Exercise 4 Report
by
Alexandra Permar
GEOG 591 | 4.2.2012
Computed Mean Wetness Index in bold below:
Statistics
ID
Min. Max. Avg.
Range Total St. Dev.
0
2.007 20.699 5.273 18.692 1410266.300 1.632
1
2.203 20.373 4.959 18.170 800061.912
1.779
Dem_10m_br2_WI (Wetness Index) Map
Range of Values: 2.007159 to 20.69921
1
I. Question 6, Part A: Maps of Si Values with m=0.4517 m-1
Si = 2.5 Map (S2.5 = 2.5+0.4517*(4.959-‘dem_10m_br2_WI’)
Min to Max Range = -4.609854 to 3.833346
2
Si = 2.8 Map (S2.8 = 2.8+0.4517*(4.959-‘dem_10m_br2_WI’)
Min to Max Range = -4.309855 to 4.133347
3
Si = 3.1 Map (S3.1 = 3.1+0.4517*(4.959-‘dem_10m_br2_WI’)
Min to Max Range = -4.009854 to 4.433346
4
Si = 3.4 Map (S3.4 = 3.4+0.4517*(4.959-‘dem_10m_br2_WI’)
Min to Max Range = -3.709854 to 4.733346
5
Si = 3.7 Map (S3.7 = 3.7+0.4517*(4.959-‘dem_10m_br2_WI’)
Min to Max Range = -3.409854 to 5.033346
6
Si = 4.0 Map (S4.0 = 4.0+0.4517*(4.959-‘dem_10m_br2_WI’)
Min to Max Range = -3.109854 to 5.333346
7
II. Question 6, Part B: Maps of Saturated Areas with m=0.4517 m-1
sat_2.5 = ‘s2.5’ < 0 Map
8
sat_2.8 = ‘s2.8’ < 0 Map
9
sat_3.1 = ‘s3.1’ < 0 Map
10
sat_3.4 = ‘s3.4’ < 0 Map
11
sat_3.7 = ‘s3.7’ < 0 Map
12
sat_4.0 = ‘s4.0’ < 0 Map
13
III. Question 6, Part C: Maps of Return Flow with m=0.4517 m-1
rf_2.5 = ('s2.5'<0)*abs('s2.5') Map
Return Flow Range: 0 to 4.609646
14
rf_2.8 = ('s2.8'<0)*abs('s2.8') Map
Return Flow Range: 0 to 4.309855
15
rf_3.1 = ('s3.1'<0)*abs('s3.1') Map
Return Flow Range: 0 to 4.009854
16
rf_3.4 = ('s3.4'<0)*abs('s3.4') Map
Return Flow Range: 0 to 3.709854
17
rf_3.7 = ('s3.7'<0)*abs('s3.7') Map
Return Flow Range: 0 to 3.409854
18
rf_4.0 = ('s4.0'<0)*abs('s4.0') Map
Return Flow Range: 0 to 3.109854
19
IV. Variable Source Area Maps, Calculations with m=0.4517 m-1
sat_2.5_cwt_area = AREA('sat_2.5_cwt',false,0) Map
Total Saturated Area = 334700 m2
20
sat_2.8_cwt_area = AREA('sat_2.8_cwt',false,0) Map
Total Saturated Area = 251900 m2
21
sat_3.1_cwt_area = AREA('sat_3.1_cwt',false,0) Map
Total Saturated Area = 187600 m2
22
sat_3.4_cwt_area = AREA('sat_3.4_cwt',false,0) Map
Total Saturated Area = 145400 m2
23
sat_3.7_cwt_area = AREA('sat_3.7_cwt',false,0) Map
Total Saturated Area = 112700 m2
24
sat_4.0_cwt_area = AREA('sat_4.0_cwt',false,0) Map
Total Saturated Area = 83400 m2
25
cwt_mask_area = AREA('cwt_mask',false,0) Map
Total Catchment Area = 1.61348E+07 m2
26
V. Question 6, Part A: Maps of Si Values with m=4.517 m-1
Si = 2.5_m2 Map (S2.5 = 2.5+4.517*(4.959-‘dem_10m_br2_WI’)
Min to Max Range = -68.59855 to 15.83346
27
Si = 2.8_m2 Map (S2.8 = 2.8+4.517*(4.959-‘dem_10m_br2_WI’)
Min to Max Range = -68.29855 to 16.13346
28
Si = 3.1_m2 Map (S3.1 = 3.1+4.517*(4.959-‘dem_10m_br2_WI’)
Min to Max Range = -67.99855 to 16.43346
29
Si = 3.4_m2 Map (S3.4 = 3.4+4.517*(4.959-‘dem_10m_br2_WI’)
Min to Max Range = -67.69855 to 16.73347
30
Si = 3.7_m2 Map (S3.7 = 3.7+4.517*(4.959-‘dem_10m_br2_WI’)
Min to Max Range = -67.39855 to 17.03346
31
Si = 4.0_m2 Map (S4.0 = 4.0+4.517*(4.959-‘dem_10m_br2_WI’)
Min to Max Range = -67.09855 to 17.33347
32
VI. Question 6, Part B: Maps of Saturated Areas with m=4.517 m-1
sat_2.5_m2 = ‘s2.5_m2’ < 0 Map
33
sat_2.8_m2 = ‘s2.8_m2’ < 0 Map
34
sat_3.1_m2 = ‘s3.1_m2’ < 0 Map
35
sat_3.4_m2 = ‘s3.4_m2’ < 0 Map
36
sat_3.7_m2 = ‘s3.7_m2’ < 0 Map
37
sat_4.0_m2 = ‘s4.0_m2’ < 0 Map
38
VII. Question 6, Part C: Maps of Return Flow with m=4.517 m-1
rf_2.5_m2 = ('s2.5_m2'<0)*abs('s2.5_m2') Map
Return Flow Range: 0 to 68.59855
39
rf_2.8_m2 = ('s2.8_m2'<0)*abs('s2.8_m2') Map
Return Flow Range: 0 to 68.29855
40
rf_3.1_m2 = ('s3.1_m2'<0)*abs('s3.1_m2') Map
Return Flow Range: 0 to 67.99855
41
rf_3.4_m2 = ('s3.4_m2'<0)*abs('s3.4_m2') Map
Return Flow Range: 0 to 67.69855
42
rf_3.7_m2 = ('s3.7_m2'<0)*abs('s3.7_m2') Map
Return Flow Range: 0 to 67.39855
43
rf_4.0_m2 = ('s4.0_m2'<0)*abs('s4.0_m2') Map
Return Flow Range: 0 to 67.09855
44
VIII. Variable Source Area Maps, Calculations with m=4.517 m-1
sat_2.5_m2_cwt_area = AREA('sat_2.5_m2_cwt',false,0) Map
Total Saturated Area = 3786700 m2
45
sat_2.8_m2_cwt_area = AREA('sat_2.8_m2_cwt',false,0) Map
Total Saturated Area = 3633300 m2
46
sat_3.1_m2_cwt_area = AREA('sat_3.1_m2_cwt',false,0) Map
Total Saturated Area = 3480300 m2
47
sat_3.4_m2_cwt_area = AREA('sat_3.4_m2_cwt',false,0) Map
Total Saturated Area = 3335000 m2
48
sat_3.7_m2_cwt_area = AREA('sat_3.7_m2_cwt',false,0) Map
Total Saturated Area = 3197800 m2
49
sat_4.0_m2_cwt_area = AREA('sat_4.0_m2_cwt',false,0) Map
Total Saturated Area = 3073300 m2
50
Graph of Variable Source Area vs. Average Saturation Deficit when m=0.4517 (The y axis should be
dimensionless because the “area” is devided by the “area.”)
Variable Source Area vs. Average Saturation Deficit
Variable Source Area (m2)
2.50E-02
2.00E-02
1.50E-02
1.00E-02
5.00E-03
0.00E+00
2.5
2.8
3.1
3.4
3.7
4
Average Saturation Deficit (S)
Graph of Variable Source Area vs. Average Saturation Deficit when m=4.517
Variable Source Area vs. Average Saturation Deficit
Variable Source Area (m2)
2.50E-01
2.00E-01
1.50E-01
1.00E-01
5.00E-02
0.00E+00
2.5
2.8
3.1
3.4
Average Saturation Deficit (S)
51
3.7
4
It is apparent in the graphs of VSA vs. Average S above that the variable source area tends to decline as
the mean saturation deficit increases in value. This indicates that as the saturation deficit becomes
greater (on a given plot of land) and the land therefore becomes drier, the variable source area
contracts/shrinks in size. The total amount of land that is wet is less when the average saturation deficit
is high compared to that when Savg is low.
There is also a difference between the two graphs where m=0.4517 vs. m=4.517. It appears as though
when m is greater the variable source area is greater as well; the sizes of the VSAs above differ by
approximately 1 degree of magnitude between the two graphs. There is also a smaller decline of VSA
observed as Savg increases in value from 2.5 to 4.0 (when m is larger), indicating the value of the VSA is
not as sensitive to changes in Savg when m is larger than the cited optimal value of 0.4517 m-1. With
increasing of m, the decline in variable source area by increasing saturation deficit tends to be
steeper and more dramatic. This indicates that model is highly sensitive to m value (-1.0).
24/25
52