1. Application of CITYgreen in Benefit Assessment of Stephen F. Austin State
University Green Space for Runoff Reduction of Water Quality Improvement
Eric M. Finke, Sean A. Pessarra, David L. Kulhavy and Daniel R. Unger
Arthur Temple College of Forestry and Agriculture, Stephen F. Austin State University, Nacogdoches, Texas
Abstract:
Based on the analytical framework and calculations of the
CITYgreen model to assess air and water quality improvement
and stormwater runoff reduction, the ecological and economic
benefits of the urban green spaces of the Stephen F. Austin
State University campus were estimated. This research can
provide references for campus planning and urban green
space establishment, and provides a fiscal bottom line for the
health, ecological, and economic benefits for campus green
space.
Introduction:
Our urban forests perform vital environmental services that
translate directly into municipal cost savings and increase
health and well being for urban dwellers. By slowing
stormwater runoff, improving air quality, and filtering ground
water, “a city’s green infrastructure is as indispensable as its
sanitation department” (American Forests 2004). To attract the
attention of city planners and budget officials, the contributions
of urban forests need to be translated into real dollar savings
assisting planners and city managers with solutions to
municipal problems in conjunction with engineering.
In the modeling of the Stephen F. Austin State University
campus the CITYgreen 5.0 extension for ArcGIS 9.3.1 was
used to assess land cover, soil type, slope and precipitation
affecting stormwater runoff volume, water and air quality
parameters; and methods to enhance carbon storage and
sequestration. The CITYgreen models used to attain the
following results are based on data collected by the EPA,
Purdue University, and Natural Resource Conservation
Service. Conclusions:
Maintaining the current green space on the SFASU campus is
vital to protecting stream, groundwater, and air quality, and
reducing stormwater runoff and the cost of controlling excess
water. CITYgreen shows that urban green space is both
ecologically and economically beneficial.
References:
American Forests. CITYgreen for ESRI ArcGIS: Calculating the Value of Nature. Washington D.C.:
American Forests, 2004.
Bruns, Dale. 2007. Land use planning with CITYgreen: GIS software estimates economic benefits of
“green” infrastructure. Wilkes-Barre, PA: National Consortium for Rural Geospatial Innovations.
Peng, Lihua, Shuang Chen, Yunxia Liu, and Jin Wang. "Application of CITYgreen model in benefit
assessment of Nanjing urban green space in carbon fixation and runoff reduction." Frontiers and Forestry
in China. 3.2 (2008): 177-182.
Vernier, Matt. 2008. CITYgreen Analysis and Land Cover Data for mapping Green Infrastructure. Ann
Arbor, MI: Sanborn Map Company, Inc.
Table 3. Percent change in contaminant loading reflecting the replacement of the
existing tree canopy land cover area with another land cover.
Water Quality
Parameter Urban
Trees -
Grass/Turf
Understory Impervious
Open Space -
Grass/Scattered
Trees
Biological
Oxygen Demand 91.8% 21.6% 106.6% 13.1%
Cadmium 129.6% 30.5% 150.5% 18.5%
Chromium 194.9% 45.8% 226.3% 27.9%
Chemical
Oxygen Demand 223.4% 52.5% 259.4% 32.0%
Lead 29.0% 6.8% 33.6% 4.1%
Nitrogen 40.8% 9.6% 47.4% 5.8%
Phosphorus 115.1% 27.1% 133.7% 16.5%
Suspended
Solids 90.0% 21.2% 104.5% 12.9%
Zinc 20.0% 4.7% 23.2% 2.9%
Table 4. Initial construction costs for addition municipal facilities managing excess
stormwater runoff when replacing all campus tree cover with different land covers
types.
Replacement Land Cover Cost
Urban $ 5,811,889
Trees - Grass/Turf Understory $ 1,453,910
Impervious $ 6,663,941
Open Space - Grass/Scattered Trees $ 2,100,037
Table 2. Estimated annual air pollution removal rate for trees and cost of best
available technology equivalent.
Lbs. Removed/yr Dollar Value/yr
Carbon Monoxide 478 $ 234
Ozone 5373 $ 18,983
Nitrogen Dioxide 2388 $ 8,437
Particulate Matter 5612 $ 13,237
Sulfur Dioxide 2149 $ 1,855
Total 15999 $ 42,746
Table 1. Carbon storage and sequestration of current total green space.
Tons Stored (Total) 5764
Tons Sequestered (Annually) 45
Results:
NAIP 2004 leaf-on imagery, 1 meter resolution
Tree Canopy: 133.9 acres (34.4%)
Figure 1. Rasterized landcover of SFASU campus used for
CITYgreen analysis.
Figure 2. NAIP 2004 imagery used for modeling overlayed with
impervious layers.