A2 Flashcards
What is direction of dip?
The direction that water would flow if poured into the surface, measured using a compass.
What is angle of dip?
From 0 degrees for horizontal bedding to 90 degrees from vertical bedding, measured using clinometer
What are the two aspects to the dip of a plane?
Direction and angle
How is dip recorded?
Using direction and angle, written as 140/38 direction from north to angle
What is the zone above the water table known as?
Vadose water
What is vadose water composed of?
An unsaturated zone composed of slow moving water and capillary water
Describe the behaviour of slow moving water
Percolates downwards to join phreatic water below the water table
Describe capillary water
Held above the water table by surface tension forces
What is the water in the zone below the water table known as?
Gravitational water
Describe 4 points of the gravitational (phreatic) water
(Gravity, pore spaces, pore pressure, flow)
It is subject to gravity
It saturates the pore spaces in soil below water table
Has an internal pore pressure greater than atmospheric
Flows laterally
What is permeability defined as?
The rate at which water under pressure can flow through interconnected voids (pore spaces) within a soil
What is the formula for permeability?
q=Aki
How is permeability tested for in granular material such as sand?
Through the constant head test
How does the constant head test work?
A volume of water is discharged through a sample, time and head difference is measured, resulting in flow rate of water
How can darcy’s equation be rearranged using flow rate and hydraulic gradient?
q=Aki , k=q/Ai,
q=Q/t, i=change in h/L
k=QL/tA(change in h)
