Back in the Saddle Again

I took April and May off. It was a year ago that I started field checking, so today I started on the west, and final, section of the map. Just recon today, it was too wet to actually make pencil marks on paper.

The west map is where all the park construction is taking place. Lots of construction photos on the photo page - here's the visitor center:

From Chattahoochee Bend

And the restroom at the day-use area:

From Chattahoochee Bend

I plan to give the construction areas a wide berth until they are finished. The west map is big, bigger than the other two. It runs from the flat rock area that gives Flat Rock Road it's name all the way to the river and then hooks south to run along the shoreline. Lots of confusing logging roads - confusing because they are not yet mapped, but that will change over time. There are rock features extending from Flat Rock Road west for at least 500 meters, maybe further, but not as far west as the visitor center.

Looks like the planners did a good job. Each developed area is on a different spur, so as you drive west you come to the Visitor Center, the pioneer camping, the residence and maintenance areas, and the campground. The day-use area is actually the furthest west, and is in the flood plain. I assume there will be a boat ramp - they have logged an area right to the water's edge.

A lot of work remains to be done on the park road. It is only a swath of logged area right now - the construction workers are using the logging roads to get access. Some of the park road will coincide with the old logging roads, some of it will be new construction.

So, my plan is to work the area north of the construction and north of the powerline first, sorting out the logging roads as I go. Once I finish that as far west as the river and the day-use area I'll decide what to do next. There is no construction in the flat rock area west of Flat Rock Road and no construction in the area south of the day-use area - so there are plenty of spots to keep me busy for the next few months until the construction is finished.

550 Acres or 2.23 square kilometers

Everything field checked so far has been drafted. That's 2.23 sq km, or a little more than half of the northern half of the map. The southern half of the map is bigger though. I'm averaging about 40 hours/sq km for field checking. If you factor in the drafting and other prep work, it's more like 68 hours/sq km. This is in terrain that is very familiar to me. When I move into the boulders south of the powerline my speed will probably decrease. But next I will move into the bend of the river, which has different terrain but no boulders: fields, pine plantations, and flood plain.

Hopefully I can work in another 80 hours before the end of the year and have the northern map completely field checked. I may take a weeks vacation, a "staycation", and just work on the map in October.

But there is enough to run on now. 550 acres is plenty for an orienteering meet - but that will have to wait for lots of other things to happen first.

Spider Population Explosion

It all begins with just a handful in April. Those have babies and the babies have babies and so forth and so on. How many generations are there in one summer? Who knows, but by the end of August there is a spider web on every branch. Wearing a bill cap is a necessity. Imagine blundering into a web and having the spider dangling before your eyes, or looking down at your shirt to see one crawling up towards your neck. By the end of he day I am covered in webs.

The good news is I finished another page this weekend - eight hours on Saturday and six on Sunday. The area west of the inholding is done, including the beaver swamp. It's about 200 meters long and 150 meters wide. Most of the long, wide flat area is light green and almost featureless. A nice creek meanders through it. The lidar contours are indispensable for mapping that creek. As long as he drop is 2 feet or so, the lidar picks it up. I used to have to do this by pace and bearings.

And what is this thing? More important, how did it get out in the middle of the woods with no roads anywhere around? It's a meter tall and three meters long, made out of that hard black plastic. There's some sort of gate at one end. It looks like a standpipe for a pond. I suppose it could have floated down the mighty Chattahoochee in a flood - it's about 150 meters from the river.

Another milestone - once I get caught up with the drafting, I will have enough map to run on. My plan is to finish the first deliverable for the orienteering club before Christmas. Next area will be north into the Chattahoochee Bend. Much different terrain - open fields, pine plantations, and flood plain.

One Mile an Hour

I set the GPS to record some stats while I field checked on Saturday. Five and a half miles of walking back and forth and up and down for five and a half hours - averaging about a mile an hour. It seems like I should have covered a large area it I walked for five and a half miles, but no - that's not the way that field checking works. Up the bottom of a reentrant, then down a little higher up, then up on the spur, then repeat in the next reentrant. Backtrack when I find a mistake. Wander about in the flat by the river, poking around in the tall cane, then try to sort out an old road that appears out of nowhere. So there is a lot of walking for a small amount of area covered.

I have proof that the river floods the park. Found lots of plastic trash congregating in this section. The river bank is two contours high (six meters), so that's a pretty good flood that can deposit trash that high. I mapped the closest approach of the river to the hills - only thirty meters. That's almost a cliff. South of that spot the hills retreat to a distance of 400 meters - that's a lot of flat land. That's where I started seeing the plastic that had washed down from Atlanta - not sure why it would start to appear there. Probably has something to do with the topography.

The riverside vegetation is thick in his area, which means that I spent quite a bit of time poking around. There is always a rise of land at the bank, followed by a depression and then another rise of land. All very subtle. Getting the contours straight is very important for an orienteering map. The small changes are what will make the map interesting.

Found the first spot where I could actually get down to the water. Usually the bank is so steep and muddy that the only way to get down is to fall. A small gully (which I mapped) gave me the opportunity to get down without getting covered in mud. The view upstream and downstream.

That's the last of the river pictures until I finish the rest of this page. Now I need to work my way south through some logged areas to the big powerline, while skirting the beaver pond. I'm curious to see how extensive the beaver swamp is.

a dark and gloomy morning

It doesn't take much cloud cover to make it dark and gloomy beneath the leaf canopy of July in Georgia. Very little actual light makes it to he forest floor, and this morning, with rain approaching, it was so dim I had a hard time reading the map.

I covered a lot of area with little actual pencil marks on paper to show for it. I'm starting a new section since I had finished encircling the first area of "meadows". This is still the area west of the small power line. I like to start a new section by using a linear feature ( no matter how obscure) to define it. Not much luck finding anything here. I thought there would at least be an old road running down the spurs but there was nothing. I wandered out to the northeast where one of the old homesteads is located. This is the one with the corn combine and the large barn. I ended up walking the edge of the pine plantation (planted in rows running east and west) out a spur until I could join with a stream I had already mapped. There are several areas of pine plantation that will be on the map. I have mapped areas like this before at Joe Kurz, and will use the directional area symbol for them so that the orientation of the rows of trees will be obvious.

I still need to go back and do the "meadows" - but I will save that for a time when I have enough gumption to tackle it. It will be very important to the map to get the vegetation correct in those areas.

More pictures on the photo page.

Independence Day Mapping

Spent five hours this morning adding more area to the map. I'm still working in the deep forest surrounds the "meadows", saving the actual meadows for later. These hills are the closest to the river of any in the park, several coming right down to the water's edge. Also found the first depression along the river - about 50 meters long. I thought it was a hill on the lidar basemap since there were no tag lines - of course on the orienteering map there will be no doubt what is up and what is down.

Found another quartz pit, where someone (probably Creek Indians) removed all the quarts from an outcropping. One deer skeleton, several small cliffs, and the first of the open fields along the river. These fields are all man-made. Unless the park maintains them by cutting they will gradually revert back to forest. Check the photo page for more new photos.

On the technical side, I have not used the GPS since I started the map. As long as I keep in contact with the basemap so that I always know exactly where I am, it is much quicker to put pencil to paper than to go through the extra added steps of using a GPS.

Arrowhead pit?

Found a pit in my mapping today. Quartz rock had been dug out of it. I've seen this before, at Russell State Park on the Savannah River. It's possible that the pit was dug by the Creek Indians while looking for material to construct arrowheads. There's no flint here - quartz was about their only choice for sharp stone tools. Of course all that stopped when the deer trade began and the Creeks could afford to buy rifles.

The county name where the map is located - Coweta, comes from the name of a Creek town on the river, although I believe the actual town wasl located down near Columbus. The Creeks stayed around their towns in the summer and on their hunting grounds on the rivers and "creeks" during the winter.

I mapped five hours today in the heat. It was 93 when I got back to the truck at noon. I start at first light to beat the heat. It's not too bad really. I wear a long sleeve synthetic running shirt that is very light and white. Long sleeves to keep off the skeeters and the deer flies and horseflies. I also wear a bandana around my neck to keep the deer flies off.

Worked on the west of the "meadows" area. I'm just not up to tackling the difficult and detailed meadows in this heat. I worked the deep, dark woods, going up and down the spurs and reentrants, filling in the vegetation boundary on the west side of the meadows. It will be quite a job to get the vegetation cover correct in the meadows - a job for another day. I plan to work around them until I have them completely defined, then come back and fill in the different shades of yellow and green in the meadows.

Small Victory

Today I finished the area east of the small powerline over to Flat Rock Road. It's pretty satisfying to actually finish off an area, no matter how small. This section is narrow, no more than 200 meters wide, and I can use the powerline poles as references - after I put them on the map, of course.

Found some pits that someone had dug in this area, as well as the usual root stocks. Also finished the last of the pine forest, which has a narrow strip west of the road.

Worked my way all the way north to where the powerline bends to the east. Here I got totally confused. The photo and the powerline did not agree. I was right at the edge of the photo and I didn't have the next photo north printed out. Gave it up until another time.

At this point I have finished about 0.6 sq km.

By the time I got back to the truck it was 82 degrees. Whoo.

A Beautiful Sunny Day

Finally some sunshine so I can get some field checking done. Spent about six hours walking to and fro and back and forth, still in the area along Flat Rock road north of the power line. Got a break about mid-day when the pine forest opened up with visibility of 200 meters at least through the scattered pine trees. That's a beautiful area - reminds me of the longleaf pine forest over at Choccolocco in Alabama. Of course, it will require diligence on the part of the foresters to keep it looking this good - burns at least once every two years would be good. Orienteers love controlled burns. They really clean out the undergrowth and encourage the larger trees.

Found a double decker tree stand, easily the tallest I have every found while mapping. Two photos are on the photo page. I did not climb it - too rickety for me, but I did put it on the map.

And the ticks are out. I probably picked up twenty or thirty - mostly seed ticks about the size of a pinhead, but also four or five dog ticks. I need to find some peremethrin(?) to treat my shoes and socks.

So a good day. The 0.3 sq km between the inholding and the eastern boundary along the road are now mapped. On the next trip I'll work on finishing everything east of Flat Rock road north of the powerline.

First field checking trip

Rain, rain, rain. I hoped to get at least one full day in this weekend, but the rain just keeps coming. I had to wait until Memorial Day to get a half day in between rain showers.

But the map is started now. I began with the area north of the powerline and along Falt Rock Road. There is a 400 meter wide and 800 meter long corridorhere which should be very important when we finally get around to setting orienteering courses here. Although it sounds small, that's still over 0.3 sq. km. I only managed to get 0.1 sq km done before the rain came back.

LIDAR contours

The map took a major step forward this week with the acquisition of LIDAR contour data from the Coweta County GIS department. LIDAR is the latest and greatest method of generating contours (and other data) using airborne radar and digital signal processing. This is great news, and should make the finished product much better.

Getting it into a usable form took most of a day. The county supplied two foot contours in a shape file. I had to use qgis, wich is an open source GIS program (free) to translate it from lat/long coordinates to UTM WGS84 in zone 16N. Then I used a demo program to convert from shape to dxf. The dxf file still needed some massaging, which I did with sed in OS X. After all that I was able to import the dxf and have it magicall line up with the geo-referenced aerial photos.

Here's an example.The purple lines are the lidar data. The green lines are the USGS contours from the DRG. The blue lines are contours generated from the USGS DEM. There's a lot of difference.

[caption id="attachment_64" align="alignright" width="425" caption="LIDAR Contour Example"][/caption]

DEM -> contours -> OCAD

Using a USGS digital elevation model (DEM) to generate contours for an orienteering map might be described as "garbage in, garbage out." The USGS DEM is crude at best, at least from the viewpoint of an orienteering map.

But what this technique does offer is the ability to generate contours at a different interval than a USGS quadrangle map. For the Chattahoochee Bend map, I need countours at a 3 meter interval. The USGS quad has 20 foot contours. The object is to take the DEM, run it through some utility programs, and generate contours at a 3 meter interval that I can use a a crude base map.

Every contour must be redrawn during field checking to more accurately match the terrain, but there is an advantage to having contours at the correct interval to start from.

So I got a DEM of the area, for free, from the Georgia GIS Data Clearinghouse. This came in NAD27, which is what I was using with the DOQQ and NAIP photographs, so my OCAD map is already using those coordinates. If I were using some other coordinate wywtem I would have to convert so hat all my data sources are on the same page of the hymnal.

I use the GDAL utilities to do coordinate transformations and to generate the contours. These are command-line programs that are available for almost every operating system. I'm using a mac - not that it matters. The program to generate contours from a DEM is gdal_contour. The command looks like this:

gdal_contour -a contour -i 3 e3384d8.dem whitesburg.shp

The default output is a shape file. Unfortunately, the GDAL utilities don't seem to be able to generate DXF files, which is what OCAD needs. So I had to find a program on the net to do the conversion. I used Arcv2cad, which had a demo version. The dxf file is then imported into OCAD and the contours converted to a symbol. I actually copied the contour symbol and changed the color to gray.

So how does the output look? And how does it compare to the USGS quad contours? Here's an excerpt of the map:

[caption id="attachment_26" align="alignnone" width="341" caption="USGS contours and DEM contours"][/caption]

The USGS contours are in brown, and are at a 20 foot interval. The DEM contours are in gray at a 3 meter interval. So there should be about twice as many DEM contours. Note also that the DEM contours are points connected by straight line segements, and the USGS contours, which are taken from the DRG, are smooth lines.

This excerpt is about 850 meters east to west and 600 meters north to south, so you can see that there is not a lot of elevation chage on this map.

So is this useful? I would like to have both in the field, so that I can contrast and compare. The DEM gives me a clue where the extra contour line should go.

This would not be useful in a map with relief detail that could be obtained with photogrammetry. Photogrammetry would be a vast improvement when there is more relief and there is detail to be discovered. But this is such a "gentle" area that the photogrammetry is not going to reveal much, and comprehensive field checking is needed anyway. It is during the field checking that the detail will be added and the contours smoothed.

NAIP photographs

I am wrestling with the decision of whether to have photogrammetry done or not. It's the traditional way to go. But this map lacks intricate contour detail, so it is debatable that photogrammetry will do any good.

What is needed are recent aerial photographs. I found a new program from the department of Agriculture that is trying to take recent photographs, and I bought two photos that cover most of the park from 2007.

The first example below is a portion of the barerock area. There is a swath of rock features that run across the map. The second is of the northern tip of the horseshoe bend, showing some of the old fields and the new pine plantations. The quality and size of the photo excerpts is reduced, of course.

[caption id="attachment_23" align="alignnone" width="256" caption="Bare rock at Chattahoochee Bend"][/caption]

[caption id="attachment_22" align="alignnone" width="256" caption="Horseshoe Bend"][/caption]

The plan is to load these into Ocad as templates, and print them at 1:7500 with grid lines and other info, then take them out into the field and use them for field checking.

First Visit

Chattahoochee Bend State Park has been in the works for years. I don't know all the details, but I remember first calling the DNR about the park back in 2004. Recently Laurie and I have seen more and more aricles in the Newnan paper, and Laurie went to an organizational meeting of the Friends of Chatahoochee Bend State Park group that is forming. She is a great organizer - I wish she could do all the things that I hate doing - making phone calls, finding contacts.

We finally found out that the park is moving forward, with an opening date projected for 2010. Two years - just time enough to make an orienteering map.

The last map that I made, of Duke's Creek/Smithgall Woods, took two years. Before that I mapped FDR State Park, Joe Kurz WMA, Sweetwater Creek State Park, and Cochran Mill Park. That's a lot of time on the ground making maps. And that is where the work is actually done, on the ground - not sitting in front of a computer screen.

So I made a trip out to the new park site to see what I could see. While the park is in this state of limbo, the DNR is allowing deer hunting. Hunting season starts Saturday, and the act of walking up and down and back and forth while making a map is not really compatible with deer hunting! So I make a special trip out there on a Thursday afternoon, (after a dental appointment - ouch!).

It's about twenty miles from my house, downstream on the River, in the next county south - Coweta County. It's actually right across the river from the map we have at McIntosh Reserve. McIntosh is a much smaller area though.

The first thing I noticed while driving in is that no work has been done yet on making this tract of land a park - rough gravel roads. Then I noticed recent logging activity. Not clear cuting, but thinning. The pine forests on the top of the hills was being thinned. Some of the areas seem to have been thinned some time ago, and are looking pretty good, other areas are actively being cut. I was impressed by how clean it looked. Sometimes the loggers leave huge piles of slash, but there was none of that visible.

I parked at the hunting kiosk, and was immediately mistaken for a hunter. Must be the gray beard. Since I was carrying a map (I had thrown together an improved USGS quad with the boundaries on it) I was mistaken for someone who knew something. I knew nothing, of course, except what I had read about the hunting season. I impersonated a hunter by keeping my mouth shut, signed in at the kiosk, then drove down Flat Rock Road.

I found the southern boundary, turned around and parked on the flat rock area. Looks like a miniature Arabia Mountain. Lots of little nooks and crannies that are bare rock. Should be great orienteering when mapped correctly! I proceeded down hill to the west from there, and saw plenty of boulders on that downhill, reminiscent of Cochran Mill. There's more logging in that direction, with new roads cut across the hills - too bad. Once down off the hills, the logging stopped, or maybe they just haven't gotten this far yet? Made my way down to the river for the obligatory photo looking out onto the water, then I climbed back up to check out the private property.

There is about a square kilometer of private property that is an "inholding", completely surrounded by parkland. The boundary is well marked. There is a house, or hunting shack, hiding in there.

Then I proceeded north,looking for the open fields that are marked on the USGS quad. Found plenty of overgrown farmland, and some collapsed houses and barns and old farm equipment, but no open fields. I don't think I went far enough north - the photos on google maps show some fields way up in the bend of the river. Or they may be all overgrown now...

Made my way back to the truck, Saw plenty more hunters out scouting for opening day. I pity the poor deer - saw plenty of them while out in the woods, and lots of sign.

So what did I learn on this first trip? It's typical of the other maps we have in this area, with the added unique open rock areas. There are a lot of little hills, spurs, saddles, and reentrants that should provide a good challenge too. Looks like it will make a great map, depending on what happens with the "improvements" as they construct the infrastructure for the park and how extensive the logging is. If the logging is just thinning, followed by controlled burns, it should make it better for orienteering.

Next step in the process? Obtain permission from the DNR to actually make a map before the park is open for business...