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01.1 What is this course about and what are some of the
GIS has matured sufficiently to handle complex urban, social, economic, and/or environmental problems providing further motivation for casting GIS work in terms of a decision support approach. The principal motivation for focusing on planning, improvement programming and implementation decision work within urban-regional land, transportation, and water resource settings is that decision activity in such settings is pervasive within communities around the world. The Regional and Urban GIS: A Decision Support Approach textbook was written to carry that message.
01.2 Define GISystems in terms of three perspectives; and what
is the advantage of using those three perspectives?
GIS: a combination of hardware, software, data, people, procedures, and institutional arrangements for collecting, storing, manipulating, analyzing, and displaying information about spatially distributed phenomena for the purpose of inventory, decision making and/or problem solving within operations, management, strategic contexts as related to issues at hand.
- The three perspectives drawn out through this definition:
- a) Components of a system-
- a combination of hardware, software, data, people, procedures, and institutional arrangements
- b) Processes used in working with the system-
- for collecting, storing, manipulating, analyzing, and displaying information about spatially distributed phenomena
- c) Motivation for system use (each of these is also a process)-
- for the purpose of inventory, decision making and/or problem solving within operations, management, strategic contexts as related to urban issues.
- GIScience – the conceptual underpinning of systems development and use.
- GIServices – the use of Cyberinfrastructure to host Web Services
- GISociety – the influence of GIS on society and society on GIS
01.3 What is the significance of GIS as a decision support
RUGIS Chapter 1 Section 1.1.4 GIS as Decision Support Systems
Two decades ago David Cowen (1988) described GIS as a decision support system involving the integration of spatially referenced data in a problem solving environment.
- Basic decision aids of GIS
- - data management as an aid to extending human memory,
- - graphic display as an aid to enhanced visualization, and- spatial aanalysis functions to extend human computing performance.
- Beyond these GIS-common decision aids
- - Special features include modeling, optimization, and simulation functions required to generate,evaluate, and test the sensitivity of computed solutions.
- - Other functions such as statistical, spatial interaction, and location/allocation models can befound in special GIS software packages.
- Instead of expanding a GIS toolbox indefinitely by adding new models and procedures,
- - modelers provide application programming interfaces (APIs).
- - API allows enhancing the decision support function of GIS by adding models that supportvarious capabilities.
Examples of such decision aiding models linked with GIS include various environmental models andmultiple criteria decision making (MCDM) models used for evaluation of land planning decisions.
Developers of special GIS decision support software – called spatial decision support systems (SDSS)
- Strategies of linking analytical models with GIS.
- - file exchange mechanisms (so called loose coupling),
- - data exchange protocols such as dynamic data exchange (so called tight coupling),
- - implementations of predictive/prescriptive models and decision support functions in GIStoolboxes (so called embedded coupling).
- Linking analytical models with GIS have been recently expanded by various software technologies
- open source programming languages
- Sun MicroSystems Enterprise Java Beans
02.1 What is the significance of decision situation topics
land resource, transportation resources, and water resources management?
Land, Transportation, and Water Resource Management
Many people would agree that land, transportation, and water resources, and the relationships between and influences among them are fundamental issues in an urban and regional context. Each of those substantive topics when taken separately and when addressed together can benefit from an integration of GIS and decision analysis.
- Land Resource Decision Issues
- •Landscape/land cover – the “lay of the land” in regards to surface characteristics.
- •Land parcel ownership – rights to a surveyed portion of land for carrying out various kinds of activities; this ownership can be public, private, quasi-public.
- •Land zoning – the permissible uses for the portion of land according to certain regulations as defined by the governing body having jurisdiction over the land. Land is zoned for certain uses, while other uses are prohibited to reduce external effects.
- •Land use – relationship between particular parcels and their interpretation of use, e.g. commercial, residential, industrial, or recreational uses all have particular externalities.
- •How should we reduce land environmental hazards when use results in degraded landscape, prohibiting certain kinds of land uses to take place safely?
- Transportation Resource Decision Issues
- •What approaches should we use to address sustainable transportation development issues, all having geospatial implications? Some approaches include Vehicle / Fuel Technological Changes, Road / Vehicle Operations Improvements, Demand Management
- •Mobility improvement within a transportation system often requires social and environmental disturbance mitigation. Impact analysis can be performed to compute the degree and nature of disturbances associated with various alternatives for transportation system improvements. Choosing among the alternatives is a matter of minimizing or maximizing the beneficial/detrimental impacts associated with those alternatives. Mitigation involves increasing the beneficial impacts while reducing the detrimental ones. What mitigation approaches are better than others in the context of a particular transportation system?
- Water Resource Decision Issues
- •Impacts on environment and people often involve a tradeoff among improving conditions. Farmers and salmon both need Columbia River water. Giving to one is taking from the other. How can we balance conflicting needs by considering the location and changes in water flow through dams?
- •Access to fresh drinkable water continues to be a major global problem. Groundwater and surface water rights and resources are sometimes managed separately, but they have an influence on each other. How should we management them together as an integrated resource?
- •How can we address water quality, and in particular water contamination, as a significant public health issue?
02.2 What is the significance of decision situations for
planning, improvement programming, and project implementation?
The terms “planning, programming, implementation, management, and decision making” show up in books of all kinds. A sixth is considered “emergency situations”. Unforeseen circumstances occur from time to time for which we might act in the current to be prepared for such emergency circumstances. How can we sort out the use of these terms so we can feel comfortable using them?
Our focus is on planning, programming, and implementation decision support situations, and particularly land, transportation, and water resources, due to their routine and pervasive nature. That does not mean we cannot understand the nature of emergency management decisions, as we will clarify a little later in its relationship to PPI.
A plan is implemented over a long period of time. From time to time (e.g. every 5 years) plans are updated, as are the transportation plans for metropolitan planning organizations across the U. S. as mandated by federal law.
Capital improvement programs fund capital improvement projects across a six-year time period, composed of a two-year scope, two-year design, and two-year build phases. Budgeting for water recycling capital improvement programs commonly occurs every two years to move projectsalong, and address several facilities at a time – the priority list. A program is commonly linked to a plan, e.g. transportation or water resource plan, whether it is broad-based comprehensive plan or single-purpose functional plan. Consequently, a program is the implementation of a plan.
Project implementation is initiated and completed to build out a plan as funded through a program. Projects differ in size from very large (mega) projects to rather small projects.A mega project is a redevelopment of an Interstate Highway Corridor for several miles or a large bridge or a regional wastewater facility. Those size projects could cost hundreds of millions of dollars. A small project would be realignment at a two-lane highway intersection for perhaps a few hundred thousand dollars, or the redevelopment of a park.
Emergency management can be considered the “compression” of all three plans, programs, project implementation within two different contexts: mitigation and response. In any case, our focus will be on each of the decision activities of planning, programming, and implementation, and how plans, programs and projects are linked. As such, there is a direct connection between community values and plans.
Consider this observation by Lewis Hopkins, from his book Urban Development: The Logic of Making Plans that speaks to underlining considerations in planning…
“Plans are meaningless without intentions, and intentions are derived from knowledge and values. Intrinsic values set the basis for deriving instrumental values by determining what values will not be traded off with others. Instrumental values organize means by establishing how much something is worth as an input to achieving these intentions. These values are at least in part derived from individuals and are inherently subjective. Values might be assessed objectively, that is, assessed in such a way as to be replicable if assessed by some other observer of the subject. Values are better interpreted, however, as inter-subjective, which implies that both an individual’s interests may be distorted and that socially shaped values may lead to desirable behaviors. Shaping attitudes about the consumption of land for urban uses may be more effective toward the survival of humans and other species than either regulations or incentives directed at behavior.” (Hopkins 2001 p. 168)
If we are unclear about the assessment level of the values referred to in the above quoted passage, then we risk losing some values and/or misprioritizing other values.
3.1 How have local governments regulated growth through conventional approaches?
- Public sector is the regulator of community activity – standard approaches
- - Why regulate? reduce external affects of people’s actions on other people, i.e. reduce resulting effect
- - Many of 19,000+ municipalities are too small and 3,100 counties in U.S. not growing rapidly for “specific growth regulations”, but land use law has been in place for a while
- Common techniques for conventional regulatory approaches that jurisdictions use across decision situations.
- - Planning decision situations
- 1) comprehensive plans : 10 to 20 year horizon, multiple scales and foci (Plate 2.1, Fig 2.1)
- 2) subdivision regulations and plans: developer plans required when land subdivided (Fig 2.2)
- - Improvement programming decision situations
- 3) capital improvement programs: infrastructures to serve the public e.g., streets, parks, waterways, etc. (Plate 2.2)
- - Project implementation decision situations
- 4) zoning ordinances: most common of regulatory instruments (Plate 2.3)- concerns them all
- 5) Public participation is a growing challenge for governments
A major problem involves the disconnects between/among issues within decision situations due to complexity.
03.2 What are growth management approaches; and what is the difference between a top-down and bottom-up approach to growth management? RUGIS Chapter 2 Section 2.2
- What’s different in Growth Mgt than under conventional regulatory approach?
- - More recently communities identify “what seems to be a growth problem as a specific category”.
- - A way of organizing community efforts to anticipate future development and problems that might occur.
- Approaches/Techniques for growth management stem from community concerns:
- •Concern: managing the location and character of community expansion,
- Technique(s) to address concerns: e.g. urban growth boundary, development policy area, infill-redevelopment, and others
- •Concern: preserving natural resources and environmental qualities and features
- Technique(s) to address concerns: e.g. land acquisition, conservation zoning, water quality/erosion control regulations, delineating critical areas, and others
- •Concern: ensuring efficient provision of community infrastructure
- Technique(s) to address concerns: e.g. functional infrastructure plans, facility exaction, impact fees, transportation demand mgt. and others
- •Concern: maintaining or creating desirable quality of community life
- Technique(s) to address concerns: e.g., design reviews, incentive and performance zoning (bonuses for mixed use and density), historic preservation and others
- •Concern: improving economic opportunities and social equity
- Technique(s) to address concerns: e.g., economic development incentives, affordable housing programs and others
- •Concern: regional and state guidance of community development
- Technique(s) to address concerns: e.g., coordination of local planning, development review having regional impact and others
Each of those problems involve(s) a type of “change in a community”. Thus, a geographic information system database as an inventory of phenomena/features across space and time is one way of representing a basic understanding of that change. For example, change in land use activity as in housing and commercial development; change in transportation activity as in the mobility freight and people; and change in water resource activity as in the degradation of waterways. These are sample of the growth management concerns that can be addressed by a set of maps for various time periods.
In Washington State, "[c]urrently, 29 counties and 218 cities (representing 95 percent of theState’s population) are fully planning under the [Growth Management Act or] GMA. Remaining ten counties and their cities are planning for resource lands and critical areas only." (Washington State 2006, p. 1) To implement a comprehensive plan and organize access to information about growth management, the Washington State Growth Management Act (GMA 1991), specifies that a comprehensive plan can be a set of maps and/or a geographic information system.
The goals for such plans (hence the maps that are expressions of those plans) are the following.
- Summary of Washington State Growth Management Act Goals
- - Encourage development in urban areas where public facilities and services exist or can be efficiently provided.
- - Reduce urban sprawl.
- - Encourage efficient, multimodal transportation systems.
- - Provide affordable housing for citizens of all income levels, promote a variety of housing densities and types, and preserve the existing housing stock.
- - Promote economic opportunity consistent with the capacities of the state's natural resources and public services and facilities.
- - Respect private property rights.- Provide timely, fair and predictable permit review processes.
- - Conserve and enhance natural resources.
- - Retain open space, conserve fish and wildlife habitat, increase access to natural resource lands and water, and provide recreational opportunities.
- - Protect the environment and enhance the state's high quality of life.
- - Encourage citizen participation in the planning process and ensure coordination among jurisdictions.
- - Ensure that public facilities and services are adequate.
- - Preserve historic and archaeological resources.
- GIS capabilities are needed to address almost all of those goals in a direct manner.
- Many counties use similar capabilities as in the following.
- See Table 2.3 GIS Growth Management Web GIS Services Accessible to Public(Alchua County 2006b)
03.3 How can we compare and contrast growth management and sustainability management in terms of competing objectives and generational equity?
RUGIS Chapter 2 Section 2.3 Comparing Growth Management and Sustainability Management
Drawing growth management and sustainability management views into focus, we suggest a perspective about “community and regional sustainability”, that makes use of Farrell and Hart’s (1998) description about competing social, economic, and environmental objectives for communities that may or may not be considered together with carrying capacities, and Rees’ (1998) description about the importance of generational equity in sustainable community developmen
tSee Figure 2.3 A framework for characterizing community and regional sustainability in terms of three levels - weak, semi-strong, and strong. Weak and semi-strong sustainability can be considered growth management in some circumstances.
03.4 Which of the five dimensions for decision situations provides the most leverage for integrating situations?
- Table 2.4 Five Dimensions for Integrating Planning, Programming, and Implementation
- (1)functional activities - land use, transportation, and water resources
- (2)community conditions - social, economic, and environmental
- (3)decision process scales - planning, programming, and implementation
- (4)geographic scale - regional, county, city-wide, small area
- (5)temporal scale - strategic, tactical management, operational
The best dimension to use depends on the decision situation at hand, but functional activities and decision process scales are by far the most common basis for linking situations broadly speaking. Community conditions, geographic scale and temporal scale are used for addressing detailed linkages in data. We will consider a number of these dimensions throughout the course.
An integrated, situation assessment can be undertaken by taking those dimensions (within Table 2.4) two at a time (in pairs) as is depicted in Table 2.5
Investigating any two columns or any two rows within the table constitutes an integrated, situation assessment. One can choose an analytic interest that is any two rows and/or columns simultaneously. Such a choice implies that the third, fourth, and fifth dimensions are taken as “control” dimensions, i.e., that is they do not change in the particular situation assessment at hand.
04.1 What are two types of projects used in this course?
- To undertake a GIS project we make use of one or more methods.
- •Method - sequence of steps in which data are processed to carry out GIS workflow
- •Method step - contains one or more techniques for collecting, storing, preparing, analyzing, and displaying data.
- •Technique - basis for performing an operation on data; a GIS capability, implemented as a software tool
Pull those ideas together into a “GIS decision support project”. For this course, be aware of difference between a GIS project and a community improvement project.
The term community project has a special significance when it comes to improving communities, particularly to planners, public works directors, council people, and the stake holding public (a reference to those who care). For example, a wastewater treatment facility is a community improvement project, but the process of siting such a community project as presented in the case study provides a step by step method for undertaking a GIS project.
The GIS project is the data processing activity (i.e., analysis of information to identify facility location). “Project” will likely always require one or more adjectives in order to keep the idea straight. GIS project method is a workflow intentionally structured to carry out data processing activities. GIS projects make use of fundamental capabilities during a workflow.
04.2 What are some of the basic capabilities of GIS?
Types of GIS software capabilities perform decision support activities.GIS software capabilities (also called functions) operate with data, transforming data into information. As such, GIS software capabilities perform GIS-based transformations.
- GIS transformations - facilitate a transition “from data to information” by processing the elements of a database (as constituents of a map) and deriving their
- a) spatial properties and/or relationships, e.g., distance, direction, pattern, and/or
- b) non-spatial properties and/or relationships, e.g. set membership, greater or less than, and/or
- c) temporal properties and relationships, interval of time, and/or
- d) a combination of those depending on complexity of operations used.
In ArcGIS, a user has access to GIS capabilities through wizard-like tools, i.e., software implementations of specific functions. The tools are grouped into toolsets, which in turn comprise toolboxes. Table 3.1
identifies some general categories of GIS capabilities typical tomost GIS. We can see that some toolboxes contain tools that operate on various aspects of thedecision problem, content, structure, and process.
Counting the number of entries (X) for each toolbox across the table columns reveals that DataManagement tools and the Map Visualization tools are the most versatile in terms of addressinginformation needs in general.
Toolboxes (hence tools) are presented in an order in which a GIS analyst might encounter them.
: Geocoding also called georeferencing is the process of assigning a location,usually in the form of coordinate data values to a feature.- assigns a coordinate to a feature, e.g, like assigning street addresses to coordinates.- creation, maintenance, and deletion of address locators, including coordinates.
Linear referencing is a measuring system for linear features such as river mile and routemilepost. These tools are found in their own ArcGIS toolbox, but they are of the same generalclass of functions as geocoding tools. A linear reference is a geocode along a linear feature.
Data Management Tools
: capabilities to perform tasks from managing basic structures, such asfields and workspaces, through projecting and reprojecting coordinates of features/raster cellscomprising a geodataset, to more complex tasks related to topology and versioning.
- Tools can be organized around toolsets, which are data management function-specific.
- - Fields toolset contains tools that make changes to the attributes fields of a feature class
- - Joins toolset contains tools that add and remove a table join;
- - Relationship Classes toolset contains tools that create associations between feature classes, andbetween feature classes and tables, and the
- - Raster toolset contains tools that create and manipulate raster datasets.
- Map Visualization Tools : capabilities we use to compose displays. Although some GIS likeArcGIS have a separate software module for performing map visualization, the packaging of toolcapabilities is really a result of a “product offering”, i.e., how to make tools available within aproduct for supporting customer needs (aka marketing), rather than overall functional similarity.
- - add, delete, and change data layers on a map.
- - change the symbolization on a map.
- - highlight features on a map, either by location or by attribute.
- - pan, zoom, identify various features within a data layer, and measure distances betweenfeatures.
- Feature Analysis Tools : offer processing for feature (vector data model) spatial relationships.Commonly these contain sets such as Extract, Overlay, Proximity, and Statistics.
- - Extract toolset contains tools employing attribute and/or spatial queries to extract features andtheir attributes;
- - attribute queries utilize relational (e.g. >, <, =) and/or Boolean (AND, OR, XOR)operators;
- - spatial queries utilize spatial relationships of distance, containment, overlap, andintersection to extract features.
Grid Analysis Tools
- - Overlay toolset contains tools to combine, erase, modify, or update spatial features. All ofthese tools involve transforming two or more existing sets of features into a new single set offeatures exposing spatial relationships between the input features.
- - Proximity toolset contains tools to determine the proximity of features within a feature set. Tools can identify features that are closest to one another, calculate the distances around them, and calculate distances between them. A buffering tool to create an exclusionary or inclusionary zone around a feature is one of a distance-based tool.
- - Statistics toolset contains tools for computing descriptive statistics on attribute data. The statistics include frequency count of each unique attribute value, mean, minimum, maximum, and standard deviation.
: contain capabilities for analyzing continuous surfaces represented by grid cell (raster data model) layers. Map algebra (ArcGIS Spatial Analyst extension) is the GIS language of spatial analysis for continuous surfaces offering a set of functions for individual raster cells, cell neighborhoods, cell regions, and an entire raster layer.
Network Analysis Tools
: support GIS analysts for performing tracing along networks. There are many different kinds of networks, based on the feature behavior. Electric networks are not the same as natural gas networks, which are not the same as highway networks, or sewer networks, or for that matter storm sewer networks are very different than water supply networks.
When to apply certain of the tools from the toolsets is a matter of GIS project workflow, that is how we should sequence the GIS operations to perform work.
04.3 How might we describe a basic GIS-based workflow approach?
Let us use first explore a simplified workflow approach for a GIS project. What kinds of tools might be used?
- 1) Identify project objectives (e.g. concerns about growth of wastewater and how to address it)
- e.g., What is the problem to be solved, e.g., in terms of criteria as in Table 3.2?
- Who is the intended audience?
- Will data be used again?
- What are the final products expected?
- 2) Create a project database (for examining the wastewater facility location problem)
- e.g., Designing the database (lab assignment is rather simple – naïve - in this regard)
- Acquiring the data (for example from various organizations as in Table 3.3)
- Automating/preparing the data for further analysis (as in Figures 3.1, Table 3.4)
- Managing the data
- 3) Analyze the data (to identify several options for location suitability)
- e.g., geometric modeling as in calculating distances, generating buffers;
- calculating area coincidence modeling as in overlaying data layers;
- adjacency modeling as in path finding, nearest neighbor, and allocating
- (Example analysis workflow See Figures 3.2, 3.3, 3.4)
- 4) Present the results (of the analysis) to those interested
- e.g., create a particular type of map (Example sketch layout See Figure 3.5)
05.1 How might we describe a nuanced GIS-based workflow method?
Some times decision problems are a bit more complicated or complex. Carl Steinitz (40 years of GIS at Harvard) developed a landscape modeling workflow process to address complex, regional planning decision problems, we will call a nuanced workflow. The workflow can be used for planning, improvement programming and project implementation. However, the content, structure, process, and context of decision problems would likely be different since the information needs are different in each of those situations.
The six-phase nuanced workflow method has been applied in practice in several GIS-related projects that address urban-regional landscape issues over the past ten years or so around the world (See the bibliographic references to Steinitz in the textbook). In January 2010 at a GeoDesign Summit, Esri President Jack Dangermond highlighted the Steinitz landscape modeling approach calling it one of the foundational methods in GeoDesign.
Phases are framed by a set of critical questions that you can ask yourself (or your colleagues).
- 1) Representation Modeling
- In a nuanced method, GIS analysts should be asking questions like:
- - How should the state of the urban-regional community with regard to the particular issue at hand be described in terms of a database design that is modeled as value trees or value hierarchies?
- - What data categories are to be represented by measurements of attributes, space, and time?
- - Whose concerns about these design questions should we consider? Are there other groups that should be consulted to make sure we have incorporated all the relevant data into the representation model?
Complex decision problems are fraught with various interpretations of concerns about urban-regional communities. Stakeholder perspectives from diverse groups, even if these are groups within a single organization tend to align with various concerns, often these are called stakeholder interests. It can be said that those differences of interest are the basis of stakeholder groups. Working with a variety of stakeholder groups on an oil leasing decision problem in the Santa Barbara Channel, Edwards and vonWinterfielt (1987) organized stakeholder interests into value trees (values, goals, objectives, criteria) to show the similarities and differences among environmental, social and economic objectives and criteria according to different stakeholder groups. Where did the information from Table 3.2-3.4
come from for arriving at a database design (content categories and structure of the database)?
Lot more on value trees and databases when we get to a deeper look into database design…
- 2) Process Modeling
- Several questions could be posed related to a process model.
- - If a representation model forms a categorical content and structure foundation for a process model, then how might we examine relationships among land use, transportation, and environmental elements over time as a basis for articulating process?
- - What are the relationships among the spatio-temporal elements, such as land use and transportation, that provide us insight and better understanding of urban-regional process?
- - What land use, transportation, and or water resource processes do we need to consider?
- - How does the land use, transportation, and or environmental transformation process work?
Urban-regional growth processes need be considered if we are to better understand how communities change. Porter (1997) characterizes growth in America’s communities as being mostly driven by land use change. Landscape change is commonly a land use change issue (Steinitz et al. 2004). Land use change is supported by access to transportation, as it is very difficult to get to places without transportation infrastructure, e.g. like highways or bikeways. The land use and transportation theme connection is fundamental in growth management. Graphic in Figure 3.6
shows a process of wastewater flow.
- 3) Scenario ModelingSeveral questions could be posed as related to a scenario model.
- - How does one judge whether the current state of the urban-regional environment is working well?
- - What are the metrics of judgment, e.g., esthetic beauty, habitat diversity, cost, nutrient flow, public health, public safety, and/or user satisfaction, in order to evaluate the nature of change?
- - Which of these do we want to consider in a scenario? How many can people consider without getting lost within an information glut?
A process model forms a functional foundation for a scenario model. Scenario models develop out of tweaking assumptions about processes, as we can change the input to a process. Given a different set of assumptions about how change might occur, we can generate a variety of scenarios. Sometimes people refer to scenarios as “worst case” or “best case”. Those references must be explicit about what “worst” means and what “best” means. This comes back to understanding values, goals, objectives and criteria that are part of scenario descriptions. Figure 3.7
highlights a portion of wastewater flow.
- 4) Change Modeling
- Several questions could be posed as related to a change model.
- - By what actions might the current representation of the urban-regional landscape be altered, whether conserving or changing the landscape in regards to what, who, where, when, how much, how many, etc.?
- - At least two important types of change should be considered. One is how the landscape might be changed by current trends. Modeling trend leads to a projection model as the basis of change.
- - A second could be, how might a community be changed by implementing design action? This leads us to developing intervention models as the basis of change. Intervention is a pro-active approach to change.
- - Again, how many variables can we consider in these models before being overwhelmed?
Many people say that the only constant in the world is change. A scenario model forms the basis of what to consider about change. Scenario models provide a foundation for change models as we take the “before conditions” and contrast them with “after conditions” for a particular scenario. The result of social, economic and environmental conditions that differ in a major way(or not) is the outcome of a change model. Plate 3.1
shows result of a change due to siting a facility.
- 5) Impact Modeling
- Several questions could be posed as related to an impact model.
- - A change model forms the basis of “what content, structure, process” change are important enough to consider as impacts, i.e. major changes that matter to someone?
- - What predictable impacts, i.e., the outcomes of changes, might those changes influence and/or cause?
- - What impacts are less predictable because changes and processes are not well understood?
Impact models are perhaps more difficult to construct than the previous models, because impact models rely upon good information output from all of the preceding models. Impacts due to urban-regional growth - whether land use impacts, transportation impacts, water resource impacts - are difficult to estimate. The difficulty arises from what is not known about processes. Although considerable data exist, when it comes to modeling impacts, we never seem to have enough of the right (aka appropriate) data. Figure 3.8
shows land parcels outside the river buffer that have not been excluded from site selection consideration.
- 6) Decision Modeling
- Several questions could be posed as related to a decision model.
- - How is a decision to change, conserve, and/or improve the “landscape” to be made in regards to urban-regional impacts?
- - How can a comparative evaluation be undertaken based on a sensitivity of impact change among alternative courses of action?
- - How are we to treat impacts in an equitable manner?
The reason this nuanced workflow process is so interesting is that the final model phase is a decision model. GIS has for a long time been touted as a decision support system (Cowen 1988). However, this nuanced workflow process makes this idea explicit and clear because of the inclusion of the decision modeling phase. One thing to remember is that all previous models lead to this model. An impact model forms the foundation for how to characterize alternatives for a decision process as in Figure 3.9
. Weighting of objectives (site criteria), whereby area size is given the most weight (20 out of 100 points), and elevation and distance to floodplain the least (10), generates map in Figure 3.10, whereby site 64 is ranked the highest. When we trade-off one impact against another we can set priorities for what we value. Chapter 7 of this book will get into much more detail about these issues.
Facing UNCERTAINTY in Modeling
- What if we do not have the time, resources, insight, and/or data to undertake all of the above models? If not, then we introduce information uncertainty into the GIS workflow process. It is better to know by intention than by ignorance.
05.2 What is a synthesized GIS-based workflow method? RUGIS Chapter 2. Section 3.2.3
Comparing the two workflow methods, we see similarities and differences in the phases.
Combining them articulates a synthesized method (Table 3.5). Removing the process modeling phase and combining the change and impact modeling phases makes the nuanced workflow look similar to the simplified (basic) workflow. Every time we eliminate one of the six phases weintroduce additional information uncertainty into the resulting information in our GIS project. Eliminating the process modeling phase means that we do not have insight into the details of process change that underlie scenario development. Eliminating change modeling leaves the impact models in a naïve state – no information about change makes the impact information somewhat uncertain. What is a GIS Analyst to do? Can you/we/organization/community live with the uncertainty? Why or why not? Throughout your lab assignments, consider where information uncertainty is added to the workflow process.
06.1 How might you characterize the difference between closed systems decision problems and open systems decision problems?
If we could enumerate all parts of a system, then we would have a closed system. If we cannot enumerate all parts of a system then we have an open system. The two types of problems are intertwined. The wastewater flow problem is at the core of the wastewater facility site planning problem. Content, structure, process, and context of the waste water flow decision problem are all part of the location decision problem, whether planning for a single or multiple sites. We can consider those components to help differentiate simple, difficult, complicated, and complex systems problems.
See Table 4.1 for components of a decision problem viewed from a “systems” perspective
06.2 How do we use decision situation assessment to improve our understanding of GIS-based workflow from a general level perspective? RUGIS Chapter 4 Section 4.2.1
We can undertake assessment at four levels of detail; each level should be customized to your “need to know” more about the decision problem. Let’s consider the wastewater recycling facility plan you are developing for Green County (King County?).
- A general level assessment considers the three major concerns (See Figure 4.1).
- -What are the concerns about convening a decision situation?
- -What are the concerns about the process involved in a decision situation?
- -What are the concerns about the outcomes of a decision situation?