Grand Falls, Arizona: Dune Field Sand Transport 2017 - 2019

As part of a NASA-funded study of sediment flux rates at a Mars analog site, we installed a suite of instruments in a small dune field near Grand Falls, Arizona. Data released in this report was collected from 02/07/2017 to 05/22/2019. The Grand Falls (GF) dune field is located on the Navajo Nation. It lies ~70 km NE of Flagstaff, AZ, 2 km east of Grand Falls, and just north of the Little Colorado River (LCR). The dune field consists of barchans, smaller dunes/ripples, and bare interdunes with indurated surfaces, all features commonly found on the Martian surface. We measured sediment flux using a Multi Layer Solid State Saltation Sensor (MLS4) and a set of three Big Spring Number Eight (BSNE) passive sediment samplers, at 20, 50, and 100 cm above ground level (AGL). The samplers are weighing BSNEs (wBSNE) that automatically weigh and log accumulated sediment weight. The Sensit and wBSNE data, as well as wind data collected from a set of three anemometers (installed at the same heights as the wBSNEs), were taken, then averaged and logged at ten second intervals. The experimental BSNE (xBSNE), designed and built by the maker of the wBSNEs, passively collects sediment at ~50 cm AGL and records data as time-lapse photos of the collection chamber taken at 15 minute intervals. Our instruments were positioned ~120 m downwind from an active barchan that migrates ~30 m/year. This research is funded by the NASA Planetary Science and Technology from Analog Research (PSTAR15) program, project #NNH16AC66I. Research was conducted with the permission of the Navajo Nation and the Leupp Chapter. Any persons wishing to conduct geological investigations on the Navajo Nation must first apply for and receive a permit from the Navajo Nation Minerals Department, P.O. Box 1910, Window Rock, Arizona 86515, telephone # 928-871-6588.