Recent experiences, including the cases of Hurricane Katrina and Andrew, have highlighted a serious need for early and transparent development of Engineering Policy for the built environment. This need is especially critical in the case of climate change and the potential for a rise in the global mean sea level. In essence, we lack a framework that allows us to understand and integrate the contributions from current scientific and engineering knowledge to the ongoing policy and economic discussion of means and methods to protect coastlines from sea level rise. This framework should also highlight the most important areas where a better understanding is needed, and equally important, where engineering solutions are unwise, impractical, or both.
The framework we propose to develop includes a conceptual model and more detailed, localized predictive models to understand the likely impact of sea level rise on coastlines in general and ports specifically; the protection structures and the required design and construction services needed for varying degrees of protection, the environmental impact of such structures, and the cost-value ratio of such structures. The framework will also highlight areas where current scientific knowledge and engineering and construction practices fall short of providing adequate answers.
As a consequence of global climate change, it is likely that the mean sea level will rise to an extent that some type of additional coastal protection structures will be necessary. Prudent design principles dictate that coastal structures designed to resist large forces such as, wind water and earthquakes are designed to specific conditions known or believed to be possible at each specific site. This is done primarily to insure efficient design, i.e. the minimum reasonable structure (and cost) needed to meet the design criteria. In the case of sea level change this basic engineering principle is of distressingly little use, for the reason that the credibility of those design criteria is largely unknown and untestable.
In the case of climate science, our knowledge and simulation capability is improving daily; nonetheless, the level of certainty is still far below the standards typically used for major infrastructure projects in the developed world. Specifically, estimates of the sea level change that could be expected in a reasonable planning horizon range from 50 centimeters to close to 10 meters. Just as concerning is the uncertainty surrounding the rate and timing of the potential sea level change. It is precisely this question of the rate of change that gave the original impetus to our current project. It should be self-evident that there is a (hypothetical) rate of sea level change at which we will not be able to protect or move quickly enough. At present, no one knows what that hypothetical rate might be.
It should be equally self-evident that there is a flexible, but finite capacity of the world's design and construction industry, particularly when it applies to the design and construction of coastal structures - which often require specialty equipment and construction techniques, which are not universally available, particularly in the developing world. Moreover, estimating the total industrial capacity of the design and construction industry is more difficult than for many other industries largely because the basic unit of production is ill defined, diverse and often driven by specific local conditions. Nonetheless, this estimate will be a critical component of rational planning from engineering, policy and investment points of view. Fortunately, recent advances in construction simulation and planning by CIFE and others have made the process of developing this estimate tractable. The basic strategy is to use the simulations to create the initial conditions for an iterative solution to the estimate of the total industrial capacity.
We have been developing a simulation of the world’s design and construction requirements for a hypothetical rise in the mean sea level of 2 meters. The choice of 2 meters is an arbitrary one, especially so given the level of uncertainty of climate models. Nonetheless, it does represent a value within the range of current estimates, and also represents a kind of minimum change at which virtually every port of the world will have to design and construct some type of protective structure. One outcome of this simulation will be to identify a rate of sea level change at which the current industrial capacity of the design and construction industry will be exceeded. The scale of such a simulation requires that the level of design specificity for any given location be reduced to the minimum reasonable extent. Typical industry practice would consider this to be an early stage conceptual design. However, considering the potential impact and scope of the effort, the conceptual design should take the concern of many stakeholders into consideration. Consequently, to improve the credibility of the “minimum design specificity” we plan to extend the scope of our project to include expertise in fluid dynamics, wave physics, ecology and economics.
To date, our simulations have included only the most basic data on the physical environments of the world's ports and harbors, including data on river flood stages, time to concentration of the relevant watersheds, and “typical” wind and storm surge conditions. We believe that the development of better information with a consistent methodology would greatly enhance the utility of our simulations. In particular, understanding the critical tidal, riverine and estuarine fluid dynamics conditions as well as wind wave overtopping conditions is critical to this end. Likewise, our economic evaluations have been restricted to publicly available data on the volume of container cargo and estimated value of port operations. Because of the scale of our simulation and the necessity of normalizing economic data, we suggest the development of a “cost – value” metric rather than a more conventional and specific cost - benefit ratio. This “cost – value” ratio addresses only the volume of shipping with a normalized value for the container equivalents metric published by most ports. This approach is a first approximation for one method that might be used to rank the ports in order of priority for construction sequencing. Other metrics for construction sequencing in our simulation might include resiliency of the ports and the surrounding communities. Such a metric would include:
- Vulnerability of transportation networks (highways, bridges, train tracks)
- Upland elevations and acreage of FEMA V-Zones
- Regional port redundancy (Are there other ports nearby? Do they have excess capacity?)
- Local energy storage capacity (just-in-time deliveries have resulted in many tank farms being dismantled)
- Dependence on the port within local/regional economy (how big a part does the port play)
- Level of preparedness of individual businesses, the port, the city, the region, etc.
This aspect could build on the Ranking Port Cities with High Exposure and Vulnerability to Climate Extremes: Exposure Estimates recently published by the Organization for Economic Co-operation and Development. That study focused more on a macro-level approach that looked at population density, wealth, and protections in place.
In addition, the integration of the built and natural environment in a consistent engineering framework is a discipline still in its infancy. We propose to include the enumeration of ecosystem functions as part of the overall framework project and to include those functions as part of the “cost - value” metric previously discussed. It is a given that many if not all of the ecosystem functions associated with any given port will be altered given a sea level change of the magnitude envisioned. Whether the rates of those functions will increase or decrease is not obvious. Whether the ecosystem service value of those functions will be increased or decreased is also not obvious. Our goal is not to establish a real value for these functions, but to place them in a context (i.e. likely or not to be affected) that will enable follow on work to clearly identify these impacts. Finally, another reason to study and understand this problem at two levels of detail (at least) is to learn how well a conceptual model can predict the protection and necessary design and construction work needed and estimate the cost-value ratio. A conceptual model is needed so that we don't overemphasize one concern over another. More detailed, localized models are needed to validate and improve the assumptions in the conceptual model and establish the minimum design specificity.
The planning group will also consider developing metrics for additional economic modeling components, such as local, regional, and national economic consequences of impacts on local port operations due to climate change, consequences of “no action” on the economies at these different scales, factors that could contribute to more resilient economies, economic ripple effects due to port shutdowns from severe storms, the potential for release of chemical pollutants in massive quantities from port laydown and cargo areas, and the effect of debris/objects that are being stored that may be washed away in a storm surge and cause more damage to other areas.
-Martin Fischer (lead), Professor of Civil and Environmental Engineering; Director of the Center for Integrated Facility Engineering
-Ben Schwegler (lead), Consulting Professor of Civil and Environmental Engineering; Chief Scientist and VP, Research & Development, Walt Disney Imagineering
-Stephen Monismith, Professor of Civil and Environmental Engineering, Director, Environmental Fluid Mechanics Laboratory
-Oliver Fringer, Assistant Professor of Civil and Environmental Engineering
-Meg Caldwell, Senior Lecturer in Law; Interim Director of the Center for Ocean Solutions
-Austin Becker, Ph.D. Student E-IPER (Emmett Interdisciplinary Graduate Program for Environment and Resources); formerly with the URI Coastal Resources Center and the Rhode Island Sea Grant