addressing climate change adaptation in regional transportation plans

Addressing Climate Change Adaptation in Regional Transportation PlansA Guide for California MPOs and RTPAsinland flooding, but does not have the resources to generate revisedfloodplain maps (which require, at a minimum, information on projectedrainfall intensity, runoff coefficients, and concentration areas), a solution maybe to expand the floodplain boundary in GIS by a given percentage ordistance. While not a rigorous method, this approach could highlight criticalassets proximate (but not yet in) current floodplains that it may be prudent toconsider – without the costs of conducting hydrological analysis.Figure 11.2 illustrates the combination of data layers for climate andtransportation information using sea level rise as an example.Using data from the California GIS Data Library layers on ports and roads,coupled with climate layers from the Pacific Institute, one can make a highlevel assessment of the risk and vulnerability of ports infrastructure. In year2000, approximately 6 square miles of Los Angeles County are inundated byflooding in a 100-year storm event. In 2100, approximately 11 square miles ofLos Angeles County are projected to be inundated, and inundation spreadsfurther inland. Figure 11.2 shows inundation at two major ports – the Port ofLong Beach and the Port of Los Angeles. At this time, the two ports arecurrently evaluating the risk in their own separate climate adaptation studies.If more localized assessment is of interest in the area around the Ports, theprocesses described in this guide allows planners/data users to add onclimate layers and transportation assets at a finer grained level for a moregranular assessment approach.2. Thresholds. Exposure can be determined based on established thresholds orrules of thumb. This test is more appropriately applied to stressors that arenot conducive to precise geospatial representation (such as extremetemperatures). The key factor is an estimate of the climate stressor thresholdthat, when exceeded, may pose a hazard to infrastructure. For example, acommon threshold for temperature, found throughout the literature ofweather-related transportation vulnerability and cited by both engineers andmaterials researchers, is 95°F. Temperatures of 95°F or greater may causerutting of some asphalts, kinking of rail tracks, and abnormal expansion ofstructures and structural elements. Although exceeding this threshold doesnot necessarily, or even often, result in these impacts, 95°F is a key point atwhich these impacts become realistic enough to generate concern frominfrastructure managers.11-4 Cambridge Systematics, Inc.