LESSON 7 Flashcards
It results predominantly from precipitation that has reached the zone of saturation in the Earth through infiltration and percolation. Has the lowest priority on the water from precipitation, hence, its utilization should be limited. Sources of recharge and surface waters
Groundwater
the pores of soil contain both water and air in varying amounts; the water in the upper layers of this zone is called soil moisture
Zone of Aeration
the pores of the soil or rock are filled with water; the water in this zone is called groundwater
Zone of saturation
Can be used interchangeably with influence stream; separator of zone of aeration and zone of saturation
Water table
A geologic formation which contains water and transmits it at rate sufficient to be economically developed for pumping
Aquifer
It is the opposite of Aquifer ; rate insufficient to be economically developed for pumping
Aquiclude
TYPES OF AQUIFER
Unconfined/Water table aquifer
Confined or artesian aquifer
Semi-confined or leaky aquifer
Perched Aquifer
has a water table serving as the upper surface of the zone of saturation
Unconfined/Water table aquifer
one where the groundwater is confined by a relatively impermeable layer
Confined or artesian aquifer
the upper confining layer is leaky or semi-permeable
Semi-confined or leaky aquifer
its lower limit is relatively impermeable layer while its upper surface is a free water surface on water table
Perched Aquifer
AQUIFER PROPERTIES
Porosity
Specific yield
Specific retention
Aquifer conductivity or permeability
Transmissibility
Storage coefficient
capacity of a formation to contain water
Porosity
Water that can be extracted y gravity flow; measure of the volume of water yield per unit soil volume
Specific yield
water retained by the soil formation against the force of gravity
Specific retention
measure of the ease with which an aquifer will transmit water; influenced by both the properties of water and aquifer materials
Aquifer conductivity or permeability
measure of the potential discharge of wells penetrating an aquifer, its magnitude is an indication of the economic value of an aquifer as a source of water supply
Transmissibility
water yielding capacity of a confined aquifer
Storage coefficient
Water table well (Confined or Unconfined)
Unconfined
Artesean Well
Confined
THREATS TO GROUNDWATER QUANTITY
Quantity
-Overdraft
-Drawdown
-Subsidence
Quality
-Point Sources
-Non-point sources
Growing population ; increase in quantity of groundwater being withdrawn to meet the demands of the growing population
Quantity
Occurs when groundwater is removed faster than recharge can replace it. Main effect is saltwater intrusion in coastal basins
Overdraft
Lowered water table temporarily, caused by pumping
Drawdown
Results from overpumping which causes sinkholes. Permanently reducing storage capacity
Subsidence
inorganic compounds, pathogens and organic compounds can harm water quality, affecting the health of humans, fish and wildlife. Scientists continually learn more about contaminants, their sources and prevention practices.
Quality
widespread, seemingly insignificant amounts of pollutants which, cumulatively, threaten water quality and natural systems
Point sources
List of Point sources
Septic systems
Agriculture
Construction
Grazing
Forestry
Recreational activities
Careless household management lawn care and parking lot
Other urban runoff
easily identified because they usually come out of a pipe
Non-point sources
Example of Non-point sources
Sewage treatment plants
Large injection wells
Industrial plants
Livestock facilities
Landfills
Others
