LAB 06/ MODULE 15: KARST LANDSCAPES AND GROUNDWATER

Note: Please refer to the GETTING STARTEDmodule to learn how to maneuver through and answer the lab questions using Google Earth ().

KEY TERMS

Students should know and understand these terms:

Aquifer	Dissolution	Stalactites
Cave	Groundwater	Stalagmites
Cavern	Karst landscape	Subsidence
Carbonate rock	Sinkhole	Tower karst
Disappearing stream	Speleothems	Water table

 

LAB LEARNING OBJECTIVES

After successfully completing this module, you should be able to the following tasks:

·         Identify karst features on a topographic map and aerial photo

·         Identify land uses associated with karst topography

·         Identify components of the groundwater system

·         Explain how water enters, flows through, and exits the ground

·         Explain how caves and caverns are formed

·         Explain how the hydrologic cycle functions

·         Identify land uses associated with groundwater

 

 

INTRODUCTION

This module examines Karst landscapes and groundwater. Topics include caves, caverns, sinkholes, aquifers, infiltration and groundwater movement. While these topics may appear to be disparate, you will learn how they are inherently related. The modules start with four opening topics, or vignettes, which are found in the accompanying Google Earth file. These vignettes introduce basic concepts karst landscapes and groundwater. Some of the vignettes have animations, videos, or short articles that will provide another perspective or visual explanation for the topic at hand.  After reading the vignette and associated links, answer the following questions. Please note that some links might take a while to download based on your Internet speed.

 Expandthe INTRODUCTION folder and then select Topic 1: Introduction.

 Read Topic 1:Introduction.

Question 1: What human disturbance is evident in both surface and subterranean karst environments?

A.   Human dwellings

B.   Pollution

C.   Agricultural land use

D.   Dams for hydroelectric power

 Read Topic 2: Karst Landscapes.

Question 2: How are caves and caverns, once underground, now visible on the surface in mature tropical karst environment?

A.   A decrease in water levels exposed the caves and caverns

B.   Terracing of mountains for agricultural production exposed them

C.   Tectonic uplift and weathering and erosion of mountains exposed them

D.   Removal of vegetation exposed the caves and caverns

 Read Topic 3: Groundwater

Question 3: How does the “ground” (soil, rock, topography) influence groundwater movement? (Check all that apply).

A.   The ground can temporarily hold or store the water

B.   Groundwater generally conforms to the topography of landscape

C.   Soil type affects infiltration rates

D.   The ground does not influence groundwater movement

 Read Topic 4: Human Interaction.

Question 4: According to the website, what are three methods used to mitigate subsidence? (Check all that apply).

A.   Repressuring of wells through aquifers

B.   Artificial recharge of aquifers from the land surface

C.   Reduction of pumping draft

D.   Repressuring of aquifers through wells

 

 Collapse and uncheck INTRODUCTION.

For the rest of this module, you will identify and explain the geographic distribution, patterns, and processes associated with karst processes and groundwater. In doing so, you will recognize and appreciate the impact that these processes and features have on the surface.

 

GLOBAL PERSPECTIVE

   Double-click GLOBAL PERSPECTIVE, and the select Global Karst Distribution.

Karst environments are found throughout the world, and are found in nearly all climates and locations on earth. Many metropolitan cities are found in these karst landscapes. Moreover, many of these cities also are situated above or near large aquifers that provide water (in the form of groundwater) to the city and surrounding areas.

For Questions 5 to 8, double‑click and check each question to arrive at the city located in a karst environment. To find the associated large aquifer system located beneath or adjacent to the city of interest, select Global Aquifer Distribution and click global map. Fill in the blanks below with the answer:

	City	Associated Aquifer
Question 5	A.   Miami B.   Tampa C.   Cairo D.   Paris	A.   Gulf Coastal Plains B.   Eastern European C.   Central Asian D.   Western Desert
Question 6	A.   Moscow B.   Paris C.   London D.   New York	A.  Gulf Coastal Plains B. Eastern European C. Central Asian D. Western Desert
Question 7	A.   Cairo B.   Dubai C.   Johannesburg D.   Nairobi	A.   Eastern Africa B.   Sahara Basin C.   South Africa D.   Karoo Basin
Question 8	A.   Paris B.   Bonn C.   Rome D.   Madrid	A.   Southern Europe B.   Germanic Basin C.   Parisian Basin D.   Alpine Aquifer

 

 Collapse and uncheck GLOBAL PERSPECTIVE.

KARST TOPOGRAPHY

 Expand the KARST TOPOGRAPHY folder, and then double‑click and select Dunnellon, Florida.

 After the topographic map displays in Google Earth, expand the Feature A folder, and then select both Feature A and Feature A Profile.
Note: You might have to zoom out to clearly see Feature A.

Notice that the contour lines are enclosed and hachured.

Question 9: What do enclosed hachured contour lines topographically represent?

A.   Water body

B.   Hill top or high point

C.   Depression

D.   Unsure about exact location of contour

 

Question 10: What do enclosed contour lines without hachured lines topographically represent?

A.   Water body

B.   Hill top or high point

C.   Depression

D.   Unsure about exact location of contour

 

Question 11: What type of karst landform is Feature A?

A.   Sinkhole

B.   Cave

C.   Cavern

D.   Tower Karst

 Right click the term Feature A Profile and select Show Elevation Profile

Question 12: What is the relief (difference in elevation between maximum elevation and minimum elevation) within Feature A using the elevation profile (in feet)? (Select the answer closest to what you see in your elevation profile window).

 

A.   70 feet

B.   1,393 feet

C.   900 feet

D.   9 feet

 

 Uncheck the folder Feature A. Verify Dunnellon, Florida is still enabled, and then double‑click and select Feature B.

Question 13: Why would these features have to be on the surface?

A.   Ground is too soft to construct them underground

B.   Ground is too wet to construct them underground

C.   Risk of wastewater contaminating groundwater

D.   Risk of groundwater contaminating wastewater

 

 Uncheck Feature B. Verify Dunnellon, Florida is still enabled, and then double‑click and select Feature C.

Question 14: What is this feature?

A.   A lake

B.   A pond

C.   A spring

D.   A swamp

 Uncheck Feature C. Verify Dunnellon, Florida is still enabled, and then double‑click and select Feature D.

Question 15: What is this feature?

A.   Stream

B.   Road

C.   Trail

D.   River

 Uncheck Feature D. Double‑click and select Feature E. Notice what the feature looks like in the Topographic map.

 Uncheck the Dunnellon, Florida topographic map. Use the Historical Imagery option to set the date to 1/5/1999. Compare the water in the feature in 1999 to the water feature on 1/17/2010.

Question 16: What has happened to the water level in Feature D?

A.   The water level has increased

B.   The water level has decreased

C.   The water level has remained the same

D.   Unable to determine

 Uncheck Dunnellon, Florida.

Now we will go to Mt. Gambier, Australia.

 Double‑click and select Umpherston Sinkhole. Click the link on the call out box for Umpherston Sinkhole and watch the short video clip.

Question 17: What is this sinkhole used for?

A.   Landfill

B.   Garden

C.   Swimming pool

D.   Golf course

 Collapse and uncheck KARST TOPOGRAPHY

TOWER KARST LANDSCAPES

 Expand the TOWER KARST LANDSCAPES folder.

 Double‑click and select Tower Karst.

This is an example of tower karst in southern China, near Guilin, in Guangxi Province. These towers are the final remaining pieces of a limestone outcrop. The rest of the limestone has been weathered and eroded. The slope of these landscapes can be quite steep.

 Select Slope. Right‑click Slope, and then select Show Elevation Profile.

Question 18: What is the average positive slope (percentage)? (Select the answer closest to what you see in your elevation profile window).

A.   80%

B.   32%

C.   74%

D.   -91%

Question 19: What land use is found throughout the valleys? (Hint: you may have to pan around the image).

A.   Commercial buildings

B.   Industrial complexes

C.   Agricultural fields

D.   Golf courses

From the video you watched in the Introduction part of this Module, we know that there are many caves and caverns in the Karst landscapes of Florida.

Question 20: Would you expect to find many caves present in the tower karst landscape?

A.   Yes, because caves are a common feature of karst landscapes

B.   No, because erosion has exposed the caves

C.   Yes, because high water levels create caves

D.   No, because low water levels create caves

 Collapse and uncheck TOWER KARST LANDSCAPES

 

 

CAVES AND CAVERNS

 Expand CAVES AND CAVERNS. The following is a list of four of the most spectacular caves and caverns located in the world. Click Longest cave to begin answering the following questions.

	Cave Name	Country
Question 21: Longest Cave – This is the longest cave system in the world, at over 627 km	A.   Krubera Cave B.   Mammoth Caves C.   Gatrell Caves D.   Antarctic Caves	A.   USA B.   Canada C.   Russia D.   Australia
Question 22: Deepest Cave – This is the deepest cave in the world, at 2,191 m	A.   Krubera Cave B.   Mammoth Caves C.   Gatrell Caves D.   Lechuguilla Cave	A.   USA B.   Georgia C.   Russia D.   France
Question 23: Scientists Only – As part of the Carlsbad Caverns National Park, the pristine condition and unique speleothems (cave formations) allow only cave scientists and geologists to have access	A.   Krubera Cave B.   Mammoth Caves C.   Gatrell Caves D.   Lechuguilla Cave	A.   USA B.   Spain C.   Egypt D.   Australia
Question 24: Sacred Space –This cave – arguably a sacred space to Paleolithic peoples- contains over a thousand cave paintings, some of which date back 17,000 years	A.   Krubera Cave B.   Mammoth Caves C.   Lascaux Cave D.   Lechuguilla Cave	A.   Russia B.   France C.   Canada D.   Australia

 

 Collapse and uncheck CAVES AND CAVERNS.

 

GROUNDWATER

 Expand the GROUNDWATER folder. Double‑click and select Gray County, Kansas.

This is Gray County, Kansas. As you can tell from the center pivot irrigation circles, agriculture is the dominant land use in the county. The Arkansas River – running west to east – bisects the county. There is not enough water in the river to provide sufficient water for irrigation. Therefore, water source for irrigation is groundwater.

We cannot see the aquifer that is supplying the water for irrigation, but we do have well information that indicates the depth of the water table. In general, we assume the deeper the water table, the deeper the well.

 Double‑click and select Well Depths.

This map shows the depth of the water table. It was created using data from 100 wells. The more yellow the area, the shallower the well and the more blue, the deeper. The deepest wells have a depth of approximately 500 feet.

 Double‑click and select, Surface Profile. Right‑click Surface Profile, and then select Show Elevation Profile.

This surface profile line is approximately 25 miles in length and the elevation varies by 24 meters only. This is not much change in elevation over 25 miles.

With the elevation profile showing at the bottom of the screen, run your cursor along the x-axis. Look at the position of the red arrow, relative to the well depth map.

Question 25: What is the relationship between surface elevation and well depth?

A.   In general, the higher the land elevation, the deeper the well depth

B.   In general, the lower the land elevation, the deeper the well depth

C.   In general, the higher the land elevation, the shallower the well depth

D.   Unable to tell from image

 

Question 26: What does this relationship suggest?

A.   In this area, groundwater levels tends to rise and fall with the topography of the land

B.   In this area, groundwater levels are relatively the same

C.   In this area, wells are only drilled where the groundwater level is near the surface

D.   Unable to determine.

 Double‑click and select Withdrawal.

This is a map of the High Plains aquifer showing changes in the water table level for a twenty year period (1980-1999). Green areas are relatively stable, but as the color changes from yellow to red to pink, the level of the water table falls, over 60 feet in the pink areas. The dominant land use is agriculture.

Question 27: Why is the water level in some portions of the High Plains aquifer dropping? (Check all that apply).

A.   Agricultural use is withdrawing water

B.   Recharge rates are less than withdrawal rates

C.   Recharge rates are more than withdrawal rates

D.   Unable to determine

 

 

 

Sources:

Circle of Blue. 2011. http://www.circleofblue.org/waternews/2010/world/chinas-karst-region-infographics/ Accessed May 23, 2011.

Page 3. Photo: Groundwater emerging from a limestone cave, Tennessee, USA (Photo courtesy of Dr. Nancy Hoalst-Pullen)

Page 4. Photo: Tower karst landforms, Guangxi Province, China. (Photo courtesy of Dr. Mark W. Patterson)

Page 5. Photo: Center pivot irrigation using groundwater. (Google Earth  at 38 05 18N, 99 02 48W)

 

Page 6. Photo: A sign denoting subsidence from 1925-1977 in the San Joaquin Valley, California, USA. (USGS) http://water.usgs.gov/ogw/pubs/fs00165/

Page 7. Photo: Karst landscape in southern France. (Wikimedia) http://upload.wikimedia.org/wikipedia/commons/e/e9/Karst_minerve.jpg

 

 

Extra resource: http://ga.water.usgs.gov/edu/quizgw.html