lecture 12 Groundwater

Groundwater

______ is the water found underground in the cracks and spaces in soil, sand, and rocks. It is stored in and moves slowly through geologic formations of soil, sand, and rocks called aquifers

Hydrological cycle

Groundwater

_______ interacts with surface water systems (rivers & lakes) and the ocean

Hyporheic zone

Water is exchanged between surface and ground water in the _______

Primary porosity

_______ is the original porosity system formed during deposition of sediments

Secondary porosity

______ forms subsequently or results from a separate porosity that enhances the overall rock porosity

Folds and faults

______ & ______ are secondary porosity

Total porosity

_______ is the ratio of the volume of voids the total bulk volume of rock

Porosity

The volume percentage of voids or openings in a rock and rock’s ability to hold water.

Permiablility

The capacity of a rock to transmit fluid through pore space and fractures.

Permiable

_______ rocks allow water to flow easily

High, low

Ground water flows from ____ to _____

Perpendicular

Flow is always _____ to the lines of equal potential

Recharge

I after located in deep aquifers takes thousands of years to ______

Water table

The __________ mimics surface topography within a uniformly permeable rock

József Tóth (1963)

Discovered groundwater discharges not only in the deep valleys built in the sides of higher topographic elevations

Unconfined aquifer

Pumping in an __________ well lowers the groundwater surface (water table) and the area affected by the pumping is called the cone of depression.

Well drawdown

The total amount the water level drops in the well as it takes time for water to seep between grains

Subsidence

Excessive well extraction causes _______

Darce’s Velocity

And apparent velocity representing the velocity of water move through an aquifer were and open conduit

Base flow

Portion of the stream that is delayed shallow surface flow is sustained between precipitation events and fed to streams by delayed pathways

Effluent (gaining stream)

Ground water flows into a stream

Influent (losing stream)

Water flows into saturated zone

Dry stream bed

Changes in water table can result in a __________

Septic tanks

_______ are a big cause of ground water pollution

Salt water intrusion

Occurs where too much fresh water is pumped out of the ground and replaced by brackish and eventually salty water