Turns out that graphs in ArcGIS are pretty damn handy.

It was recently brought to my attention that the graphing tool in ArcGIS could be really useful if you had the right type of data (thanks to ND at UO). Well, I spent most of today trying to refine a longitudinal profile of the Owyhee River from my coveted LiDAR data set, and it occurred to me that I had some useful data. 

My goal beyond just examining the profile was to indicate the locations of major landslide complexes along the river corridor to investigate how they may influence the river’s gradient.  I actually extracted the profile data from the data using a tool in GlobalMapper which I like. I converted the data to an excel spreadsheet, opened the sheet in Arc and then exported it into my Geodatabase as a feature dataset. Once it was in there, I created a graph of the data (basically the profile) and began to select points on the profile along key reaches that I had mapped. Lo and behold, those points i selected on the map lit up in the profile graph. Sweet. This was huge. It goes both ways as well. Select points on the graph, and they light up on the map. 

Restrict the displayed points on the graph to those selected on the map and you can export them as a subset of the data. This step comes in really handy for plotting the exact position of the landslide complex-reaches on the overall profile figure. Previously, I had stupidly brute-forced this process. Typical. The result is below:

Also very useful is to plot the profile data in the form of cumulative distance vs. slope of channel segment. This graph immediately indicates important trends and anomalies in the data. Turns out that the anomalously high slope values and negative slope values relate, in this case, mainly to inadvertently collected data from vegetated bars, extremely coarse gravel bars, and even wave trains at some of the rapids. Thus, an important and informed QA step can be taken to clean out the riff-raff. In general, though, you can see how useful this method is for zeroing-in on areas of key interest. For example, many of the points on the map below correspond to rapids

 

 

 

 

Posted via email from Fresh Geologic Froth

Critics are everywhere

I was in the field yesterday doing some mop-up following a field review of a map. While checking a contact I had mapped that was queried by one of the reviewers, I happened upon this blunt assessment of my interpretation rolled up in a desert shrub.

Posted via email from Fresh Geologic Froth

Flash Earth and Geohacks…Who knew? Not me.

Just happened upon a sweet and simple geobrowser called Flash Earth…very smooth and easy to understand. Added bonus for me is that it links to high-res images of my favorite field area that are available only in Yahoo and Bing Maps:

Seems my pals at Google still just don’t care about SE Oregon. Anyway, I found the site by perusing the details in an exif header in one of my geotagged photos. Was checking that out in Irfan View, a program I was aware of but hadn’t tried yet. Turns out, it is well worth a look:

Which led me to the GeoHack wiki:

The internets are amazing, no? Totally cool.

 

 

 

Posted via email from Fresh Geologic Froth

Mapping yet another tortured river…the Mighty Bill Williams River, AZ

It is tortured river season in my office. Lately, I have been tackling Nevada’s mighty Walker River and its shrinking terminal lake (new term is terminus lake…but that is a bit soft); and Oregon’s Owyhee River and its travails with lava and landslides; but now I am back on to the Mighty Bill Williams River of Arizona. You know, the Bill Williams River.

Included below is a snippet of the map I am working on. Shown are 6 generations of lines that document major changes in the channel, most since a dam was finished in the late 60s. One day soon, this map will actually make sense, I promise.

The BWR is a special case. It is a roughly 35 mi stretch of river that traverses the hot desert below the confluence of two rivers that collectively drain more than 5000 square miles of western Arizona. Alamo Dam sits just below the confluence and traps essentially all of the sediment that would otherwise have gone down the BWR and to the Colorado River (well, at least to Lake Havasu). Also important to note is that the pre-dam BWR could attain peak discharges ranging up to 100,000 cfs, whereas the post-dam BWR can hardly exceed 7000 cfs owing to the outlet works of the dam. Thus, large runoff events that would have otherwise blasted through the system in a week or less (Spikes) are now converted to protracted, flat-topped hydrographs that lumber through the channel for up to several weeks to months (Bricks). Recall that these bricks are also sediment-free except for the sed picked up in the channel below the dam.

The result is an interesting experiment in channel change, sediment budgeting, and inadvertent (or otherwise) tamarisk farming. 

I won’t be posting daily updates of this map, so don’t worry. Be assured, however, that I will make a lot of noise when I finally finish it. This one is a long, long, long, time coming. Just ask the sponsors.

Some other BWR info: 

http://geofroth.blogspot.com/2008/09/how-to-eat-geospaghetti.html

http://www.fort.usgs.gov/Products/Publications/pub_abstract.asp?PubID=21745

http://picasaweb.google.com/drjerque/Bill_Williams_River_geotagged?feat=directlink

 

Posted via email from Fresh Geologic Froth

Lost in the woods? You need LiDAR.

Last week I had the chance to explore the upper McKenzie River valley in the Oregon Cascades. My tour guide was a UO PhD student in volcanology. She was showing me the range of interesting lava-water interaction features that characterize the valley. A very cool and unbelievably scenic place. 

Luckily, she has some LiDAR data of the area. This was my first chance to hit the field with LiDAR in hand of an area covered by old-growth forest. In other words, entirely non-trivial vegetation cover that is disconcerting in both its density and its scenic values. Two main conclusions: 

1. It is amazing how well the LiDAR data reveal the topography through a dense forest cover. I knew this, but living it for a day was very convincing. Many small to medium scale details in the surface of a thickly forested Holocene lava flow are painfully obvious in the imagery (below). For the desert rat in me, they were easier to see in the imagery than they were on the ground at first. Eventually, I was able to relate the two once I could see past the forest, but the imagery was far more revealing of the local geomorphology. 

Typical scene in the field area…locally, forest cover is thicker. Photo from surface of the lava flow evident in imagery below.

2. The LiDAR in this case also revealed some major features that had previously gone unnmapped at a fundamental level. We found / explored a very prominent volcanic feature in the midst of the lava flow that, according to the 24k USGS base and the 10 m DEM, does not exist. However, it is almost absurdly obvious in the LiDAR data. Mind you, this feature is not trivial in scale. It tops out at nearly 90 m above the valley floor and is has a 150 by 200 m footprint. It (the ‘Pimple’) is extremely steep-sided (as we discovered climbing to the top). It is also enigmatic geologically…potentially a glacially modified and exhumed volcanic fissure. Not sure on that.

Looking down from the Pimple. A seriously steep hike.

The 24k topographic map rendition of the area shown in the two LiDAR images.

Slope-shaded map of the LiDAR data

Hillshade map of the LiDAR data.

The point is that this very conspicuous feature is very mappable, but was overlooked in the development of the 24k map. A bit surprising in that it corresponds to a major ‘peak’ in the forest canopy. I will admit, however, that if you were out there in the rain, you could walk right by it. Certainly makes you wonder what else out there has gone unnoticed by the USGS topographic maps we once relied so heavily upon. Yikes…

Thanks to ND for the field trip and the LiDAR map snips.

 

Posted via email from Fresh Geologic Froth

Recent digital geology presentation: It’s here, don’t fear, get into it.

Posted via email from Fresh Geologic Froth

Digital Geoscience links from GSA, part 1

Here is a preliminary list of links to sites and resources that where mentioned during the Digital Innovations in Geoscience sessions at GSA:

Declan DePaor's geology kml projects:

http://www.lions.odu.edu/~ddepaor/Site/Google_Earth_Science.html

A simple, free, and effective program for geotagging your digital photos:

http://www.geosetter.de/en/

Google's free, geospatially aware photo-managing software, Picasa:

http://picasa.google.com/

The amazing digital pen that you should really use:

http://www.livescribe.com/

The nearly as amazing digital pen you should consider using in the field:

http://www.adapx.com/

One of many resources from SERC, this one is about using Google Earth to understand geologic maps. File this under uncanny obviousness. Shame on you if you don't incorporate this approach into your teaching.

http://serc.carleton.edu/NAGTWorkshops/structure/teaching_geo_map_interp.html

Virtual Field work:

http://www.virtualfieldwork.org/Welcome.html

The mighty Gigapan Robot:

http://gigapan.org/

More to come.

Posted via email from Fresh Geologic Froth

Are you a geo-luddite?

If so, breakdown and join the 21st Century. Besides, this rock is heavy.

Posted via email from Fresh Geologic Froth

Digital Geology Sessions at GSA…Sunday and Monday

Check out the lineup for our Innovative (we hope) and Ambitious (for sure) session on Sunday:

P6: Pardee Keynote Symposium–Google Earth to Geoblogs: Digital Innovations in the Geosciences
Sunday, 18 October 2009
Portland Ballrooms 251/258

1:30 PM – Talks

1:30 PM
DIGITAL GEOLOGY IN THE 21st CENTURY: IT’S HERE, DON’T FEAR, GET INTO IT
P. Kyle House, Nevada Bureau of Mines and Geology & University of Nevada

1:45 PM
ONEGEOLOGY – MAKING GEOLOGY ACCESSIBLE
Ian Jackson, British Geological Survey

2:00 PM
I TWEET, THEREFORE I AM: SOCIAL NETWORKS IN THE GEOSCIENCES
M. Lee Allison, Arizona Geological Survey

2:15 PM
ONE MAP – MANY MAPPERS: IMPLICATIONS OF INNOVATIVE MAPPING, MODELING, AND NETWORKING TECHNOLOGIES FOR GEOSCIENCE EDUCATION
Declan G. De Paor, Old Dominion University

2:30 PM – Demonstration

GIGAGEOLOGY: VIRTUAL FIELD TRIPS IN A Web2.0 WORLD
Ronald C. Schott, Fort Hays State University

3:00 PM – Interactive Display Booths

EXPLORING WITH GOOGLE’S GEOSPATIAL TOOLS
Mano Marks, Josie Wernecke & Tina Ornduff, Google Inc.
John E. Bailey, University of Alaska Fairbanks

EMERGING DIGITAL TECHNOLOGIES FOR GEOSCIENCE EDUCATION AND OUTREACH
Peter A. Selkin, University of Washington
Declan G. De Paor, Old Dominion University
Janice Gobert, Worcester Polytechnic Institute
Karin B. Kirk, Carleton College
Steve Kluge, Resources for GeoScience Education
Glenn A. Richard, Stony Brook University
Steven J. Whitmeyer, James Madison University

USING DIGITAL TOOLS FOR GEOLOGY
Kyle House, Nevada Bureau of Mines and Geology & University of Nevada
Ian Jackson, British Geological Survey
M. Lee Allison, Arizona Geological Survey

MONITORING ROCK FALLS IN YOSEMITE VALLEY WITH THREE-DIMENSIONAL, HIGH-RESOLUTION PANORAMIC IMAGERY
Greg M. Stock, National Park Service
Eric Hanson & Greg Downing, xRez Studio

4:30 PM – Discussion

Even more on Monday:

T160: From Virtual Globes to Geoblogs: Digital Innovations in Geoscience Research, Education, and Outreach (talks) schedule and abstracts

T160: From Virtual Globes to Geoblogs: Digital Innovations in Geoscience Research, Education, and Outreach (posters) schedule and abstracts

Stay tuned to Outcrop.org for subsequent developments and post-meeting extravaganza.

Posted via email from Fresh Geologic Froth

LiDAR-derived contours are useful, too.

Sure, I have gone on and on about the amazing visualizations you can get with some tweaking of LiDAR data; however, it turns out that a pretty basic representation is also quite useful…contours. Yes, contours. Sometimes smaller scale features remain somewhat ambiguous in hillshades or slopeshades, but high-res, short interval contours from the LiDAR data can eliminate most of the ambiguity. In this case, it is a tiny area that I have struggled with on the Owyhee River. Here, a large landslide entered from the north, shoved the river channel to the south, and the river eventually worked its way back to the north to some extent. The array of surficial deposits in the void that comprises the right hand side of the image south of the river record this sequence of events as well as subsequent sedimentation by tributary fans. The contours really highlight the fans, and in conjunction with discernible drainage patterns evident in the LiDAR, it is clear what is fan and what is river, right?

2-m Contours were generated in GlobalMapper and exported as shapefile to view in Arc.

Note, Ian Madin (at DOGAMI) gave me the tip on contours especially as they relate to resolving fan features. He was right…it works!

Posted via email from Fresh Geologic Froth