NRGS Geospatial Blog

So – There’s a problem in East Tennessee as reported in Newspapers and the Intertubes. Essentially 3 types of songbirds (American Goldfinches, Purple Finches and Pine Siskins) are dying from an apparent salmonella outbreak. I saw this first sitting in a restaurant flipping through the newspaper. So after filling up my bird feeder this morning I decided to get online and look to see where the outbreaks were occurring. I know that the outbreak of bird death is probably larger than gets reported since the bird has to die somewhere you can find it.

I think I literally did about 30 – 50 searches on Google looking for a county name in East Tennessee. I learned two important things.

1. No one reports the news anymore – 1 to 5 people report it. 500 others just link or copy to the original article. I would at least try to change the wording a bit as was suggested by High School Teachers.
2. No one has a map of the affected counties because of my reason above and no one lists all the counties in one article. I found 6 of the 7 to 9 affected counties in 3 articles.

So I’m not as far as I can tell I’m not in the affected area but I did wash out my bird feeder.

Since the news has become entertainment more than anything else someone tried to link the salmonella outbreak to Peanuts since Peanuts are in bird food. Except the birds that are dying don’t eat Peanuts. But don’t let facts interrupt a good story.

Anywho – My 15 minute map using ESRI’s Data and Streetmap data layers. Please excuse the poor cartography. I wonder if this is a migration route.

So, I’ve been using Archydro off and on again for a project. I’ve actually been trying to make it fit in which has been less than easy. In the interest of time and money I should probably stop trying to make it fit.

I needed to delineate watersheds in the project area. I had a 12 digit HUC – but I wanted to go smaller.  So I drag out ArcHydro and promptly couldn’t remember the steps. ArcHydro comes with several different users manuals. Reading the manuals to me is more of a trial in patience and meditation. The directions make sense probably if you’re a hydrologist – but if you’re not then you’re pretty much SOL. I even bought a book….which I can’t send back….but it looks nice on the shelf.

So after digging I found a user guide – or actually some notes from a class that used ArcHydro version 1. Most of the steps from the class were applicable – so I worked my way through them and decided to write it all down for posterity.

So I started with this:

This is the 10 meter DEM data taken (Actually 10 Meter NED) from the USGS Seamless Site. I clipped it out using the Watershed data from the National Hydro Dataset and the streams are from the same site. The streams are apparently fom the 1:24k Blue Line Streams.

So add in the ArcHydro Toolbar and here we go. Starting with the Terrain Processing menu on the left.

1. DEM Reconditioning or making an AgreeDem
2. Fill Sinks
3. Flow Direction
4. Flow Accumulation
5. Stream Definition
6. Stream Segmentation
7. Catchment Grid Delineation
8. Catchment Polygon Processing
9. Drainage Line Processing
10. Adjoint Catchment Processing
11. Drainage Point Processing

Most of the time I stuck with the defaults. The first step is the sketchiest. An AgreeDEM takes streams and elevation data and composites the two. The streams are burned in by dropping the elevation a little and creating something that “enhances” the watersheds…or forces them out. Typically the two data sources need to be related. I believe the NED and streams are – at least for 10 meter because in most cases 10 meter dems are (I believe) a rasterized contour plate.

…and now you have:

Overall – not bad. There was a little bit of editing around the edges to fix some goofs. But it worked.

So I wrote at earlier that I didn’t get ArcHydro. I get it now.

I spent the better part of the weekend reading documentation and reading implementation articles (Thank you Saint Johns Water Mangement District).  ArcHydro Makes sense now. I think….actually know that’s what I was missing – the practicality of the whole thing. Of course after reading several articles it would help to be a hydrologist – I guess that one class in College will have to do…..now if I only could find my hydrology book.

So I started today pouring through the NHD Dataset. Now that I understand the NHD I can start building the ArcHydro model for the Conasauga River Alliance. I’m thinking about doing a smaller area first before attempting the entire watershed. I lucked out in that there was 10 meter DEM data for the area as well as 1:24k NHD data. ArcHydro 1.2 works with ArcGIS 9.3 -well actually works as far as I know. I may hit a snag in the next day, but so far so good. I heard that ArcHydro 1.3 was under development/Beta – hopefully it will be out soon.

With any luck this can help or at least play a part in the Fecal Coliform/Septic tank cleanup that they are currently undertaking.

I’ve been working with a client  on a voluntary basis – The Consasauga River Alliance. The CRA are working in North Georgia/Southeast Tennessee on the Conasauga River – The watershed is..uh….Bigger than some – I don’t have all my data reprojected as of right now so I don’t have exact numbers. The group has been extremely successful without really using a GIS.  I was asked to provide some plots – from there I just kept compiling data. As a GIS person I’m amazed how much they’ve gotten done without a GIS. They’ve been able to put people on the ground and get things done.

Watershed Conservation isn’t so foreign that I don’t know where to start – but foreign enough that I’m not sure what they need. In the “good old days” you would start from scratch and digitize everything. Sites like the Georgia Clearinghouse have made that pretty much unnecessary. I found all the Hydro Information from the National Hydrography Dataset.  So my plan is to implement ArcHydro as the starting point. I’ve had some experience with the Extension but not being a Hydrologist is a bit of a drawback.

Archydro strikes me as one of those things that just has to click – I’ve read a book – read the documentation – I’ve played with it….but it just doesn’t click….or hasn’t clicked yet. I’ve had less problems on this go around than I’ve had on others. I’ve got to re-project all my data and finish processing all the 10 meter DEM data.

Anyway – more to come as this starts building. I hope to be able to build a Data Model (which I’m very familiar with) and hopefully publish it. Maybe it can help other Conservation groups with at least a starting place.