Updates and Improvements To The Arroyo de Los Pinos Research Station

The Arroyo de los Pinos is a state-of-the-art research facility located in Socorro, New Mexico. The ephemeral basin, which drains to the mainstem Rio Grande, was selected in 2015 as a site to study sediment transport in ephemeral streams. Sediment contributions from ephemeral tributaries have been identified as a major source of uncertainty when attempting to conduct a sediment budget for the Middle Rio Grande due to the complications inherent in monitoring water and sediment in flashy ephemeral streams. Many of the techniques at the Arroyo de los Pinos research station were described at the previous SedHyd (Varyu, 2019), with various journal articles and student theses/dissertations reflecting the analysis conducted with the collected data. The Arroyo de los Pinos research station continues to evolve. In the last few years, many additions have been made to improve the ability of researchers to quantify the discharge rating curve, characterize turbulent flow during an ephemeral event, and expand investigation into surrogate methods as a means of quantifying sediment flux in flashy ephemeral systems that are difficult to monitor, as compared to methods typical for perennial streams. Pressure transducers along with channel geometry and theoretical equations have been used to develop a rating curve since inception of the research facility. In recent years, both handheld radar and a permanently-mounted LSPIV camera have been supplemented to improve the quality of the rating curve at the research station. Although radar and LSPIV aren’t new technologies for perennial systems, their application to semi-arid ephemeral streams is rare in the literature. Repeat drone surveys of the channel near the station and of the confluence with the Rio Grande provide the data necessary to characterize in-channel geometry change due to a flood event as well as the ability to assess the fluvial processes occurring at the confluence and how the Arroyo de los Pinos and the Rio Grande interact during different times of the year. Active impact sensors continue to monitor data as a potential bedload surrogate at the primary monitoring station. Seismic sensors are being explored as another surrogate method for bedload and is the result of international partnerships and an NSF research grant. Five broadband seismic sensors and nearly 70 seismic nodes (smaller frequency range devices) have been deployed so that the seismograms and derived power spectral density data can be assessed for applicability/viability to predict bedload. Highly accurate data continue to be monitored in real time in an ephemeral stream that supplies sand and gravel-sized sediment to the Middle Rio Grande. The eventual results of this data collection and analysis effort will lead to higher-confidence estimates of sediment transport and sediment delivery rates from ephemeral streams to mainstem rivers using demonstrated techniques in the semi-arid Southwestern United States.