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					                               WATER RESOURCES – LAB EXERCISE



INTRODUCTION

During the past several weeks, we have been exploring the basic construction of our planet through
the “Earth and Evolution” sequence. As we investigate our interaction with the environment around us
in, “Environment and Hazards”, we will examine one particular aspect of our environment and the
potential hazards it is at risk for (or that we may impose on it!). You will apply many of the skills
learned in the previous labs, such as mapping, use of Excel and a basic knowledge of Earth’s
materials.

The one aspect we will focus on this semester will be Earth's water resources. Specifically, we will be
investigating where groundwater, as one of the water resources humans rely on heavily for drinking
water, is found in the Earth's crust, how it moves within the crust, and how it is susceptible to and
becomes contaminated by human activities.

In this first lab we are going to focus on familiarizing ourselves with the following basics of water
resources:

- Where water is found on Earth (Water Reservoirs)
- How it moves from one "reservoir" to the next (Hydrologic Cycle)
- Effects on Earth's reservoirs
- A focus on groundwater

You will be using ESRI ArcGIS software to complete portions of this lab. Many of the instructions are
included so that you will be able to easily use the software. We will also be going over much of this
together in lab. If you have any questions while completing the lab, just call your instructor or the TA
over to your table. The GIS portions of this lab were based on labs from the Exploring Water Resources textbook by
Hall-Wallace, Walker, Kendall, and Schaller.




WATER RESERVOIRS

1. Fill out the table on the next page with as many of the Earth’s reservoirs as you can. As and
example, oceans have been listed (and ranked) as the Earth’s largest reservoir.


2. After you have listed the reservoirs, go back and rank them by size (volume). One is the largest
(oceans) going higher in number the smaller the reservoir.


3. Finally, classify the reservoir based on how easily fresh water can be obtained from it. (easy,
moderate, difficult)
 Reservoir                   RANK                                     Accessibility
                                                                      (Fresh Water)
 Oceans                      1




Earth’s Ocean Basins

We will begin our look at the Earth’s reservoirs by investigating Earth’s oceans.

Launch the water.mxd exercise in ArcGIS, ArcMap.

1. Using the legends in the table of contents, how deep is the deepest parts of the oceans?

2. Using the Topographic Profile tool (I will show you this in class) generate a graph for the following
areas.

       Mid-Atlantic Ridge
       Nazca Trench (West Coast of S. America)
       Hawaii
       One of your choice

Either print a copy of each, or paste each into a word document and print your document. Turn this in
with your lab.

       To print graph, access graph properties, or copy the graph, right-click on the graph window header. This
       will bring up all your options.

3. Describe your observations of the topographic profiles here:
Measuring Earth’s Reservoirs

For this exercise you will need to access the Information Tables for each of the Ocean Volume layers. To do this,
right-click on each ocean in the list of layers and select> Open Attribute Table. You will then be able to access
the statistics function by right-clicking on the depth column heading.


  OCEAN          Max Depth (km)           Mean Depth (km)         Surface Area (km2)            Volume (km3)
                       (statistics)           (statistics)               (identify)         (=Mean Depth x Surface Area)

   Atlantic
   Indian
   Pacific
    Arctic
  Southern
      TOTAL

4. Fill in the table above with information from the ArcMap project.


Open the ice2.mxd ArcMap document.

   Ice Cap          Mean Thickness (km)                      2
                                                     Area (km )        Ice Volume (km )
                                                                                       3
                                                                                              Water Volume (km )
                                                                                                                    3
                           (statistics)
 Antarctica
 Greenland
    TOTAL

For this exercise you will need to access the information tables for each of the layers. You will then be able to
access the statistics function by right-clicking on the thick_km column heading. We will calculate the areas
together.

5. Fill in the table above.

For the atmosphere, open the atmosphere.mxd ArcMap document. You should see a map of the
world Mean Water Vapor. This has been calculated according to the amount of water vapor in a
column of air reaching from the surface of the Earth to the top of the atmosphere, a height of about 50
km. The units are cubic meters of water per square kilometer of surface area.

6. Briefly describe the distribution of the Earth’s atmospheric water vapor. Which regions have large
quantities and which have smaller?




7. Turn on the Mean Temps. layer. Briefly describe where mean temps are highest.




8. How does the distribution of mean high temps compare to the distribution of water vapor?
9. Finally, we want to calculate the total volume of water vapor in the atmosphere. To determine this,
open the information table for the water vapor layer by right-clicking on the layer in the table of
contents and selecting > Open Attribute Table. Right-click on the Water Vapor Volume column
heading and choose statistics. Your answer will be the sum of water vapor volume.

What is the total volume of water stored in the atmosphere? (Remember to include units) Give your
answer to the nearest 1,000 km3 .

10. Now you will summarize the volume of all the Earth’s reservoirs in the table below. When you
have filled the table in, generate a pie graph in excel to show the percentages of each of the
reservoirs.
Reservoir                           Water Volume (km3)                Percent of total water
Groundwater                         8340000
Freshwater Lakes                    125000
Inland Seas                         104000
Soil Moisture                       67000
Rivers                              1250
Oceans
Continental Ice Caps
Atmosphere
                           TOTAL
11. How does the actual volumes calculated above compare to the predictions you made in the first
table of this lab?


HYDROLOGIC CYCLE

The hydrologic cycle is a description of how water moves through the different reservoirs described
above. Below is a diagram showing the various reservoirs and how water is transferred between
them.




                                                                                      NASA
RESIDENCE TIME

The table to the right gives the time it takes for       Reservoir           Approx. Res. Time (yrs)
water to cycle completely through a particular
                                                         Oceans                      34,000
reservoir.
                                                         Glaciers                       40
Imagine a drop of water enters the reservoir –           Snow Cover                    0.4
the approximate residence time is the time it            Soil Moisture                 0.2
would take for the drop to go through and                G-water: Shallow              200
eventually be removed from the reservoir.                G-water: Deep               10,000
The residence time is dependent on the                   Lakes                         100
volume of the reservoir and the rate at which            Rivers                       0.04
 water passes through it.



1. Why do you think the oceans have such a long residence time?



2. Why would deep groundwater have such a long residence time?




3. If a contaminant entered any of the reservoirs that humans might use, which of those do you think
would be the easiest (quickest) to clean up based on residence time? Which ones would be the
hardest (slowest)? Explain why.




4. The residence time also affects how much of a renewable resource (easily replenished due to
connections with other reservoirs in the hydrologic cycle) the reservoir is. Which of the reservoirs that
humans rely on do you think would be the most difficult to maintain (keep volume consistent) over a
long period of time if water was being removed for human use? Explain why.
EFFECTS ON EARTH'S RESERVOIRS

Due to differences in residence time, each reservoir will “react” differently to changes in the volume or
rates of water entering or exiting the system. The following examples look at effects on a few of
Earth's reservoirs.


RIVERS - Iraq/Kuwait

As you can see from the satellite images on the next page, significant changes have occurred to the
rivers in southern Iraq and Kuwait. These images center on an area northwest of the Persian Gulf,
where the Tigris and Euphrates Rivers meet and flow through Iraq's narrow corridor to the Gulf. Use
these images and the information in the website to answer the following questions.

http://edcwww.cr.usgs.gov/earthshots/slow/Iraq/Iraq




                                              1972                                               1990




                                             1997

1. Label all areas of deep and shallow water and areas of vegetation.



2. Summarize what has changed in this area in the past 20 years. Indicate where water and
vegetation have moved or been removed. What reasons could have led to this change?
FOCUSING IN ON GROUNDWATER

The reservoir that we will focus on over the next several weeks will be groundwater. We will first
examine how water is transported through this reservoir. Then we will investigate some
environmental issues which arise from our use of this resource.

This exercise will be our first practice with understanding some basics about groundwater flow.




This is a map (on next page) of a contoured water table in weakly cemented sandstone. The map
also shows a source of pollution, a stream bed, and several monitor wells used to check water
quality.

To set the scene, the factory at “X” wishes to dispose of a liquid toxic waste. Instead of piping it
overland a kilometer to a waste disposal site, the factory managers opt to put the toxic waste into the
underground through an injection well in their building, which is possibly illegal. An injection well is
one through which fluids are added to the ground water. Before beginning injection, a network of
wells, labeled “A” through “H,” is installed to monitor the quality of the ground water. Before injection,
all monitored wells had good quality water. Thirty days after beginning the injection, all the wells still
show good water. Fifty days after injection began well “C” recorded contamination by the factory’s
waste fluid.


1. On the map, indicate the flow direction for the ground water. Note: flow lines are always at right
angles to the contours on the water table. (Some lines have already been drawn.)
2. What is the apparent speed of the ground water, in meters per day, between the injection well and
well “C”? This is called apparent speed, since water really travels on curved paths and not in straight-
line paths as we might calculate it here. In addition to time elapsed, you need to know how far it is
between the injection well and well “C”.




Apparent ground water speed = ________________meter/day.



3. Assuming this rate of flow, how long will it take the pollution to travel from the injection well to well
“D”? ______________ days.


4. Town “R” gets its water from the well indicated on the map. What should the town board know
about the risk of contamination of its well? How long will it take for the pollution to reach town “R’s”
well?




5. News travels fast. What can you tell Town “S” about the risk to its well and the reason for your
answer?




6. Town “T” asks the same questions. What do you tell them? Why?

				
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