Lecture 9 Flashcards
(15 cards)
What is the hydraulic gradient?
The slope of the water table, calculated by (elevation difference / horizontal distance).
What’s the difference between a spring and a well?
Spring = natural outflow of groundwater where the water table meets the surface; Well = manmade opening to access groundwater.
What’s the most effective solution to groundwater contamination?
Prevention.
What makes groundwater contamination difficult to detect?
It moves slowly, so pollution can remain hidden until people get sick.
What is land subsidence and what causes it?
Sinking of the ground when water is pumped out faster than recharge, causing sediment compaction.
Why is groundwater considered a non-renewable resource in some areas?
Because recharge is slower than withdrawal; it could take 100,000s of years to replenish.
What is an artesian well?
A well where water rises on its own due to pressure in a confined aquifer.
What’s the difference between the zone of aeration and the zone of saturation?
Aeration = pores filled with air and some water (above the water table); Saturation = pores completely filled with water.
What is a cone of depression?
A conical-shaped dip in the water table caused by pumping from a well.
What is drawdown?
The lowering of the water table around a well due to heavy pumping.
What is an aquitard?
An impermeable layer that prevents water flow.
What is an aquifer?
A permeable rock or sediment layer that transmits groundwater freely.
What’s the difference between porosity and permeability?
Porosity = % of rock with pore space; Permeability = how easily water flows through it.
What is the upper boundary of the zone of saturation called?
The water table.
What is the zone of saturation?
All open spaces in sediment/rock are filled with water; this is where groundwater resides.
