New Mexico Geological Society Annual Spring Meeting & Ft. Stanton Cave Conference — Abstracts

The Arroyo de los Pinos is a tributary of the Rio Grande that transports tons of relatively coarse sediment into the river annually through flash flood events. The focus of this research is to determine where sediment erodes and deposits in the arroyo reach leading into our monitoring station and to document how much enters the Rio Grande. If too much sediment deposits downstream it can lead to problems for infrastructure such as sedimentation in reservoirs and increased channel maintenance needed for flow conveyance. To investigate these concerns, we have started using Structure from Motion (SfM) photogrammetry from drone-based air photos. The pictures captured through the drone flight are analyzed in a program called AGISOFT, in conjunction with the coordinates of the control points marked by targets, to create DEMs of the terrain. With those DEMs we can then create a digital elevation model of difference (DoD) in GIS to show the difference between two DEMs of interest and quantify the deposition and erosion. DEMs from previous years compared to our most recent DoD show that deposition has increased in the thalweg of the channel and the higher points in the channel have eroded, leading to a flatter bed surface. A significant amount of sediment has deposited at the mouth of the channel creating a fan that will likely be transported by the Rio Grande as flow increases. The next goal of this research is to compare these results with the sediment transport models BORAMEP and HEC-RAS to determine the best sediment transport equation to use for modeling ephemeral streams.