Midterm 1 Terminology Flashcards
Porosity
The pore space of an aquifer is the spaces or voids between the solid material. The porosity of the aquifer is the volume of void space to the total volume, typically expressed as a percentage.
Moisture Content
the quantity of water contained in a material
Saturation
Saturated conditions occur when all of the voids, spaces, and cracks are filled with water. Unsaturated conditions occur when the voids, spaces, and cracks between soil, sand, gravel, or rock are filled with a combination of air and water.
Vadose Zone
Area where water content varies depending on weather
Capillary Fringe
The area where groundwater is drawn up into the pores or spaces in the sediment above the water table by capillary action
Saturated Zone
Area below the water table, contains groundwater
Water Table (Phreatic Surface)
Location where groundwater is at atmospheric pressure
Unconfined Aquifer (Water Table Aquifer, Phreatic Aquifer)
An aquifer that’s upper bound is the water table
Perched Aquifer
An aquifer that is above the zone of saturation, in the vadose zone
Confined Aquifer
An aquifer that’s upper bound has a confining layer that does not transmit water, and is under pressure
Artesian Aquifer
An aquifer that is confined between impermeable material that is under positive pressure. When a well is drilled into an artesian aquifer, water flows to the surface
Aquitard
Confining layer of an aquifer that leaks
Aquifuge
Confining layer of an aquifer that is impermeable but contains water (ex: clay)
Aquiclude
Confining layer of an aquifer that is impermeable and does not contain water
Lithography
Types of rock
Stratigraphy
Subsurface layers
Igneous Rock
Ex: granite. Hard, can see mineral grains
Sedimentary Rock
Clastic Sedimentary (ex: sandstone) - formed by consolidation, possible porosity
Nonclastic sedimentary (Ex: limestone) - formed by precipitation
Metamorphic Rock
Rocks formed from igneous and sedimentary rocks
Primary Porosity vs Secondary Porosity
Primary: porosity that is present when the geologic layer was originally formed
Secondary: porosity formed by dissolution, fracturing
Drift
Transport of material while materials are weathered by glaciers
Till
Material transported by ice, unsorted
Moraine
Material transported by ice, organized structures
Drumlin
Oval or elongated hills believed to have been formed by ice
Esker
Scraggly ridges made of sand and gravel deposited by glacial meltwater
Outwash
Material transported by water, sorted by particle size (settle out by Stoke’s Law)
Alluvial, fluvial deposits
Geologic material found in ancient river bottoms, tends to be coarser grained
Lacustrine Desposits
Geologic material found in ancient lake bottoms, tends to be finer grained
Soil Texture
12 soil texture classes, based on a soil texture triangle, which uses % of sand, silt, and clay to type the soil texture. Soil ranges also by particle size
Soil Color
Munsell Color System Hue • R - red • YR - yellow red • Y - yellow Value • darkness or lightness Chroma • how clearly does the hue show
Aquifer
A geological layer that contains and can transmit water
Evapotranspiration vs Potential Evapotranspiration
Evapotranspiration is hard to estimate, as it depends on soil moisture, type of plants, sunlight, etc. If we assumed soil moisture is not a limiting factor (under conditions of unlimited water), ET = PET.
PET can also be estimated empirically, using the Blaney-Criddle of Thornthwaite Eqn’s
Homogeneous Assumption
Hydraulic Conductivity does not change with position
Heterogeneous Assumption
Hydraulic Conductivity changes with position
Different types of heterogeneity
• Layered
• Trending
• Discontinuous
Isotropy
Hydraulic Conductivity is the same in the x and z direction
Anisotropy
Hydraulic Conductivity is not the same in x and z directions
Transmissivity
the ability of the aquifer to transmit groundwater throughout its entire saturated thickness
Specific Storage
= volume of water that a unit volume of aquifer releases under a unit decline in piezometric head
Storativity
specific storage in units of flow per unit width
Specific Yield
water yielded from the dewatering of pores
Flow Nets
Graphical depiction of equipotential lines (h = constant) and flow lines). Used in interpretation of numerical solutions, h = f(x,y,z,t)