Simon Dixon writes an excellent piece (admittedly published January 2014) that summarizes some of his PhD efforts in England that looked at how adding woody debris to a river in smaller catchments might effect flood conditions downstream in a more urbanized setting. The results seem to suggest that the answer is a classic ‘it depends’. On the encouraging side, it appears as though allowing floodwaters to innundate floodplain forests can help. To quote “the real take home message is the restoration of floodplain forests to entire “subcatchments” of the main catchment always decreases flood peak height after 25 years of growth, and can have dramatic effects.” Three cheers for forested floodplain restoration and connectivity!
The piece is an excellent read as are the other posts in The River Management Blog.
Posted in flooding, large wood debris | 1 Comment »
Well, it’s September and it appears as though this update was released in back in March. In any event, the latest version of PeakFQ is now 7.1 and it is available for download here:
Be sure to read the version history which will discuss the new functionality in the program.
You might also want to read about what the Subcommittee on Hydrology, Hydrologic Frequency Analysis Work Group’s piece on Determining Flood Frequency using Expected Moments Algorithm here:
Posted in flooding, software, USGS gage data | Leave a Comment »
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
The stage change in 39 hours was just shy of 14 feet!
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.
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.
Posted in flooding, hydrology, USGS gage data | Leave a Comment »
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.
Posted in monitoring, river restoration | Leave a Comment »
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:
Adding photos from Flickr, PicassaWeb or WindowsLive
Rotating arrows to show azimuth:
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!
Posted in Excel tools, GIS, monitoring | Leave a Comment »
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.
Posted in geomorphology, USGS gage data, watershed analysis | Leave a Comment »
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:
Updates to ArcHydro, GeoRAS and GeoHMS are provided.
Thank you ESRI!
Posted in GIS, software | Leave a Comment »