Article

Climate and Water Monitoring at Pecos National Historical Park

A blanket of white and gray clouds over a rocky, tree-covered hill with a pink house at the top.
Pecos National Historical Park

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Overview

Together, climate and hydrology shape ecosystems and the services they provide, particularly in arid and semi-arid places. Understanding changes in climate, groundwater, and surface water is key to assessing the condition of park natural resources—and often, cultural resources.

 At Pecos National Historical Park, our Southern Plains Inventory and Monitoring Network scientists study how ecosystems may be changing by taking measurements of key resources or “vital signs” year after year, much as a doctor keeps track of a patient's vital signs. This long-term ecological monitoring provides early warning of potential problems, allowing managers to mitigate them before they become worse. We monitor climate, weather, and groundwater, among other vital signs at the park.

Groundwater conditions are closely related to climate conditions. Because they are better understood together, we report on climate in conjunction with water resources. Reporting is by water year (WY), which begins in October of the previous calendar year and goes through September of the water year (e.g., WY2021 runs October 2020 through September 2021).

This article reports the results of climate and water monitoring done at Pecos National Historical Park in water year 2021.

Old mission church mud walls in a grassland with tree covered mountains in the background.
Mission church at Pecos National Historical Park

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Climate and Weather 

There is often confusion over the terms, “weather” and “climate.” In short, weather describes instantaneous meteorological conditions (e.g., it's currently raining or snowing, it's a hot or frigid day). Climate reflects patterns of weather at a given place over longer periods of time (seasons to years). Climate is the primary driver of ecological processes on Earth. Climate and weather information provide context for understanding the status or condition of other park resources. 

Methods

Since 1916, Pecos National Historical Park has operated a National Oceanic and Atmospheric Administration Cooperative Observer Program (NOAA COOP) weather station (Pecos National Monument #296676; Figure 1). This station typically provides a reliable, long-term climate dataset; however, in WY2021 it was missing data on 135 days. As a substitute, all analyses for this report use gridded surface meterological (GRIDMET) data from the station location for this water year and for the 30-year averages. Subsequent reports may revert back to the NOAA COOP weather station data depending on future data quality.

GRIDMET is a spatial climate dataset at a 4-km resolution that is interpolated using weather station data, topography, and other observational and modeled land surface data. GRIDMET estimated temperature and precipitation may vary from actual weather at a particular location because of the availability of weather station data and the difference in elevation at the location and elevation assigned to a grid cell. Data from both the weather station and GRIDMET are accessible through Climate Analyzer. 

Map of Pecos National Historical Park with a well and weather station in the main unit and a well to the northwest in the Pigeon's Ranch unit.
Figure 1. Groundwater wells and weather station at Pecos National Historical Park.

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Recent Findings 

Precipitation

Annual precipitation at Pecos National Historical Park in WY2021 was 14.39" (36.6 cm; Figure 2), 1.65" (4.2 cm) less than the 1991–2020 average. This deficit occurred primarily in the cool season (October–March), which received only 2.35" (6.0 cm), less than half of the 1991–2020 average. Precipitation in the warm season (April–September) totaled 12.04" (30.6 cm), 1.06" (2.7 cm) more than the 1991–2020 average for those months.

Air Temperature

The average annual air temperatures in WY2021 were similar to the 1991–2020 averages. The average annual maximum air temperature in WY2021 was 66.0°F (18.9°C), which was similar to the 1991–2020 average. The average annual minimum air temperature in WY2021 was 33.9°F (1.1°C), only 0.4°F (0.2°C) cooler than the 1991–2020 average. The WY2021 average monthly maximum and minimum temperatures were within 3.0°F (1.7°C) of the 1991–2020 averages for the entire year.

A line graph of temperature and a bar graph of precipitation in each month of water year 2021.
Figure 2. Climogram showing monthly precipitation and average maximum and minimum temperature in WY2021 and the 1991–2020 averages. 

GRIDMET/Climateanalyzer.org

Drought

Reconnaissance drought index (Tsakiris and Vangelis 2005) provides a measure of drought severity and extent relative to the long-term climate. It is based on the ratio of average precipitation to average potential evapotranspiration (water loss due to evaporation and plant transpiration if water supply is not limited) over short periods of time (seasons to years). The reconnaissance drought index for Pecos National Historical Park indicates WY2021 was slightly drier than the 1991–2021 average from the perspective of both precipitation and potential evapotranspiration (Figure 3).

Reference: Tsakiris G., and H. Vangelis. 2005. Establishing a drought index incorporating evapotranspiration. European Water 9: 3–11.

A bar graph of a drought index compared to normal by water year from 1991 to 2021
Figure 3. Reconnaissance drought index, WY1991–2021.

GRIDMET/Climateanalyzer.org

snow covered field, rock wall, and mission church ruins
Snowfall at Pecos National Historical Site

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Groundwater 

Groundwater is one of the most critical natural resources of the American Southwest, providing drinking water, irrigating crops, and sustaining rivers, streams, and springs throughout the region.  

Methods

Pecos National Historical Park groundwater is monitored in two wells (Figure 4). The New Mexico Bureau of Geology and Mineral Resources began monitoring both wells in 2020. The well at the trading post (WL-0206) is monitored continuously and the well at the Glorieta Battlefield Trail (WL-0207) is monitored annually. The data are available at the Healy Collaborative Groundwater Monitoring Network.

Recent Findings 

Groundwater levels in WY2021 were stable and relatively shallow (Table 1 and Figure 4). The average depth to water at WL-0206 for the period of continuous monitoring (17 December 2020–26 August 2021) was 41.27 ft below ground surface (bgs); however, this includes measurements recorded when the well was pumping or recently pumped, causing temporary decreases in water level of up to 20 feet. The WL-0206 static water level was likely slightly higher. Water level in WL-0207 was only 0.09 ft lower than the previous measurement made in WY2020.

A line graph of depth to water in two wells during water year 2021.
Figure 4. Depth to water (feet below ground surface) at two groundwater monitoring wells, water years 2020–2021, Pecos National Historical Park. White circles indicate manual measurements collected when the well was being pumped or was recently pumped.

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Article created by the Southern Plains Inventory and Monitoring Network.

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Pecos National Historical Park

Last updated: April 3, 2024