Retracing a Hike

Nicole Stotz
American River College, Geography 350: Data Acquisition in GIS; Spring 2010

Abstract

In 2009 a group of volunteers hiked to a remote mining cabin in the Inyo Mountains, in hopes of restoring it.  Trails are not maintained, and information online is scare.  To create personal trail maps and profiles, a hand-traced trail was digitized from an old topo map.  Various shapefiles were gathered from CalAtlas - orthoimagery, DEMs, and background information on roads and boundaries.  Trail profiles were created with 3D Analyst, and a 3D scene was created in ArcScene.  Further study should focus on updated trail conditions and history, as much of this information is out of date or scattered across multiple sources.

Introduction

Between the Sierras and the Great Basin, the Inyo Mountains contain evidence of the area's mining history.  Prospects, mining cabins, and a network of trails extend throughout the area.  In May of 2009 one of these cabins, located at Beveridge Ridge, was restored by a crew of volunteers.  The location is remote - all supplies were brought in by helicopter, and it's a two day journey by car and foot to the cabin site.  The trails into the interior are not well marked, not well known, and not well maintained.  

There are many sites that list trail information - but these are either known trails, or ones denoted by GPS points.  The best (and only) information for a good portion of the hike in was a weather beaten copy of a topo map with a hand traced trail.  Working from the map copy, is it possible to create a better map?  Using ArcMap and ArcScene, trail profiles, maps, and a 3-D model were created - the usefulness to be tested when the weather improves.

Background

Remnants of the various attempts at mining are scattered across the Inyo Mountains.  Beveridge Ridge was one of several mining districts active from the 1870s to just before WW1.  Gold and silver prospects brought an influx of miners and money to remote areas of the range.  By the 1880s, enough money was coming out of the Beveridge prospects to establish a small town and mill site, named Beveridge.  A tram carried ore down the steep mountain sides to the canyon below, and a network of mule trails meandered to the dock at Swansea on Owens Lake.  A steamship transported the ore to the railroad.

By WW1, the Los Angeles Aqueduct had diverted most water from the Owens River to the south, drying up Owens Lake.  Swansea became a dry dock, and the ore from the prospects was depleted.  Beveridge became a ghost town, and the miner's trails were forgotten and overgrown. 

Beveridge is located on BLM lands, and is mostly wilderness.  Hikers rediscovered the extensive miner's trails in the 1970s, and established a partnership with the BLM to restore parts of the trails.  A few are marked on area topo maps and described on the BLM site (Ridgecrest office).  These are not nicely maintained trails, and the environment can be harsh.  Some of the few existing mining cabins are used as shelter by hikers.

One of these cabins is located on Beveridge Ridge, above the ghost town of Beveridge.  Harsh weather at 8500+ foot elevation left the 100+ year old cabin in danger of collapse.  In May of 2009, a group of volunteers from various organizations attempted to stabilize the cabin.  Because of the remoteness, all supplies were transported by a Forest Service helicopter.  Volunteers drove in along an existing 4WD path, and then hiked for two days to reach the cabin.

Methods

I started with a weather beaten copy of a topo with a hand traced trail.  This particular quad didn't contain the 4WD trails, but neighboring quads were listed on the map legend.  CalAtlas contains all California quads, and it was fairly easy to download the ones I needed (six in all).  These were mosaicked into a new raster in ArcMap.  Next, I scanned the relevant section of the weather beaten topo at the highest resolution possible.  This was opened in ArcMap, and then georeferenced to the newly created quad raster.

I created separate shapefiles for each feature I wanted to digitize: trails, 4WD, and trams.  Using Editor, I did a heads up digitization of the georeferenced map copy - this became the trails layer.  I repeated this for the trams layer, using the mosaicked quad raster as reference.  A few sites contained information on the 4WD trails in the area - the specific one leading to the trailhead is called the Swansea grade.  I georeferenced an image from 4x4 site and added it as an overlay on the mosaicked quad raster.  These two layers were used as reference for the creation of the 4WD layer.

After the digitization was complete, I used the line interpolation tool in 3D Analyst to produce trial profiles.  A 30m DEM was acquired from the USGS.  Using each layer as an overlay, I traced over the digitized trails.  This gave me a file that associated X,Y coordinates with an elevation, which was then exported to Excel to convert from meters to feet.  A chart was produced for each digitized layer that shows elevation gain and loss.  Trail length was derived from the digitized shapefiles.

Simple area maps were created with information from CalAtlas - major roads, water features, and towns in Inyo County. Each layer was clipped to Inyo County, with only major features selected and labeled.  The first mapped overlayed this information with the DEM, and the second utilized NAIP orthoimagery from CalAtlas.

The final step was to produce a 3D model of the area using ArcScene.  NAIP 1m resolution color imagery from 2009 was acquired from CalAtlas, with four images per quad.  20 of these images were mosaicked together, and draped over the DEM layer, with a vertical exaggeration of 4.  I had some trouble adding the digitized trails layers to the model, and so left them off.  

Results

Digitized trails with mosaicked 7.5'' USGS quads.  Blue = 4WD trails, and green = hiking trail.


Trails overlayed with DEM.  Trams = yellow.

Trails overlayed with NAIP orthoimagery.



3D view created in ArcScene, using the NAIP imagery draped over the DEM.  Owens Valley is on the left, with the Inyo Mountains on the right.


Trail profile created for hike from New York Butte to Beveridge Ridge cabin.


Trail profiles created for 4WD trails.

Analysis

The maps and trail profiles that were produced provide me with a good overview of the trail environment.  While they look fairly simple, I was surprised at that information that could be extrapolated from a weather beaten map copy.  

Gathering the information was very interesting.  The 7.5'' quads this is based on cover a very small area, and California is a huge state.  The naming conversions aren't very clear, and it took a bit to locate the correct maps, DEMs, and NAIP images.  While looking through a populated places shape file, I found the towns of Beveridge and Swansea - no one has lived in those towns in decades.  Beveridge is a ghost town high in the Inyos, while not much of Swansea remains.  They can both be found on Google maps.  

Producing the 3D model in ArcScene was troublesome.  The 1 meter NAIP imagery takes a long time to render, and I couldn't access any DEMs smaller than 30 meter resolution.  Displaying the trails didn't quite work, I'm not sure why.  I decided to leave them off the scene for now.  

The trail models were easy to create.  While 3D Analyst has a tool for a graphical result, the measurements were in meters.  Since I didn't want to reproject my data, it was easiest to export everything to Excel and use a simple formula to convert to feet.  Length of the trail was left off, as I was unable to get miles to display correctly.

Conclusion

There are quite a few mining and pack trails throughout the Inyo Mountains, and not much information exists on them.  The little information available is usually a written description - it's hard to find trail maps and profiles online.  To fill this gap, some people have put up GPS points and pictures, but that doesn't give an good overview of the trail.  My aim in creating these maps and trail profiles was to add to some of the scarce information available.

This could turn into an on going project.  The trails on the 7.5'' quads are just a few of the trails in the area, and the last map is at least 10 years old.  Springs marked on the map are not completely accurate - at least one is dry.  Hikers usually leave notes at known rest areas about these conditions - new hikers wouldn't know about these things.  4WD drive trails and conditions are scattered across different forums and sites.  If all this information was gathered in one place, more people would know about the trails.  The downside is increased human impact in a fragile ecosystem, and injury in very remote backcountry areas.    

A profile for the the largest tram in the area was also created.  This carried salt for 12 miles over the entire range, from the Saline Valley in east to the Owens Valley in the west.  There are other trams in range as well.  It would be interesting to research the historical transportation network - trails, trams, rail, and ship.  If the trails are ever developed, historical background would be useful in establishing miners' trails versus modern trails.

References