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CSULB Geospatial Research and Mapping (GRAM) Field Program
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The Sweet Stench of Discovery (and swamps)

Posted on June 21, 2013 by Courtney

Today was a pretty darn awesome day.

I went to bed last night with very little idea of what I was going to do today, and woke up with a game plan. Well, maybe it wasn’t quite that simple, but for the sake of time, let’s just go with that.

We left for the field this morning at the usual time, but this time the hydrology group made a pitstop at the house where Dr. Becker is staying to discuss our projects and work out some technical issues. As I had only up until that point used a GPS, there weren’t really any technical issues on my end, so Emily helped me set up the level-logger to measure tidal influence in the marsh area, and showed me how to use a conductivity probe to test salinity. After a few misdirect

ions on my part and one rather unpleasant near-encounter with a large spider, we found a suitable patch of open water and a low-hanging tree from which to hang the logger. It made me a bit nervous to leave it there overnight, but given all the trouble we had getting to the area, I’m not sure anyone will be passing any time soon.

I spent the next 5 hours or so after that repeatedly dunking the conductivity probe in no less than 72 discrete points spanning about a quarter mile. The process was a bit repetitive, but since the sensor doesn’t log but instead gives direct feedback, I was able to see the changes in salinity as I went and begin to form ideas of what was happening. Contrary to my initial hypothesis of flow direction and salinity, the water appeared to get more saline the farther I went upstream. The conductivity was only about 1,125 uS at highest (the ocean being 58,000 for reference), but still higher than typical drinking water. Ultimately, I left the field confused and wondering if I had somehow broken the conductivity meter, but it was a problem quickly solved.

Being that this was the first dynamic data I’ve ever had to call my own (ground control points don’t count), I was like a kid in a candy store when it came time to put it in the computer. I was way too lazy to look for a GPS cord, so I spent the next hour entering all the latitudes and longitudes by hand (because that’s so much less work than looking for a cord, apparently), once in Google Earth and then again in ArcMap because I didn’t trust it (they were identical). The really exciting part was entering the temperature and salinity data and finally seeing it all on a map, where very suddenly the trends (thankfully there were some) became apparent. Even though I’m still not entirely sure why there appears to be saltwater flowing (possibly intentionally, as I found a mysterious hose), some of the other hydro groups data appears to offer some clues.

Julianna found an aquifer map that, when overlaid, shows that the marshy area I’m studying falls exactly within an uncontained aquifer, meaning that there could be saltwater seeping into the groundwater. In addition, the LiDAR data (which is gorgeous, by the way), showed differences in elevation that sets all of the marshes right around sea level. This helps to distinguish this set of ponds (some of which are manmade) from the set of even more rectangular ponds next to them, which are held above sea level and apparently filled with pipes.

Our final conclusion in all of this is that there is more exploration to be done, more water to be tested, and some land-owners to question and that tomorrow I will probably fall into a marsh at some point (that one’s my conclusion). Hopefully, if all goes as planned (as if that ever happens), after tomorrow we’ll have a better idea of what’s causing the strange saltwater flow and how that relates with the rest of the hydrologic system in the valley. I’m loving how all of our separate projects are coming together to create something so overarching.

Now, adventure needs energy and energy needs sleep, which means it’s bedtime once again!!! (I really like sleep) Goodnight!

 

Rainbow data is the best data. (and LiDAR is the best thing ever)

 

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