.Examples of precipitation include rain, hail, sleet, and snow.


3/31


4/31

When the water reaches the earths surface, some of itWhen the water reaches the earths surface, some of it

will flow along the surface of the earth as runoff whilewill flow along the surface of the earth as runoff whilethe rest of it soaks into the soilthe rest of it soaks into the soil--called recharge.called recharge. Down, down, down the water goes through the soilDown, down, down the water goes through the soil

until it becomes groundwater and is stored in theuntil it becomes groundwater and is stored in theaquifer below.aquifer below.

Once the water has joined the aquifer, it doesnt stopOnce the water has joined the aquifer, it doesnt stopthere.there. The groundwater slowly moves through the spacesThe groundwater slowly moves through the spaces

and cracks between the soil particles on its journey toand cracks between the soil particles on its journey to

lower elevations.lower elevations. This movement of water underground is calledThis movement of water underground is calledgroundwater flow.groundwater flow.


5/31


6/31

the groundwater comes to a discharge area where itthe groundwater comes to a discharge area where it

enters a lake or stream.enters a lake or stream.

the water will once again be evaporated and begin thethe water will once again be evaporated and begin thecycle again.cycle again.

Water has been transported through the water cycleWater has been transported through the water cyclefor millions of years and will continue this cyclefor millions of years and will continue this cycle

forever. In the water cycle.forever. In the water cycle.

water is constantly on the move.water is constantly on the move.


7/31


8/31

AQUIFERS, AQUITARDS, ANDAQUIFERS, AQUITARDS, AND

SPRINGSSPRINGS A geologic formation from which significantA geologic formation from which significant

amounts of ground water can be pumped foramounts of ground water can be pumped fordomestic, municipal, or agricultural uses is known asdomestic, municipal, or agricultural uses is known as

anan aquifer.aquifer. Aquifers are vertically separated from each other byAquifers are vertically separated from each other bygeologic formations that permit little or no water togeologic formations that permit little or no water toflow in or out.flow in or out.

A formation that acts as such a water barrier is calledA formation that acts as such a water barrier is called

aquitard.aquitard. It is much less permeable than a nearby aquifer butIt is much less permeable than a nearby aquifer but

still permits flow (e.g., sandy clay).still permits flow (e.g., sandy clay).


9/31

SPRINGSSPRINGS

Springs form where the water table intersects with theSprings form where the water table intersects with theland surface:land surface:

Sometimes ground water is forced into a springSometimes ground water is forced into a spring

because a low permeable layer of rock or finebecause a low permeable layer of rock or finesediments (clay) keeps the water from percolatingsediments (clay) keeps the water from percolatingdeeper.deeper.

A spring may also occur where subsurface pressureA spring may also occur where subsurface pressure

forces water to the surface through a fracture or faultforces water to the surface through a fracture or faultzone that acts as a conduit for water movement fromzone that acts as a conduit for water movement froma confined aquifer.a confined aquifer.


10/31


11/31


12/31


13/31

GROUND WATERGROUND WATER

Ground waterGround water occupies the zone of saturation. As depicted inoccupies the zone of saturation. As depicted inthethe hydrologic cycle diagramhydrologic cycle diagram,,

ground water moves downward through the soilground water moves downward through the soil

byby percolationpercolation and then toward a stream channel or large bodyand then toward a stream channel or large bodyof water asof water as seepageseepage.. The water table separates the zone of saturation from the zoneThe water table separates the zone of saturation from the zone

of aeration.of aeration. The water table fluctuates with moisture conditions, duringThe water table fluctuates with moisture conditions, during

wet times the water table will rise as more pore spaces arewet times the water table will rise as more pore spaces areoccupied with water.occupied with water.


14/31

DIRECTION AND SPEED OFDIRECTION AND SPEED OF

GROUNDWATER MOVEMENTGROUNDWATER MOVEMENT Ground water moves from higher elevations to lowerGround water moves from higher elevations to lowerelevations and from locations of higher pressure to locationselevations and from locations of higher pressure to locationsof lower pressure.of lower pressure.

In groundwater hydraulics (the science of groundwaterIn groundwater hydraulics (the science of groundwater

movement), water pressure surface and water table elevationmovement), water pressure surface and water table elevationare referred to as theare referred to as the hydraulic head.hydraulic head. Hydraulic head is the driving force behind groundwaterHydraulic head is the driving force behind groundwater

movement. Groundwater movement is always in themovement. Groundwater movement is always in thedownward direction of the hydraulic head gradient.downward direction of the hydraulic head gradient.

The hydraulic gradient is often but not always similar to thatThe hydraulic gradient is often but not always similar to thatof the land surface.of the land surface. Groundwater movement in gravels and sands is relatively rapid,Groundwater movement in gravels and sands is relatively rapid,

whereas it is exceedingly slow in clay or in tiny rock fractures.whereas it is exceedingly slow in clay or in tiny rock fractures.


15/31

GROUND WATER MOVEMENTGROUND WATER MOVEMENT


16/31

GROUNDWATER FLOW ANDGROUNDWATER FLOW AND

EFFECTS OF PUMPINGEFFECTS OF PUMPING Water is recharged to the groundWater is recharged to the ground--water system by percolation of waterwater system by percolation of water

from precipitation and then flows to the stream through the groundfrom precipitation and then flows to the stream through the ground--waterwatersystem.system.


17/31

Water pumped from the groundWater pumped from the ground--water system causes the water table towater system causes the water table tolower and alters the direction of groundlower and alters the direction of ground--water movement. Some water thatwater movement. Some water that

flowed to the stream no longer does so and some water may be drawn inflowed to the stream no longer does so and some water may be drawn infrom the stream into the groundfrom the stream into the ground--water system, thereby reducing thewater system, thereby reducing theamount of stream flow.amount of stream flow.


18/31

Contaminants introduced at the land surface may infiltrate to the waterContaminants introduced at the land surface may infiltrate to the watertable and flow towards a point of discharge, either the well or the stream.table and flow towards a point of discharge, either the well or the stream.(Not shown, but also important, is the potential movement of(Not shown, but also important, is the potential movement ofcontaminants from the stream into the groundcontaminants from the stream into the ground--water system.)water system.)


19/31

WaterWater--level declines may affect the environment for plants and animals.level declines may affect the environment for plants and animals.For example, plants in the riparian zone that grew because of the closeFor example, plants in the riparian zone that grew because of the closeproximity of the water table to the land surface may not survive as theproximity of the water table to the land surface may not survive as thedepth to water increases. The environment for fish and other aquaticdepth to water increases. The environment for fish and other aquaticspecies also may be altered as the stream level drops.species also may be altered as the stream level drops.


20/31

CONFINED (CONFINED (CLOSEDCLOSED) AQUIFERS) AQUIFERS

Confined (closed) aquifers are sandwiched in between denseConfined (closed) aquifers are sandwiched in between denseimpermeable layers of earth material called animpermeable layers of earth material called an aquicludeaquiclude..

Ground water is replenished by percolation of water from theGround water is replenished by percolation of water from thezone of aeration downward to the zone of saturation, or in thezone of aeration downward to the zone of saturation, or in the

recharge zone of a confined aquifer.recharge zone of a confined aquifer. The recharge zone is where the confined aquifer is exposed atThe recharge zone is where the confined aquifer is exposed at

the surface and water can enter it.the surface and water can enter it. Aquifers replenish their supply of water very slowly.Aquifers replenish their supply of water very slowly. The rate of ground water flow depends on the permeability ofThe rate of ground water flow depends on the permeability of

the aquifer and the hydraulic gradient.the aquifer and the hydraulic gradient. Permeability is affected by the size and connectivity of porePermeability is affected by the size and connectivity of pore

spaces. Larger, better connected pore spaces creates highlyspaces. Larger, better connected pore spaces creates highlypermeable earth material.permeable earth material.


21/31

Artesian waterArtesian water is ground water confined under pressure between layers ofis ground water confined under pressure between layers ofrelatively impermeable, underground rockrelatively impermeable, underground rock--called acalled a confined aquiferconfined aquifer..

Artesian water rises to the top of the aquifer and sometimes above landArtesian water rises to the top of the aquifer and sometimes above landwhen a well taps the confined aquifer.when a well taps the confined aquifer.

Confined aquifers are limited in number. In this type ofConfined aquifers are limited in number. In this type ofaquifer,aquifer, waterwater travels between the nontravels between the non--porous rock layers like gravel,porous rock layers like gravel,sandstone, or granite and the rock elements hold thesandstone, or granite and the rock elements hold the waterwater ..

WaterWater penetrates into the earth through cracks and pores until all the gapspenetrates into the earth through cracks and pores until all the gapsare occupied withare occupied with waterwater and saturation is reached.and saturation is reached.

Saturation is completed when theSaturation is completed when the waterwater, flooding the soil,, flooding the soil,arrives at hard rock layers, and further penetration is notarrives at hard rock layers, and further penetration is notpossible.possible.

WaterWater in aquifers is called groundwater. A reliablein aquifers is called groundwater. A reliablegroundwater replenishment system is essential for the survivalgroundwater replenishment system is essential for the survivalof humans and the earthof humans and the earth..


22/31

UNCONFINED AND CONFINEDUNCONFINED AND CONFINED

AQUIFERAQUIFER


23/31


24/31

UNCONFINED AQUIFERSUNCONFINED AQUIFERS are aquifers that have noare aquifers that have no

confining layers between the water level and ground levelconfining layers between the water level and ground level..


25/31

CONFINEDAQUIFERSCONFINEDAQUIFERS are aquifers that have a confining layer betweenare aquifers that have a confining layer betweenthe water level and ground level.the water level and ground level. A confining layer is a layer ofA confining layer is a layer of materialmaterial

that has little or no porositythat has little or no porosity..


26/31

PERCHED AQUIFERSPERCHED AQUIFERS are aquifers that have a confining layerare aquifers that have a confining layerbelow the groundwater, and sits above the main water table.below the groundwater, and sits above the main water table.


27/31

OtherOther ExamplesExamples


28/31


29/31


30/31


31/31

http://www.frogtech.com.au/groundwater/http://www.frogtech.com.au/groundwater/ http://www.civilengineergroup.com/characterizehttp://www.civilengineergroup.com/characterize--

aquifer.htmlaquifer.html www.physical environment.comwww.physical environment.com http://groundwater.ucdavis.edu/Publications/Harter_FWhttp://groundwater.ucdavis.edu/Publications/Harter_FW

QFS_8083.pdfQFS_8083.pdf http://www.groundwater.org/kc/gwwatercycle.htmlhttp://www.groundwater.org/kc/gwwatercycle.html

final report for hydrology 1

Documents