Lecture 6 Flashcards
What is Groundwater
Water that exists underground in saturated zones beneath the land surface. Including all subsurface sources including those in soil solution
Void Spaces
(pores/fractures) in the bedrock
What are void spaces important for maintaining
- streamflows
- drinking water
- irrigation
Groundwater Distribution (Aeration/Unsaturated/Vadose zone)
Land surface to top of the phreatic zone
Groundwater Distribution (Capillary Fringe)
Region in which water seeps/wicks up from vadose zone
Groundwater Distribution (water table)
Top of saturated zone
Groundwater Distribution (saturated zone)
- Region in which space is filled with water
- Coincides with most rivers and lakes at surface to swamps, ponds
Groundwater Distribution (Aquifer)
Layer of water bearing material (permeable; supports springs)
Groundwater Distribution (Aquitard)
Layer that retards water flow (ex. clay)
Relatively impermeable
Groundwater Distribution (Aquiclude)
Layer absorbs, holds but does not transmit water
Impermeable
What is a Perched Water Table
Aquifer that occurs above the regional water table
What is a Spring
Exit point at which groundwater emerges from the aquifer and flows onto the top of the Earth’s crust to become surface water
What is a Well
Is a hole made into the ground to access water contained in an aquifer
What is a Watershed (Surface Water)
An area of land in which percipitation drains to a common point on a stream, river, pond, lake or other body of water (drainage basin)
What is the Groundwater Divide
A curve representing the water table ridge (described with contours of the groundwater level) that seperates the flow domain into subdomains
Where does Groundwater Divide Flow
Flows from upland recharge areas to valley discharge areas
What is an Aquifer?
Geological formations:
1. stores
2. transmits
3. yields water
What does the Aquifer Depend on:
The geology: recharge, aquitards, aquicludes, etc.
What are Unconfined (water table) Aquifers Influenced By:
Atmosphere (need pump)
What is an Artesian Well:
A well that brings groundwater to the surface without pumping because it is under pressure within a body of rock and/or sediment in a confined aquifer
Wells: Cone of Depression/Ascension
Active withdrawal of groundwater can have consequences by changing the slope or shape of the water table
- Continental and Costal wells
What is Hydrodynamic Equilibrium
When discharge = recharge
Hydrodynamic Disequiliburium
Discharge > recharge
That is Groundwater Hydrology
Deals with the distribution and movement of groundwater in soils and rocks of the Earth’s crust
What is Groundwater Hydrology based on?
- Hydraulic gradients: i = change in h/ change in length
- On gradient
- Groundwater flows perpendicular to equipotential lines
Groundwater Hydrology Abilities and Characteristics (3):
- Porosity
- Permeability
- Dispersivity
Groundwater Hydrology: Porosity
Ability to hold water (void spaces)
P = Volume (pore)/ Volume (total)
Groundwater Hydrology: Permeability
Ability to transmit water
Hydraulic Conductivity (k):
k = QL/ Aht, time to flush a sediment-filled column
Groundwater Hydrology: Dispersivity
Ability to mix groundwater
Permeability: Hydraulic Conductivity (k) Depends on:
- Pore size
- Path Length
- Friction in the Pore
- Fluid Viscocity
- Density
Hydraulic Conductivity (k) What Does the Equation Do?
Measures k (cm/s) in diverse materials like stream sediments using a constant-head pereameter
Hydraulic Conductivity (k) What Does k Depend on:
The material
Darcy’s Law for Groundwater Flow:
Discharge (Q) = (permeability (k) x Area x hydraulic gradient (i))/ (effective porosity (η))
Velocity (V) = (permeability (k) x hydraulic gradient (i))/ (effective porosity (η))
Groundwater Biology: What is Epigean?
Surface dwelling
Groundwater Biology: What is Hypogean?
Being, living or growing underground or below surface
Groundwater Biology: What is Stygobiont/Stygofauna?
Groundwater-dwelling organisms
Groundwater Biology: What is a Stygophile?
Surface-dwelling (epigean) species with incipient adaptation to the groundwater life and able to maintain permanent subterranean populations
Groundwater Biology: What is Stygobite?
Obligate groundwater inhabiting species
Groundwater Biology: What is Stygoxene?
Species only occuring sporadically in groundwater habitats without permanent subterranean populations
Features of Groundwater Biology
- Typically small
- Eyeless
- Colourless
- Adapted to dark
- Nutrient-poor
- Spatially constrained
- Interstitial habitats
Groundwater Environments
- Spatial gradients (water depth)
- Environmental conditions change
- Ecological factors change
- Upper and lower boundaries
- Metazoans vs. Microbes
Groundwater Environments (changes in environmental conditions):
Decreased light, decreased oxygen, increased temperature, increased sulfer
Groundwater Environments (changes in ecological factors):
- Decrease organic carbon
- Increase in oligotrophy
- Decrease in photosynthesis
- Decrease in predation
- Decrease in competition
- Increase in detritivory
- Increase in omnivory
- Increase in chemoautrophy
Groundwater Environments (Upper Boundary)
Ecological factors/interactions determine species limits
Groundwater Environments (Lower Boundary)
Physiological factors determine species limits
Groundwater Biology Characteristics: Subterranean Evolution (3 phases)
- Loss
- Increase
- Decrease
Groundwater Biology Characteristics: Subterranean Evolution - Loss
Loss of eyes, pigmentation, wings, water regulatory processes, and various other physiological strategies
Groundwater Biology Characteristics: Subterranean Evolution - Increase
In appendge length and life span
Groundwater Biology Characteristics: Subterranean Evolution - Decrease
In the number of eggs (but increase in size and development time) and respiratory metabolism
Does below ground reflect the above ground faunal diversity
No
What Taxa are the most Abundant, Widespread, and Taxonomically Diverse Groups in Groundwater
- Copepoda
- Isopoda
- Amphipoda
What is a Truncated Food Web:
The lack of basal trophic levels to opportunism and redundacy with convergent evolution and high rates of endemism
Groundwater Contamination - Types (5)
- Agricultural
- Commercial
- Industrial
- Municipal
- Specialized
What Zones are the more vulnerable to contamination
Vadose Zones (unconfied aquifers)
What is LNAPL?
Light Non-Aqueous Phase Liquid (less dense than water)
What is DNAPL?
Dense Non-Aqueous Phase Liquid (denser than water)
