Karst Processes And Landscapes

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Karst Processes And Landscapes

Lecture 14  

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What is groundwater and how does it accumulate?
2nd largest potential source of freshwater (22%) and it accumulates by percolation
How is percolation controlled?
By a rocks porosity: the percentage of the total volume of a rock or soil that consists or pure space within a rock.
What is permeability and what is it controlled by?
The capacity of a material to transmit fluids or how well fluids move through it.   Controlled by fluid's viscosity, hydrostatic pressure, the size of the openings, and the degree to which the openings are interconnected.
What is the Zone of Aeration?
The Zone of aeration is a permeable layer and has a permeability rate of > .01m/day...water passes through this zone/layer
What is the Zone of Saturation?
The zone of saturation is where water collects. This zone is above and impermeable layer (rate < .01m/day) water collects here.
What is an Aquifer?
An aquifer is an underground layer of water-bearing permeable rock or unconsolidated materials (gravel, sand, silt, or clay) from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology. Related terms include: an aquitard, which is an impermeable layer along an aquifer, and an aquiclude (or aquifuge), which is a solid, impermeable area beneath an aquifer.
What are the three types of impermeable layers?
1)aquitard 2)aquiclude 3)aquifuge  
What is the Water Table?
The water table is the upper limit of the zone of saturation.
What is an Unconfined Aquifer?
An Unconfined Aquifer is the zone of saturation. It has a permeable layer above and an impermeable layer below. (fig. 13.5 pg 342)
What is a Confined Aquifer?
A Confined Aquifer has an impermeable layer above and below it, and is recharged in select places. (fig 13.4 pg 342)
What is an Artesian Well?
A flow of water onto the surface under pressure from a confined aquifer. (fig 13.10 pg 348)
What is a spring?
a surface flow of water that emerges from underground...not under pressure from an unconfined acquifer.
What is a stream?
water flowing on the surface, in a watercourse, where the water table is above the surface: can be permanent or temporary.
What is a thermal Spring and Geysers?
Water heated to high temperatures usually associated with recent volcanic activity (fig 13.11 and 13.13 and 13.25 pgs 350, 351, 363)
What is Ground Subsidence?
If groundwater is removed in large quantities, surface may react by sinking to fill in the new space.
What is salt water encroachment?
reach in book pgs. 365-67
What is Karst?
a type of landascape associated with the chemical erosion of soluble limestone (caco3) or dolomite (camg[co3]2)
What are the key ingredients in Karst and where does in occur?
Water is a key ingredient, without water there is no Karst. May occur at the surface or below the surface. A few other rock types may also form Karst...evaporites
What is the basic process of Carbonation?
Carbonation occurs when carbon dioxide is dissolved in water or an aqueous solution. This process yields the "fizz" to carbonated water and sparkling mineral water, the head to beer, and the cork pop and bubbles to champagne and sparkling wine. As long as the solution stays unsaturated the ions remain siddolved. with the addition of more and more Ca+2 ions the solution becomes saturated or even supersaturated and a precipitate may form.
What are the basic steps (including the formulas) to create carbonation?
1) Water combines with carbon diozide to form carbonic acid CO2 + H2O >>> H2CO3 5) The net process can be shown as CaCo3 + CO2(dissolved) + H2OCa++ + 2HCO3-   2) Then carbonic acid dissociates readily into its ionic state CO2(dissolved) +  H20H+  +  HCO3 -   3) Calcite dissociates into its ionic state CACO3 Ca++  + CO3- -   4) Hydrogen atom of equation 2 combines with the carbonate ion to form anotherbicarbonate ion, and the Ca++ ion is released from the calcite crystal into the water. CO3-  + H+ = HCO3-  
What affects the process of carbonation?
the amount of CO2 in the water affects the strength of the cabronic acid, which affects the rate of dissolution.   the more CO2 = the stronger the acid = more dissolved limestone.
describe how temperature affects Karst
*Cold water can hold more CO2 *There is not as much Karst in colder areas because there is less begetation in colger areas meaning there is less CO2 in the soil. *warmer areas have more vegetation so they can hold more CO2 in the soil
describe how the mixing effect affects Karst
*When water of differing solution strengths mix they yield a new solution which is unsaturated , so more Ca+2 ions can dissolve into the water.
describe the flow-rate effect
Slow moving or still water will reach saturation sooner than faster moving water.
describe climate controls in terms of Karst production
*cold regions yield little karst development: sparse rainfall and vegetation leads to little co2 in the soil. permafrost and frozen water *mid latitude, cool humid areas yield well developed karst since there is abundant rainfall and vegetation (co2 in the soil) *arid-semi-arid areas yield little karst: lack of water (low precipitation and high evapotranspiration rates) *Tropical areas yield well developed karst: abundant rainfall and vegetation, high rate of chemical reactions.
what is the key factor is Karst?
The amount of CO2 in the water. Most CO2 comes from the soil.    atmosphere = .03% by volume snow = .1% by volume soil = 1-3% by volume higher vegetation amounts = higher CO2 levels
What are some seasonal differences of CO2 levels?
*seasonal soil Temp differences: increase soil temp = increased soil CO2 *Seasonal water flow differences *seasonal vegetation differences
Karst Landforms
different references and researches have different categories or classification schemes: EX: temperature Karst vs. Tropical vs. Caribbean Karst, etc.   Common Surface Karst Landscapes
Doline Karst
Areas of numerals dolines or sinkholes *most widely distributed type of karst landscape *various types of dolines: solution, collapse, suffosion, subsidence *Avg size ranges from 10-100m wide and 2-100m depth *Doline Karst located in s. indiana, cent. kentucky and tennessee, north florida
What is a doline?
a small usually shallow circular to oval shaped closed depression created by remains of material from below the surface.
What is a uvala?
2 or more dolines which have coalesced into one.
What is cockpit Karst?
area of depressions surrounded by S towers or cones, forming a star shaped pattern. Found in Jamaica.
What is Cone and Tower Karst?
Similar to cockpit karst, but with steeper-sided towers, smaller depressions, and usually not star-shaped. found in belize, cuba, south mainland china, indonesia
What is FluvioKarst?
A landscape of deranged drainage, blind valleys, large springs, or most any running water system in limestone formation areas. found in europe. *also includes such features as dry valleys and semi-blind valleys. also areas of sinking disappearing streams with swallow holes. (Look up onlineeeee)
What is a Polje Karst?
Large flat floured closed depression often filled with alluvium floors and susceptible to flooding. Found in the fromer qugoslavia and adjacent countries. 1-5km wide and up to 60km long. water flows across the polje floor, disappearing into a swalow hole or ponor (cave openning)
What is a Labyrinth Karst?
Intersecting solution corridors and canyons . can be several km in extent. Ex. Nahanni  River Basin NW territories, Canada
what are common underground Karst Landforms and Features?
What is a cave?
caves: a natural openning in the earth large enough to admit a human being, usaully with an elongate cavity produced by solution, aided by mechanical erosion of subterranean flowing water.  
Where are caves found?
*found in karst areas, one created by the dissolution of bedrock, primarily limestone, by circulating water.
How big are caves? what are their components and shapes?
Cabes vary from a few meters to hundreds of km. longest known cave: mammoth cave (flint system), kentucky 500km = 310 miles   Components: entrances, terminations, passages, rooms   Shapes: 2 broad classes 1) Single Conduit passages: linear passages, angulate passages, sinuous passages 2) Maze passages: network mazes, anastomosing mazes, spongework mazes
What are some cave features?
Speleothems, Stalagmite, stalactite, column, and tufa
What is a speleothems in a cave?
A secondary fchemical crystallization/depositional feature of caves, the general term for all cave formations.
What is a stalagmite in a cave?
Depositional feature which builds up from the floor
What is a stalactite in a cave?
depositional feature which grows downward from the ceiling
What is a column in a cave?
Reaches from the floor to the ceiling, may be a stalagmite and stalactite that have joined or one or the other which has grown from one side to the other
What is a tufa in a cave?
Precipitate which forms along a wall, on rocks, and other surfaces.