Feeds:
Posts
Comments

I live in Massachusetts and really am not terribly knowledgeable about Florida surface water hydrology. I do know that it is a flat state, it has karst geology and that groundwater plays an important role.  I lived in Northern California for a number of years and spent a good bit of time reviewing USGS gage data. The coastal terrain tended to be steep and storms off the Pacific were capable of dropping significant amounts of rain.  The first time I saw a gage’s stage reading increase by over 15 feet in less than a day I was rather surprised, but over time I became more comfortable seeing such rapid stage increases.

Florida recently experienced some staggering amounts of rainfall. I heard reports indicating 22 to 26 inches of rain falling. As such, I had to go to the USGS NWIS Florida site to get a handle on how the rivers were responding.  As of this writing (May 1st, 2014) a number of gages are currently coded in black which the USGS labels as ‘High’). The Shoal River response caught my eye as it reminds me of responses that look like a Humboldt County California gage might look after a Pacific storm hits.

The Shoal River near Mossy Head (drainage area 123 mi2) was running at 348 cfs (2.8 csm) the morning of April 29 and peaked during the late afternoon on April 30 at 7580 cfs (61.6 csm) .  You can also see that the USGS sent hydrographers to the gage during just prior to the peak. Well done USGS and I hope that life and limb were not risked to obtain these data.

348 cfs to 7580 cfs in a little over a day and a half

348 cfs to 7580 cfs in a little over a day and a half

The stage change in 39 hours was just shy of 14 feet!

Nearly 14 feet of stage change in a day and  half

Average stage increase on the rising limb on April 30 was 8.4 in/hour

As impressive as this storm was, the historic data at this site indicate five events that were larger than 8,000 cfs. Even though roughly two feet of rain fell, other storms and antecedent conditions in past have led to even greater storm runoff.

April 30th flood will be the new flood of record

The data indicate five previous floods that were larger

As fascinating as I find these data, this is the classic case of what I refer to as the “hydrologist’s dilemma”.  We find these rare events exciting and interesting, yet at the same time, many people are suffering and are experiencing a life changing natural disaster.  It goes without saying that my thoughts and prayers are going out to the people in Florida who are now facing the challenge of a post flood situation.  May your fellow neighbors, place of worship, elected officials, local businesses and insurance companies all be a source of inspiration and may you be a more flood resilient community in the end.

Worthwhile Reads

Wendi Goldsmith is the CEO of the Bioengineering Group and has recently published a book, Bioengineering Case Studies with some her colleagues through Springer.  This book includes a number of case studies and highlights several stream bank slope stabilization techniques whereby best practice techniques were used.

The release of this book is timely as this past fall, the Army Corps of Engineers Hydrologic Engineering Center announced in its Fall 2013 newsletter that the bank stability analysis model, BSTEM, will be incorporated into HEC-RAS.  One aspect of BSTEM that sounds intriguing is that it can compare factor of safety values for existing conditions and banks that have been subjected to stabilization methods. Until now, HEC-RAS has only been able to assess scour/incision vertically. With the incorporation of BSTEM, it seems as though lateral erosion can be modeled as well.

Another worthwhile read recently released is the MA Department of Fish & Game Division of Ecological Restoration’s 2013 Annual Report which is focused on the value of restoration and is available as a pdf here.

Pre and post project photographic monitoring has been around for a while.  I’ve seen some drab appendix tables that list the lat/long and the azimuth for where each photograph was taken. I’ve also seen photographs jammed into an appendix as well. Why not take a more modern approach using the features ArcGIS.com and photo hosting services such as Flickr or PicassaWeb? Assuming you have your lat/long, azimuth and photo filename in Excel, a pretty powerful online map can be made that shows where each photo was taken, the direction of the photo and the photo itself in a map that can be panned and zoomed and presumably have a recent aerial photo basemap.

Here are three ESRI blog posts that can help make such a map:

How to configure pop-ups:

http://blogs.esri.com/esri/arcgis/2013/07/25/custom-attribute-display-pop-ups/

Adding photos from Flickr, PicassaWeb or WindowsLive

http://blogs.esri.com/esri/gisedcom/2011/02/25/map-your-photos-with-arcgis-explorer-online-automating-the-process/

Rotating arrows to show azimuth:

http://blogs.esri.com/esri/arcgis/2014/01/06/rotating-layer-symbols/

If you have an ArcGIS.com organization prescription, then you can take the map you’ve made with all your georeferenced photos, configured pop-ups and arrows showing the photo azimuth and then put that dynamic map into a PowerPoint presentation. Pretty cool!

The USGS has reviewed several gauges throughout the state and has now developed regional bankfull geometry curves.  For those of us waiting for these data so that we can put them to use on projects, this is a great development.  The study does have a few geographic limitations, so take note of those caveats before putting the equations to use.
http://pubs.usgs.gov/sir/2013/5155/

 

Every year, ESRI hosts its annual users group meeting in San Diego.  For several years now, the day before the big conference opens, the hydro/water resources folks at ESRI host a 1 day seminar.  All the videos from that one day event can be viewed here:

http://video.arcgis.com/series/36/hydro

Updates to ArcHydro, GeoRAS and GeoHMS are provided.

Thank you ESRI!

Earlier this year, the USGS has released a web mapping service called Streamer.

http://nationalatlas.gov/streamer/Streamer/streamer.html

It’s a fairly straightforward tool.  A user can either trace a channel upstream or downstream. From there, users can get a summary or detailed report that has some basic information such as how many states the river is in, or how many USGS gages are on the trace.

A bit more background on the tool is available here: http://nhd.usgs.gov/newsletters/News_July_13.pdf

AIR Worldwide has just released a special edition of it’s newsletter  that highlights some of the challenges to the private flood insurance market in the US.  Here they are:

“The first challenge is the market itself. Because of the U.S. Government’s heavy involvement, the private flood insurance market has not been attractive to insurance innovators and pioneers. The market still has to fully embrace flood as a peril that can be insured in a profitable way—an opportunity that AIR’s new flood model can help realize.

A second challenge is the very size of the U.S. AIR has overcome this challenge with a state-of-the-art precipitation model that couples a global circulation model with a regional numerical weather prediction model to produce realistic precipitation patterns.”

As I wrote previously, the National Academies Press released its book Mapping the Zone, a key recommendation was the acquiring high resolution  elevation data (e.g. LIDAR).  AIR Worldwide is adding to the conversation by taking a forward looking approach and doing it’s best to predict likely precipitation regimes.

The dynamic here is rather interesting.  FEMA has changed its flood insurance premium policy in 2012 due to the Biggert-Waters act.  In some case, flood insurance premiums are skyrocketing, such as in some coastal areas that were hit by Hurricane Sandy.  Properties located within floodplains are also affected by this policy.  Obviously, no one has a crystal ball, but I am interested in hearing what people think some trends could be with respect to existing home and new homes being built within floodplains.  Historically, I would completely agree that FEMA has been heavily involved in the private insurance market.  With Biggert-Waters now in affect, subsidies being eliminated and premiums going up, it’s not clear to me how large FEMA’s involvement with distorting price will be with respect to influencing flood insurance premiums.  Not only will Biggert-Waters have a large effect on the private insurance market, but it seems as though there will have to be some real on the ground changes in land use.  I suspect many homeowners and businesses located within a floodplain will now be motivated to take a harder look at various flood proofing measures.  FEMA’s list of retrofitting measures includes raising a property’s elevation, wet and dry floodproofing, relocation, constructing levees and floodwalls and demolition.   Now that premiums are increasing substantially, I’m curious to know if demolition or abandonment might become more prevalent.

The property casualty insurance market isn’t an area I’ve covered too much on this blog, but given the damage that floods induce on people and fluvial and riparian ecosystems, it seems like a topic worth some review.  Currently, the Property Casualty Insurance Association of America is having their annual meeting in Boston.  For Twitter followers, the #PCIAM20123 hashtag might be of some interest.

Follow

Get every new post delivered to your Inbox.

%d bloggers like this: