Final Prep Flashcards
Reserves vs Resources
Reserves are quantities that can reasonably be assumed to exist and are producible with existing technology under present economic conditions.
Resources include present reserves as well as deposits not yet discovered or deposits that have been identified but are not recoverable under present technological and economic conditions.
-> Reserves are a subcategory of resources
M. King Hubbert’s Approach to estimating resource cycles
- Consumption would follow a course that might begin with exponential growth while the resource is abundant and relatively cheap
- As new sources are harder to find, prices go up and substitutions would begin to take some of the market
- Consumption rates peak and then begin a downward trend as the combination of high prices and resource substitutions would prevail
- Downward trend will become steep when the energy needed to extract and process the resource exceeds the energy derived from the resource itself
-> A graph of resource consumption rate versus time would start at zero, rise, peak, and then decrease back to zero, with the area under the curve equaling the total resource consumed
-> Gaussian Curve
Describe a typical growth curve for bacteria
- Lag Phase - Little to no growth, when the bacteria are first introduced in a new medium
- Exponential Phase - A period of rapid growth after the bacteria have adjusted to their new environment
- Stationary Phase - When the food supply begins to be depleted, or toxic metabolic products accumulate, no-growth phase
- Death Phase - When the environment becomes more and more hostile, population declines
Maximum Sustainable Yield
The maximum rate individuals can be removed without reducing the population size
Demography
The study of human population dynamics
Crude Birth Rate
Number of births per 1000 population in a giver year (simplest measure of fertility)
Total Fertility Rate (TFR)
The average number of children that would be born alive to a woman, assuming current age-specific birth rates remain constant through the woman’s reproductive years
Aquifer
An underground formation of permeable rock or loose material which can produce useful quantitates of water when tapped by a well.
Vadose Water
Water in the unsaturated zone
Unsaturated Zone
Characterized by the presence of both water and air in the spaces between soil particles. Here, water cannot be pumped, so it is essentially unavailable for human use
Saturated Zone and Water Table
Characterized by all water filling all spaces between spoil particles. The upper boundary of the saturated zone is called the water table
Capillary Fringe
The transition region between the saturated and unsaturated zones. Here, water rises into small cracks as a result of the attraction between water and rock surfaces
Groundwater
Water in the saturated zone
Confined Aquifer
An aquifer sandwiched between two confining layers (usually rock)
Artesian Well
A well drilled into a confined aquifer under pressure resulting in water naturally rising above the upper surface of the confined aquifer
Piezometric or Potentiometric Surface
A line drawn at the level to which water would rise in an artesian well
Flowing Artesian Well
When enough pressure exists in a confined aquifer to cause water in a well to rise above the ground level and flow without pumping
Specific Yield (or Effective Porosity)
The volume of water that can actually be drained from an unconfined aquifer per unit of area per area of decline in the water table
Hydraulic Gradient
The slope of the water table in an unconfined aquifer, measured in the direction of the steepest rate of change.
Hydraulic Head
The vertical distance from a reference datum plane (usually taken to be sea level) to the water table.
Problems with Darcy’s Law (3)
- Assumes linearity between flow rate and hydraulic gradient (invalid in some circumstances).
- Breaks down when flow is turbulent
- Invalid when water flows through extremely fine-grained materials and it should only be used when the medium is fully saturated with water
Homogenous vs Heterogenous Aquifers
Homogenous: Aquifers that have the same hydraulic conductivity throughout
Heterogenous: Aquifers in which hydraulic conductivity differs from place to place
Pump-and-Treat Technology
The process of installing properly located extraction wells to pump polluted groundwater out of the aquifer, where it can be cleaned in an above-ground treatment facility, and used or returned to the aquifer
Capture-Zone Curve
The outer envelope of the streamlines that converge on the extraction well. The extraction well is located in a region with a uniform and steady regional groundwater flow that is parallel to and in the direction of the negative x-axis
