4/28/15: COASTAL HAZARDS IN THE US: USGS PORTAL TOOL

The USGS Coastal Change Hazards Portal is a new tool that allows anyone to explore how coasts change due to: extreme storms, shoreline change, and sea level rise.

Extreme Storms: this allows ‘real-time and scenario-based predictions of storm-induced coastal change, as well as the supporting data, are provided to support management of coastal infrastructure, resources, and safety.’ For example, let’s focus on the Gulf Coast and a scenario of a hurricane (any category). Let’s see how a Cat 1 and a Cat 5 possibly looks like (with probabilities of collision (dune erosion), overwash, and inundation for sandy beaches along the Gulf and Atlantic coasts during a generalized hurricane landfall): see figures for both. The most probable areas should be risks areas and treated as such in an emergency.

Shoreline Change: this shows: ‘historical shoreline positions and rates of change along ocean shorelines of the United States’. Looking into the East coast now, offshore Norfolk, see figures for long-term coastal change rates, and for the short-term rates (<30 years rates of shoreline change for open-ocean shorelines of the US ranging from 1970's to 2001).

Sea level Rise: there are two methods used to address this: a Coastal Vulnerability Index (CVI), and a probabilistic assessment of shoreline change. 

• CVI: ‘a preliminary overview, at a National scale, of the relative susceptibility of the Nation's coast to sea-level rise through the use of CVI. This classification is based upon the following variables: geomorphology, regional coastal slope, tide range, wave height, relative sea-level rise and shoreline erosion and accretion rates. The combination of these variables and the association of these variables to each other furnish a broad overview of regions where physical changes are likely to occur due to sea-level rise’. A quick image shown here shows how much red (very high vulnerability) California coasts possess.

• Probabilities of Shoreline Change: ‘this dataset was used to develop and evaluate the performance of a Bayesian network (BN) that predicts long-term shoreline change associated with sea-level rise. The BN is used to define relationships between driving forces, geologic constraints, and coastal response, which includes observations of local rates of relative sea-level rise, wave height, tide range, geomorphology, coastal slope, and rate of shoreline change. Using this information, the BN is used to make probabilistic predictions of shoreline change in response to different future sea-level rise scenarios’. See same area of CA and look at the area of south San Francisco.

As you can see this new tool will help tremendously to manage areas and to get a broad idea of what is happening on the US coasts.

All for now-

4/21/15: EXTREME WEATHER IN THE U.S.

This week we are exploring extreme weather events and/or cyclones. In today's figure from weatherunderground you can see how in the States there are a few events/advisories happening at the same time, not uncommon.

Knowing your weather patterns matters. As the climate changes, so will the weather. As an example, 2014 was the warmest year on modern record, according to the National Oceanic and Atmospheric Administration (NOAA) and the National Aeronautics and Space Administration (NASA), working independently. 

Global patterns like more droughts, more heavy downpours, heat waves, etc. can be linked to extreme weather events (NOAA). NOAA staff says: “The point here is that these events are causing up to billions of dollars of damage. As we see the increasing trends in these metrological and hydrological extremes, as a society we really need to think about how we are going to manage the risk, how we’re going to adapt to these changes in extremes.”

NOAA’s National Climatic Data Center provides a variety of information detailing all these extreme weather events. Their yearly maps of U.S. Billion-dollar weather and climate disasters are very informative (figure). 

The center says that in 2014, there were 8 weather and climate disaster events with losses exceeding $1 billion each across the United States. These events included a drought event, a flooding event, 5 severe storm events, and a winter storm event. Overall, these events resulted in the deaths of 53 people and had significant economic effects on the areas impacted. Further cost data and figures on individual events in 2014 will be announced in mid-2015.

Interesting times…

4/7/15: LANDSLIDES IN CA

Landslides impact California’s terrain often. These are generally related to precipitation patterns, in particular if there has been previous months of drought conditions. In 1982, a series of landslides near San Francisco killed 33 people and closed the Golden Gate Bridge. A total of 18,000 different landslides took place in the San Francisco Bay Area following a very heavy rain storm (data collected by aerial surveillance in the days following the event). Two fast-moving fronts carrying extremely heavy rain passed through in a 36-hour period, during which the area received an amount of rain equal to half its average annual precipitation. 

Another famous unstable area is La Conchita. A mudslide of 400,000 tons of mud in 2005 killed 10 people. This should not be surprising as the exact same place suffered another hill collapse in 1995, destroying 9 homes. See topographic map on the right that shows both sites. Note where we build our houses..

The obvious approach is study well the soil in where we put homes and also learn from previous occurrences, understanding that areas that are unstable will continue being so  (La Conchita is not alone; Oso area had been unstable before the 2014 event).  Detailed geologic reports have been made in the past of these places, but the personnel that has the power to act have not followed up/ignored them or have not read them.

Gravity always wins. We know better?

After the 2005 disaster, there was an attempt of a $50-million grading project. There were also calls for the county to buy up all the homes through eminent domain and never allow anyone to live there again. It was an idea that came and went, as was the grading project.

Here is the USGS page with information on how to identify landslides and what to do if one happens.

[http://www.history.com/this-day-in-history/landslides-kill-33-in-california; http://www.usgs.gov/blogs/features/usgs_top_story/rain-and-landslides-in-california/; http://www.latimes.com/local/california/la-me-la-conchita-20150104-story.html#page=1; http://pubs.usgs.gov/of/2005/1067/508of05-1067.html]