Introduction
In 2022 the expedition obtained several TinyTag™[1] temperature data loggers that could be left logging for over one year. The results from 2022 to 2023 have been published in the previous expedition report[2] and available on the expedition website[3].
There are many caves in the Tresviso – Andara area, some are resurgence caves at around 500m altitude and others high in the mountains between 1,700m and 2,000m in altitude. The loggers placed in entrances high up would be measuring the incoming, external, air temperature, whereas at the resurgence it would be water temperature. Water temperature would be subject to several factors: how long the water was underground equilibrating with cave temperature and the temperature that it was when it entered the cave system. The time underground will be related to flow (i.e., has it rained recently).
Some of the resurgence caves emit water from an unknown catchment area. By monitoring the temperature, it may be possible to gain information about where the water came from.
The loggers were reset, at the end of the 2023 trip, and a few moved to different locations, in order to continue the monitoring into 2024.
Temperature loggers were placed in the following locations:
| # | Cave | Location | Catchment |
| 1 | Cueva de la Rio Chico | About 60 m from the resurgence entrance, and 1 m above the streamway | Unknown – Sumps going upstream |
| 2 | Cueva de la Cabeza de Vaca | About 50m from the resurgence entrance, and 0.3 m above the streamway | Unknown – Sumps heading upstream |
| 3 | Cueva del Nacimiento de Urdon | About 40 m from the resurgence entrance, and 5 m above the normal streamway | High Andara peaks –local inlets assumed |
| 4 | Cueva de la Marniosa | About 1.5 m above the streamway at the bottom of Papoose pitch- a significant way into the cave. | Head of the Sobra valley |
| 5 | Cueva de la Marniosa | The bottom of a trench that occasionally forms a lake, 0.2m from the floor | Unknown – local inlets assumed |
| 6 | Cueva del Nacimiento de Urdon | Consort Hall, a dry chamber about 1.1 km from the resurgence | High Andara peaks –local inlets assumed |
Table: Logger locations 2023-2024.
In addition, a logger was placed below the first pitch in Torca del Picu Boru (T169 Flowerpot), but this was unfortunately left in a less than ideally location and was damaged by water, resulting in no results.
Another logger was placed in the Death Race 2000 chamber in Cueva del Nacimiento, this was not collected for logistical reasons.
Picture: Sensor locations 2023-2024.
Cueva de la Rio Chico
As per the previous year, the TinyTag™ is about 50m from the entrance.
The data sets between 2022-2023 and 2023-2024 are qualitatively quite similar:
Graph: The Rio Chico temperature profile 2023 vs 2024
The logger was programmed to start on the 25 September. The season changes according to the exact weather patterns, however, there is a spike in the data from mid-October onwards suggesting more variable water flow (probably related to rain fall) until the lowest temperatures are reached in March. The temperature then starts to rise suggesting a general increase in general temperatures. From mid-May onwards there are fewer spikes, suggesting less rainfall.
Note that the second year the cave reached ‘summer’ temperatures at the start of June whereas the previous year the temperature was warming into August.
Cueva de la Marniosa – Trench
In Cueva de la Marniosa, there is a 3m deep trench that occasionally fills with water. A TinyTag™ was placed about 20 cm from the base of the trench.
Graph: The Trench temperature profile 2023 vs 2024
As before, there is a pulse like shape that is assumed to mean the trench is flooded. Over the first year, there was a drop in temperature that may mean enough water was passing through (possibly from snow melt) that it didn’t reach equilibrium before flooding the trench. This year there was no such artifact; possibly indicating less wet or less snow.
Also of note, is that the temperature was increasing from June, unlike the previous year when the temperature was constant. Although only 0.15 C it indicates a change, which could be related to the draft in the cave or external conditions.
In 2022-2023 the initial flat temperature is 0.01 C higher than the final flat temperature of the last four months. These two together may indicate that specific air currents at and around the TinyTag™ after flooding may be influenced by mud left from the flooding events.
Analysis of times when the trench becomes a pool.
| 2022-2023 | 2023-2024 | ||
| Date | Duration (days) | Date | Duration (days) |
| 20/11/2022 | 7 | 12/11/2023 | 1 |
| 09/12/2022 | 6 | 21/11/2023 | 4 |
| 16/01/2023 | 8 | 28/11/2023 | 8 |
| 27/01/2023 | 2 | 15/12/2023 | 1 |
| 18/02/2023 | 8 | 20/12/2023 | 3 |
| 08/03/2023 | 6 | 06/01/2024 | 4 |
| 12/05/2023 | 6 | 25/02/2024 | 11 |
| 12/03/2024 | 2 | ||
| 23/05/2024 | 2 | ||
| Total | 43 | 36 | |
Table: Trench days flooded comparison.
The second year has more ‘wet’ events, but the duration that it is flooded is shorter. Experience suggests the pool only floods after heavy rainfall, indicating the second dataset represents less heavy rain.
Cueva de la Marniosa – Papoose
About 1 hours caving into Cueva de la Marniosa is a stream canyon. The stream sinks about 2 km away at the head of the Sobra valley.
Graph: The Papoose temperature profile 2023 vs 2024
Qualitatively, the trends are quite similar, with drops in temperature that probably relate to external weather (rainfall, snow melt).
From June onwards, the temperature stabilises. However, in the years 2023-2024 the stable temperature is 0.1 C higher than the previous year.
Cueva de la Cabeza de Vaca
This TinyTag™ was placed at stream level, just inside the cave. Both years’ datasets pick up a day-night oscillation.
Graph: The Cueva de la Cabeza de Vaca temperature profile 2023 vs 2024
Qualitatively, the results are identical with a seasonal drop and recovery in temperature.
Unlike the previous datasets described here the temperature between years is unchanged.
Cueva del Nacimiento de Urdon – Entrance
Graph: The Cueva del Nacimiento entrance temperature profile 2023 vs 2024
In the above graph the winter of 2022-2023 was much colder than the winter of 2023-2024. The temperature of April to July was warmer during the second dataset, although becoming similar during the second half of the summer.
Cueva del Nacimiento de Urdon – Consort Hall
This is a new placement for this year away from any obvious water sources. The sensors placed in caves with water nearby or in water, show a weekly variation of about 0.4 C (presumably rain events). However, the Consort Hall sensor covers a very narrow range, and, if similar rain events are being captured, they only show a variation of 0.02 C:
Consort Hall is a dry chamber (there are drips nearby) away from the streamway. It is quite high and is probably the trunk route for air moving through the cave.
Graph: The Cueva del Nacimiento – Consort Hall temperature profile 2023
Although it is a slight change, Consort Hall gets slightly warmer over winter. The upturn in temperature mirrors the downturn in temperature at the resurgence.
Conclusions
Both Cueva de la Marniosa and Cueva del Rio Chico show the cave has warmed slightly between 2022-2023 and 2023-2024. The warming is probably related to the water catchment.
The location of the Cueva de la Cabeza de Vaca sensor may be dominated by the external air temperature but doesn’t show an equivalent year on year rise. This sensor has now been moved further into the cave for future logging
The Cueva del Nacimiento entrance shows a higher temperature earlier in the year, does that mean the lower catchment is warmer, but the higher catchment remains cold?
Further works
Although the change is minor, it would be interesting to measure pressure at Consort Hall, also, measuring the draft (if possible) at Consort Hall may give some correlations.
Continuing to measure the Cueva de la Marniosa locations to see if the year-on-year variation is effectively random or showing a trend.
[1] TinyTag Plus 2 TGP-4017 https://www.geminidataloggers.com/data-loggers/tinytag-plus-2/tgp-4017
[2] Tresviso 2023, Tresviso Caves Project (2023)
[3] https://tresvisocaves.info/science/