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The Site Signature Method of Land Suitability Planning
in River Corridors 1
David P. Hill l
Abstract-This performance-based methodology was developed for
location and construction of a variety of land uses in fragile environments.
Landscape character and land uses are represented by graphic "signatures."
Through synthesis,
a
land suitability plan is created. Site specific
performance
criteria
assure
environmental
protection
while
allowing
developers locational flexibility.
INTRODUCTION
The flexible plan is appropriate because in
diverse and fragile environments, the question is not
so much "where" development occurs, but "how" it
occurs.
The methods of construction and land
management determine the future health of a river
corridor. Developers will be the first to declare
that for profit, "location is everything." The Site
Signature
Method
allows
the
developer
some
flexibility in land use location, but requires . the
design meet site specific performance criteria before
construction can begin.
Nearly all North American cities are sited
along river corridors, but few have been able to
effectively plan for the variety of land uses desired
along the river banks. The complex physical and
biological systems of the river corridor are seldom
addressed by conventional zoning
controls.
The
unique aesthetic and cultural systems of the river
corridor are likewise ignored, or if addressed the
controls
are
frequently
cumbersome
prescribed
amendments. The river corridor becomes a jumble of
innappropriately
sited
land
uses.
The
riparian
ecosystem suffers from the abuses of insensitive
land development, and citizens suffer from the loss
of a scenic and biological resource.
By allowing developers leeway to choose the
sites with more profit potential, they can afford to
invest in a more intellegent design. The design must
perform to design criteria based on the carrying
capacities of the river corridor as established by
the scientific community. The result is a river
corridor planned according to the wants of the
public and designed
to the satisfaction of the
scientific community.
The Site Signature Method is being developed
as a flexible planning process for location and
construction
of
multiple
land
uses
in
fragile
environments without loss of the existing natural
and social amenities. Based on the tenet that
conventional zoning does not adequately address the
synergism of characteristics in diverse environments,
this method provides a process that analyses the
biological, cultural, aesthetic and physical character
of the existing landscape. This includes all pertinent
information
from
the
scientific
community
to
establish important indicators of and rules for river
health.
INVENTORY AND ANALYSIS
The first step of the process is to tailor the
study
to
the
region.
A river
corridor in a
mountainous region will have a different character
than a river corridor in a coastal plain. A region
whose people have been conservative with land
development will have a different character than a
region which has had liberal land development. This
trait is easily detectable in the landscape, and
important in setting up the landscape inventory and
planning program. A preliminary survey is circulated
within the community to understand the collective
attitude
toward
the
river.
These
actual
and
perceived traits of the physical and social landscape
compose the "character of the region," and set a
framework for site inventory.
A key feature of this method is applied
community input. To fit future development with the
existing social fabric, the community decides the
site character desirable for . each proposed land use.
The product of this exercise, a flexible multi-use
plan,
is
liberal in locational requirements
for
proposed land uses.
1.
Paper
presented
at
the
first
North
American
Riparian
Ecosystems
Conference.
(University of Arizona, Tuscan, April 16-18, 1985.
z.
David P.
Architect with the
Orleans, La.
With an understanding of the character of
the
region,
the
river
corridor
boundary
is
determined.
Normal
determinants
for
the
study
boundary include the visibility of the river, the
existing
land
use
patterns
and
jurisdictional
boundaries, the extent of the floodplain and first
Hill is Apprentice Landscape
Caplinger Group, Ltd., New
398
order watershed. Inside the study area boundary, the
river corridor is divided into sites for more intense
study. Sites vary in size depending on existing
landscape patterns, such as pro.i:Jerty lines, bridges,
roads or the crests of hills. In the United States,
the Army Corps of En~ineers measures rivers in
miles above the mouth , and their data serves well
here to mark sites. Depending on the frequency of
change in the landscape, sites have longitudinal
boundaries at intervals of half mile, one mile, five
miles, and can be referrenced by the A.C.E. river
mile number.
Magnitudes are totalled for each dimension
and these
totals are the basis for the "site
signature." The site signature represents a site just
as a person's signature represents the character of
that person. It is the endorsement of the amounts
on the sitesheet, like a person's signature is the
endorsement representing the amount of a personal
check.
RIGHT 372.0
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Each site is an area from the centerline of
the river to the respective left or right lateral
boundary. A study with one mile longitudinal site
boundaries will have two sites per mile, one on
each side of the river.
~
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t--
The
Site
Signature
Method
analyses
the
landscape in two ways. The MAGNITUDE of the
landscape is a quantitative statement about how
much or how great site characteristics are. The
CONDITION of
the landscape is a
qualitative
assessment about the health of sites. These terms
were used by Jones and Jones (1973) in the
Nooksack Methodology. The Site Signature Method
uses magnitude to determine character for land use
location, and condition is applied to establish site
specific performance design criteria.
--
CURRENT 1.»1) USE
.. lndustrlol/s...,:,port
"'CCII'Tmel'ciol/lnstitutlonal
~Residential
SiteAccet.s
Potential Access
Access to River
CU.TUW.. sc:mE
~
Ad)uotod
Clarity of Edge
lncldenc:e of Edge
1..AN0SCAPE INTEGRITY
RIVER FORM
lllmds,flointbars,Outcrops
Pools,Holes,Folls,Riffles
SP~~ Frcm River
SeNe of Eneloaur•
RIVER INTEGRITY
WATER QUALITY
ABD£TIC SCOI£
~
r::o:
i
Sea..
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SLOPE
(1.4'1>
7-12'1>
12-25'1>
25~ +
S.:..o
DEPTH TO BEDROCK
GROI.JI'VWATER RECHARGE
PHYSICAL SCORE
&odoblllty
FOU'Idation Suitability
Septic Suitability
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SOILS
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ACCESS
A.OOOPLAIN
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Contrast of Lcnctnarlu
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EDGE
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rn
Pi:
-
Sea••
FAU""Type
Sco.e
RIVER A.ORA
Type
RIVER FAU""Type
BIOLOGICAL sc:mE
FORM
~
I.-Portion of the River Corridor for the
Roanoke River iD. Southwestern Virginia. Note
river miles, boundaries at 1/Z mile events in
the landscape.
~
A. ORA
Type
Sco.e
..J
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Figure
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HISTORICAl. L»>)MARI<S
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w
ARCHAEOLOGICAl. SITES
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This method studies four dimensions of the
landscape:
biological,
cultural,
aesthetic
and
physical. Each of the four dimensions is composed
of characteristics that can be found along the river
corridor. The magnitudes and conditions of each
characteristic are noted on the "sitesheet" for each
site.
1'...
QI..T\MAL
_L
l\
1/
ll.
1\ I§J
~·
SITE SIGNATURE
Right
372.0
Figure Z.-Sitesheet for the right bank site at mile
371..0 along the Roanoke River.
399
<
lol
SIGNATURE
SIGNATURE
0
SITES HIGHLY APPROPRIATE FOR
INDUSTRY
SITES HIGHLY APPROPRIATE FOR
SUPPORT FAGILITIES
SIGNATURE
SIGNATURE
SITES HIGHLY APPROPRIATE FOR
AGRICULTURE
SITES HIGHLY APPROPRIATE FOR
RESIDENCES
Cl
...,.
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...,.~
PHYSK:Alo
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~
'
aJLTURAL
PHYSK:AL
J
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..........
v
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I
SITE SIGNATURE
Left
369.5
SITE SIGNATURE 3~"f.~
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if
PHYSK:AL
Cl
g
2
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~
~
)I' ~"'-
""'"m'-
PHYSK:AL
1/
~
SITE SIGNATURE
Figure
~
'
Left
380.0
,
~,
ll'
Clli..TURAL
~
r\.
aJLTURAL
,.
~
1'5
~~2
\ ..
~~
~
,.m
I
\
Clli..TURAL
ll'
(
'I
SITE SIGNATURE
Right
380.0
3.-Signatures of several other sites along
the Roanoke River. There is a pattern of
larger site signatures upstream. These are
more pristine sites, away from urbanized
areas.
Figure
In order to find the sites appropriate for
each proposed land use, a second, more detailed
questionnaire
is
circulated.
Depending
on
the
complexity of the project, the instrument is either
circulated to planning and design professionals in
the community or to the community citizens. There
is a matrix of questions. The first asks the
biological character of a site appropriate for each
proposed land use category. The second asks the
cultural character appropriate. Desirable aesthetic
and physical character make-up the third and fourth
questions. The questionnaire is designed so questions
are the ordinals which were used to establish the
site signature
grids.
Patterns of response
are
plotted on a grid congruent to the site signature
grid. These are called Land Use Signatures.
SYNTHESIS
4.-Several Land Use
Roanoke River Project.
for
SIGNATURE
SIGNATURE
SITES HIGHLY APPROPRIATE FOR
RESIDENCES
SITES HIGHLY APPROPRIATE FOR
RESIDENCES
SITE SIGNATURE
The synthesis of information is a clear and
simple process. To discover whether a site is
appropriate for a particular land use, the Land Use
Signature is overlaid with the Site Signature. If the
corner points of the Site Signature fall within the
shaded area of the Land Use Signature, the site is
appropriate for the land use. If the proposed land
use will be innappropriately sited, the incompatible
dimensions are immediately visible. The decision can
be
traced
in
the
score
sheet
to
landscape
characteristics. Traceability is a welcome benefit of
the method.
Signatures
Figure
Left
372.0
SITE SIGNATURE
the
Right
372.0
5.-Site Right 37Z.O is appropriate for
residences. The physical character of the site
across river rules it out for the same land
use.
A graphic synthesis is performed for the entire
river corridor, crossing each Site Signature with
each Land Use Signature. Some sites will be
appropriate for almost all land uses, some for one
or two, some only for preservation. The product of
this exercise is the flexible Land Suitability Plan.
400
~~~
~"
~~~.~
~~:i"
c;
~/}·
c;
374.0
~/
~J'
etc. Each site has a distinct palette of different
conditions. The conditions of the example site are
noted with asterisks in figure 2.
/J~
'<qj
~:;~
"
According
to
the
Land
Suitability
Plan,
institutions,
recreation,
and residences
may
be
located on the example site. In order to be
constructed,
the
chosen land use(s) must have
minimum impact on the noted conditions. Given the
incentive for higher potential profit, a developer
can afford to invest in a sound design which will
perform to these site specific standards.
372.5
PROPOSED LAND USE ________________________
SITE I(JGI.-lT
LANK - 372.... 0
LOCATION l<.IVE:R~tDE. PQIVE
APr~~6RJ~~~ NSIITUTID~.
e
,.,,!<-. 694-
RECREAIIDI--J, 1<BIPf'\4::E'$
PROPOSAL
EVALUATOR ______________________________
DATE ______________________________
Figure 6.-Portion of the Land Suitability Plan for
the Roanoke River Corridor.
RIVER CORRIDOR
DESIGN EVALUATION
DESIGN EVALUATION
*
NOTES
CHARACTERISTIC CRITERIA
The last part of the Site Signature Method is
the Design Evaluation. The Planning Commission or
similar body of the jurisdiction can use this simple
tool to control proposed development in the river
corridor. In the Virginia Statutes, (15.1-863) there
is a clause which allows jurisdictions to "divide
their jurisdictions into districts for the purpose of
applying
different
building
codes
requirements.
(Blair, 1969)." This allows jursdictions to establish
the River Corridor Zone. Within the River Corridor
Zone, multiple land uses are permitted as long as
they can be built in accordance with both the
conventional. standards established for land uses
throughout the jurisdiction (setbacks, etc.) and the
performance criteria of the River Corridor Zone.
Uf'.:IQUE 1"-"W3ITAT5
Only those octtvilles which are insepercilile
water use are allowed withi" 100' of bonk.
.Design
~st
established
'~~~··;~;:;~;dinonce.
o"
be
fran
vegetaiive
"planted
;n
river
cover.
occo•donce
Public easement occess reqvired in 100' Riparian Stnp.
A~O-i,.',LOLOLICAL SITES
~~~y;~;~ ~n~nt~~c!~ ~~~~=ol~ic~l\ ~:rS:s~~~~ !~tes tf~r ~
HIS l Ot{ICAL/CUL TURAL SITE:.S
Options detennined at preliminary site pian review.
u.Ji\)UE !I,.,AGEAtHLlTY
Design must perfonn to Jmayeabiltty Fonnvlo.
year interim period before site disturbance.
*
I
,<~I"';IU
VII::WS ,}.
'J,. Ul. TY OF ltV\1\GI::S
*
All Pro1K"ts--E)(ecvted in accordance wllh
,
Sedin~·
When
implemented,
the
flexible
Land
Suitability Plan alone is not sufficient control over
the land use of the river corridor. Although a site
is "zoned" for any land use that appears on the
LSP, in order to be built, the proposed land use
must meet the performance criteria derived from
the conditions of the desired site. By using site
plan reviews, the Planning Commission requires a
developer to sift his proposed development through
the Land Suitability Plan (first, coarse sieve). The
design evaluation is the second, fine mesh sieve a
proposed development must pass before it can be
built.
Virginia Erosion
·l·Jiion Control Stondords.
Septic f'-,~:1•1.'
redmrge zoow.
to
Hef••r
pred,,!oons.
prohtbited
~ool
Survey
above
for
the
major
preliminary
groundwater
perfar•nonce
APPROVAL:
PRELIMINARY------------ANAL _ _ _ _ _ _ _ _ __
Figure 1.-A Design EYaluation Sheet set up for the
conditions of the example site. The example site
has five special requirements beyond those of the
conventional code.
Even
though
allowed
by
the
LSP,
the
prospect of mitigating some potential land uses with
the difficult conditions of some sites will be either
physically or financially impossible, thus preserving
them. Other sites will have few or no difficult
constraints posed by site conditions, and can be
developed intensively. The above figure shows how
the method directly transfers 11 is" statements to
11
Thou shalt 11 statements.
Proposed designs perform
to existing stable amenities by passing impact
formulae or by avoiding fragile areas.
Conditions of the landscape are noted in each
dimension of the study. They describe the health of
sites. Unique features, the diversity of features,
fragile
features
are
noted,
as
well
as
all
characteristics that have been encroached upon. For
instance, a unique biological condition may be the
"existance of
a
threatened species." A unique
cultural condition may be "an historical landmark,"
401
Plan review and advice by experts is arranged for
evaluation of rapidly changing or extremely fragile
criteria.
This
will
assist
the
developer,
who
sometimes has little knowledge of the requirements
of the social and natural landscape, but has an
ability to recognize the cost of dealing with the
legislated constraints posed by some sites. More
importantly, this will assist the local planning body,
for
discretionary controls require
informed and
defensible decisions. Ofcourse, all sitesheets and
design requirements must be available to the public,
so Site Signature Method assessments must be in a
tight,
implementable
package.
The
studies
are
detailed, decisions are traceable, and the product
can be reproduced.
Although in the developmental stages, the Site
Signature Method serves as a medium between the
developer, scientest and constituent by addressing
the concerns of each. By employing the medium, the
landscape
can
be
developed
without
loss
of
biological, cultural, aesthetic or physical resources.
This
"site
specific
zoning"
results
in
an
appropriately developed landscape which celebrates
the character of the river corridor.
LITERATURE CITED
The Site Signature Method is proposed as a
performance based zoning methodology for sensible
location and sensitive construction of multiple land
uses in fragile environments. Site specific criteria
require that construction in the river corridor fit
the
environmental
conditions,
rather
than
the
sometimes arbitrary conditions posed by conventional
prescriptive zoning manuals. Land planning decisions
are
tied
to
the
existing landscape
character.
Currently, this method has not smoothly tied the
multiple land uses to each other. This suitability
concern has been incorporated as an addendum into
the evaluation stage
of proposed projects. To
improve this method, adjacent land use compatability
needs to be considered in the inventory stage.
Blair,
Frederick H. 1969. Toward a Regulatory
System:
For
Use,
Occupancyand
Construction.
Planning
Advisory
Service
Report #Z43. Chicago: A.S ..P.Q.
Hill,
David P. 1984. The Site Signature Method of
Land Suitability Planning and the Roanoke
River Reclamation Project. Blacksburg, Va.:
David P. Hill.
Jones, Grant and R. Jones. 1973. Nooksack. Seattle,
Wash.: Jones and Jones, Inc.
Meshenberg, Michael J. 197 6. The Administration of
Flexible Zoning Techniques. Planning Advisory
Service Report #318. Chicago: A.S.P.Q.
402