Chinese Theatre in the Big Room, Carlsbad Cavern

This summer, I will be working on the Visitor Use Management (VUM) Project. VUM is a framework for park management to analyze visitor impacts on visitor experience and park resources. There is a delicate balance between allowing the public access to national parks for their enjoyment and preserving natural resources for future generations and their enjoyment. Carrying capacity refers to the type and level of visitor use that a park can sustain given its resources; several parks are already beyond their carrying capacity. The framework starts with defining the limits of acceptable change, or the minimally acceptable conditions, then developing and carrying out monitoring studies, if the data show the park has surpassed the limits of acceptable change, then park management must take an action to address this. The cycle repeats always relying on data driven analysis.

Sound monitoring device in the Big Room

Easily imaginable impacts on visitor experience are crowding—think Yellowstone and Yosemite if you’ve been, remember the nightmare of trying to find parking or reserving a camping spot? In Carlsbad, the major impact on visitor experience is noise—on my second day, I was shadowing a ranger when a disgruntled visitor complained to us of a very noisy school group—noise in the Big Room is amplified and echoed. We have a device in the Big Room to measure and log decibels every minute, and one of my projects this summer will be to analyze this data.Resource protection is cave conservation; impact is commonly measured with broken speleothem inventories, photomonitoring, and impact mapping.

The Broken Speleothem Inventory in Carlsbad Cavern was completed in March 2019 thanks to 200+ hours of volunteer work. Prior to this, the last inventory was completed in 1993. Such a big gap in data makes it hard to correlate management practices with the number of broken speleothem, a quantification of visitor impacts, and as a result the “Carlsbad Caverns Speleothem Breakage Report 2019” prepared by Aria Mildice and Jake Tholen recommends completing a Broken Speleothem Inventory every five years. Broken speleothem are marked with green dots so they will not be counted again in the next inventory. The 2019 inventory found 11,434 new breaks in 26 years, an average of 439 breaks per year, which is an 80% decrease in annual formation breakage as compared to prior inventory data.

Figure from “Carlsbad Caverns Speleothem Breakage Report 2019”

During my three months at Carlsbad Caverns, I will assist Geoscientists-in-the-Parks Intern, Aria Mildice in holding a committee meeting with interpretive rangers to define the limits of acceptable change and solicit feedback on VUM monitoring studies. I will complete impact mapping of the Big Room and produce a GIS map as a final product, if my government background check clears in time so I can use the computers. Impact mapping is a process of visualizing impact with color gradients—this can help us identify areas and patterns of heavy impact. We have had ongoing CO2monitoring, but I will place new sensors, collect and analyze data. We are concerned about the impact of poor air quality on visitor safety, especially on holidays when the elevator lines are long elevating COlevels. Finally, I am going to create a standard operating procedure and begin test runs for a photomonitoring project, which is taking photos of important areas with the same frame and lighting over time to visually determine impact.

Sonia Meyer impact mapping

There are many different methods to quantify impact, which will be done as part of the VUM project, but these are the ones I will be working on during my three months here. This is a long, continuing, and cyclical process of monitoring impact metrics and analyzing data to help the cave management team adjust limits, protocols, and operations to best preserve Carlsbad Caverns and the visitor experience. And then repeat.


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