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Data from a flume investigation using Fiber Optic Distributed Temperature Sensing (FO-DTS), U.S. Geological Survey Geomorphology and Sediment Transport Laboratory, Golden, Colorado, fall 2019

October 5, 2021

Evaluating technologies and approaches to identify the movement of fine sediment over coarser substrate has implications for monitoring the condition of habitat restoration sites. This goal motivated testing the efficacy of Fiber Optic Distributed Temperature Sensing (FO-DTS) as a technique for detecting the migration of sand bedforms over coarser bed material. Experiments were conducted in a laboratory flume at the USGS Geomorphology and Sediment Transport Laboratory (GSTL) in Golden, Colorado. An approximately 20-meter length of fiber optic cable was placed in the flume. The first 5 meter segment of cable was buried in approximately 5 centimeters of gravel substrate and extended from the upstream (top) to the downstream (bottom) of the flume. The next 10 meter segment of cable was placed on the gravel surface and extended from the bottom of the flume to the top of the flume and back to the bottom of the flume. The final 5 meter segment of cable was buried in the gravel and extended from the bottom of the flume to the top of the flume. The gravel had a median grain size of approximately 10 millimeters. The sand, introduced at the upstream end of the flume using a sediment feeder, had a median grain size of 0.6 millimeters. Water in the tail tank was heated for 12 hours and then the heater was shut off for 12 hours. Water from the tank was circulated through the flume during this cycle and a temperature profile was recorded with a Silixa XT-DTS along the entire length of the FO cable at 0.25 meter increments once every minute. This data set contains the results of 6 experiments conducted at GSTL during the fall of 2019. The first experiment, performed on November 17, 2019, can be considered a control wherein the heater was cycled for 12 hours without upstream sediment supply. In the subsequent experiments the heater was cycled for 12 hours and sediment was added at the upstream end of the flume over a period of four hours. The downstream advance of the bedform was monitored by the FO-DTS which was used to detect regions of thermal dampening caused by the overlying sand.

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