CarolinaNorth591Powe..

Sarah Giles
Holly Kuestner
Steven Orr
Qi Zhang
1. Impervious Surfaces’ Effects on Flow Accumulation (Holly)
2. Variable Source Area (Holly)
3. Catchment Delineation (Qi)
4. Erosion Potential (Qi)
5. Maximum Likelihood Classification (Steven)
6. Assessment of Future Development Scenarios (Sarah)
1. Isolate
Isolate
catchments
stream reaches
with high
withimpervious
high accumulation
sensitivity
(to (to
aid aid
in storm
in storm
water
water
planning)
planning)
1.
2.
3.
4.
1
Fill DEM
Calculate Flow Direction
Reclassify Steven’s land-cover raster as a binary
raster of impervious/non-impervious surfaces
Weight the flow direction raster with this binary
raster to calculate impervious-weighted flow
accumulation (stream network accounting for
paved areas)
2
4
3
Isolate catchments with high impervious sensitivity (to aid in storm water planning)
Weighted accumulation map shows how impervious
surfaces impact flow accumulation.
Unweighted
Weighted
Isolate catchments with high impervious sensitivity (to aid in storm water planning)
Weighted accumulation map shows how impervious
surfaces impact flow accumulation.
Catchments with areas
accumulating >50
upslope impervious
pixels
Areas accumulating >50
upslope impervious pixels
Weighted Flow
Accumulation
Identify areas likely to become saturated (to aid in storm water planning)
1.
2.
3.
4.
Load DEM into TAS, breach all pits
Calculate Wetness Index using d_infinity
Calculate mean Wetness Index using
Statistical Analysis
Use raster calculator to calculate
saturation deficit :
𝑆𝑖 = 𝑆 + 𝑚(𝜆 − 𝑊𝐼𝑖 )
5.
Graph variable source area versus mean
saturation deficit
Breach Pits in TAS
Calculate WI
Use m, s_ parameters from class:
• m = 0.4517
• s_ = 2.5, 2.9, 3.19, 3.60, 4.0
Mean WI
Saturation Deficit
Identify areas likely to become saturated (to aid in storm water planning)
Further extension: Repeat the prior
procedure for all 127 sub-catchments of the
Carolina North forest.
M- and S_bar values should be specific to
Carolina North.
0.025
Variable Source Area
A comparison of the results for all
catchments could reveal which are most
prone to saturation during storms.
Variable Source Area with Different Saturation Deficit
Scenarios for Carolina North
0.02
0.015
0.01
0.005
0
2.5
2.9
3.19
3.6
Average Saturation Deficit
4
Steps:
1. Pre-processing
Fill depressions
Flow direction
Flow accumulations
2. Stream definition (fig. a)
Number of cells – 150
2
Areas – 0.015118 Km
2. Stream segmentation
3. Catchment delineation (Fig. b)
4. Catchment polygons (Fig. b)
Relative Stream Power
RSP = As ^ 1.0 * tan(S)
As: specific catchment area
S: local slope
A measure of the erosive power of
flowing stream network.
Downslope change
To measure the change of the slope,
defined as the derivative of relative stream
power. The higher the value is, the larger
extent the stream power changes and thus
the easier the soil erosion happens.
Catchment selection
High values of dRSPdx:
33 catchments
soil erosion are
potentially to happen
conifer
Low downslope change:
94 catchments
sediment are potentially
to deposit
impervious surface
other land cover
Land Type/Class
Pixel Count
Total Percentage
Dirt
15024
Turbid Water
1137
Land Type/Class Pixel Count
Total %
Land Type/Class
Acreage
Total Percentage
6.05%
Non-Vegetation
46016
18.54%
Dirt
53.06
6.05%
0.46%
Vegetation
202233
81.46%
Turbid Water
4.0342
0.46%
100.00%
Pavement
9548
3.85%
Pavement
33.765
3.85%
Grass
14077
5.67%
Non-Forest
60093
24.21%
Grass
49.726
5.67%
Coniferous
105074
42.33%
Forest
188156
Coniferous
371.23
42.33%
Deciduous
83082
33.47%
75.79%
100.00%
12.03%
33.47%
8.18%
29855
293.53
20307
Impervious
Deciduous
Urban
87.97%
8.18%
100.00%
218394
71.739
248249
Pervious
Urban
Total
Total
877.0842
100.00%
Land Type/Class
Acreage
Total Percentage
Forest
664.76
75.80%
Water
4.0342
0.46%
Grass
76.256
8.70%
Commercial
132.034
15.06%
Total
877
100.01%
In this table, we have the total number or percentage
of pixels that are classified as the specific land type or
class.
In this table, we have a breakdown of how much
acreage each land type or class takes up in the total
area of Carolina North.
100.00%
In these tables, we have the total
number or % of catchments that are
greater than 50% of Non-Vegetation or
Vegetation.
As you can see, a majority of
nearly 83% of all 127 catchments
have a greater than 50%
vegetation surface type.
As expected with the other two
statistical figures, there is a
majority (91%) of catchments
that are pervious greater than
50%.
Surface Type
Total Number
Total %
Non-Vegetation (>50%)
22
17.32%
Vegetation (>50%)
105
82.68%
127
100.00%
Non-Forest (>50%)
30
23.62%
Forest (>50%)
97
127
76.38%
100.00%
Impervious (>50%)
11
8.66%
Pervious (>50%)
116
91.34%
127
100.00%
76% of the catchments have
mostly forest within their
individual areas.
WHAT THESE NUMBERS MEAN:
From these numbers, it is easy to see that of the 127 catchments found on the
Carolina North Property, it is more likely for a catchment to have the properties
of a vegetative, forest with pervious qualities.
Looking at the image, one can verify this by seeing the majority of area covered with
forest and only a minority portion of cleared land visible.
CLASSIFICATION:
The image to the right makes a big impression on the land
cover use with the total acreage of Carolina North. We see
the entirety of the land and can clearly know that forest
cover is the majority. Another key point to mention is the
loss of a carbon sink when this space is cleared for
development.
The largest area that is present where human interaction is
evident is in the bottom right hand corner where
urbanization and the airport are the majority of land cover.
Land use classification using ENVI and
ArcMap.
Remote sensing
image of Carolina
North
Number of acres of
each type of land
cover
Land
Type/Class
Dirt
Turbid Water
Pavement
Grass
Coniferous
Deciduous
Urban
Total
Land
Type/Class
Forest
Water
Grass
Commercial
Total
Acreage
Total Percentage
53.06
4.0342
33.765
49.726
371.23
293.53
71.739
6.05%
0.46%
3.85%
5.67%
42.33%
33.47%
8.18%
877.0842
100.00%
Acreage
Total Percentage
664.76
4.0342
76.256
132.034
877
75.80%
0.46%
8.70%
15.06%
100.01%
Estimate changes
in recharge, runoff,
and nonpoint
source pollution
L-THIA (Long Term Hydrologic Impact
Analysis)
Scenario 1:
 + 18 acres of commercial, -9 acres forest, -9 acres grass
Scenario 2:
 + 18 acres of commercial, -18 acres grass
 So, more of the 311 acres of
conserved land should be in the form
of forest (scenario 2), preferably
mixed in with the development.