LAND SUITABILITY ANALYSIS:
DEVELOPMENT AND APPLICATION OF A COMPOSITE METHOD
LAND SUITABILITY ANALYSIS:
DEVELOPMENT AND APPLICATION OF A COMPOSITE METHOD
LAND SUITABILITY ANALYSIS: DEVELOPMENT AND APPLICATION OF A COMPOSITE METHOD
A thesis presented
in partial fulfillment of the requirements for the degree of Master of Planning and Community Development
University of Colorado Denver, Colorado
I am indebted to the faculty of the College of Design & Planning, University of Colorado at Denver.
Dr. Daniel J. Schler, Acting Dean & Director of Department of Planning & Community Development, has encouraged me, a foreign student, not only to accomplish my study, but also to become accustomed to a different social life. I am also in debt to Dr. Thomas A. Clark, my thesis advisor, for his stimulating ideas and support.
There were many other factors that made this study possible. I particularly wish to express my appreciation to the staff of the Community Development Department,
City of Northglenn, Colorado; Jerom D. Starling, Director; Patrick T. Breitenstein, Senior Planner; and Brian C. Davis, Landscape Architect & Planner, for their helpful suggestions regarding the case study. Additionally, my working experience in the City of Northglenn should be an invaluable part of my career. Furthermore, I really appreciate Ms. J. Lorell's help in typing this thesis.
Finally, I owe most thanks to my wife, Jeongkak, for her devoted assistance in every part of my study as well as my life. Hereby, I dedicate this thesis to my wife and my daughter, Ryangwan, who have been waiting, assisting and encouraging me with great pacience and forebearance.
TABLE OF CONTENTS
LIST OF FIGURES.............................................v
LIST OF TABLES.............................................vi
CHAPTER I. INTRODUCTION.....................................1
1. The Statement of Problems............................1
2. The Purpose and Objectives...........................2
3. The Significance.....................................2
4. Methodology & Outline.................................3
CHAPTER II. LAND & LAND USE PLANNING........................5
1 . Land & Man............................................5
. 2. Land Use Planning.....................................6
2) Land Development Process............................9
3) Land Use Planning..................................10
CHAPTER III. METHOD OF LAND SUITABILITY ANALYSIS...........14
1. Environmental Planning...............................14
1) Nature of Human Environment........................14
2) Environmental Planning.............................15
3) Basic Environmental Inventories....................16
4) Locational Identification for Environmental Data..17
2. Land Suitability Analysis............................19
(1) Role and Purpose................................19
(1) The Quantitative Approach.......................20
(2) The Qualitative Approach........................22
3) Techniques for Synthesizing Data...................24
(1) Mathmatical Combination Method..................24
A. Ordinal Combination Techniques..................24
B. Linear Combination Techniques...................26
C. Non-linear Combination Techniques...............28
(2) Factor Combination Techniques.................28
(3) Rules of Combination..........................29
3. Microcomputer Application..........................30
(1 ) Software......................................32
(2) Developing a Program..........................32
(3) Mathmatical Operation.........................33
4. Analysis of Urban Land Requirements................33
(1 ) Variables.....................................33
(2) Method and Process............................34
2) Open Space.......................................36
3) Commercial and Industrial Land...................36
CHAPTER IV. CASE STUDY...................................39
1 . Study Area.........................................39
2. Method and Process.................................42
1) Uniform Grid System..............................42
2) Method and Process...............................42
3) Evaluation System................................45
3. Environmental Data & Spatial Data..................47
1) Environmental Data & Rules of Evaluation.........47
(1 ) Geology.......................................47
(4) Flood Plains & Drainage.......................57
(5) Solar Radiation...............................60
2) Spatial Data & Rules of Evaluation..............63
(1) Accessibility to Main Street..................63
(2) Sound Level...................................63
(3) Accessibility to Water & Sewer................68
(4) Site Feature..................................68
4. Analysis of Urban Land Demand......................72
(1 ) Variables.....................................72
2) Open Space..................................... 75
3) Commercial & Industrial.........................76
5. Computer Analysis..................................79
1 ) Process.........................................79
(1) Susceptibility to Landsliding................79
(2) Open Space Analysis..........................81
(3) Residential Analysis.........................81
1) Land Suitability Map............................88
2) Preliminary Land Use Plan.......................88
CHAPTER V. CONS LUST I ON...............................92
LIST OF FIGURES
2-1. Interaction Among Various Actors..................10
2- 2. Elements of Land Use Planning.....................11
3- 1. Geographic Encoding System........................18
3-2. The Quantitative Approach.........................21
3-3. The Qualitative Approach..........................23
3-4. Ordinal Scale.....................................24
3-5. Ordinal Combination Using Shades of Gray..........25
3-6. Ordinal Combination with Numerical Indices........25
3-7. Data Transformation...............................26
3-8. Linear Combination................................27
3- 9. Factor Combination Method.........................29
4- 1 . Land Form.........................................39
4-2. Study Area........................................40
4-3. Overlay Grid System...............................43
4-4. Method and Process................................44
4-5. Data Transformation...............................47
4-6. Geology & hydraulic Characteristics...............48
4-6-1. Hydraulic Characteristics.........................49
4-8. Slope Analysis....................................56
4-9. Angle of Repose for Slope Materials...............55
4-10. Flood Plains & Drainage............................58
4-11. The three Main Hydrologic Zone.....................59
4-12. Solar Radiation....................................61
4-13. Relative Access to Main Streets....................64
4-14. Wayside Noise Level for Transit Trains of
4-15. Noise Level from Railroad..........................66
4-16. Accessibility to Water/Sewer.......................69
4-17. Site Feature.......................................71
4-18. Existing Land Use..................................74
4-19. Suitability to Open Space..........................84
4-20. Suitability to Residential Revelopment.............87
4-21. Land Suitability Map...............................89
4-22. Land Use Plan......................................91
LIST OF TABLE
3-1. Basic Environmental Inventory..................... 16
3-2. Locational Identification Modes....................17
3- 3. The Quantitative and The Qualitative Approach......23
4- 1. Coding Form........................................46
4-2. Analysis of Geology................................51
4-3. Soil Analysis......................................54
4-4. Slope Analysis.....................................55
4-5. Evaluation of Flood Plains & Drainage..............59
4-6. Evaluation of Solar Access.........................62
4-7. Evaluation of Accessibility to Main Street.........63
4-8. Evaluation of Noice Level..........................63
4-9. Evaluation of Accessibility to Water/Sewer.........68
4-10. Evaluation of Site Feature.........................70
4-11. Development of Commercial & Industrial.............76
4-12. Employment in the City of Northglenn...............77
4-13. Ratio of Employment to Developed Land..............78
4-14. Industrial Land & Commercial Land..................78
4-15. Susceptibility to Landsliding......................80
4-16. Open Space Analysis................................82
4-17. Residential Analysis...............................85
4-18. Development Pattern................................88
1. The Statement of Problems
This reasearch proposes to examine and evaluate the methodology of computer assisted Land Suitability Analysis. In doing this study, I have defined five tasks. They are as follows:
. to review and examine the concepts of land use planning and environmental planning.
. to analyze and evaluate various land suitability analysis methodologies to determine which are the most effective and reasonable.
. to apply a computer assisted methodology to land suitability analysis and the generation of land use alternatives .
. to estimate and project the demand for land use activities in a planning area.
. to apply the results of land suitability analysis, while accomodating the market demand for land.
2. The Purpose & Objectives
This research is intended to develop and apply a method for assisting the decision process in land use planning.
More specifically, I have tried to:
. identify the importance of environmental impacts on land conversion,
analyze and apply land suitability analysis,
. develop or utilize a computer system, particularly, a microcomputer system for land suitability analysis,
. pursue a estimation and projection methodology for land use demand, and
. suggest an appropriate spatial pattern of land uses for the case study area.
3. The Significance
A growing concern with the natural environment has paralleled the growth of urban areas. The rapid rate of urbanization and the consequent destruction of natural systems has fostered this environmental concern. As our understanding of natural systems has increased, a scientific background for the practice of environmental planning has become essential.
All land is not the same. Physical and geological characteristics must be considered along with geographic locations. Therefore, we should try to plan so that each site can be developed in harmony with restraints imposed by the environment.
In the land use planning process, the method, used to delineate the relative suitability of each location for various types of urban development and subsequent urban activities is very important. In this study, degrees of suitability, by type of land use and type of environmental objectives have been determined by land source inventories. These inventories are expressed in a set of maps created through a land suitability analysis. Today's technology in computer makes it possible to apply computer systems in performing land suitability analysis and creating a land inventory.
This study, it is hoped, will be important for intergrating knowledge of the land use planning process learned in the classroom. Also, the case study method should be very helpful for understanding the reality of the land use planning process and for linking theory to practical reality.
4. Methodology & Outline
Through the literature review, I have tried to examine urbanization, environmental problems and the significance of environmental considerations in land development. This research is concentrated on the analysis of the methodology of land suitability analysis as well as its purpose, role and characteristics in the land use process.
In this case study, I tried to develop ways in which to apply land suitability analysis at the local level, how to interpret environmental factors and how to compensate for
limitations in land suitability analysis. In analyzing the data for this study area, seven environmental attributes are evaluated: geology, hydrology, slope, soil, solar radiation,
flood plains and drainage. In addition, four spatial attributes are considered: access to main streets, access to water & sewer service, noise level and site features.
In estimating and projecting employment and population, a combination of ratio and linear trend analysis was used. Forcasting years are defined to 1990 or 1995.
In accordance with the increased use of computer systems, it is desirable and appropriate to explore a computer application method throughout the case study. In this study, I tried to use a microcomputer system (the Rainbow 100 System, by Digital Equipment Corp.) for compiling, adding, and sorting information. This computer application shows the usage of spreadsheet. (Lotus 123)
Finally, I tried to suggest a preliminary land use plan for the study area according to the results of this land suitability analysis.
LAND & LAND USE PLANNING
1. Land & Man
Land provides people with living space, with the raw materials necessary for filling material needs, and with opportunities for satisfying human needs. People look to alnd as a habitat, for the food they eat, for fibers and other materials needed to clothes their bodies and to provide housing and manufactured goods, for building sites for recreation opportunities, and for secenery and open space.
People often refer to ground, soil, or earth as land and speak of land as something on which they can walk, build a house, plant a garden, or grow a crop. The early economists viewed land as the sum total of the natural and manmade resources. There has been a notable increase of interest in land and land use in recent years. Society develops and uses land resources partly because it must do so in the process of sustaining life and partly because the products of resource developments can add substantially to the quality of life. Man's basic motivation for resource development stems from his urge for survival and from his desire to secure something more out of life than the food and shelter needed for subsistence. Man develops resources so that he may better use
them to maximize satisfaction.
The quality of land resources available for particular uses at any given time ordinarily depends on the interaction
of a variety of factors. Among these are the natural physical characteristics of land and the economic, institutional, and technological settings within which land uses evolve. Although nature has provided man with a vast resource heritage, the gifts of nature are not scattered evenly. Therefore, man has often found that he must cope with the problems of uneven resource distribution and unfavorable natural conditions. Limitations involving these limit the area suited for any particular uses. Within the limits set by these conditions, economic, institutional, and technological factors usually play dominant roles in determining the actual amounts of land resources that will be used at any given time.
2. Land Use Planning
The evolution of urban areas has been from farm to samll town, to city, to large metropolitan area. In the late twentieth century, it is said that Americans are a metropolitan people. Today, nearly 70 percent of the American people live in or near metropolitan areas that have populations greater than 50,000. It is expected that by the year 2000, 85 percent of Americans will be urban residents. An urban region is considered as an area with at least one million people, in which there is a zone of metropolitan areas. In 1920 there were ten urban regions that contained approximately one third of the total population of the country.
By 1970 there were 16 urban regions with three-quarters of
the population, and by the year 2000, there will probably
be at least 23 urban regions containing five-sixths of the
nation's people. Therefore, metropolitan population growth
is now a basic feature of the transformation from agrarian
to industrial life in the U. S.
In the late 19th century, the adaptation of rail transportation to intra-urban movement signaled the beginnings of wide spread population decentralization and functional specialization of local land areas. But these railroad carriers restricted urban expansion to those areas located near railroad lines. The development of motor vehicles helped overcome these limitation and accelerated the expansion process. The speed and flexibility of automobile, together with the growing ubiquity of the paved road, fostered an encompassing zone of daily interaction. Additionally all improvements in communication contributed significantly to
the social and economic integration of expanding urban *3
As expansion progressed, formerly independent towns and villages scattered around the central city lost their specialized services and institutions to the centers. A large number of these towns and villages became residential suburbs whose new function was to house commuting workers. A small number became commercial satellites of the central city, providing standardized goods and services to the nearby population. Others were transformed into industrial suburbs, as manufacturing industries moved out their production
facilities from the congested center, but continued to maintain administrative offices there. Thus, urban expansion eliminated both the autonomy and heterogeneity of the surrounding towns and villages, absorbing them into a single diffuse 4
Amos Hawley views urban expansion in his book as a progressive absorption of more or less unrelated population into a single organization. According to him, the phenomenon involves centrifugal and centripetal movements. Centrifugal movements are occured as new lands and populations are incorporated into a single organization. Centripetal movements make possible a sufficient development of the center to
maintain integration and coordination over the expanding
complex of relationship.
Urbanization obviously occupies and uses land for spe-' cialized purposes. Also, urbanization renders a large portion of the soils within the urbanized area impervious,
modifies rivers, and changes the previous landscape to suit *6
human use. Important urban land problems are associated with the succession of land uses that takes place with urban growth: the provision of needed housing, recreation, open
space, rapid transit, parking, and other facilities, enhancement of the urban environment, the redevelopment of blighted areas, and planning of the future growth of urban area.
With the sprawling outward growth of urban area, these problems have spilled over into the suburban and fringe communities. In addition, these communities came to face the
expenses of providing schools, water and sewer systems, paved
streets, and other public services.
However, this process need not totally destroy the land.
It should be the objective of a civilized society to achieve a harmonious, attractive, convenient and healthy living environment. If growth is properly planned and directed and if regular review and reevaluation of the goals and objectives are conducted, urban areas should be able to maintain a balance between acceptable environmental degradation and constructive use of environment.
2) Land Development Process
The development process of land can be examined as the process in which raw land is changed to urban uses and existing urban uses are continued, terminated, or changed to new uses through conversions or redevelopment. The development process is thus a series of stages, with different actors
involved in the decisions which lead to transition from one
stage to the next.
The many actors in the development process may be grouped
into four categories, and there are numerous interactions
among and between them. (Fig- 2-1) The dividing line between some groups, like elected officials and non-elected officials is clear, although the same individual may be a member of this and other groups as well. But it may be hard to draw the line between other groups, such as land-owners and developers, for one person may be playing both roles at the same time. These various interacting groups take raw land, building materials of various kinds and construction
equipment, and hire skilled labor to produce a final product. In the development process, the various actors work both
in cooperation and in rivalry. They must cooperate to some degree if only unconsciously. The efforts of many groups and persons interweave in numerous complex ways to produce economic out puts of value to each. But there is also rivalry, since each wishes to gain as much as he can at the expense of the others, if necessary. In this sort of process, each actor looks at the objective or measurable aspects of the situation,
but each also seeks to understand his competitor-rival, and
the latter factor may be as important as the former.
Interactions among various actors and interest groups in the suburbanization process, (source: Marion Clawson, Suburban Land Conversion in the U.S., 1971)
3) Land Use Planning
When most citizens make choices about where to live, the
quality of life is usually an important consideration. This
interest in the quality of life has supported land use plann-
* 1 2
ing since the City Beautirul era of the nineteenth century. Also, city planning became firmly established, in a legal
sense, with the Supreme Court decision of Village of Euclid
vs. Ambler Realty Co., which strongly affirmed the power of
a municipality to regulate use of private land, under defined
conditions and with proper procedural safeguards. Therefore,
city planning became a means for systematically anticipating
and achieving adjustment in the physical environment of a city
consistent with social and economic trends and sound princi-
pies of civic design.
City planning involves a continuing process of deriving, organizing, and presenting a broad and comprehensive program for urban development and renewal. It is designed to fulfill local objectives of social, economic, and physical well being, considering both immediate needs and those of the foreseeable future.
Land use planning, which is part of the city planning
process, is concerned with the location, intensity, and
amount of land needed for the various space using functions 1 4
of city life. In a frame-work for land use planning, activities, peoples, and locations all interact; each can be examined in terms of its relationship with others. (Fig. 2-2)
Elements of Land Use Planning
Among the questions that might be asked are: who lives in a certain location; what activities exist there; which activities relate to groups of people; and what is the spatial
distribution of different groups?
Land use creates the spatial distribution of various city functions in patterns of concentration or dispersion The natural patterns might be reinforced and the new patterns might be created through zoning and other land use controls. Therefore, land use planning is a management process in which development occurs according to overall community goals and objectives, influenced by personal goals of the individual actors.
It is clear that the traditional land development process has not led to fully satisfactory land use patterns. There is a need for continuing land use planning and regulation as well as for reform in the process of using land. The land use plan, now usually part of a more comprehensive urban plan, remains as the primary planning vehicle for land use planning. Zoning ordinances, subdivision regualtions, and other rules provide the implementation component. However, the emphasis is shifting from the physical plan to more rational regual-tion of the process.
The ad-hoc process of zoning is a poor way to ensure the efficient and environmentally safe use of land. The degradation of the environment is seen as a part of the typical land development process, because development has resulted in ecological problems. Sprawl has resulted in dependence on the
automobile and consequently, air pollution. Actually, neither developers nor public bodies still might give much attention to the environment-development relationship. Land use planning and regulation must clearly be reevaluated.
1. Raleigh Barlowe, Land Resource Economics, P. 188
2. Edward A.-Keller. Environmental Geology, 2nd ed., p. 245-246
3. Brian J. L. Berry and John D. Kasrda, Contemporary Urban Ecology, p. 197
4. Ibid., p. 198
5. Amos Hawley, Human Ecology: Theory of Community Structure, P. 369
6. Edward A. Kell, op. cit., p. 246
7. Raleigh Barlowe, op. cit., p. 3
8. F. Stuart Chapin, Jr. and Edward J. Kaiser, Urban Land Use Planning, p. 237
9. Marion Clawson, Suburban Land Conversion in the U.S., p. 10
10. Ibid., p. 101-102
11. Marion Clawson, op. cit., p. 78-79
12. Anthony J. Catanese and James C. Snyder, editors, Introduction to Urban Planning, p. 234
13. Chapin and Kaiser, op. cit., p. vi
14. Marion Clawson, op. cit., p. 73
Catanese and Snyder, op. cit., p. 235
METHOD OF LAND SUITABILITY ANALYSIS
1. Environmental Planning
1) Nature of Environments
The human environment is made up of the natural resources
of the earth and cultural modification. Natural resources
have been processed, changed, or arranged for the use of man.
Human activities have changed the atmosphere, waters, and lands.
The greatest danger to the human environment may be caused by
people who fail to consider the broad environmental consequences
of human action. The accelerating increase in population, the application of technology without considering the effects of it, and the lack of control over land use contribute to environmental crises.
The relationship between organisms and their environment are illustrated by the concepts of biotic communities and ecosystems. A biotic community is an assemblage-of various species of plants and animals inhabiting a common area which affect one another. A combination of such a biotic community with the physical environment is known as an ecosystem. In the broad sense the human environment is the biosphere. It is the sum of all the ecosystems of the earth. Therefore people exist as part of a particular ecosystem. It is impossible to separate an individual human from the biosphere. Man is dependent on the interrelationships of living things within their physical
environment. Man's urban systems are intricately related to the ecosystems on which they depend for their continued exis-tence.
In the biosphere, energy from the sun is available to activate the living process. Chemicals from air, water, and soil are available as building blocks for living organisms.
There must be a supply of energy to activate the life process. The pricipal source of energy for any biotic community is sunlight. But in any transfer of enrgy from one to another, some energy always escapes from the system. Most transfers of energy in natural ecosystem are inefficient. But life plays an important role in conserving energy. In the absence of life, energy becomes degraded, i.e., dispersed through space until it is no longer capable of doing work. As yet, man is unable to store significant quantities of energy without making use of life processes. When living communities are destroyed and the land made barren, the energy on which life and man depend is again wasted and no longer stored for future use.
2) Environmental Planning
Natural resources and environmantal protection legislation have awakened the public to the importance of public policy making to achieve sound environmental planning. What was once only an interest in environmental protection and basic conservation has become an appreciation of resource capabilities,
management, and planning.
In practice, planning is not a substitute for the work of the natural scientist. The planner should respond to the
findings of the natural science, interpret them as they apply to planning situations, and carefully observe the consequences. Planning is appealing in the relative certainty of the principles applied and simplicity of most methods. Planning analysis leads to sound conclusions when definitions and characteristics of the environment are clear. While the overall objective of contemporary planning theory is to provide those responsible for creating land use policies with a sound basis for their decisions, an objective of the environmental planning process is to find ways to do things with the least damage to natural systems as possible. Environmental planning is concerned with the interaction of human works with natural systems.
3) Basic Environmental Inventories
Inventories of characteristics and conditions are the first
step in developing a basis for an environmental plan. A general
classification of attributes, such as land water, climate,
ecological system, and social or cultural characteristics
appears in Table 3-1.
Table 3-1 Basic Environmental .Inventory
LAND WATER CLIMATE ECOLOGY
Topography Surface Drainage Soil Landscape geology Croud Water Surface Water Shoreland A Coastal Zo Zone (Aquatic Support System) Climate Microclimate Airsheds Wildlife (Species A Habitat) Ecosystem Supports Indication of Stress A Survival Ecosystem Condition
4) Locational Identification for Environmental -Data
Environmental data are almost always associated with a stable location in space. There are a number of ways of iden-tyfying and utilizing the geographic dimensions of environmental data.(see Table 3-2 and Fig. 3-1)
Table 3-2. Locational Identification Modes
MODE TYPE TO BE ASSIGNED THE VALUE USE
point system discrete point for recording sample point data on areal condition(air quality, water quality)
predetermined irregular polygon irregular polygon, i.e., parcel, census blocks or tracs, and other man-determined units economic,population, land use, housing, and activity system data. difficult for overlay approach
uniform grid system cell of uniform shape and size general plan-making satellite imaginary system and other geographic system for computerized analysis and other mapping
flexible irregular shaped polygons irregular polygon (not determined) census bureau's DIME file and other computerized analysis
Fig. 3-1. Geographic Encoding Systems
POINTS PREDETERMINED UNIFORM
fewer sample points
more sample computed!ed:
points points connected
by straight lines
computerized points connected by straight lines
* Coding is indicated by cross-hatching, and locational error introduced by each method is illustrated by the lightly shaded area. (sourcetChapin and Kaiser, Urban
Land Use Planning, 1979)
2. Land Suitability Analysis
(1) Role and Purpose
Traditonal and current approach in land use planning has
stressed the efficiency of urban development and urban activity
systems. An emerging perspective now includes a broader range
of environmental variables and environmental effects. Chapin
considered these tow methods as the "man-centered approach/nature
exploiting approach" and the "nature-centered approach".
To support the community's pursuit of environmental quality,
the environmental inventory and analysis system is important.
The purpose of land suitability analysis is to delineate
the relative suitability of each location in the planning juris-
diction for various type of urban development and activity.
Land suitability analysis serves as an in-design evaluation
tool for planning areas that retain impotant natural environ-
mental features. Land suitability analysis generates a more optimal spatial allocation of future urban activities and open space. It is designed to assure that land use evaluations give adequate attention to the environmental impacts of land conversion.
There are some basic assumptions in land suitability analysis. It assumes a locational environmental characteristics rendersthe site inherently more suitable for some land use than for others. Also, it is possible to interpret environmental data to determine such suitability based on specific
environmental and other objectives, standards, and design
. *10 principles.
In the process of land suitability analysis, expert judgement by planners and natural scientific knowledge of natural environmental features controls the outcome of the evaluation. Ultimately, however, the determination of "best" use depends not only on environmental analysis but also on market condions.
According to the manner by which information is organized,
McAllister explains two general ways of approaching to land
suitability analysis; informal (qualitative and holistic) and
* 1 1
formal (quantitative, additive).
(1) The Quantitative Approach
In this approach, numerical ratings are assigned to subclasses of each land characteristic and aggregated for each land parcel into a grand index of land suitability for a particular use. If the suitability for several land uses is being evaluated, the procedure is repeated for each land use.
In McHarg1s map overlay method, the quantitative nature of the ratings is not explicit. The ratings are expressed in the form of shades of gray or color, assigned to each of several subclasses of a land characteristic: the darker the shade, the less suitable the subclass for the proposed land use (or the reverse). But, the darkness of shades can be expressed in numerical value. The visual process of adding shades can be reduced to a mathmatical equation. For example, if land characteristics are grouped in three classes, they may be assigned
the ratings 1, 2, 3, in the quantitative approach, or white, light gray, and dark gray in the map overlay method, from most to least suitable. The map overlay technique produces a pattern of light and dark shades indicating the estimated aggregate suitability of each land parcel for a particular land use.
The use of explicit numerical ratings has the obvious advantage of revealing the precise values corresponding to the aggregated suitability. Sometimes, according to the relative importance of that characteristic in determining overall suitability, a special numerical value (a multiplier) is assigned each land characteristic. But the problem in the numerical rating is the accuracy of the degree of suitability for each rating. We can not tell that a soil type of rating 3 is precisely 3 times less suitable than another soil type of rating 1 .
Fig. 3-2. The Quantitative Approach
SOIL SOIL SLOPE
( INDEX MATRIX)
In this approach, the basic assumption is that the contribution of a land characteristic to the suitability of a particular use can be determined independent of other characteristics. (Fig. 3-2)
(2) The Qualitative Approach
In the Quantitative approach, these shadings do not represent ratings. Instead they serve the purpose of identifying each subclass of a characteristic on a map. The maps for each land characteristic aid the planner in preparing a composite map of land characteristics. The composite map does not contain aggregate shadings. The ecological zones and other key features of the study area are expressed on the composite map. In order to determine the suitability of each land parcel for a particular use, a set of land use principles is applied to the map. The principles represent the judgement of planners and scientists on the importance of retaining different types of undeveloped lands in their natural state, the importance of retaining resource land in their current use, and the capability of the land for accommodating the proposed use. In this approach, the contribution of one characteristic to overall suitability depends on the others with which it is joined. This approach provides planners and scientists more flexibility in judging suitability, enabling them to use deeper knowledge of the unique ecology of the study area and how it would be affected by any possible land use change. (Fig. 3-3)
Fig. 3-3. The Qualitative Approach
soil the composite map
Table 3-3. The Quantitative & The Qualitative Approach
Characteristics formal i nformal
Method addition combination
Each Land Characteristics independent dependent
Decision formulated flexible
3) Techniques for Synthesizing Environmental Data
(1) Mathmatical Combination Method
A. Ordinal Combination Technique (Fig. 3-5 and 3-6) Ratings are determined by using shading levels or numerical values with 2 (dichotomous analysis) or 3 (trichotomous analysis) ordinal measurements. (Fig. 3-4) The ratings of each subclass are assumed independent. They are therefore additive. Particularly for the addition of ordinal values, this mathmatical operation is technically invalid. The value 3 is not exactly three times less suitable than the value 1. Also, some characteristics may not be added or subtracted.
Fig. 3-4. Ordinal Scale
SUITABILITY LEAST SUITABLE MODERATE SUITABLE MOST SUITABLE
SHADE LEVELS ^ '
NUMERICAL VALUES 3 2 1
If sufficient resources are not available, the time-honored ordinal approach may be the only alternative. Thus, the ordinal combination of such variables, though technically invalid, may not be wholly inappropriate in
Rata each category ot each factor for each land use
Factors and Categones U1 Land Uses U2 U3
Category A iiiimm
Category A 5 3
Category B wmaam
Note Darner shading indicates greater suitability, or less, deeending on whether the analyst is emphasizing environmental capability or vulnerability.
Fig. 3-5. Ordinal Combination Using Shades of Gray
and Kaiser, 1979)
Map ratings for each land use. one set of maps tor eech land use
Factor 1 Suitability Map
Factor 2 Suitability Map
Overlay single-factor suitability maps to obtain composite map. one map for each land use
Composite Suitability Map
Fig. 3-6. Ordinal Combination with Numerical Indices
and Kaiser, 1979)
Rate each category of each factor for each
Factors and Land Uses
Categones U1 U2 U3
Category A Category 8 2 1
Category A 2
Category 8 Category C 3 1
B. Linear Combination Techniques (Fig. 3-7)
In this technique, there is an attempt to transform original ratings of subclasses to interval data so that the operation of addition and multiplication can be validly applied. This transformation converts the rating scale to one expressed as a proportion of maximum observed values with the range 0 to 1.0 (Fig. 3-8).
The interval scale used in the original rating in the "linear combination" method corrects one of the problems of the ordinal combination method. But the problem of handling interdependence among the subclasses still remains. However, a weight or multiplier can be assigned to each subclass. In this case, while ratings of each subclass are the estimates of relative influences among subclasses, weighting multipliers are estimates of relative influence among separate characteristics.
The linear combination technique can not be applied
appropriately to all combinations of characteristics. But
this technique has been used in many land suitability 1 3
Fig. 3-7. Data Transformation
SUITABILITY LEAST SUITABLE MODERATE SUITABLE MOST SUITABLE
3 2 1
INTERVAL SCALE 1.0 0.67 0.33
3-8. Linear Combination Method
Rate each category of eacn factor on an inter-
val scale reflecting relative influence among categones. transform to common scale, weight
each (actor to reflect its relative influence
among factors Land Use
Factors and Categones U1 U2 U3
Raw Transformed Rating Rating
Factor 1 Weight
Category A 2 10
Category S 1 to- 5
Factor 2 Weight
Category A 2 67
Category B 3 10
Category C 1 33
Overlay single-factor suitability maps to obtain composite map, one map for each land use
Composite Suitability Map
Chapin and Kaiser, 1979)
C. Non-linear Combination Technique Interdependence among land characteristics could be handled if the combination equation were not linear. In this case, it is required that the appropriate relationships among land characteristics be known as non-linear mathmatical functions.
Most non-linear equations usually generate suitabilities
regarding generation of impact rather than suitability for
land use. For example, soil-loss and storm-water run off
equations are not linear. The results may become one of the
characteristics being combined with other characteristics in
assessing overall land suitability by one of the other 1 4
This technique overcomes the problems of interdependence
among factors, but so far it has not been operationally use-
* 1 5
ful for generating overall land use suitabilities.
(2) Factor Combination Technique (Fig. 3-8)
Initially, land characteristics (factors) are combined to indentify homogeneous regions before assigning any suitability rating. Then, each combination of characteristics and subclasses is rated judgementally for its suitability, with interaction between characteristics consciously taken into account.
This technique is suitable for studies involving only
a few characteristics. A larger number of characteristics
makes it infeasible to determine the suitability ratings
* 1 6
for each combination.
Factor Combination Method
Overlay factor category maps to obtain composite land categones map; sometimes called map of environmental regions
Composite Mao of Environmental Regions
STEP 3 Rate each region for each land use
Regions U1 U2 U3
(Source: Chapin and Kaiser, 1979)
(3) Rules of Combination
This technique is a compromise between the non-linear combination method and the factor combination method. The rules assign suitabilities to sets of combinations of types rather than to single combinations and are expressed in terms of verbal logic rather than in terms of numbers and arithmetic. The process of determining suitabilities is more explicit than in the factor combination method and can deal with interdependence .
Rules of combination can be applied to construct the
composite suitability ratings map without having to deal with each possible combination individually. If the rules are stated explicitly, they can be used to generate maps directly without compiling a suitability table for all combinations. This is an obvious saving of effort compared to the factor combination technique. Such rules are explicit and subject to a close and careful examination. The rules, if carefully devised, can also handle interdependence among land characteristics .
3. Micromomputer Application 1) Introduction
Microcomputers have become an indispensable part of many business, professional and scientific activities, because of their low cost (compared with past computer prices) and their remarkable capability. It is now possible to have a powerful computer capability of low cost.
The computer varies in size and power and can serve many users at every level and everywhere. All computers consist of 3 main components; Central Processing Unit, Main Memory or RAM (random access memory) system and peripherals (Input devices and Output devices).
The CPU (Central Processing Unit) is a vital component in the computer, where instructions are translated and data are examined, altered and moved to and from various locations within Memory Components. In microcomputers, the CPU is known as a microprocessor. It consists of many chips.
Another component is the main memory or RAM (Random Access
Memory) System, where instructions and data are stored by the CPU and retrieved when necessary. These two components are the central part of the computer. Other components are called peripherals; input devices, output devices and auxiliary storage. Input devices, such as key boards, light pens, graphics tablets and computer "mice" are widely used. Monitors/terminals, printers, and plotters are common output devices. For auxiliary storage, cassette tape, floppy disk and magnetic tape are used.
In utilizing the computer system, there are some motivations for moving from manual data analysis to computerized
Once the initial costs and time have been expended, the cost and time required for managing information is considerably lower than when information is handled manually.
Large amounts of data can be stored compactly and retrieved easily.
Data analyses that would be technically impossible or economically infeasible through manual means can be done by computer.
Data can be updated more readily than through manual
For computer application in this study, we basically need a system by which the map overlay process can be performed either graphically or mathmatically. In mainframes, there are many systems for graphics, mapping and interactive
analysis. Various kinds of such software have been developed in microcomputer systems, but there are still severe limitations in applying microcomputers in the map overlay process.
In order to perform this process by computer, there are three possibilities; using available software, developing or improving programs with a particular computer language, and utilizing a business management system to perform the map overlay process mathmatically.
(1) Sof tware
Computer software is the set of programs or instructions which tells the computer how to combine or manipulate the data. Recently, lots of software systems have been developed and are available in the computer market. But there are still some problems in their performance and guiding documentation. Alrealy programmed software can not satisfy users completely. The manufacturers do not provide users with reliable and efficient documentation. Many books and articles about using software systems have been written by other specialists (System Analysts or Programmers).
For this study, there are unfortunately few programs available for microcomputers. A possible way to surmount this problem is to select a program for graphics or mapping and to improve or modify it for conducting a particular operation, like the map overlay process. In this application, all kinds of peripherals for graphics are required. Also, it may take a long time to alter a selected program.
(2) Developing a Program
For this study, it is possible to develop a program which can perform the map overlay process. In order to do so, a knowledge of computer language and programming skills is required. It is desirable and indispensible that computer specialists and planners help each other and conduct such research together. This is the reason why planners have to know how to apply the computer systems.
(3) Mathmatical Operation
This application is the easiest of three possibilities for this study. We might not need any peripherals for graphics and mapping. We can select efficient programs from the various kinds of business and management software available.
In this application, analysis is performed mathmatically. Therefore, it is required that all data be transformed to numerical data. This application is an economical method because we do not have to acquire for graphic peripherals.
4. Analysis of Urban Land Requirements
1) Residential ^
Population: Population size gives an indication of
the overall dimensions of the physical environment and supplies a basic standard for the estimation of space needs for
* 1 9
various categories of land use. Future trends in population size become the basis for estimating future dimensions and future space needs. Some portion of the population will be housed in group quarters such as nursing homes, college
dormitories, military barracks, etc. They should.be subtracted from the population prior to calculation of residential needs since they do not require conventional housing.
Dwelling Unit Occupancy: The average of persons per dwelling unit is a key variable in projecting future housing needs and residential land area. This figure must be increased to reflect vacancy rates for each dwelling unit type.
Future Housing Mix: The future housing mix is a function of the existing housing mix, current shortages or surplusses, income levels, relative housing costs, and housing preferences. The mix of housing units to be added should be compared to recent anticipated construction in order to evaluate the reasonableness of the change that will be necessary to achieve the desired mix.
Future Housing Starts: The distribution of housing starts by dwelling unit type also must be projected for each interval in the planning period.
Replacement for Loss: Some number of housing units will be lost each year due to fire loss, demolitions, and conversions to other than residential use. The rate will will generally be higher in older areas.
(2) Method & Process (Refer to Chapter IV. 4.)
Step 1. Population Growth
Projected Total Population
Proj ected Population in Group Quarters
Population for which Residential Unit will be needed
Population for which Residential Units will be needed
Population that can be housed in existing DU 1s at future occupancy rates
Population for which additional units will be needed
rate by housing
= the number of existing housing type (i)
H= the size of projected occupancy type (i)
Step 2. The Increment of DU1s (total number of additional
Population Increment in each Housing Type
Pj x Rti fr trial by housing type (i))
. The Number of Housing Unit
P. x Rti _________
the average dwelling unit occupancy)
. Total Increment of DU1s ( du)
zsdu x Rti = /^p it Rti
i 0. : i 0 .
Trial-and-error: Adjust the trial ratio for each dwelling type (Rtj_) until getting the result of close ratio to projected distribution of housing.
. Additional Units: The number of units is of additional units to be occupied during the interval.
Step 3. Projected Residential Land Demand
. Total dwelling units needed at end of projection interval
Occupied Units at beginning of period
Additional Units + to be occupied during interval
Occupied Units at end of period
. Adjustment for Vacancies
Occupied Units at End of Period
Vacancy Rate at End of Period
Number of Units Adjusted by Vacancy Rate
. Adjustment for Losses
Number of Units Adjusted by Vacancy Rate
Total Number of Units Needed
. Number of Units Contributing to Land Conversion
Total Number Existing Total Units of Units (Occupied + Vacant)
Number of Units Contributing to Land Conversion
. Projected Residential Land Demand
Number of Units Contributing to Land Conversion 2 3
Dwelling Units Per Acre at End of Period
Land Area (Acre)
2) Open Space
Projection of acreage for other uses might be made by either projecting need as a percentage of developed area, or, preferably, by establishing criteria in terms of acres per 1,000 population for each non-residential use.
3) Commercial and Industrial Land
Future demand for commercial or industrial land can be projected according to the growth of employment in particular areas. First, the ratio of developed commercial or industrial
employment for the past period (acre/employment)- can be estimated. According to this ratio, the future land demand for commercial or industrial can be projected from the projected employment.
1. Raymond F. Dasman, Environmental Conservation, 3rd ed., p. 6
2 Ibid., p. 100
3. Ibid., p. 100
4. David C. Hoeh, "Environmental Planning", Introduction to Urban Planning, Anthony J. Catanese and James C. Snyder, editors, p. 208
5. Ibid., p. 215 290
6. Chapin and Kaiser, op. cit., p. 300 303
7. Ibid., p. 289 290
8. Ibid., p. 291
9. Donald H. McAllister, Evaluation in Environmental Planning, p. 186
10. Chapin and Kaiser, op. cit., p. 291
11. McAllister, op. cit., p. 189 201
12. Chapin and Kaiser, op. cit., p. 310
13. L. D. Hopkins, "Method for Generating Land Suitability Map", JAIP, p. 392
14. Chapin and Kaiser, op. cit., p.312
15. Hopkins, op. cit., p. 393
16. Ibid., p. 394
17. Davon M Schneider with Syed Amanullah, Computer Assisted Land Resource Planning, p. 3
Vergil G. Stover, Method and Techniques for Urban Planners,
(course notes), p. 19. Chapin and Kaiser,
3.1 3.17 op. cit., p. 162
1. Study Area
The western part of the piedmont is within the front
range urban corridor. That part of the piedmont contains
most of the corridor population. The landforms of Colorado
piedmont are divided into lowlands and uplands. According
to predominant landforms, the piedmont uplands are divided
into bench-and-valley uplands, low rolling uplands, complex
uplands, and composite upland. The City of Northglenn is in low rolling uplands of the piedmont uplands. The subdued topography of most city area is caused by a cover of eolian silt and sand. (Fig. 4-1)
The City of Northglenn is located about 12 miles north of the heart of Denver. Interstate Highway 25 bisects this community, while serving as the primary arterial. The community is served by the Union Pacific Rail Road, with spurs into the industrial park. Most major truck carriers serve the city. Intra-city bus service is provided by the Regional Transportation District (RTD).
For this case study, the largest city-owned tract of vacant land was selected. The site of 250 acres is located on the east side of the city, between 104th Ave and 112th Ave. Most of the adjacent area is undeveloped. This site
Fig. 4-2. Study Area
f MHTrarw r*
1 1 2TH I
is isolated by the Union Pacific Rail Road from most of the city. Two storm drainage channels pass from west to east through the site and intersect in the middle of the site.
2. Metho and Process
1) Uniform Grid System
To analyze and synthesize the selected data, a uniform grid system was adopted, because grid cell data can be easily used for overlay approaches and is more useful for computerized analysis. A cell of uniform shape and uniform size is the basic geographic unit. A matrix of cells was produced by laying a uniform grid structure over the planning area.
The study area is a part of an urban area. This urban area already has a basic grid system of streets and avenues. Also, it is often desirable that individual blocks be developed homogeneously. Therefore, the cell size was determined according to the existing urban grid system.
2) Method and Process (Fig. 4-4)
Geology, Soil, solpe, flood plains and drainage, and solar radiation data were selected as environmental factors. Because this area is in the urban development area, wildlife, climate, and vegetation data were not considered. Hydrology was exanined as a reference, but was not considered as an attribute.
090 045 044 029 o ro 00 o CO o ro o o *
059 046 043 030 027 o * o * 002
058 047 042 o CO (* 026 o ** cn o ** o 003
057 048 o 032 025 o CTl 600 004
077 076 o CTl 056 049 040 033 024 O * o o 00 005
078 075 062 055 050 039 034 023 o 00 007 006
090 079 074 063 054 o cn * 038 035 022 019
o VO 089 o 00 o 073 064 053 052 037 036 o ro 020
099 092 088 o 00 072 065
o o 098 093 087 082 o "wl 066 -
o e* o * O VO 094 086 083 070 067
o CO t1 o ro 096 095 085 084 690 068
Fig. 4-3. Overlay Grid System
METHOD & PROCESS
COLLECT------------------> ANALYZE --------------> SYNTHESIZE ---------> LAND SUITABILITY
GEOLOGY CREATE CELLS
SOIL (OVERLAY GRID)
FLOOD PLAINS /DRAINAGE RULES OF EVALUATION
SOLAR RADIATION ASSIGN VALUE
SPATIAL DATA TO EACH CELL
ACCESS TO MAIN STREET
ACCESS TO WATER/SEWER OF LAND DEMAND
SOCIAL / ECONOMIC DATA COMMERCIAL / INDUSTRIAL
POPULATION OPEN SPACE (RESTRICTED)
COMPUTER ANALYSIS SUBTRACTIVE PROCESS OPEN SPACE
FLOOD PLAINS POTENTIAL LANDSLIDE
OPEN SPACE OPEN SPACE
(PRESERVATION) ANALYSIS OF RESIDUAL RESIDENTIAL
(TRICHOTOMOUS) (GOOD, FAIR POOR)
Fig. 4-4. Method and Process
Three types of spatial data (accessibility to main street, accessibility to water and sewer system, and noise level) were mapped.
Other social/economic data were collected for analysis of urban land demand in study area.
To assign the ratings to each cell, a coding form was created. (Table 4-1)
Land inappropriate for development may be subtracted from
the site. This land might include all steep land, major site
amenities (ex. a meadow, a stand of tree, land bordering stream,
steep cliffs, rock out crops, old buildings, prime vistas, etc.),
and other lands to be held for preservation (habitat area:
streams, edge of forest, bogs, ponds, etc.). Because the
process of subtracting valued features is judgemental, each
category should be accompanied with a list of implications and
directions for development.
In this study, a subtractive process was used. First,
100 year flood plains were eliminated. Next, potential landslide areas and finally open space for preservation were eliminated.
The remaining areas were analyzed for residential development.
3) Evaluation System
For evaluating each subclass of a land characteristic, ordinal scales with three categories; good,fair, and poor were used. In the mathmatical overlay process with a computer, ordinal scales were transformed into interval scales with the
Table 4-1. Coding Form
Cell No. Grade Cell No. Grade Cell No. Grade 1 |Cell No. 1 Grade
001 027 053 079
002 028 054 080
003 029 055 081
004 030 056 082
005 031 057 083
006 032 058 084
007 033 059 085
008 034- 060 086
009 035 061 087
010 036 062 088
Oil 037 063 089
012 038 064 090
013 039 065 091
014 040 066 092
015 04l 067 093
016 042 068 094
017 043 069 095
018 044 070 096
019 045 071 097
020 046 072 098
021 047 073 099
022 048 074 100
023 049 075 101
024 0 vrv O 076 102
025 051 077 103
026 0 52 078 104
mid-point value of each ordinal scale. Through the use of summation, interval scales were transformed into ordinal scale again. (Fig. 4-5)
Fig 4-5 Data Transformation
Interval Scale i I 1
0.00 0.33 0.67 1.00
(With 2 attributes) I i H 1
(With 3 attributes) 0.00 0.66 1.34 2.00
0.00 0.99 1.91 3.00
(With 4 attributes) t t t (
0.00 1.32 2.68 4.00
Ordinal Scale | Poor | Fair Good j
3. Environmental Data & Spatial Data
1) Environmental Data & Rules for Evaluation (1) Geology (Fig. 4-6)
General information of material at and near the surface is useful for making preliminary site evaluations and land use decisions.
. Post-piney Creek and Piney Creek Alluvium (upper holo-cene): thses units are part of flood-plain and terrace deposits
less than 20 feet thick and commonly 5-15 feet thick. This
-LAND SUITABILITY STUDY
Fig. 4 6. Geology & Hydraulic Characteristics
HYDRAULIC CHARACTERISTICS OF CITY OF NORTHGLENN &STUDY AREA
(ADOPTED FROM HYDRAULIC CHARACTERISTICS OF THE PRINCIPAL BEDROCK AQUIFERS IN THE DENVER BASIN, COLORADO BY S. G. ROBSON, 1983:published by USGS)
MAIN AQUIFERS CONDUCTIVITY TRANSMISSIVITY OCCUPIED AREA
DENVER AQUIFER 0.5 ft/day -50 ft2/day MOST OF CITY, except STUDY AREA
ARAPHAHOE AQUIFER 2.0 ft/day 300- ft2/day MOST OF CITY
LARAMIE-FOX HILLS AQUIFER 0.5 ft/day 50-70 ft2/day MOST OF CITY
DENVER BASIN AND TRACES OF GENERAL- GENERALIZED GEOLOGIC SECTIONS THROUGH THE DENVER BASIN
IZED GEOLOGIC SECTIONS
_____________________ 4 (ADOPTED FROM HYDROLOGIC INVESTIGATION ATLAS BY U S G S)
Fig. 4-6-1. Hydraulic Characteristics
unit is made up of 20-70 percent silt and clay, 36-65 percent
sand, and 0-15 percent granule to pebble gravel. Structures
built on these units tend to have problems. Even these units
are easily excavated with power equipment, viritcal cuts are *3
. Colluvium (upper holocene): this unit is a part of
slope deposits which are mantled by thin surficial deposits
that have moved under the influence of gravity or running water.
This unit is made up of 60-70 percent silt and clay, 20-30
percent sand, less than 10 percent granules and pebbles. Most
of this unit is less than 10 feet thick and commonly 5 feet
thick. Structure on this unit may be susceptible to damage
owing to differential compaction under heavy loads and uneven
heaving under light loads. Slope stability is generally poor,
owing to landslide potential.
. Loess (upper pleistocene): this unit a part of an
eolian deposit generally less than 17 feet thick, which was
blown from alluvium exposed along valley floors. This unit is
made up of 70-80 percent silt and clay, 20-30 percent sand,
and about 1 percent granules. Excavation is easy with hand
tools or light power equipment. Foundation conditions are only
fair, owing to considerable frost heaving and to excessive
compaction and differential settlement.
. Denver Formation (paleocene and upper cretaceous): the Denver formation consists of sedimentary rock units, like claystone, siltstone, shale, sandstone and minor amounts of conglomerate and limestone. Denver formation underlies most
of the Denver metropolitan area. Thickness is about 930 feet. Most claystone and siltstone are easy to excavate with power equipment. These rock types tend to have poor foundation conditions and relatively unstable natural and man-made slopes.
In contrast, most sandstone and conglomerates are moderately difficult to excavate with power equipment. These rock units have good foundation conditions and stable natural and man-made slopes.
Table 4-2. Analysis of Geology
TYPE AGE FOR DEVELOP- MENT FOR OPEN SPACE
post-piney creek and piney creek alluvium flood plain and terrace deposit upper holocene poor good
colluvium slope deposit upper holocene poor fair
loess eolian deposit upper pleisto- cene fair fair
Denver formation sedimentary rock units paleocene and upper cretaceous good poor
(2) Soil (Fig. 4-7)
The relationship between soil composition and various
types of non-agricultural land uses is often not so apparent
as that between soil composition and agriculture. Increasingly,
decision-makers are turning to soil surveys to help guide in
site selections for residential, industrial, and other forms
of development that involve surface and surface structures.
Soil texture and composition are generally the most meaningful for land development. In this study, a county soil survey was used to evaluate each subclass of soil. (Table 4-3)
' i ; 8
: 5 x
LAND SUITABILITY STUDY--------
. * ** am*
Table 4-3* Soil Analysis
Soil series Depth (in) USDA Texture Shrink- swell Potential Building Foundation Home site Land- slide Resid- ential Open Space
Lw 0-3 6 36- loam, clay, & stratified loam gravel low to moderate low severe severe poor poor good
P1B.P1C 0-9 9-18 26-30 loam clay loam & silt loam moderate high low to moderate moderate to severe moderate poor good poor
ReD 0-9 9-28 28- loam & clay loam clay & clay loam shale & sandstone moderate high severe moderate good fair fair
ShF 0-l4 14_ silty clay shale high severe severe poor poor good
U1C 0-30 30-48 48- loam & clay clay loam shale & sandstone high moderate severe severe fair poor good
* Data Source j Soil Survey of Adams Count, Colorado 1974
(3) Slope (Fig. 4-8)
It is realized that land uses have slope limitations and that the slope has been misused in many modern developments. Disturbance of stable slopes may result in failure. Slope requirements for various land uses and the angle of repose of each soil were examined to evaluate ratings for identifying susceptibility to landsliding. (Table 4-4 and Fig. 4-9)
Fig. 4-9. Angle of Repose for Slope Materials
(source: Marsh, Landscape Planning, 1983)
Table 4-4. Slope Analysis
10 20 fair
20 - good
* note: this ratings are to identify the susceptibility to landsliding.
Fig. 4-8. Slope Analysis
(4) Flood Plains and Drainage (Fig. 4-10)
The urban explosion has placed great land use pressure
on flood plains and coastal zones, resulting in not only
natural disaster, but also serious environmental alteration of
these settings. Destructive floods cause severe economic and
social disruption, because major economic losses as well as
loss of life may befall a large portion of a community, rather
than just a few individuals.
Information about flood plains allows for assigning land uses to these zones according to flood hazards. In this study, 100 year flood plains were eliminated in the subtractive process, in order that no development is permitted there.
Clearing and development of land often has an influence on drainage networks. Deforestation and agriculture may initiate soil erosion and gully formation. As gullies advance, they expand drainage networks. Urbanization also leads to considerable change in the shape and density of a drainage network.
The procedure for building land use plans for small drainage basins begins with a definition of the stream system, patterns of run-off and the three hydraulic zones (upland zone,
collect zone, and conveyance zone). (Fig. 4-11)
In this study, 100 year flood plains and 100-500 year
shallow flood plains were identified. With the use of a topographic contour map, drainage divides, drainage patterns formed by run-off, and flowing streams (gullies) were mapped and evaluated. (Table 4-5)
' ................................................ -
LAND SUITABILITY STUDY-
FLOOD PLAINS & DRAINAGE
iSffi'-VS mu s~~ "
*-- . * l 1 !
Fig. 4-10. Flood Plains & Drainage
Fig. 4-11. The Three main hydrologic Zone
(source: Marsh, Landscape Planning, 1983)
Table 4-5. Evaluation of Flood Plains & Drainage
RESIDENTIAL OPEN SPACE
100 yr flood plains eliminated eliminated
100-500 yr shallow flood plains poor good
drainage divide good poor
run-off slopes fair fair
gullies r poor good
(5) Solar Radiation (Fig. 4-12)
Planning for solar access introduces important new considerations into the conventional development process. Factors affecting energy conservation and the availability of sunlight for diplacing annual energy demands are taken into account. Also, solar access should be considered along with other land planning techniques in the lot desgnation process to increase the potential for future solar energy use in a development. Enhancing the beneficial use of the sun's energy adds to the marketability of homes. Resale values of homes and lots with
good solar orientation may be greater than those of convent-
ional homes and lots.
The latitude and topography of the site affect both the
availability of sunlight and the length of shadows cast by
objects on the site. The slope and orientation of land
largely determine the amount of radiation received.
Proper orientation of streets, lots and home is the single most important design strategy in energy-conserving solar access planning. Proper home orientation controls heat loss and gain, allowing the maximum amount of solar radiation to be received during the heating season and the minimum during cooling season.
South slopes are preferable for solar energy use, because they absorb more winter solar radiation than other slopes and tend to be warmer. Shorter shadows cast on south slopes enable buildings to be built taller and closer together without obstructing solar access, thus making higher density develop-
Fig. 4-12. Solar Radiation
Flat land has better solar access than east-west or north slopes, but is less desirable than south slopes. As east and west facing glazing is difficult to shade, homes built on east or west slopes should be oriented toward the south with the major glass area located on the south wall. North slopes are the least desirable for solar access, but it is possible with careful planning to provide homes with solar access.
In this study, according to the 40 degree north latitude solar path diagram, most sunny, partly shaded and most shaded areas were delineated on the map. (Table 4-6)
Table 4-6. Evaluation of Solar Access
ORIENTATION RESIDENTIAL OPEN SPACE
most shaded north slope poor good
partly shaded east-west slope fair fair
most sunny south slope good poor
2) Spatial Data & Rules for Evaluation (1) Accessibility to Main Street (Fig. 4-13)
Relative accessibilty was estimated by relative distance from both 104th Ave. and 112th Ave. The first zone from these main streets is rated fair for residential because of direct effect of noise (Table 4-7)
Table. 4-7. Evaluation of Accessibility to Main Street 2
RESIDENTIAL OPEN SPACE
RDU*= 2, 3 good poor
RDU =1,4 fair fair
RDU = 5 poor good
* note: RDU = Relative Distance Unit
(2) Sound Level (Fig. 4-15)
This site is isolated from the rest of the city by the Union Pacific Rail Road. The right of way of this railroad is also southwest border line of the site. On this railroad, sometimes 3-4 trains pass by a day, however, sometimes only 3-4 trains pass by a week. Most of the trains are about 1000 feet long and used for freight transport. These trains can be considred as a sound origin. Fig. 4-14 shows the way-side noise levels for one-car, two-car, eight-car and very long train, as a function of distance from the track center-
LAND SUITABILITY STUDY
Fig. 4-13. Relative Access to Main Streets
Noise barriers installed along the right of way will reduce
noise levels at 50 feet by 10 to 13 dB. According to the
DHUD (Dept of HUD) exterior stands for residential areas,
noise levels which do not exceed 65 dB for more than 8
* 1 5
hours per 24 hours is mormally acceptable.
In this study, the length of a train was considered to be 1000 feet. The formular for "Geometric Attenuation in Sound Level" was used.
For Line Source Propagation
Sound Level ^ Sound Level ^ = 0
Where: 0< = Coefficient
r. = the Distance from Sound Origin (the first place)
r~ = the Distance from Sound Origin (the second place)
In this formular, withing the distance of 3/10 of train full length, 0<= 10. Beyond that distance CX = 20.
Fig. 4-14. Wayside Noise Level for Transit Trains of various Lengths (Source: U. S. Dept of Transportation, Transportation Noise and its Control, 1972)
LAND SUITABILITY STUDY
Noise Level from Railroad
Sound Level Calculation
Distance Without Sound Barrior With Sound Barrior Formular to be used
50 ft 85 dB 73 dB (85-12) L1-L2 = 10(log^)
300 ft (3/10 of train length) S a 85 Sa = 10 log(^) 85 S = 10 log 6 a = 8 S = 77 (dB) Sb 73-Sb = 10 log (3) - 10 log 6 - 8 S, = 65 dB b
x ft (when noise level is 65 dB 6 5 dB 77-65 20 log (J^q) 12 = 20 log ("3^0) 1Og3~00 = '6 x 4 300 x 1200 (ft) N/A because noise level at 300 feet is already acceptable r 2 L -L 20(log-4) 1
For residential development, each zone' is rated. (Table 4-8). Table 4-8. Evaluation of Noise Level
Distance from the Center of Railroad Row Evaluation
Within 300 feet Poor
300 1200 feet Fair
beyond 1200 feet Good
(3) Accessibility to Water & Sewer (Fig. 4-16)
The existing watermain is located in 112th Ave. Also, a possible connecting point with the force main for the sewer is also on 112th Ave. Therefore, spatial data was analyzed from 112th Ave. (Table 4-9) 4
Table 4-9. Evaluation of Accessibility to Water/Sewer
1 2 Good
3, 4, 5, 6 Fair
7, 8 Poor
(4) Site Feature (Fig. 4-17)
Three typical features were considered in this site.
The northwest corner is being used as a boseball complex. This area might be considered as a potential athletic park. The The area located in the middle of the westside is surrounded by railroad and two streams (flood plains). In terms of topography, this area is very much lower that the level of the railroad. Therefore, it appeared that this site has severe
ACC.KSSfBa.rv TO WAtfO 36VYFB
Fig. 4-16. Accessibility to Water/Sever
constraints for development. This site might be considered as a preservation area.
The area in the middle of the eastside is where the original farmstead of this site still exists. This kind of feature can be considered as a historical preservation area. (Table 4-10)
Table 4-10. Evaluation of Site Feature
Site Feature For Open Sapce
Potential Athletic Park Fair
Natual Preservation Good
Historical Preservation Good
LAN U SUITABILITY STUDY
-17. Site Feature
4. Analysis of Land Use Demand (Fig. 4-18)
Residential land demand was projected between 1985-1990. (1) Variables
* a 1985 *b 1990
Population, total 31,000 37,182
Population in group quarters 170 204
Dwelling Unit Occupancy (peraon/unit)
single-family(SF) 3.5/unit 3.5/unit c
multi-family(MF) 1.9/unit 1.9/unit
Vacancy Rate (%)
S F 2.3 * c 2.3 C
M F 5.3 5.3
Future Housing Mix (%)
S F 77 % *d 65 %
M F 23 % 35 %
1 00 100
Dwelling Units/Gross Acres
S F 2.3/ac. *c 3.3/ac.
M F 20.4/ac. 20.4/ac.
Existing Housing S F M F *
2339 1 0237
* a. estimated by Northglenn
b. projected by Adams County
c. projected by trends
d. desired by Northglenn
EXISTING LAND USE
Fig. 4-18. Existing Land Use
Step 1. Population Growth
. 37,182 - 204 = 36987
population group quarters to be accomodated
in 1990 in 1990 in 1990
existing housing unit (1985, estimated by Northglenn)
Total Occupied Vacant Vacancy Rate
S F 7898 7713 1 85 2.3 %
M F 2329 2216 1 23 5.3 %
7898 X 3.5(person/unit + 2 in 1990) 339 X 1 . 9 = 32087
S F M F can be accom-
dated by existing units in 1990
. 36978 32087 = 4891 --------This population will need housing
Step 2. The Increment of Dwelling Units first try ( 85 % S F, 15 % M F)
4891 _____ + ___________ = 1 573.9 ---- 1 574 (dwelling units)
Desired Housing Mix: 65% ; SF, 35% ;MF
1574 X 0.65 X 3.5 = 3581 (person)--- 77.4 %
1574 X 0.35 X 1.9 = 1047 (person)---22.6 %
* In this try, 4628 and the percentage of SF & MF population are too much different.
second try( 77 % S F, 23 % - M F)
4891 + 1668 (unit)
3.5 1 .9
S F : 1668 X 0.65 X 3.5 = 3794 (person) 77.4 %
M F : 1668 X 0.35 X 1.9 = 1110 (person) 22.6 %
* In this try, the result is cose enough to assumption.
1668 X 0.65 = 1084 S F
1668 X 0.35 = 584 M F
Step 3. Projected Residential Land Demand
. Total Occupied DU's to be needed in 1990, when vacacy rate;
-S F : 771 3 + 1084 = 8797 ----------------- 2.3 %
M F : 221 6 + 584 = 2800 ----------------- 5.3 %
. Adjustment for Vacancies
S F : 8797 / (1 0.023) = 9004 M F : 2800 / (1 0.053) = 2957
. Adjustment for Losses ( 0 % )
S F : 9004 / 1 .0 = 9004 M F : 2957 / 1.0= 2957
; in this case, Northglenn has relatively new housing. Loss rate is assumed 0 %.
. Number of Units contributing to Land Conversion
S F : 9004 7898 = 1106 (units)
M F : 2957 2339 = 618 (units)
Projected Residential Land Demand
340 (ac.) 30 (ac.)
This city will need 370 acres for residential developments until 1990.
2) Open Space
* 1 7
According to the Adams County Comprehensive Plan, it is appeared that the standard acrage of park and open space in the metropolitan area is 10 acres per 1000 people. Northglenn's population in 1990 is projected to 37,182. Therefore, necessary park lands can be calculated as follows;
37182 X 10/100o = 371*82 ----- 370 acre
There are developed parks & open space of 110 (ac.) and school
parks of 55 (ac.) currently existing in the city. By 1990, the city will need approximately 200 additional acres of park land to be developed.
3) Commercial and Industrial Land
Table 4-11. shows the ratio between developed land and
zoned land in commercial and industrial uses.
Table 4-11. Development of Commercial & Industrial
1975 1980 1985
Industrial Zone 168.98 219.54 219.54
Developed area 16.81 48.26 104.92
Developed/Zoned 9.9 % 28.6 % 47.8 %
Commercial Zone - - 372.51
Developed area 157.38 201.77 256.3
Developed/Zoned - - 68.8 %
For projecting the demand of industrial and commercial lands, the ratio of idustrial employment to developed industrial zones and commercial employment to developed commercial zones were used in this study. In order to do the projections, information about the employment by industry was needed. However, information for the Denver Region Employment is only available up to the year 2000. For the city of Northglenn,
the employment needed to be projected from the regional employment figures. This process is not simple, and could be the subject of an entire study. These methods require many variables to be considered and very complex processes including projections od population, employment and others, defining the relationships between variables, calibration process, and allocation process.
In this study, the combination way of increasing trends and a ratio (i.e., local employment/regional employment, ind-strial employment/total employment, commercial employment/ total employment, etc.) were used. Among industry classifications, minig, contract construction, manufacturing, transportation and public utilities are considered as industrial employment. Whole sale and retail trade, finance, insurence and realestate, and services are considered as commercial employment. (Table 4-12)
Table 4-12. Employment in the City of Northglenn(in thousand)
1975 1980 1 985 1 990 1 995 2000
Denver Region 671 .4 869.5 1034.3 1208.6 1362.9 1524.7
Northglenn 4.838 6.036 7.419 8.898 10.365 11.853
Industrial .358 . 579 .783 1.011 1 .258 1 .521
Commercial 2.133 2.971 3.814 4.750 5.749 6.515
Table 4-13. Ratio of Employment to Developed Land
1975 1 980 1985
Industrial Employment (E) 358 579 783
Developed Industrial Land (ac.) 16.81 48.26 219.54
ratio (E/ac.) 21 .30 12.00 7.46
Commercial Employment (E) 2113 2971 3814
Developed Commercial Land (ac.) 157.38 201.77 256.33
ratio (E/ac.) 13.43 14.72 14.88
While the ratio of industrial employment to developed industrial land is decreasing, the ratio of commercial employment to developed commercial land is stable. For industrial land projection, the ratio of 7.46 was used. For commercial land projection, the ratio of 15.68 was used (Table 4-14)
Table 4-14. Industrial Land & Commercial Land
1990 1 995 2000
Industrial Employment 1011 1 258 1 521
Industrial land(ac.)*a 1 36 169 204
Commercial Employment 4750 5749 651 5
Commercial Land(ac.) b 303 367 416
* a. & b. are calculated as followings.
Projected Employment/ ratio (employment/developed land)
ratio : industrial --- 7.46(Ei/ac.)
101 1 / 7.46 = 1 36 be needed in 1990
4750 / 1 5.68 = 303 be needed in 1990
According to the result, existing zoned land for industrial and commercial uses will accomodate projected employments by the year 1995 or 2000.
5. Computer Analysis
In this study, Lotus 1-2-3 was used with the Rainbow 100 system (Digital Equipment Corp.) for compiling, adding, and grading information. With the electric spread sheet, all cell ratings were input and analyzed by adding and grading. In grading the results, the ordinal values were assigned for each cell according to a certain interval of summation. Anpther alternative is to let the computer sort the summation in ascending or descending order and to divide the ordered cells into 2, 3, or 4 groups with the same interval. According to the needs of the land and the situation, a group of higher or lower valued cells might be selected as the suitableland for each development.
(1) Susceptibility to Landslide
'SUSCEPTIBILITY TO LANDSLIDING
Table 4-15. Susceptibility to Landsliding
100 year flood plains were eliminated first in the subtractive process. Soil and slope characteristics were examined to identify the susceptibility of land slides. The relationship between the repose angle of each soil and slope were considered in evaluating each cell. (Table 4-15)
(2) Open Space Analysis
After 100 year flood plains and potential landslide areas were analyzed with six characteristics. In grading the summation with 3 interval scales, fair and poor categories were appeared. The summation was graded again with two categories (0 0.5,
0.5 1.0). The upper group was selected for open space.
(Table 4-16) The results of these two analysis were mapped with three categoties; flood plains, potential landslide, and open space. (Fig. 4-19)
(3) Residential Analysis (Fig. 4-20)
After the results from the open space analysis were eliminated, the remaining cells were analyzed with seven characteristics. (Table 4-17) In this analysis, the results were mapped with two categories; good and fair. A poor category did not appear.
_ z 8
OPEN SPACE (RESTRICTED DEVELOPMENT)
CELL t GEOLOGX SOIL FLOOD SOLAR NOISE SITE TOTAL GRADE | REGRADE OVER GRADE .
001 0.50 0.16 0.84 0 .84 0.50 0.50 3 .34 2.00 3 .00 1.98 2.00 FAIR K
002 0.50 0.16 0 .84 0 .84 0.50 0.50 3 .34 2 .00 3 .00 4 .02 3 .00 GOOD
003 0.50 0.50 0.84 0.50 0.16 0.50 3 .00 2.00 3 .00
004 0.16 0.84 0 .84 0 .84 0.16 0.16 3 .00 2.00 3 .00
005 0.16 0.84 0 .84 0.50 0.16 0.16 2 .66 2.00 1.00 OVER REGRADE
006 0.16 0.84 0 .84 0.50 0.16 0.16 2.66 2.00 1 .00 0 .00 1 .00 POOR
007 LANDSLIDE - - - - LANDSLIDE - LANDSLIDE 3 .00 3 .00 GOOD 8
008 0.16 0.50 0.16 0 .84 0.16 0.16 1.98 2.00 1.00
009 0.50 0.50 0.50 0 .84 0.16 0.16 2.66 2.00 1.00
010 LANS 1. IDE - - - - LANDSLIDE LANDSLIDE
01 1 0.50 0.50 0.50 0 .84 0.50 0.50 3 .34 2.00 3.00
012 LANDSLIDE - - LANDSLIDE - LANDSLIDE
013 LANDSLIDE - - LANDSLIDE LANDSLIDE .
014 LANDSLIDE - - LANDSLIDE ~ LANDSLIDE
015 0.50 0.50 0.50 0.16 0.16 0.50 2 .32 2.00 1.00
016 0.50 0 .50 0.50 0.16 0.16 0.16 1 .98 2.00 1.00
017 0.50 0.50 0.16 0.16 0.16 0.16 1 .64 1.00 1.00
018 0.16 0.50 0.16 0.16 0.16 0.16 1 .30 1.00 1.00 u
019 0.16 0.50 0.50 0.16 0.16 0.16 1 .64 1.00 1.00 **
020 0.16 0.50 0.50 0.16 0.16 0.16 1 .64 1.00 1.00 *
021 LANDSLIDE - - - ~ LANDSLIDE - LANDSLIDE
022 0.50 0 .50 0.16 0.16 0.16 0.84 2 .32 2.00 1.00 *
023 0.16 0.50 0.16 0.16 0.16 0.16 1 .30 1.00 1.00
024 0.16 0.50 0.50 0.16 0.16 0.16 1 .64 1.00 1.00
025 0.50 0.50 0.50 0.16 0.16 0.16 1 .98 2.00 1.00 4-
026 LANDSLIDE - LANDSLIDE - LANDSLIDE 4<
027 LANDSLIDE - LANDSLIDE LANDSLIDE
028 LANDSLIDE - - - LANDSLIDE ~ LANDSLIDE **
029 LANDSLIDE - LANDSLIDE LANDSLIDE
030 LANDSLIDE - - LANDSLIDE LANDSLIDE
03 1 0.50 0.50 0.50 0.16 0.50 0.16 2 .32 2.00 1.00 =*
032 0.16 0.50 0.50 0.16 0.16 0.16 1 .64 1.00 1.00
033 0.16 0.50 0.16 0.16 0.16 0.16 1 .30 1.00 1.00
034 0 .84 0.50 0.50 0.16 0.16 0.16 2 .32 2.00 1.00
035 FLOOD - * FLOOD - FLOOD *
03 6 FLOOD - FLOOD FLOOD
03 7 0.50 0.16 0.16 0 .84 0.16 0.16 1.98 2.00 1.00 *
038 FLOOD - - FLOOD - FLOOD *
03 9 FLOOD - - - FLOOD - FLOOD
040 FLOOD - - - - FLOOD FLOOD *
041 FLOOD - - - FLOOD - FLOOD >
042 FLOOD - - - FLOOD FLOOD
043 FLOOD - - - FLOOD - FLOOD
044 FLOOD - - - - FLOOD - FLOOD
045 LANDSLIDE - - - - LANDSLIDE LANDSLIDE -
046 LANDSLIDE - - - LANDSLIDE - LANDSLIDE
047 FLOOD - - - - FLOOD - FLOOD
048 FLOOD - - - - FLOOD FLOOD
049 FLOOD - - - ~ FLOOD FLOOD
050 0.50 0.50 0 .50 0.84 0.16 0.16 2 .66 2.00 1.00
Table 4-16. Open Space Analysis
Table 4-16. (continued)
Fig. 4-19. Suitability to Open Space
ooooooooo ooooooooo ooooooooo ooooooooo 005
SSSSSSSSS SSSSSSSSS SSSSSSSSS sssssssss 015
sssssssss sssssssss sssssssss sssssssss sssssssss sssssssss sssssssss sssssssss
sssssssss sssssssss 031
034 ppppppppp ppppppppp
ppppppppp ppppppppp ppppppppp FPFPFFFFF ppppppppp ppppppppp ppppppppp ppppppppp
SSSSSSSSS POTENTIAL SSSSSSSSS LANDSLIDE SSSSSSSSS
ooooooooo ooooooooo ooooooooo ooooooooo ooooooooo ooooooooo ooooooooo 063 064 065 066 067 068
ooooooooo ooooooooo ooooooooo ooooooooo ooooooooo ooooooooo ooooooooo ooooooooo 074 073 072
077 078 079 080 081 082 083 084
090 089 088 087 OF6 085
OOOOOOOOO OPEN SPACE 100 101 102
6 _.... z e
CELL 4 GEOLOGY SOIL FLOOD SOLAR TO STREET TO W & S NOISE TOTAL GRADE
001 OPEN OPEN OPEN OPEN OPEN OPEN OPEN _ OPEN
002 OPEN OPEN OPEN OPEN OPEN OPEN OPEN - OPEN
003 OPEN OPEN OPEN OPEN OPEN OPEN OPEN - OPEN
004 OPEN OPEN OPEN OPEN OPEN OPEN OPEN - OPEN
, 005 0 .84 0.16 0.16 0.16 0.50 0 .84 0 .84 3.50 2.00
006 0 .84 0.16 0.16 0.50 0.50 0.84 0 .84 3 .84 2.00
. 007 LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE - LANDSLIDE
008 0 .84 0.50 0 .84 0.16 0.50 0 .84 0.84 4.52 2.00
009 0 .so 0.50 0.50 0.16 0.50 0 .84 0.84 3 .84 2.00
0 10 1 Ut I I* ONOSL I DE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE - LANDSLIDE
0 1 1 0 SO 0 NO 0 .SO 0.16 0.50 0.84 0.50 3 .50 2 .00
0 1 i I im . AMill 1 : w l AWOSllDC LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE - LANDSLIDE
01 1 11* . Am>+i | :m LAOOtLlDC LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE
0 1 4 i 11 AWU% i i lit i ao*l 11: LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE * LANDSLIDE ,,
0 l % 0 SO 0 NO 0.16 0.84 0.84 0.84 0.84 4.52 2 .00
01b 0 .so 0 SO 0.16 0.84 0.84 0.84 0 .84 4.52 2 .00 *
017 0.50 0 .SO 0.50 0.84 0 .84 0 .84 0 .84 4 .86 3 .00 i I.
018 0.84 0.16 0 .50 0.84 0 .84 0.84 0.84 4.86 3 .00
019 0 .84 0.16 0.16 0.84 0 .84 0.84 0 .84 4.52 2 .00 *
020 0.84 0.16 0.16 0.84 0.84 0.84 0 .84 4.52 2.00 N
021 LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE 1-
022 0.84 0.16 0.84 0 .84 0.84 0 .84 0.84 5.20 3 .00 -
023 0.84 0.16 0.50 0.84 0.84 0 .84 0 .84 4.86 3 .00
024 0 .84 0.16 0.16 0.84 0.84 0.84 0.84 4 .52 2 .00 .
025 0.50 0.16 0.16 0 .84 0.84 0 .84 0 .84 4.18 2 .00
026 LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE
027 LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANUbLi UE LANDSLIDE *5
028 LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE - LANDSLIDE
029 LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE
030 LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDbLIDfc. LANUb L fDE ..
031 0.50 0.16 0.16 0 .84 0.84 0.50 0.50 3.50 2 .00
032 0.84 0.16 0.16 0.84 0.84 0.50 0.84 4.18 2.00
033 0.84 0.16 0.84 0.84 0.84 0.50 0 .84 4.86 3 .00 4J
034 0.50 0.16 0.16 0.84 0.84 0.50 0.84 3 .84 2.00
035 FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD - FLOOD 2
036 FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD :
037 0.50 0.50 0.50 0.16 0 .84 0.50 0 .84 3 .84 2 .00 v
038 FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD r
039 FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD
040 FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD
041 FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD
042 FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD - FLOOD
043 FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD - FLOOD
044 FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD - FLOOD
045 LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE
046 LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE
047 FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD
048 FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD - FLOOD
049 FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD
050 0.50 0.50 0.16 0.16 0.50 0.50 0 .84 3 .16 2 .00
Table 4-17. Residential Analysis
i.v.......... .................... .... ..................... . _______________________________________________
051 0.84 0.16 0.16 0.16 0.50 0.50 0 .84 3.16 2 .00
052 0.84 0.16 0.50 0.16 0.50 0.50 0 .84 3.50 2 .00
053 0 .84 0.16 0.50 0.16 0.50 0.50 0 .84 3.50 2.00 *
' 054 0 .84 0.16 0.16 0.16 0.50 0.50 0 .84 3.16 2 .00
055 0.84 0.16 0.50 0.16 0.50 0.50 0.50 3.16 2.00
056 FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD - FLOOD
I 057 FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD FLOOD - FLOOD
058 0 .84 0.16 0.50 0 .84 0.50 0.50 0.50 3 .84 2.00
059 LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE LANDSLIDE
, 060 OPEN OPEN OPEN OPEN OPEN OPEN OPEN - OPEN
061 OPEN OPEN OPEN OPEN OPEN OPEN OPEN OPEN
062 OPEN OPEN OPEN OPEN OPEN OPEN OPEN - OPEN
063 0.50 0 .84 0 .84 0.50 0.16 0.50 0.50 3 .84 2 .00
064 0.50 0 .84 0.16 0.50 0.16 0.50 0.50 3 .16 2 .00
065 0.50 0.84 0.16 0.50 0.16 0.50 0 .84 3.50 2 .00
066 0.50 0 .84 0.16 0.50 0.50 0.50 0 .84 3 .84 2 .00
067 0.50 0 .84 0.16 0.50 0.50 0.50 0 .84 3 .84 2.00
068 0.50 0.84 0.16 0.50 0.50 0.50 0.84 3 .84 2 .00 ..
069 0.50 0 .84 0 .84 0.50 0.50 0.50 0 .84 4.52 2 .00
070 0.50 0.84 0.84 0.50 0.50 0.50 0.84 4.52 2.00
071 0.50 0 .84 0 .84 0.50 0.50 0.50 0 .84 4 .52 2 .00
.. 072 0.50 0 .84 0.84 0.50 0.16 0.50 0.50 3 .84 2 .00
073 0.50 0.84 0.50 0.50 0.16 0.50 0.50 3 .50 2.00 *-
.1 074 0.50 0.84 0.16 0 .50 0.16 0.50 0.50 3.16 2 .00 **
075 OPEN OPEN OPEN OPEN OPEN OPEN OPEN OPEN x>
076 OPEN OPEN OPEN OPEN OPEN OPEN OPEN - OPEN n
077 0.50 0.84 0.50 0.16 0.16 0.50 0.16 2 .82 2 .00 "
078 0.50 0.84 0 .84 0.50 0.16 0.50 0.16 3 .50 2 .00
J 079 0.50 0.84 0.84 0.50 0.16 0.50 0.50 3 .84 2.00
080 0.50 0.84 0 .84 0.50 0.50 0.50 0.50 4.18 2 .00 *
081 0.50 0 .84 0 .84 0.50 0.50 0.50 0.50 4.18 2 .00 ..
.. * 082 0.50 0.84 0 .84 0.50 0.84 0.50 0.50 4.52 2 .00
083 0.50 0 .84 0 .84 0.50 0.84 0.50 0 .84 4.86 3 .00 *<
084 0.50 0 .84 0.84 0.50 0 .84 0.50 0.84 4 .86 3 .00
1 085 0.50 0.84 0 .84 0.50 0 .84 0.50 0.84 4 .86 3 .00
J 086 0.50 0 .84 0 .84 0.50 0 .84 0.50 0.50 4 .52 2 .00 *
087 0.50 0 .84 0 .84 0.50 0.84 0.50 0.50 4.52 2.00
088 0.50 0.84 0.84 0.50 0.50 0.50 0.50 4 .18 2 .00
089 0.50 0.84 0 .84 0.50 0.50 0.50 0.50 4 .18 2 .00 *
090 0.50 0.84 0 .84 0.50 0.16 0.50 0.16 3 .50 2 .00
091 0.50 0.84 0.84 0.50 0.84 0.16 0.16 3 .84 2 .00
092 0.50 0 .84 0 .84 0.50 0.84 0.16 0.50 4.18 2 .00 x
093 0.50 0.84 0 .84 0.50 0.84 0.16 0.50 4.18 2 .00
094 0.50 0.84 0.84 0.50 0.84 0.16 0.50 4.18 2 .00
*; 095 0.50 0 .84 0.84 0.50 0.84 0.16 0.50 4.18 2 .00
096 0.50 0 .84 0 .84 0.50 0.84 0.16 0.50 4.18 2 .00
097 0.50 0.84 0.84 0.50 0.84 0.16 0.50 4.18 2 .00
098 0.50 0.84 0.84 0.84 0.84 0.16 0.50 4.52 2 .00
099 0.50 0 .84 0 .84 0.50 0.84 0.16 0.16 3 .84 2.00
100 0.50 0.84 0.84 0.84 0.50 0.16 0.16 3 .84 2 .00
101 0.50 0.84 0 .84 0.84 0.50 0.16 0.16 3 .84 2 .00
102 LAKE LAKE LAKE LAKE LAKE LAKE LAKE LAKE
103 LAKE LAKE LAKE LAKE LAKE LAKE LAKE - LAKE
104 0.50 0.16 0 .84 0 .84 0.50 0.16 0.16 3.16 2 .00
Table 4-17. (continued)
Fig. 4-20. Suitability to Residential Development
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044 043 042 041 040 039 038 FFFFFPFFF
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045 046 047 048 049 FFFFFFFFF FFFPFFFFF FFPFFFFFF
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1) Land Suitability Map (Fig. 4-21)
All of the results were arranged into base map. (Fig. 4-21) This map shows a pattern of development. (Table 4-18)
Table 4-18. Development Pattern
Developable Land 62.5 % (159 ac.)
Open Space 37.5 % ( 96 ac.)
2) Preliminary Land Use Plan (Fig. 4-22)
According to the land suitability map, a preliminary land use plan is suggested in conclusion. First, 100 year flood plains (light blue) ere protected from any development. In highly restricted open space (dark green), there is a pssibility of landslides. This area should be planted or lanscaped, in order to be preserved. The area between the two flood streams (dark blue) might be considered as a water feature for recreation or detention purposes. The site where the original farmstead was settled (dark brown) might be considered for historical preservation. The rest (light green) was considered as parkland.
For residential development, multi-family housing development (brown) was suggested for the northern portion of the remaining developable land, while single-family housing development was suggested for the southern portion, (yellow)
Interms of solar accessibility, it was assumed that the northern
Land Suitability Map
portion (south slope) is more suitable for highrise development (2-4 stories) than the southern portion (east slope). (refer to Chapter IV. p.60)
1. Wallace R. Hansen and Eleanor J. Crosby, Geology of the Front Range Urban Corridor Environmental and Vicinity,
Colorado, p. 8 10
2. Richard Unterman and Robert Small, Site Planning for
Cluster Housing, p. 203
3. Wallace R. Hansen 73 and Eleanor J. Crosby, op. cit., p. 70
4. Ibid., p. 75 -76
5. Ibid., p. 68 69
6. William M. Marsh, Landscape Planning, p. 90
7. William M. Marsh, Environmental Analysis , p. 136
8. William M. Marsh, Landscape Planning, p. 176
9. source: Urban Drainage and Flood Control District, 1979
10. John S. Crowley and L. Zaurie Zimmerman, sive Solar Design, p. 23 24 Practical Pas-
1 1 . Ibid., p. 25
12. Ibid., p. 26
13. U. S. Dept, of Transportation, Transportation Noise and
its Control, p. 17
14. Ibid., p. 17
15. Ibid., p. 26
16. Vergil G. Stover, op. cit., p. 3.1 3.17
17. source : Adams County Comprehensive Plan , 1984
LAND SUITABILITY STUDY
LAND USE PLAN
Fig. 4-22. Land Use Plan