New Mexico Geological Society Annual Spring Meeting — Abstracts

With the advent of climate change, it is expected that the US Southwest will experience warmer average temperatures in all seasons, longer summers, shorter winters, and reduced snowpack in the higher elevations. In the northeastern part of New Mexico, the city of Las Vegas has been dealing with the threat of water shortage since the beginning of the 21st century. The Gallinas River is a tributary of the Pecos River system in northern New Mexico, yielding an average of 3,100 acre-feet of water annually. The river originates at Elk Mountain and the watershed ranges in elevation, from 4,900 to 11,600 feet. The upper Gallinas watershed is located approximately 20 miles northwest of Las Vegas, and covers approximately 52,500 acres. Land use of the upper watershed has transitioned over the past few decades from agriculture, focusing on timber, livestock, and hay production, to primarily full-time and part-time residential use and summer creation. The purpose of this study is to determine the tree canopy cover change through time and if a correlation exists between tree canopy cover, precipitation, temperature and the Gallinas River discharge from 1939 to 2015. Aerial photography and Geographic Information System (GIS) techniques have been used to determine the percentage of tree canopy cover in Gallinas watershed from 1939 to 2015. The preliminary results suggest an increase in the tree canopy cover from 1939 to 2011, 36.6% and 53.1% respectively, which can be due to reduced logging and grazing, fire suppression, and different land management practices in the area. On the contrary, results indicate a decrease (about 10.86%) from 2011 to 2014, that can be related to the thinning projects have been conducted in the last few years. By assessing changes in canopy cover, precipitation, and discharge over time, we can provide insight into whether canopy cover, precipitation patterns, or both are influencing water discharge in the Gallinas River. Statistical analysis allows us to distinguish the extent of impact each of these factors has on the discharge of the Gallinas River. This information can potentially be used by water and land managers to better inform their decisions for the utilization and management of the watershed.