Colorado State University

IPDSS - The Integrated Planning Decision Support System

The IPDSS can assess natural hazards and vulnerability caused by debris flows, landslides, and/or floods. IPDSS addresses disaster mitigation and urban planning issues.


The Integrated Planning Decision Support System (IPDSS) is a tool designed as a Decision Support System (DSS) to assist governments and communities in natural hazard and vulnerability assessment with the goal of risk mitigation. Simultaneously, it is designed to assist an urban planner in organizing, analyzing, modifying, and reevaluating exisitng or needed spatial information within land-use planning activities improving life stability through risk mitigation.

Natural disasters are considered as very complex phenomena that demand interrelations among geologists, civil engineers, geographers, planners, sociologists, and many others. Because of the complex nature of the interrelations among all the different components of these types of problems, IPDSS is proposed as a framework for the development of an overall plan. IPDSS assesses geological hazards, vulnerability, and risks to configure a land use suitability zoning model for urban planning based on a weighted average of many factors. To obtain this, the purpose and scope of the study had to include sufficient information to prepare comprehensive maps and descriptive analyses concerning the environmental and engineering characteristics of projected urban areas.

DSS Components

IPDSS is designed as a DSS to incorporate the following information: topography, aspect, bedrock and surficial geology, structural geology, geomorphology, soils (geotechnical data), land cover, land-use, hydrology, precipitation (annual average and probable minimum), and Federal Emergency Management Agency floodway maps and historic data to assess hazards. IPDSS is designed to assess any natural hazard, such as debris flows, subsidence, and floods, with probable maximum precipitation and seismicity as triggering factors for susceptibility scenarios. The regular items considered in vulnerability analysis are (1) ecosystem sensitivity, (2) economic vulnerability, and (3) social infrastructure vulnerability. The risk is assessed as a function of hazard and vulnerability.


IPDSS is a computer environmental system that provides functionality to develop specific spatial decision support without the need to write special code to perform some necessary operations.

The integration of GIS and environmental models has been improved by the application programming interface IPDS. This integration provides a common interface and information sharing and transferring between the respective components using a model built with the "C" programming language.

The IPDSS architecture is implemented on a color SUN/SPARC-workstation running UNIX under the X Window System. The system can be ported to most UNIX workstations with a limited amount of effort.

To facilitate input of extensive data, the IPDSS system is linked with GRASS and with a standardized interface. The X- Window System, and a number of interface-built tool-kits, make this an efficient integration. IPDSS allows the user to select criteria (objectives and constraints), and arbitrarily decide whether the user wants to maximize or minimize them.

IPDSS Structure

The interactive dialogue sub system and the display and interactive use components are particular critical for the effective use of the IPDSS since they provide the interaction between user and machine. These features isolate the user from the technicalities of the computer and foster a dialogue based on the user's judgements, rather than imposing the hardware engineer's or computer programmer's discipline upon the user. These models of interaction permit a quick, low-cost examination of alternative solutions as well as the capability to modify assumptions and vary decision criteria. Moreover, the IPDSS menu-driven approach was designed for users without a strong computer background. What the user needs to provide is the capability to direct the flow of information and modeling effort towards a desired goal. This creates a framework where the user creates individual applications and results using IPDSS functionality, but does not have to write the functions.

A solution approach to a complex environmental problem is handled by IPDSS through its main components: Data management subsystem (DMS), Model management subsystem (MMS), and Graphical User Interface.

IPDSS Main Components

DMS involves data collection, data transformation, map editions, and display. DMS is controlled using GIS tools. The DMS consists of a directory or mapset that stores vast quantities of land use and hazard-evaluation-oriented data, derived from national, state, and local sources and, to a lesser degree, from new field work. The files include data on geology, geomorphology, human settlement, lifelines, land-cover, seismicity, geotechnical properties, and additional files that the user might consider necessary and be able to obtain.

MMS deals with the data analysis models subsystem implemented using C programming supported by data from DMS. MMS is being developed to emulate current analysis and optimization procedures and can perform numerical modeling tasks and present the results. While GRASS within the DMS provides a suitable environment for the representation and analysis of the spatial structure, MMS is designed to capture the cited behavior, including the database and model-base management capabilities needed to construct, manipulate, modify, analyze, and query data and models. IPDSS has been designed to expedite land-use planning modeling with direct access to DMS and MMS using scientific visualization principles and the graphic user interface (GUI), which allows the user to modify the digital model and emulate the geographic environment under study.

The GUI is defined as a combination of window, menu, and icon selections designed to guide the user quickly and easily through the program. The GUI allows the dynamic coupling of existing models from the MMS to the DMS, so that the GIS itself acts as a database source to the controlling program. GUI tools provide the user with complete control over the environment in a way not possible in the traditional geo-relational system. And, in this form, the GUI provides the ability to set up a more realistic and effective modeling environment than those that have been possible through simple GIS application. This feature provides the flexibility to interact with the user where the need for the interaction reduces the effort currently demanded by a single application. The IPDSS interface is assembled in such a way that the analyst always has the impression that he/she is interacting with a single and coherent system.

Interface Design

The IPDSS interface design, which is quasi-platform independent, has a main screen layout formed by: (1) the Menu Bar on the top of screen; (2) the Control Panel on the right side of the screen; (3) the Message Box and Location information on the bottom of screen; and (4) the Display Window in the middle of the screen.

Planning Decision Process

IPDSS provides a framework that orients the user in conducting a planning decision process. The design of the IPDSS system includes a wide variety of multi- criteria factors that can be increased, partially avoided, or at least orient the users to better solutions. A logical sequence of steps for the user in IPDSS would be:

  • Reach agreement on what criteria should be included in the planning decision process.
  • Collect data for the above criteria build a digital data-base using GIS software (GRASS).
  • Examine the theoretical and historical patterns that lead to stability or instability conditions, and modify input data where necessary to meet professional and ethical concerns.
  • Calculate and categorize all constraints to be included in an individual hazard assessment, including trigger factors selection such as: probable maximum precipitation (PMP), seismic isointensity lines (isoseismal), environmental modifications (land use), etc.
  • Promote discussion of algorithms among concerned parties to develop a better and more popular planning decision solution.
  • Enforce threshold limits on vulnerability and multi-criteria components. This is implemented by selection or grouping of urban elements such as human settlement, critical facilities and public assembly sites. This leads to a more acceptable risk assessment evaluation and zoning.