US Army Corps of Engineers Los Angeles District ...

THE ARCGIS COASTAL SEDIMENT ANALYST (CSA) A PROTOTYPE DECISION SUPPORT TOOL FOR REGIONAL SEDIMENT MANAGEMENT (RSM) PROGRAM WHITEPAPER

Prepared for:

U.S. Army Corps of Engineers Los Angeles District 915 Wilshire Boulevard Los Angeles, California 90053 Contact: Heather Schlosser, Study Manager Prepared by:

Everest International Consultants, Inc. 444 West Ocean Boulevard, Suite 1104 Long Beach, California 90802 Contact: Ying-Keung Poon, Project Manager In association with: Dr. John Wilson, University of Southern California Dr. Philip King, San Francisco State University

April 2006

The ArcGIS Coastal Sediment Analyst (CSA) Whitepaper

TABLE OF CONTENTS

1.

INTRODUCTION............................................................................................................... 1.1

2.

PILOT GIS MODEL.......................................................................................................... 2.1

3.

4.

2.1

Overview.............................................................................................................. 2.1

2.2

Model Overview, Design and Architecture .......................................................... 2.1

2.3

Model Information................................................................................................ 2.3

2.4

Cost-Benefit Analyses ......................................................................................... 2.6

2.5

Model Application Examples ............................................................................... 2.6

FOCUS WORKGROUP MEETINGS..................................................................................... 3.1 3.1

Overview.............................................................................................................. 3.1

3.2

Feedback from Workshop Participants................................................................ 3.2

RECOMMENDATIONS ...................................................................................................... 4.1 4.1

State Wide GIS Model ......................................................................................... 4.1

4.2

Beta GIS Model ................................................................................................... 4.3

APPENDIX A - RECOMMENDED MODEL IMPROVEMENTS

Everest International Consultants, Inc.

i


LIST OF TABLES

Table 1.

Point Values for Recreation at Oxnard Shores........................................... 2.5

Table 2.

Comparison of benefits and costs estimated for four scenarios with new Coastal Sediment Analyst tool.................................................................... 2.8

Table 3.

H2O Conference Workshop Participants.................................................... 3.1

LIST OF FIGURES

Figure 1.

Schematic Representation of Pilot GIS Model for Regional Sediment Management............................................................................................... 2.2

Figure 2.

Schematic Representation of Ultimate GIS Model for Regional Sediment Management............................................................................... 4.2

Figure 3.

Schematic Representation of Beta GIS Model for Regional Sediment Management in Santa Barbara and Ventura Counties ............................... 4.4


ii


1. INTRODUCTION The National Regional Sediment Management Program (RSM) was implemented to develop methodologies and protocols to address and abate site-specific shoreline erosion problems at regional scales. The U.S. Army Corps of Engineers, Los Angeles District (USACE) has been given the task to implement the California component of the National RSM Program. In support of the California component of the National RSM Program, a pilot GIS model to optimize the placement of Ventura Harbor’s dredged sediment has been developed. The development of the pilot GIS model was the first step to achieve the ultimate goal of the RSM in developing a GIS-based management support tool for decision makers to evaluate future dredging and disposal options along the California coast. As a first step, the pilot GIS model was developed to demonstrate the concept of using GIS as a decision support tool. In addition, it was anticipated that through the development of the pilot GIS model, potential issues regarding model architecture, model interface design, data management structure, data requirement, and model applications would be revealed. The USACE has conducted two focus group workshops to demonstrate the pilot GIS model, and seek input from local, regional, state, and national agencies on the pilot GIS model. The first workshop was conducted on September 22, 2005, in Wrightsville Beach, South Carolina. This workshop had a target audience of other U.S. Army Corps of Engineers Districts outside of the Los Angeles District, hence, it was held at the last day of the National Regional Sediment Management Workshop, an event with many participants from other Army Corps Districts. The second workshop had a target audience from state, regional and local agencies; hence, the workshop was held on October 26, 2005 - the last day of the H2O conference in Huntington Beach, California. The H2O conference is normally well-attended by state, regional, and city officials. . The pilot GIS model utilizes the Ventura Harbor dredging and disposal operation 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 applications. This whitepaper provides a summary of the development of the pilot GIS model in Section 2. Based on the feedback from the two workshops which are summarized in Section 3, recommendations on improving and expanding the pilot GIS model to a regional model for the entire California coast are provided in Section 4.


1.1


2. PILOT GIS MODEL 2.1

OVERVIEW

The pilot GIS model presented here utilizes the Ventura Harbor dredging and disposal operation to illustrate the potential strengths and weaknesses of using GIS as a tool for sediment management decision support. The Los Angeles District of U.S. Army Corps of Engineers (USACE) maintains the navigation features in Ventura Harbor and performs periodic maintenance dredging. Under current practice, dredged material from the harbor is deposited primarily at the nearby McGrath Beach as the least cost project. The pilot GIS model was developed to evaluate the differential cost and benefits of placing dredged material at three alternative sites – Carpinteria State Beach, Oil Piers and Oxnard Shores. In developing the pilot GIS model, available data and simple analyses were conducted to define the physical characteristics of the three alternative receiving beaches, the cost functions for different transportation modes to bring the dredged material to the sites, as well as economic benefits associated with the placement of dredged material onto the three sites. This section describes the data and analyses that have been conducted for the development of the pilot GIS model, as well as the model design and model architecture. In addition, examples on the usage of the model are also provided.

2.2

MODEL OVERVIEW, DESIGN AND ARCHITECTURE

The current pilot GIS model consists 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: (1) pick candidate dredge and disposal sites; (2) specify their preferred dredging method, conveyance system, disposal strategy; and (3) calculate the costs and benefits of different dredging and disposal options. A series of user-specific inputs are required along with specially developed response functions and geospatial datasets to calculate the costs and benefits of the different dredging and disposal options chosen by the user. The current version of the CSA prototype user interface also incorporates an elaborate series of on-line help documents and various error catching routines. Figure 1 shows a schematic representation of the pilot GIS model. As mentioned above, the GIS model consists of a graphic interface that the user can specify the details of the project alternative. The GIS model has a built in data base consisting of the following information: receiver beach characteristics, beach attendance and recreational values, and cost functions for different mode of transporting sediment from Ventura Harbor to the candidate receiver


2.1


Project Identification and Specifications

Input Interface

Data

Receiving Site Characteristics

Analysis

Output Interface

Beach Morphology

Beach Attendance & Recreational Value

Transportation & Disposal Costs

Cost/Benefit Analysis

Summary

Figure 1. Schematic Representation of Pilot GIS Model for Regional Sediment Management


2.2


beaches. The pilot GIS model uses built-in analysis tools to evaluate the change in beach widths over time and to perform cost-benefit analyses. The model also has a graphic output interface to communicate with the user the cost benefit analysis results for the selected project alternatives. A brief summary of the data and analyses that have been incorporated in the pilot GIS model is provided in Sections 2.3 and 2.4.

2.3

MODEL INFORMATION

The pilot GIS model incorporates physical characteristics of the receiving beaches, cost functions for different transportation modes, and beach economic data in the database. In addition, the model includes built-in cost-and-benefit analysis functions to guide the user in the evaluation of alternative disposal options. A brief description of the data and analyses that have been incorporated in the model is provided below. Keeping in mind that the objective of the pilot GIS model was to test the concept of using GIS as a tool to develop a decision support tool, most of the data and analyses incorporated in the model were crude and should not be considered as applicable for any site-specific beach nourishment project. 2.3.1

Beach Characteristics

The benefit of widening a specific beach was calculated based on a percent increase over the existing beach width. Hence, existing width for the receiving beaches is part of the data input to the pilot GIS model. The model allows the user to specify the beach width of a chosen site. In testing the pilot GIS model, existing beach widths for the three alternative receiving beaches were estimated based on site visits. The dredged material was assumed to be compatible with the native beach material at the receiving beaches. The increase in beach width, W, at each of the three beaches was estimated as:

W =

V L( B + Dc )

where V is the beachfill volume, L is the beachfill length, B is berm height, and Dc is the depth of closure.


2.3


A simple diffusion theory (Dean1 2002) is used to estimate the lateral spreading and the reduction in beach width over time so that the corresponding reduction in economic benefits can be evaluated. The theory is likely to underestimate the reduction in beach width over time at the three receiving beaches. It was chosen because the equation can be easily incorporated into the pilot GIS model for demonstration purposes. Better estimates of site specific erosion rates will be required for real projects. 2.3.2

Economic Data

Several types of data are necessary to conduct a proper economic analysis. In particular, the pilot GIS model has incorporated the following types of data: •

Attendance at the receiver beach;

•

The costs associated with moving sediment to both the default receiver site and the site under investigation;

•

The recreational value (generally expressed as day use value) of the default site and the site under investigation and how this recreational value will change as beach width increases (decreases) with added (diminished) sediment;

•

Expected spending associated with any increases or decreases in attendance, if one wants to estimate local and State economic and fiscal impact.

Attendance Attendance was estimated after interviewing rangers and/or other local officials, looking at parking data where available, and from attendance estimates at site visits. Using this methodology, one can generally estimate attendance with a reasonable degree of certainty. Cost Function Simple cost functions were developed to cover the unit cost of transporting dredged material using truck, railroad, and barge. These unit costs were developed to cover a wide range of hauling distances to be used as input for the pilot GIS model. In addition, these cost functions were developed based on simplified assumptions (for example, it was assumed that there is direct railroad access at both the dredged location and the receiving site) and were not intended to be in a detail sufficient for any site-specific conditions. These crude estimates of unit cost were used to establish generic cost functions for the pilot GIS model. The cost of dredging was not considered by the pilot GIS model because the objective of the

1

Dean R.G., 2000: Beach Nourishment: Theory and Practice. World Scientific Publishing Company.


2.4


pilot model was to calculate the differential cost of placing dredging material at alternate sites. Dredging was assumed to have to be performed anyway. Recreational Value Recreational Value was estimated using the USACE’s benefits transfer protocol which examined the quality of the beach recreation experience in terms of several amenities: Recreation Experience, Availability of Substitutes, Capacity, Accessibility, and Environmental. The full methodology is laid out in a Corps memo.2 For example, Table 1 below presents the USACE methodology for assessing the unit day value of recreation at Oxnard Shores before nourishment. The level of amenities varies significantly depending upon the location, and an average level was used. The score of 37 points translates into a day unit value of $3.00 in July 1, 1982 dollars and $5.68 in August 2003 dollars, when the estimate was made.3 Table 1.

Point Values for Recreation at Oxnard Shores

CRITERIA

TOTAL POSSIBLE POINTS

POINTS ASSIGNED

Recreation Experience

30

10

Availability (Substitutes)

18

2

Capacity

14

5

Accessibility

18

13

Environmental

20

7

Total

100

37

The pilot GIS model considers three potential benefits associated with the increase in beach width from a nourishment project: (1) the increased width provides a more enjoyable recreational experience for visitors; (2) the increased width reduces crowding since more beach area is available; (3) an increase in width may increase attendance—though this lowers recreational value per person, it should increase recreational value overall, since more people attend. Subsequent estimates of the benefits of nourishment were estimated

2

See U.S. Army Corps of Engineers, Report # ER 1105-2, pp. 98-102, 28 December 1990 for more detail on this methodology 3

Adjusting using the CPI index at www.bls.gov.


2.5


using survey data taken as part of the pilot project as well as other survey data from earlier studies. Both the increase in attendance and recreational value depended upon the percentage increase in beach width from the current width. The overall increase in recreational benefits from a nourishment project is estimated using the estimated increase in attendance and the estimated increase in day use value from the status quo. Spending Data on spending were estimated from previous surveys taken at other beaches in California. These data were used to estimate regional and State economic impact and tax revenue impact, which local managers may want to know. As a practical matter, most of the variation in average spending per person per day at the beach depends upon the percentage of visitors who are day-trippers versus the percentage staying overnight. The responses from a small survey sample were used to estimate the percentage of day-trippers versus overnight visitors. Using this spending data, we calculate local, State, and national economic impact.

2.4

COST-BENEFIT ANALYSES

When the benefits and costs of various policy alternatives are analyzed and estimated, it is straightforward to estimate a benefit/cost ratio. However, one should be careful in interpreting these data when the estimates underlying the analysis (both engineering and socio-economic) are subject to a fair amount of uncertainty. As a practical matter, it may make sense to require a B/C ratio greater than 2 or perform a sensitivity analysis. For this Pilot study, a number of specific scenarios and calculated benefits and costs were estimated. The recreational benefits were considered to be the most important factor for State and Federal policy makers; however, data on economic and tax impact is also available in the Pilot Study. The pilot GIS model does not consider the loss in recreational benefits from a reduction in beach width at sites which are currently nourished (e.g., McGrath beach). After examining these beaches it was determined that these losses would be relatively small and a first order approximation would be to ignore them.

2.5

MODEL APPLICATION EXAMPLES

Three transportation and disposal methods (railroad, scow and tow, and truck) were used along with four sediment placement scenarios for the initial development and demonstration of the pilot GIS model for U.S. Army Corps of Engineers staff in April 2005 as follows:


2.6


•

Scenario #1 – 450,000 cubic yards of sediment dredged from Ventura Harbor and placed on Carpinteria Beach.

•

Scenario #2 – 450,000 cubic yards of sediment dredged from Ventura Harbor with 275,000 cubic yards of the sediment placed on Carpinteria Beach and the remainder (175,000 cubic yards placed on Oil Piers Beach.

•

Scenario #3 – 450,000 cubic yards of sediment dredged from Ventura Harbor and placed on Oxnard Shores Beach.

•

Scenario #4 – 450,000 cubic yards of sediment dredged from Ventura Harbor and spread equally among Carpinteria, Oil Piers, and Oxnard Shores Beaches.

The results took two forms. First, the scow and tow option provided the cheapest method of moving sediment from Ventura Harbor to the various beaches (Carpinteria, Oil Piers, and Oxnard Shores) included in each of the abovementioned scenarios. Second, the benefits of adding additional beach fill at Carpinteria Beach far exceeded the benefits of adding beach fill at the other two beaches and meant that the scenarios that placed more sediment at this Carpinteria Beach (i.e. Scenarios #1, #2, and #4 in that order) produced the most favorable benefit/cost ratios (see Table 2 for additional details). The example scenarios clearly illustrated the pilot GIS model could be a useful screening tool in selecting one or more beach alternatives for further consideration.


2.7


Table 2.

SCENARIOS

Comparison of benefits and costs estimated for four scenarios with new Coastal Sediment Analyst tool LEAST TRANSPORTATION COST

RECREATIONAL BENEFIT (PV)

RECREATIONAL BENEFIT/COST RATIO

STATE ECONOMIC IMPACT (PV)

ECONOMIC IMPACT/COST RATIO

STATE TAX REVENUES (PV)

STATE TAX REVENUE/ COST RATIO

Scenario #1 Carpinteria

$1,566,000

$30,327,494

19.4

$36,790,062

23.5

$2,943,205

1.90

Carpinteria

$605,500

$11,465,901

18.9

$14,214,735

23.5

$1,137,179

1.90

Oil Piers

$783,750

$386,322

0.5

$329,662

0.4

$26,373

0.03

$1,389,250

$11,852,223

8.5

$14,544,397

10.5

$1,163,552

0.80

$927,000

$424,903

0.5

$481,636

0.5

$38,531

0.04

Carpinteria

$522,000

$9,953,077

19.1

$12,361,540

23.7

$988,923

1.90

Oil Piers

$426,000

$202,523

0.5

$177,518

0.4

$14,201

0.03

Oxnard Shores

$313,500

$141,816

0.5

$162,439

0.5

$12,995

0.04

$1,261,500

$10,297,416

8.2

$12,701,497

10.1

$1,016,119

0.81

Scenario #2

Totals Scenario #3 Oxnard Shores Scenario #4

Totals


2.8


3. FOCUS WORKGROUP MEETINGS 3.1

OVERVIEW

Two focus workgroup workshops were conducted to seek feedback from local, regional and national agencies on the pilot GIS model. The first workshop was conducted on September 22, 2005, in Wrightsville Beach, North Carolina. The workshop was conducted during the National Regional Sediment Management Workshop; hence, most of the workshop participants were from other U.S. Army Corps of Engineers districts outside of the Los Angeles District. About 30 people participated in the workshop. During the workshop, the pilot model was presented, followed by a period of discussion. A survey form was distributed to the participants for them to provide their comments on the pilot GIS model. Thirteen workshop participants filled out (most partially) and returned the survey. The questions and responses from the participants are summarized in Section 3.2. The second workshop was held on October 28, 2005, the last day of the H2O conference that was held in Huntington Beach, California. There were twenty participants representing various State, Port and local agencies, as well as some local consultants that have been involved in beach nourishment issues in southern California. Table 3 below shows the names and affiliations of these participants. Table 3. ORGANIZATION California Boating and Waterways

H2O Conference Workshop Participants PARTICIPANT’S NAME

ORGANIZATION

PARTICIPANT’S NAME

Clifton Davenport

Mark Bierman

California Coastal Commission

Lesley Ewing

Mohammad Chang

Channel Islands Harbor

Jack Peveler

City of Oceanside

Ray Duncan

U.S. Army Corps of Engineers Los Angeles District

MaLisa Martin Susie Ming


Ying Poon

Heather Schlosser

Moffatt & Nichol Engineers, Inc.

Weixia Jin

Art Shak

Noble Consultant

Jon Moore

SAIC

Karen Green

SANDAG

Shelby Tucker

Scripps Institute of Oceanography

Julie Thomsa


U.S. Army Corps of Engineers San Francisco District University of Southern California

Karen Beresford Dan Specht John Wilson Dan Goldberg

3.1


The workshop started off with a presentation of the pilot GIS model and closed with a moderated discussion. A list of discussion topics was provided to guide the discussion to focus on the following topics: model usage/application, model improvement, and model maintenance and distribution.

FEEDBACK FROM WORKSHOP PARTICIPANTS

3.2

As mentioned earlier, a major objective of conducting the workshops is to get feedback from other agencies on how the model can be used and improved. The feedback received from the two workshops – the September workshop and the October workshop are summarized below. 3.2.1

Feedback from the September Workshop

As mentioned earlier, a survey form was distributed at the workshop. The questions and the responses from workshop participants are summarized as follows:

Would the tool be useful in your district? o

Most responded that the model would be useful to somewhat useful with suggestions on how the model could be improved. One responded that the model will have limited use for their district because sand for beach fill is unavailable for their district.

o

Most suggestions for improvement include expanding the model to include other benefits such as storm damage reduction and environmental benefits.

o

One responded that their district has inlet channels with little sediment, but not harbors. The model probably can be used to evaluate removing sand from CDFs and inland waterway dredging locations and placing material in the most desirable locations (maybe environmental restoration or stakeholder projects).

o

Maybe beneficial to economists to show/calculate B/C ratios. However, GRANDVC is currently being used which is not GIS-based, but takes into account houses and structures.

What ways could the tool be improved? o

Many responded that the model can be improved by incorporating other benefits such as storm damage and environmental (ecosystem restoration) benefits in the model. In order to incorporate these benefits, some suggested adding land use layers and structures into the database, as well as some “ecosystem functions” developed for the EFM model by John Hickey at HEC. The EFM model focused


3.2


on inland river systems, but similar development work may be possible for estuary systems. One suggestion is to add NED benefits for District use.

o

One suggestion is to generalize the terminology used in the model. For example, instead of “harbors”, say “dredging project”, and instead of “beaches”, use “placement areas”.

o

Many suggestions were related to better description and quantification of the beach characteristics and physical processes. Suggestions for improvement include: add a menu for “Dimensions of fill”, show cross section or beach dimensions, show date/season of survey, add sediment compatibility and native sand characteristics, add descriptions of beach use (e.g. public versus private), add beach erosion history,

o

There are many suggestions on the improvement for cost functions including: add cost for pipeline/hopper dredging, break out specific components to assist in computing unit dredging costs. Incorporate all related costs to move materials from/to stockpiles to transportation heads, recommend referencing MII databases for equipment and labor costs. This cost data is updated annually by others.

o

Tune to a more Federal instead of state tone. Leave both to use but add a Federal component.

o

Link the model to other tools such as 12-Map and Cascade.

What needs to be added to give the tool more function? o

Many of the suggestions on additional functions are similar to those suggested on the improvement of model capabilities as suggested above. These include adding functions for storm damage and ecosystem restoration benefits, functions on better characterization of the beaches and dredging/transportation methods.

o

There were some suggestions related to improving the GIS interface including: add barges routes, sediment characteristics, show areas of existing environmental resources, link to BEACH-FX, add better legends (e.g. explaining “green dots” represent railroad, “red dots” represent truck, etc); add location/information on areas with sediment needs and sediment excess, add lookup tables to account for changing prices.

o

Design smarter GIS model that logically limits options.

o

Develop a version for O&M decisions.

o

Grain size/sediment compatibility – correlate borrow areas/dredging areas to disposal areas.

o

Data input/output should be SDSFIE compliant – would need to work with CADD/GIS center to develop tables.


3.3


Do you have any suggestions for other GIS Decision Support Tools for sediment management? o

Sediment compatibility.

o

Could be coupled with Beach FX to serve as input to the costs side or provide some additional benefits not presently considered in Beach FX.

o

Make this tool easy/attractive for quick O & M sediment management decisions.

o

Incorporate riverine sediments/watersheds.

o

Maybe for nearshore disposal.

o

Need to make it easy to update and obvious where the data is coming from and how old it is – especially if the model is to be shared with states.

o

Regional navigation planning.

o

Marine protected areas.

o

Ecosystem restoration plan.

o

NAN & NAE efforts to look at sediment source and needs analysis.

o

Decisions based on available sediment versus needed sediment.

Do you know of anything similar? o

Most responded no except one mentioned that there are other computer aided decision support tools being developed that are not GIS linked. Examples include the “Shared Vision Planning Tool”, and an ecosystem restoration evaluation model developed by IWR (Institute of Water Research).

Would you be able to use this tool (i.e. in an IMS capacity)? o

Yes, but the simpler the format the better for wider use within District.

o

For decision making by in-house staff, not suitable for web-sharing because model might be misused or under-used.

o

Appears that tool could be deployed as IMS application. However, IMS is not “great” software, and it may consume a lot of resources.

o

IMS would not add much to its utility.

Should this tool be “model certified”? If so, what is the process? o

Most responded that the tool needs not be “model certified” especially if the tool is not a model being used for Corps planning and design for a project.

o

Not unless HQUSACE mandates certification.


3.4


Other comments

3.2.2

o

Plan a demonstration of this model for next year’s planning conferences and workshops.

o

Add temporal database of existing beach conditions (e.g. berm width, sediment conditions, active slope).

o

Database of benefits by categories as function of increased width, dredging costs borrow/dredging area and distance.

Feedback from October Workshop

As mentioned earlier, feedback from participants was obtained through a moderated discussion focusing on a list of discussion topics. This feedback is categorized and summarized below: Model Usage/Application •

The model needs to be improved to be used by non-technical user. If the model is intended to be used by non-technical people, the users need to be confident in the model data (e.g. detail information on beach characteristics and beach erosion rates) and model assumptions. The user should not have to worry about the accuracy of the data.

•

Depends on what decisions the user wants from the model. The model would be useful as a screening tool to rank projects.

•

The model could be expanded as an optimization tool, e.g. to maximize benefits. Could reorganize the code so that the model could do some automated runs for multiple scenarios to find the scenario with maximum benefits.

•

The model can be combined with an ecological model so that environmental constraints can be evaluated.

Model Improvement Suggestions on model improvement are categorized into the following categories – beach characteristics/physical processes, engineering, economics, GIS model, and miscellaneous. Beach Characteristics/Physical Processes •

Better and more detailed data to characterize beaches; e.g. better definition of beach length, retaining capacity, grain sizes, erosion rate, and seasonal variation of beach profiles.


3.5


•

Develop the coastal data based on individual littoral cells – can look at persistence and how placing sand on one location would feed other beaches.

•

Include environmental impact for beach placement.

•

Add the capability of evaluating storm damage reduction due to beach nourishment.

•

Expand database beyond Ventura County.

•

Need data for other potential sources of sediments.

Economic/Cost-Benefit •

Must look at regional benefits, not just the benefit for one beach.

•

Additional modeling will be needed to determine economic impacts to other beaches (e.g., if we normally take the dredged sediment to one particular beach, what will be the impact of not placing the sediment at that site?)

•

Are we taking into account taking more benefit from one resource to another (in other words, we are just counting what is being spent at the beach, not looking at the money that is being taken away from other areas, i.e. the mountains).

•

Include storm damage reduction as part of economic benefit.

•

How to use the limited site data (collected by Dr. King) at other beach locations?

•

Consider classifying beaches into three to five categories (e.g. high value, medium value and low value).

•

The model only considers differential costs, needs to consider total costs (i.e. includes dredging cost). Right now the tool is a source opportunity tool, the costs for obtaining the sediment will be paid for no matter what – what if we want to look at receiver sites, which may need to pay for the sediment

•

Need to provide data to the regional governments because they are the ones that will have to pay the extra (differential) cost. Need to give the region a sense of how much regional benefits they will gain.

GIS Model •

Add the constraint on whether a truck (or railroad, etc) can get to a particular beach.

•

Work with regional groups to find out what’s important for them. Consider developing a separate model/tool for each region.

•

Allow the user to specify an erosion rate for the beach so that one will know how long the benefits will last for each scenario.


3.6


•

Costs for barge and scow are dependent on the route that one draws on the screen, how accurate is that?

Miscellaneous •

Focus on having accurate information for the tool.

•

Include environmental constraints.

•

Level of details between economic data/analyses and coastal engineering data/analyses should be comparable.

Model Distribution and Maintenance •

Needs someone with the technical capability to maintain the model; e.g. SANDAG.

•

How would the data be maintained? SANDAG has a large technical services staff, they could update the model for San Diego, would need to have access to the information developed for the model. Need to “redo” the economic study for the region.

•

Regional groups should maintain the model because they would be the ones using it and would have access to the data – can work with SANDAG to figure out how much it would cost to build and maintain a similar database.

•

Consider using SANDAG for a case study on how the tool can be applied to another region.

•

Corps should maintain the model since they are the most likely user.

•

Economic data do not need frequent updates, may be once every five to ten years.

Others •

There is a decision tool for ecological benefit analyses.

•

Conduct smaller focus groups meetings targeting local, regional audiences to gain feedback on local needs, concerns and local data availability.

•

Ventura County is a good area to test the model.


3.7


4. RECOMMENDATIONS 4.1

STATE WIDE GIS MODEL

Participants at the two workshops have made many useful suggestions and recommendations on how to improve the pilot GIS model such that it can be used as a regional tool for managing sediment in California. In general, the recommendations on model improvements can be categorized into the following three areas: Model Capabilities – enhance and add capabilities such as reporting options, environmental impacts, regional impact assessment, and storm damage reduction. Additional Data Collection and Analyses – expand the data base to include other sediment source locations and receiver beach or placement locations, as well as new information that will be needed for the new model capabilities. Model Design – Improve the GIS model interface to incorporate the new model capabilities and allow future expansion of the model. The recommended expansion of the model can be built upon the pilot GIS model by adding new data and analyses “modules” to the exiting model. Figure 2 provides a schematic representation of building upon the current model for the development of the “ultimate” Regional GIS sediment management model. As shown in the figure, recommendations include new data and analyses. In addition, the capabilities of the existing modules shall also be enhanced. For example, “Transportation and Disposal Cost” is already included in the existing model, but the future model can still be improved by adding different transportation modes or include more details on the cost analyses. The regional model shall be designed in a way that it would be easy to accept new data. Similarly, the model architecture shall be designed in a way such that model capabilities can be easily enhanced by adding new or modifying existing analyses modules. Details on the recommended enhancement in the model capabilities, model design, and model data base are provided in Appendix A. As summarized in Appendix A and illustrated in Figure 2, the pilot GIS model needs to be improved in many aspects. This will require substantial efforts to collect new data, to incorporate new and enhance existing analyses, as well as to redesign the GIS model architecture and model interface. The development of such a comprehensive GIS model for the entire California coastline will require substantial support and cooperation of many state and local agencies, as well as other non-government organizations.


4.1


Input Interface

Data


Orthophotography

Add or Update Data


Environmental Data

Dredging Costs

Littoral Cell

Recreational Benefits

Source Sediment Characteristics

Infrastructure Data

Wave Climate


Beach Sediment Characteristics

Bathymetry Data

Beach Morphology

Sediment Compatibility

Regional Benefit/Impact

Wave Analysis Storm Surge


Environmental Considerations

Nearshore Placement

Storm Damage Reduction Analysis

Summary

Alternative Comparison

Select Optimal Alternatives

Analysis

Output Interface

Current Pilot Model

Future Additions

Figure 2. Schematic Representation of Ultimate GIS Model for Regional Sediment Management


4.2


4.2

BETA GIS MODEL

It would be unrealistic to assume that the current pilot GIS model for Ventura Harbor can be easily expanded to the “ultimate” regional model for the entire California coastline. Hence, it is recommended to develop the final model for the entire State of California in a series of phases organized for smaller regions. Two obvious choices for the identification of separate regions are: (1) Administration Regions - e.g. counties, SANDAG, and BEACON, and (2) Physical Regions - e.g. littoral cells. Depending on the need of the cooperating local agencies, each of these smaller regional models can be developed in a way to start adding new data and analyses, as well refining the GIS interface. Once the regional models are well tested and accepted by the various agencies, these individual models can then be integrated into one final comprehensive GIS model for the entire State of California. As the next expansion of pilot GIS model into the ultimate regional model, it is recommended that the model be expanded to include additional receiver beaches and sediment sources within the Santa Barbara littoral cell (in terms of administrative boundaries, this includes both the Ventura and Santa Barbara Counties). In addition to expanding the geographical extent, new data and model capabilities can also be added. Figure 3 graphically illustrates the expansion the current pilot model into a beta model for the Santa Barbara and Ventura Counties. As shown in the figure, additional model features are recommended to be incorporated to make the beta model for Santa Barbara and Ventura Counties, while other recommendations for the ultimate model will be added in the future. The beta GIS model can then be released to federal, state, and local agencies for betatesting on the concept, application, and use of the GIS model as a screening-level tool for managing sediment on a regional scale.


4.3


Input Interface

Data


Orthophotography

Add or Update Data


Environmental Data

Dredging Costs

Littoral Cell

Recreational Benefits

Source Sediment Characteristics

Infrastructure Data

Wave Climate


Beach Sediment Characteristics

Bathymetry Data

Beach Morphology

Sediment Compatibility

Regional Benefit/Impact

Wave Analysis Storm Surge


Environmental Considerations

Nearshore Placement

Storm Damage Reduction Analysis

Summary

Alternative Comparison

Select Optimal Alternatives

Analysis

Output Interface

Current Pilot Model

Beta Model

Future Additions

Figure 3. Schematic Representation of Beta GIS Model for Regional Sediment Management in Santa Barbara and Ventura Counties


4.4


APPENDIX A



APPENDIX A - RECOMMENDED MODEL IMPROVEMENTS Model Capabilities •

Expand model so that it can handle two situations – the case where sediment disposal is the issue (the case treated in current prototype) and second, the situation where sediment is required and the user wants to identify and rank potential sources.

•

Expand the model so that it calculates and reports totals as well as differential costs (linked to previous feature if decision is made to expand model to handle both situations).

•

Expand model so that riverine sediments could serve as sediment sources and nearshore areas could serve as placement sites.

•

Expand model so that the user can break out specific components in computing unit dredging costs, the model includes all related costs for moving materials to and from stockpiles to transportation heads, and to ensure that the full range of transportation options is implemented in model.

•

Expand model to estimate benefits to multiple downstream beaches after sediment is placed at one location (this assumes longshore drift of course) and the loss of benefit (cost) of not placing sediment at the site used now (or at the site(s) most frequently used during past 50 years or so).

•

Expand model so that it checks (and reports) grain size / sediment compatibility for potential borrow/dredging and disposal areas.

•

Expand model to include environmental impact as part of the consideration for beach nourishment alternatives

•

Expand model to include possibility of running it as an optimization tool – the model would perform multiple runs in this instance to find the scenario that offered the maximum benefit

•

Expand model to include other benefits such as storm damage reduction and ecosystem restoration.

•

Link the model to other tools such as Beach-FX, Cascade, EFM, and 12-Map.

Additional Data Collection and Analyses Beach Characteristics and Physical Processes •

Collect sediment characteristics at potential source and receiving sites. Classify the collected data in a way that it can be easily incorporated in the GIS model to evaluate sediment compatibility between the source material and the native material at the


A.1


receiving sites. Further develop a tool to estimate sediment retention potential based on the characteristics of the source material and the characteristics of the native material at the receiving end. •

Collect and summarize historical erosion data at the receiving locations. The data can be included in the GIS model to properly account for subsequent reduction in benefits resulted from beach erosion after the initial nourishment.

•

Improve understanding of sediment movement within a littoral cell for both on and offshore placement. Develop a tool for the GIS model to account for changes within a littoral cell resulted from a beach nourishment project. For example, a beach nourishment project at one location may subsequently benefit other beaches within the same littoral cell. These benefits are not included in the pilot GIS model.

•

Collect and analyze historical monitoring data of beach nourishment project. Use the data to evaluate potential impact to the marine environment due to beach nourishment.

•

Develop tool to evaluate potential reduction in wave runup/overtopping resulted from beach nourishment projects. Collect and analyze historical storm damage data to form the basis of developing a tool for the GIS model to estimate potential reduction in storm damage resulted from beach nourishment.

Economic Data and Analyses •

Collect better data on attendance and recreational value (most State Parks data were collected in the 1970’s), and in particular, on how beach nourishment project influence attendance. Accurate time-series data on attendance would allow one easily to see if nourishment increases attendance and by how much. Limited survey data collected for the pilot study indicates that nourishment is important, especially at sediment depleted beaches, but a time-series of attendance data would confirm this estimate. It would also be extremely useful to know the characteristics of visitors at various beaches and how nourishment influences attendance by visitor type. If a wider beach attracts more overnight visitors (which seems likely), this result has a significant effect of spending and also influences estimates of recreational value.

•

Expand and refine a Benefit Transfer (BT) model that could be used for regional sediment management. Such a model would have other applications, for example, a BT model would be useful for the California Coastal Commission in examining the costs of sea walls. The BT model must also incorporate how additions and reductions in beach width affect attendance and recreational (day use) value for various beaches in the State. A database of beach attributes would also be necessary in such a model.


A.2


•

Expand the cost functions of the model to include other methods of transporting sediment to the receiving sites. Since the costs of these activities also varies depending upon market conditions, also needs to create a model to account for this variance.

•

Improve understanding of regional impacts—both in terms of spending and taxation, as well as how an increase in attendance at one beach may affect other beaches in the area.

•

Collect storm damage data for the development of a model that take storm damage reduction benefits into consideration.

•

Expand economic analyses to include the benefits for ecosystem restoration.

Geospatial Data •

Need GIS layers showing high resolution orthophotography (i.e. a Google Earth-like backdrop).

•

Need GIS layers showing bathymetry (to handle potential nearshore placement sites) and rivers (to handle potential inland sand sources). These data will probably consist of shapes (feature geometry) and a series of accompanying attributes for each feature.

•

Need GIS layers showing houses and other structures (to handle wider arrange of benefits and costs). These data will probably consist of shapes (feature geometry) and a series of accompanying attributes for each feature.

Model Design •

Improve cartographic display to show more features (i.e. erosion hotspots, special environmental resource areas, etc.) and more complete metadata in a series of legends and supporting online documents – the legends, for example, should show all of the symbols (green dotes, red dots, etc.) and include a brief description of their meaning, significance, etc.

•

Simplify and generalize terminology used by tool – refer to dredging projects and placement areas instead of harbors and beaches for example.

•

Modify the user interface to show calculation of benefit/cost ratios.

•

Modify user controls and functions to facilitate better description and quantification of beach characteristics and physical processes – one possibility is to include two or more approaches with different levels of sophistication and data needs from which the user picks one and the next part of the model compiles the necessary inputs from database files, user inputs, or a combination of both as needed. In the best (i.e. most


A.3


sophisticated) case, the model might include a menu for fill dimensions and then show and/or have user work with a cross-section or beach dimensions, the date or season of the survey, sediment compatibility, the native sediment characteristics, and beach erosion history. These possibilities could be modeled in a flow diagram to supplement the text here of course. •

Modify user controls and functions to facilitate better description and quantification of transportation options and costs – one possibility is to include two or more approaches with different levels of sophistication and data needs from which the user picks one and the next part of the model compiles the necessary inputs from database files, user inputs, or a combination of both as needed (similar to last case). In the best (i.e. most sophisticated) case, the model might include call outs to one or more databases to get updated cost data (e.g. the M11 databases for equipment and labor costs that are updated annually) and a menu so that the user can first check whether or not the truck or railroad can get to a particular source or placement area and second, check the network and add additional road or rail segments to get from source to placement area (similar to what happens now when user adds scow and tow routes). These possibilities could be modeled in a flow diagram to supplement the text here of course.

•

Modify user controls and functions to facilitate better description and quantification of beach use characteristics and economic impacts – one possibility is to include two or more approaches with different levels of sophistication and data needs from which the user picks one and the next part of the model compiles the necessary inputs from database files, user inputs, or a combination of both as needed. The inclusion of a series of "typical or reference" beaches might be used here as one possibility since this would allow a user to pick the reference beach most like the one they are interested in and to use the economic information for this reference beach for the one lacking data. These possibilities could be modeled in a flow diagram to supplement the text here of course.

•

Add new functions (similar to the "ecosystem" functions in the EFM model for example) to calculate additional benefits and costs.

•

Verify that the various model inputs and output data are SDSFIE compliant and if not, modify existing data resources and protocols as necessary to achieve this result.


A.4