and Design Implementation of a Hydrometeorological Field Campaign in the Valles Caldera National Preserve, NM
Alex J. Rinehart, Enrique R. Vivoni, Marty D. Frisbee, Carlos A. Aragon, Gautam Bisht, M. Bayani Cardenas, Emily Engle, Bart Forman, Hugo A. Gutierrez, Song-Ho Hong, Luis Mendez, Kinwai Tai, 4 4 1 1 Robert L. Wyckoff, Jan M.H. Hendrickx, James Hogan, Jennifer M. Kostrzewski
1 1 1 1 3 1 1 2 1 1 1 1
1. New Mexico Tech, Socorro, NM
Abstract
In order to better understand land-surface interactions of semi-arid alpine regions, a spatially distributed soil moisture survey was held in the Valles Caldera National Preserve during the North American Monsoon season. The Valles Caldera provides a rare environment allowing the study of the alpine headwaters of the Jemez River basin, a major tributary to the Rio Grande; an unusual topography that may further elucidate the formation of convective cells in mountainous terrain; and a diverse set of ecosystems in a reasonably small area. The Jaramillo, Redondo, and La Jara watersheds were characterized in the process of this survey. The sites are organized into small transects going from wetlands near the streams to forested areas at a higher elevation to ensure that each ecosystem, aspect and elevation was sufficiently well represented. At each site, daily rainfall, meteorological variables, volumetric soil moisture, and soil temperature were measured within a small plot. Daily gravimetric soil samples were also taken to confirm the volumetric water content measurements. The data from the campaign will be supplemented by continuous installations at multiple locations and used for hydrological modeling in the region.
2. University of California, Los Angeles, CA
3. Massachusets Institute of Technology, Cambridge, MA
Experimental Design
The sampling locations were chosen to characterize all aspects and the majority of ecosystems, as indicated by vegetation type, of Redondo Peak. The seventy two sites were organized into transects of three to five sites that are located in the Jaramillo catchment, Redondo catchment, La Jara catchment, and the northern rim of Valle Grande (Figure 1). The Jaramillo, Redondo and La Jara catchments are the sites of continuous sampling studies. Each site had an event rain gauge and a staked 1-m by 1-m plot. Soil moisture was measured at five locations within the plot with the ML2 Theta Probe. Soil temperature was measured at the same five locations at 2-cm, 5-cm and 10-cm nested depths. A gravimetric soil sample was taken at each site and a calibration measurement was taken for the Theta Probe with each soil sample. Sampling has designed from July 21 to August 1, 2005, to ensure that a summer monsoon signal and strong convection and its hydrologic response were measured. It was hoped to measure both the dry antecedent conditions, a major rainfall event, and the subsequent dry down.
4. University of Arizona, Tuscson, AZ
Implementation
Between the dates of July 21 and August 1, 2005, we implemented the experimental plan in the Valles Caldera National Preserve. On July 20, there was an intense rainfall and hail event in the upper Jaramillo and Redondo catchments. Between July 21 and July 27, there were sporadic isolated storms in each of the three study catchments. During the evening of July 28, a major storm occured throughout the VCPN. From July 29 through August 1, no rain events occured and dry-down period was observed. Each catchment was sampled by a two person team with the field equipment previously described (total of four teams). The sites were sampled in the same order each day, beginning with the transect furthest upstream in a catchment for the team. Personnel stayed at the Union Building along Redondo and Creek carried out field note transcription and sample weightin after daily data collection.
Fig. 5: Final group dinner at Los Ojos in Jemez Springs, NM.
Site Description
Located in the northern Jemez Mountain of New Mexico, the Valles Caldera National Preserve (VCPN) has been the site of a varied history that has affected its physical condition. It is currently managed as a multiple use preserve of relatively light cattle ranching and logging. In the past, the ranch served for ranging purposes and was also logged extensively, as evidenced by the amount of downed wood and second growth trees. The VCNP contains the majority of the Valles Caldera, the crater of a massive rhyolitic volcano. There have multiple smaller eruptions and intrusions within the caldera, causing a chain of resurgent domes to form along with surrounding valleys. The vegetation within the VCNP consists of ponderosa pine, mixed conifer and grassland. These vegetation communities are representative of higher elevation ecosystems in northern New Mexico. Due to the extensive logging and geothermal prospecting in the VCNP, there is an extensive network of roads, both cleared arterial roads and unmapped logging roads. Ranching and logging activities also resulted in a considerable amount of lodging available in a bunkhouse, lodge, and cabins at the headquarters. This infrastructure is currently maintained and being upgraded by the Valles Caldera Trust, a new management agency in charge of multi-use activities in the preserve.
Fig. 4: Bart Forman (UCLA) and Gautum Bisht (MIT) sampling along Jaramillo Creek.
Fig. 1: An overview of a sample transect in the Redondo catchment. Site are located by the stream, in the drier grass just downslope of the forest, and approximately 10m upslope in the forest.
A D C E
B
Future Work
Fig. 3: Examples of instrumentation. From left to right, 3.5 diameter 6cm soil core and insertion tools, Kestrel 4000 Portable Weather Station, HH2 Moisture Meter, ML2 Theta Probe, and CE Digital Pocket Thermometer.
Sampling will continue on an approximately monthly period in order to yield a more temporally consistent record of seasonal transitions. There exists the possibility of a similar but abbreviated campaign being held in the VCPN in the Spring 2006 to have documentation of the effect of snow melt on the spatial distribution of soil moisture.
Instrumentation
During the campaign, we used the ML2 Theta Probe manufactured by Dynamax with the HH2 Moisture Meter. The theta probe is an impedance probe that gives, after calibration, a measure of volumetric soil moisture content. To collect meteorological data, we used the Kestrel 4000 Portable Weather Station. The thermometers were the CE Digital Pocket Thermometer. Volumetric soil samples and calibration samples were collected using a 3.5 diameter 6-cm length brass soil core. Rainfall at each site was measured daily with event rain gages.
Acknowledgements
Funding for instrumentation and logistical costs was provided by New Mexico Water Resources Research Instititute (NM WRRI), NSF SAHRA (Sustainability of semi-Arid Hydrology and Riparian Areas) Center, and the National Science Foundation (NSF). Additional support provided by numerous students at New Mexico Techs Hydrology Program, UCLAs CEE Department and MITs CEE Department. We appreciate collaborations with Fred Phillips (NM Tech), Rafael Bras (MIT), Paul Brooks (UA), and Steve Margulis (UCLA).
Fig. 2: An overview of a sample site. Each site was 1 meter by 1 meter, as indicated by the wooden stakes. Five measurement points were sampled within the plot (designated A to E), where soil moisture and temperature observations were made. An event raingauge was also postedat each site.