*Groudwater Flashcards
Name the three zones for groundwater and state where the water table is within those layers
Unsaturated zone
Capillary fringe
Water table
Saturated zone
Define unsaturated zone
includes air, water and soil, water is held in tension and is considered unavailable
What is the definition of a water table?
Upper bound of the saturated zone
What is the saturated zone?
Includes water and soil, water flows as groundwater
What is the capillary fringe?
Up to 100% saturated but water is held in tension
What is an aquifer?
A saturated layer that is permeable enough to allow water to flow through it
What is an aquitard?
A saturated layer that is not permeable enough to allow water to flow through it
An aquifer allows water to be pumped out at an economical rate whereas an aquitard does not, true or false?
True
Define groundwater
The water contained in interconnected pores located below the water table in an aquifer
Define groundwater flow
The movement of water through openings in sediment and rock; occurs in the saturated zone
Define artesian
A confined aquifer with water that flows upward out of a well without pumping
Define perched
Groundwater above a low permeability layer, usually above an aquifer
Give two definitions for hydraulic gradient
- Slope of the water table
- Difference in hydraulic head between two points
What is hydraulic conductivity?
The ability of the porous media to conduct a fluid
What is porosity?
The ratio of volume of voids to total volume
What is effective porosity and is it usually larger or smaller that porosity?
The ratio of interconnected pore spaces to bulk volume, usually larger than porosity
What is the difference between groundwater velocity and Darcy velocity (Darcy flux)
Groundwater velocity is the actual velocity through soil and Darcy flux is like pipe flow and does not account for soil
Real velocity is known as linear or seepage velocity, true or false?
True
What are the three ways contaminants are transported in groundwater? Describe them
Advection - due to groundwater flow
Dispersion - due to irregular flow paths
Diffusion - due to concentration gradient
For dispersion does smaller pores mean higher dispersion?
Yes, smaller pores = higher velocity = higher dispersion
What are the three scales of dispersion from smallest to largest?
Micro
Macro
Mega
For diffusion contaminant plumes move from high to low concentration, true or false?
True
What does retardation do?
Cause the average contaminant velocity to be slower than the groundwater velocity
Adsorption means to cling to the surface, true or false?
True
