A Geodesign Inspired Multiple Criteria Decision Tool for Prioritizing Levee Setback Project Sites

Abstract

This initial planning level tool addresses the complexity of land use decisions within the Lower Green River, WA floodplain by enabling the consideration of multiple views of a wide range of stakeholders. The tool is a four step model process created using ESRI ArcInfo and ArcGIS Model Builder to summarize the existing conditions in the lands adjacent to levees, standardize the values of eleven chosen criteria, and create an interface where stakeholders can weigh the criteria according to importance. The eleven criteria cover the subjects of cost, hazard mitigation, ecological considerations, and built capital. The individual models are referred to as the Representation Model and Process Model, Spatial Screening Model, Alternatives Criteria Model, and Decision Support Model. The models are run at a parcel level in order to create results that transfer to real world decisions in regards to land purchase and land use change. The resulting output is a prioritization list and associated mapping products ranking parcels on a range from favorable to non-favorable. The Decision Model was run to show results when weighting all criteria evenly, each criterion by itself in a sensitivity analysis, and with values derived from a hypothetical stakeholder outreach exercise where subject professionals were asked to role-play six hypothetical characters. The results from the different model runs were fairly similar, with the exception of a few criteria outputs in the sensitivity analysis. The parcels downstream of river mile seven (7) were almost exclusively considered least suitable, the parcels in the middle section between river miles seven (7) and fourteen (14) were varied, and the parcels above river mile fourteen (14) were considered most suitable. Emphasis is made on the tool process and methods more than the individual criteria and results. The goal of this thesis is not to tell a municipality where projects should occur, but to implement a process where stakeholder views can be transferred to weighting multiple criteria, with resulting location prioritization. This is the advantage of using GIS as a decision support tool, versus just a medium for a suitability analysis. The process and methods of this tool can be applied to many planning and environmental management disciplines beyond floodplain management. Examples are transportation corridor planning, low income housing development, brownfield redevelopment prioritization, and transmission line right-of-way planning. Any planning problem with the questions of what and where could benefit from this tool, as long as there is spatial data available.