2024 Annual Stream Flow Project Report
2024 was a mostly uneventful year regarding stream levels in Carroll Cave. There were no major floods and even the minor floods were nothing much. At the ladder, the highest level reached by Thunder River was 2.9 feet early morning of April 2. Below Thunder Falls the stream reached almost 3.5 feet a few hours later on April 2. Both streams normally run slightly under one foot. Another event in early June reached almost the same levels. When compared to the record flood from July 2015 (over 23 feet) these changes are very small.
A trip report records a severe thunderstorm going over the silo on July 13. The storm dropped several inches of rain in less than 30 minutes. The subsequent cave trip found that Thunder River had come up about a foot a few hours after the storm. Looking at the data, the pool below Thunder Falls reached 2.2 feet at 1:00pm, and Thunder River reached just over 2 feet at 1:30pm. This is not as much of a flood as was feared. The data shows that the stream level peaked about 5 hours after the storm.
This year I have produced several new graphs of the data. The plotting application I use is LabPlot, a very capable free application. I learned how to use some additional features this year which helped produce the new graphs. I hope they help to better explain the data.
One graph shows three lines of temperature. It compares surface air, cave air and cave water temperatures. The idea is to show how little the cave temperature varies over a year. Another graph leaves out the surface air temperature so that the very small variations in cave air and water become more apparent. It is interesting to note that the water temperature in UL2 goes both higher and lower than the water temperature at the ladder. I think this is because the data logger at UL2 is “closer” to the surface. Any water entering the cave will reach that logger a few hours before it reaches the ladder, and therefore has less time to acclimate to cave temperature.
As usual, the graphs show that changes in water level are almost always accompanied by changes in water temperature. In winter, when the water level goes up the temperature goes down. In summer both water level and temperature go up.
The rainfall graph has radar-estimated data from Climate.com along with the readings from our rain gauge on the silo. They are not identical, but they track very closely. The data from Climate.com is to the nearest 0.1 inch while our rain gauge gets to the nearest 0.01 inch. When the plot line on this graph is vertical, it is raining. Horizontal plot line means no rain. The graph is actually showing cumulative rainfall over the year.
Another new graph this year shows how stream level changes compare to rain events. It is interesting to note that the biggest changes in stream level were not associated with the heaviest rain events.
This year we had to send the data logger from below Thunder Falls in for a battery replacement. That is not a task which can be done in the field. The logger was out of commission from January 8 to February 24. The graph of its data shows a straight line between those two dates. All of the data loggers now have fairly fresh batteries. They should be good for about 4 more years before needing a change.
All of the data from 2024 is contained in a .ZIP file. There are several kinds of files. Files with .hobo extension are the raw, unfiltered data straight off the loggers. This data requires an application called HoboWare to view. There is a free version of HoboWare which has limited functionality. The .csv files are data extracted from the .hobo files. The files with “RawData” in the name have been stripped down to exactly one calendar year, and run through a spreadsheet program (LibreOffice) to calculate the water depth column. Last are the .pdf files which are the final graphs. I also included the .lml file which is the LabPlot project. That file contains all of the data and definitions for creating the various graphs.
Bill Gee