eTest 2 Flashcards
(20 cards)
What is an imaginary line called which follows a line of equal head in an aquifer?
Equipotential line
Given the water table, hydraulic conductivity and width and thickness values for the aquifer represented in the figure, calculate the rate of discharge of water through the area shown. The discharge per day is equal to Q = K.i.A
2400 m3/d
Average linear velocity of groundwater is the specific discharge divided by
Effective porosity of the medium
Which of the following statements apply to Transmissivity?
It is the discharge that occurs through a unit width and saturated aquifer height
The main functions of an aquifer are to store and transmit water. Match the following properties of storage and transmission of water to their descriptions.
- Specific Yield: Characteristic that describes the release of water under gravity
- Porosity: Void spaces between grains or in fractures
- Storativity: Measure of release of groundwater from storage in an aquifer
- Permeability: Measure of ability of a medium to transport fluid and is independent of the properties of the fluid
- Hydraulic Conductivity: Measure of ease of fluid flow through a porous medium dependent on the properties of the fluid (viscosity)
For Darcy’s law to be valid, the flow must have one key characteristic, which?
Be laminar
Match the terms with their definitions.
Heterogeneity: K is not the same in all locations
Anisotropy: K is not the same in all directions
Homogeneity: K is the same in all locations
Isotropy: K is the same in all directions
Name the following surface water -GW water interactions. (A) A lake which recieves groundwater inflow from all directions. (B) A lake which discharges surface water to groundwater in all directions. (C) A lake which recieves groundwater inflow in some areas and discharges surface water to groundwater in other areas
Picture A Groundwater discharge
Picture B Groundwater recharge
Picture C Groundwater flow-through
Which of the following processes represent outflow or discharge from a groundwater system?
Abstraction from wells
Leakage into underlying aquifer
Flow to ocean
Evapotranspiration
Given the data in the two wells shown in the figure, what is the hydraulic gradient (i) between the wells?
.0025 or .25
Using values for elevation (80m above datum), depth to groundwater (22m), and depth to screen (50m) provided in the figure, calculate elevation head (z), pressure head (hp), and hydraulic head (h). What is the z, hp, and h (in that order) for the values provided?
z = 30, hp = 28, h = 58
Which of the following statements are TRUE about confined aquifers?
Water level rise in confined aquifers is represented by the potentiometric surface.
They are also known as artesian aquifers in some countries.
They occur between two confining layers.
Hydrogeological units are important as they determine the subsurface plumbing system. Match the description to the respective hydrogeological units.
Aquifer: Saturated geological unit that stores and transmits significant volumes of water
Aquitard: All geological layers or units that have low transmission of water
Aquifuge: Impermeable unit that cannot transmit water.
Look at the groundwater (GW) contour map and match the letters A-E with the corresponding major GW feature.
GW recharge from the river: A
GW discharge to the river: C
No GW-river interaction: B
GW discharge area (e.g., well): D
GW recharge area: E
In an unconfined aquifer, not all the water in storage is available to be extracted, why?
Because surface tension of water adheres it strongly to aquifer solid particles as a film
What is the general equation for all water balances? Note that inputs and outputs are positive. A negative storage change is a decline in storage.
Inputs - outputs = change in storages
In terms of Darcy’s law, what is the volumetric rate of movement (Q, m3/day) directly proportional to?
Directly proportional to hydraulic gradient, hydraulic conductivity, and the cross-sectional area of the medium through which groundwater is moving.
The water table is defined as the undulating surface at which.
Pore water pressure is equal to atmospheric pressure
What is the Specific Yield of an aquifer?
Amount of water which is drainable under gravity from the aquifer material.
Hydraulic conductivity is the ability of a porous medium to transport fluids dependent on
Permeability of the medium and density and viscosity of the fluid
