|
Credits
Cindy
Hagley, Rich Axler
and George Host
Goals
This exercise
has three primary goals:
- To teach
students the basics of interpreting RUSS temperature and oxygen profile
data
- To introduce
students to Geographic Information Systems (GIS), particularly with respect
to interpreting maps
- To have
students link the GIS information with a model of phosphorus and sediment
loadings, and interpret these loadings in light of results from goals
1 and 2.
Introduction
This lesson
is consists of three exercises in data analysis and interpretation.
The first has the students interpret temperature and oxygen profiles
from Lake Independence and Hale Lake, which are located in agricultural
and urban-forest watersheds, respectively. The differences in watersheds
between the lakes should have an impact on water quality, particularly
those factors sensitive to nutrient inputs. The exercises integrate
RUSS data interpretation, GIS analyses and modeling exercises.
This lesson
assumes some basic knowledge of limnology and builds on density stratification,
gas solubility, and other Water on the Web labs. It also incorporates
Geographic Information System (GIS) and Phosphorus loading model exercises.
The italicized information is provided.
There is
also an advanced exercise that allows a comparison of major US Lakes
(Tahoe, Lake Erie, Lake Superior) along with the RUSS study lakes to
assess their trophic status as a function of mean depth and phosphorus
loading.
Outcomes
- ability
to interpret data from the RUSS units
- ability
to interpret GIS data
- ability
to do some simple modeling calculations and interpret the results
Keywords
lake profiles,
temperature, oxygen, geographic information systems, modeling, phosphorus
loading, sediment
Prerequisites
none
Time
Required
1-2 hrs.
WOW Curriculum
Links
Embedded
in Exercise
Procedure
* The directed
study lesson is found in the student section of WOW under the title: "Studying Modeling
Water Quality." with Part I: Analysis and Interpretation of
RUSS Data, Part II: Using Geographic Information Systems to assess
landuse
patterns within watersheds, and Part III. Using models to predict sediment
and phosphorus loadings.
* The inquiry
lesson is found in the student section of WOW under the title: "Investigating Modeling Water Quality."
Teacher
version of tables
Figure
3. Vollenweider Loading Plot of Annual Phosphorus
Loading versus mean depth. Dashed lines show boundaries of Eutrophic,
Mesotrophic and Oligotrophic lakes. Values for US lakes taken
from Horne, A.J. and C.R. Goldman.1994. Limnology & Welch, E.B.
1992. Ecological Effects of Wastewater.
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Table
4. Lake attributes derived from GIS maps or the Lake Summary Table
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| |
Ice
Lake
|
Lake
Independence
|
|
Maximum
lake depth (m)
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16.1
|
17.7
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|
Lake
area (ha)
|
16.6
|
344
|
|
Watershed
area (ha)
|
85
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1946
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|
Lake
volume (m3)
|
1.16
x 106
|
1.89
x 106
|
|
Mean
depth* (m)
|
7.0
|
5.5
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*Mean depth
= V/Ao
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Table
5. Watershed to lake area ratio
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| |
Ice
Lake
|
Lake
Independence
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Watershed
area : lake area ratio (Aw:Ao)
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5.1
: 1
|
5.6
: 1
|
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Table
6. Percent landuse from ARC-View analyses
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| |
Ice
Lake (85 ha)
|
Lake
Independence (1946 ha)
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|
Agriculture
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0%
|
72%
|
|
Urban
|
11%
|
5%
|
|
Wet
|
35%
|
17%
|
|
Forest
|
54%
|
6%
|
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Total
|
100%
|
100%
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Table
7. Areas occupied by various landuses (ha)
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| |
Ice
Lake
|
Lake
Independence
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|
Agriculture
|
0
|
1401
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|
Urban
|
9.4
|
97
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Wet
|
29.8
|
331
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Forest
|
45.9
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117
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Total
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85
ha
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1946
ha
|
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Table
8. Sediment and phosphorus loading estimates
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| |
Default
loadings (kg/ha)
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Total
suspended sediment
(TSS)
|
Total
phosphorus
(TP)
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|
Agriculture
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1013
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0.9
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|
Urban
|
200
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0.55
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Wetland
|
5
|
.05
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Forest
|
86
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0.11
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Grass
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346
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0.13
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Other
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50
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0.10
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Table
9. Predicted sediment and phosphorus loadings
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| |
Predicted
TSS (kg/yr)
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Predicted
TP (kg/yr)
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| |
Ice
|
Independence
|
Ice
|
Independence
|
|
Agriculture
|
0
|
1419335
|
0.0
|
1261
|
|
Urban
|
1870
|
19460
|
5.1
|
54
|
|
Wetland
|
149
|
1654
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1.5
|
17
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|
Forest
|
3947
|
10041
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5.0
|
13
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|
Grass
|
0
|
0
|
0.0
|
0
|
|
Other
|
0
|
0
|
0.0
|
0
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Total
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5966
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1450490
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11.7
|
1344
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Table
10. Morphometry of Ice Lake and Lake Independence
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|
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Ice
Lake
|
Lake
Independence
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|
Lake
area (104 m2)
|
16.6
|
344
|
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Volume
(106 m3)
|
1.18
|
18.9
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Table
11. Predicted annual loadings for Ice Lake
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| |
TSS
|
TP
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Areal*
|
36
(g/m2/yr)
|
.070
(g/m2/yr)
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Volumetric**
|
5.1
(mg/L)
|
0.010
(mg/L)
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*Annual load
per hectare of lake surface
**Annual load
per m3 of lake volume
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Table
12. Predicted annual loadings for Lake Independence
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| |
TSS
|
TP
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|
Areal*
|
422
(g/m2/yr)
|
0.391
(g/m2/yr)
|
|
Volumetric**
|
77
(mg/L)
|
0.071
(mg/L)
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*Annual load
per hectare of lake surface
**Annual
load per m3 of lake volume
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Table
13. Mean depth (meters) and annual phosphorus
loading (gP/m2/yr)
for selected U.S. lakes
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LAKE
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MEAN
DEPTH
(meters)
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ANNUAL
P-LOADING
(gP/m2/yr)
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Western
L. Erie
|
~8
|
7.0
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|
L.
Mendota, WI
|
13
|
0.80
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L.
Ontario
|
92
|
0.20
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L.
Superior
|
150
|
0.037
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L.
TahoeCA-NV
|
303
|
0.024
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L.
Independence
|
5.5
|
0.39
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|
Ice
Lake
|
7.0
|
0.070
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