The ArcGIS Coastal Sediment Analyst: A Prototype Decision Support Tool for Regional Sediment Management John P. Wilson Daniel W. Goldberg Christine S. Lam University of Southern California GIS Research Laboratory Technical Report No. 3 Prepared for: U.S. Army Corps of Engineers Los Angeles District 915 Wilshire Boulevard Los Angeles, CA 90017 Cover Photo: Carpinteria State Beach, September 2003 (Y. Poon) Preferred Citation: Wilson J. P, Goldberg D. W., and Lam C. S. 2004. The ArcGIS Coastal Sediment Analyst: A Prototype Decision Support Tool for Regional Sediment Management. Los Angeles, Califor- nia: University of Southern California GIS Research Laboratory Technical Report No. 3 Table of Contents Executive Summary......................................................................................................................1 Background....................................................................................................................................3 Study Authority....................................................................................................................3 Scope and Purpose................................................................................................................3 Study Participation and Coordination...............................................................................4 Model Overview and Data Inputs..............................................................................................4 Model Calculations and User Interface.....................................................................................9 Step 1 – Start CSA Application and Load Geospatial Data............................................9 Step 2 – Select Harbor and Number of Scenarios...........................................................10 Step 3 – Select Candidate Beaches for Placement of Dredged Sediment....................11 Step 4 – Select Transportation and Disposal Methods..................................................13 Step 5 – Configure Transportation Options....................................................................16 Step 6 – Review Transportation Cost Estimates.............................................................23 Step 7 – Select Method Used to Calculate Economic Benefits......................................24 Step 8 – Review Economic Impact Results......................................................................27 Steps 9 & 10 – Calculate and Display Final Cost-Benefit Ratios..................................28 Results, Limitations, and Shortcomings..................................................................................31 Conclusions..................................................................................................................................37 Literature Cited...........................................................................................................................39 Appendix A – Coastal and Economic Analyses.....................................................................41 This page left blank intentionally Executive Summary This report describes a prototype GIS-based model that is able to describe the complex, spatially dependent relationships between the cost of sediment transportation and asso- ciated (locally specific) benefits that relocation will generate in a semi-quantitative manner. The development of the Coastal Sediment Analyst prototype required the preparation of a series of custom Visual Basic programs that were integrated with the ArcGISTM geographic information system software (Environmental Research Systems Institute, Inc., Redlands, California) to create an end-user interface that allows users to pick candidate dredge and disposal sites. The user is also able to specify their preferred dredging method, conveyance system, disposal strategy, etc. The tools utilize a series of specially developed response functions by integrating them with the geospatial datasets and user-specific inputs to calculate the costs and benefits of different dredging and disposal options. Ventura Harbor and several nearby beaches in California were used to develop and test this new model. The current version of the Coastal Sediment Analyst (CSA) prototype incorporates a single user interface, an elaborate series of on-line help documents, and various error catching routines. This new tool produced similar results to those reported by Everest International Consultants (EIC) – there were small differences because the new tool cal- culated the transportation distances from the underlying geospatial datasets and these lengths were slightly different than those used by EIC, because of different assumptions that were used to estimate project mobilization/demobilization costs when two or more candidate beach sites were considered, and because different assumptions were used to estimate the recreational benefits of adding additional beach width at Oxnard Shores. There are, however, four sets of limitations and shortcomings with the current proto- type that would need to addressed in order to use this type of tool to analyze conditions at other California harbors and beaches. First, the geospatial datasets describing the harbors, beaches, rail and road network would need to be expanded to cover the entire California coast. Second, some additional data and/or functions describing the histori- cal dredging patterns at other harbors and the sediment budgets at specific beaches would need to be compiled and accessed by the CSA tool. Third, the unit costs for the final two additional dredging and conveyance methods included in the current CSA tool would need to be fleshed out. Fourth, some additional data and/or functions de- scribing the current number of beach visitors and their spending behavior and how these attributes could be expected to change with changes in beach width over time at specific beaches would need to be compiled and accessed by the CSA tool. The current Coastal Sediment Analyst prototype will be presented to focus workgroups to seek input from local, State, and Federal agencies on the potential uses and ways to improve the model in the immediate future. 1 This page left blank intentionally 2 Background The National Regional Sediment Management (RSM) Program aims to develop meth- odologies and protocols to address and abate site-specific shoreline erosion problems at regional scales. The U.S. Army Corps of Engineers, Los Angeles District is responsible for implementing the California component of the national program. This report pre- sents a study conducted in support of the California component to build a prototype or pilot GIS-based model to perform cost-benefit analysis for different dredging and mate- rial placement options related to maintenance dredging. Study Authority This particular study was conducted in accordance with the National Shoreline Erosion Control Development and Demonstration Program (Section 227) of the Water Resource and Development Act of 1996. Scope and Purpose One of the ultimate goals of the RSM is to develop a GIS-based management support tool for decision makers to evaluate future dredging and disposal options along the California coast. As a first step to achieve this goal, the present study aimed to develop a prototype or pilot GIS model to demonstrate the concept of using GIS as a decision making tool. Through the development of this pilot study, the model architecture, data structures, data requirements, and model interface were specified and tested. This pro- totype model will be presented to focus workgroups to seek input from local, State, and Federal agencies on the potential uses of the model and ways to improve the model. The prototype GIS model presented in this report utilizes the Ventura Harbor dredging and disposal operation along with the placement of beach fill at three beach locations other than McGrath Beach or South Beach (the normal disposal areas) as examples to illustrate the potential strengths and weaknesses of building these types of GIS applica- tions. The following tasks were performed to accomplish the goals of this study: (cid:190) A series of cost functions for dredge material disposal was created. (cid:190) The benefits associated with placing the dredged material from Ventura Harbor on three alternative beach fill sites were calculated. (cid:190) The differential costs versus regional benefits for the three selected beach fill sites were estimated. 3 (cid:190) The results of the differential cost-benefit analysis were incorporated into a proto- type GIS-based model that can be used to perform this same type of analysis. It has to be noted that the placement scenarios presented in the report were for illustra- tion only, and are not intended to be "real-world" projects that could implemented as specified in this report. In addition, the cost functions and benefit analyses were done at a crude level with broad assumptions to cover a wide range of possible transportation and disposal scenarios to test the prototype GIS-based model; hence, the examples in- corporated in this report should not be viewed as sufficient analyses for the specifica- tion of one or more "real-world" site-specific scenarios. Study Participation and Coordination This study is part of the California Coastal Sediment Management Master Plan, which is a collaborative effort between federal, state, local agencies and non-governmental or- ganizations. Everest International Consultants Inc., (EIC) based in Long Beach, Califor- nia, supported the work performed by the University of Southern California (USC) GIS Research Laboratory. Dr. Philip King, Department of Economics, San Francisco State University, also participated in this project. EIC performed coastal engineering evaluation for the three beach sites and prepared the cost functions from published literature and interviews. Dr. King provided the analysis of the recreational benefits associated with placing sediment at the proposed sites. His analysis relied on numerous visits to the three sites as well as the results of several visi- tor surveys that were conducted specifically for this project. Dr. King also incorporated results from other studies of California beaches and applied the U.S. Army Corps of Engineers methodology for estimating recreational value. The three authors of this report then used the results laid out in Appendix A – Coastal and Economic Analyses prepared by EIC to develop the prototype or pilot GIS-based model that could, with some additional modifications, be used to evaluate future dredging and disposal options along the California Coast. 4 Model Overview and Data Inputs The USC GIS Research Laboratory was contracted to build a prototype ArcGIS model (referred to hereafter as the "CSA" or "Coastal Sediment Analyst") that is able to de- scribe the complex, spatially dependent relationships between the cost of sediment transportation and the associated (locally specific) benefits that relocation will generate in a qualitative or semi-quantitative manner. These capabilities meant, in turn, that at least two environments were to be characterized in the GIS – one for the nearshore envi- ronment and the second for the local beaches with attributes to support the response functions described below. Ventura Harbor and several nearby beaches in California were used to develop and test this new model, which was expected to take local littoral processes, beach conditions specific to Ventura Harbor in relation to dredged sediment volume, dredge equipment and current operation costs into account, and to be able to automatically update the calculated benefit values in a near real time manner. Various model constraints posed by significant physical, economic, geomorphic, and spatio- temporal variables considered relevant for the methodology developed were to be iden- tified and specified in this final report. The completion of this prototype required the preparation of a series of custom Visual Basic programs (called scripts) that can be integrated with ArcGISTM (Environmental Research Systems Institute, Inc., Redlands, California) to create an end-user interface that allow users to pick candidate dredge and disposal sites. The user interface was de- signed in such a way that the user is able to specify their preferred dredging method, conveyance system, disposal strategy, etc. The tools utilize the response functions by integrating them with the geospatial datasets and user-specific inputs to calculate the costs and benefits of different dredging and disposal options. Two sets of response functions were extracted from Appendix A and used to construct the prototype tools described in this report as follows: (cid:190) A series of response functions that described the costs of different dredging and disposal operations at Ventura Harbor. These response functions were to be specified in such a way that they could compute the differential cost of transport- ing and disposing of Ventura Harbor dredge material from the traditional dis- posal sites used by the Engineers Operations and Maintenance Division of the Los Angeles District Army Corps versus the cost of disposing of these materials at three alternative sites identified as erosional hot spots by the Los Angeles Dis- trict Corps of Engineers in conjunction with the State of California Department of Boating and Waterways for this pilot project. (cid:190) A series of response functions that described the site-specific and regional bene- fits of several different sediment deposition strategies. These response functions were to be specified in such a way that they reflect site-specific benefits due to conditions such as beach width and rate of beach accretion-regression. This new benefit curve function was to consider the benefits derived from recreation, 5 storm damage reduction, protection of public facilities and infrastructure, tax revenue, creation of jobs, environmental enhancement, and other factors that were found to be relevant during the literature review and/or development of the methodology itself. The various forms incorporated in the user interface are user friendly and capable of providing non-GIS users with clearly defined data entry options, analysis tools, and relevant reference information (i.e. an online Help system). The analysis tools facilitate the comparison of the various dredging and conveyance options for Ventura Harbor in a systematic and reproducible manner, incorporating near real-time sediment data. The ultimate goal is to develop a suite of tools that are applicable to other localities with similar environmental characteristics. Thus, when completed, the final system should be able to be used in similar locations in coastal California under the jurisdiction of the Los Angeles District of the U.S. Army Corps of Engineers and places further afar. This final report gives some indication as to the further GIS work and/or data required to support the application of this prototype model in these other locations. The following scenarios and inputs were used for the initial development of the tools and beta demonstration provided for Los Angeles District Corps of Engineers staff at the USC GIS Research Laboratory on 7 April 2004. The names listed below in square brackets correspond to the tabs used for the Coastal Sediment Analyst user interface (see Figures 1 through 17 for actual examples): [Harbor] User is required to specify following inputs: Name of harbor – Ventura Number of scenarios – 4 [Beaches] User is required to specify following inputs: Scenarios – #1 – 450,000 cubic yards of sediment to Carpinteria #2 – 275,000 cubic yards of sediment to Oil Piers – 175,000 cubic yards of sediment to Carpinteria #3 – 450,000 cubic yards of sediment to Oxnard Shores #4 – 150,000 cubic yards of sediment to Carpinteria, Oil Piers, and Oxnard Shores Current beach width – 150 feet (Carpinteria) 50 feet (Oil Piers) 6