Streamflows at Baca and Alamosa National Wildlife Refuges using Non-Contact Technology

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The goal of this study is to design, install, and operationalize non-contact radar monitoring to measure streamflow at two sites at National Wildlife Refuges (NWRs) in the San Luis Valley, Colorado. Where traditional monitoring equipment in a stream channel is difficult to operate and maintain, non-contact radar technology is a solution that provides more cost-effective and accurate continuous streamflow monitoring. The results of this study will be used to guide the design and application of non-contact radar technology at other critical aquatic field sites with difficult environmental conditions in need of quick, effective water resource monitoring. In addition, this technology can be used for quantification of water rights and streamflows needed for restoration of endangered species habitat at NWRs.

USGS streamgage 08227510 North Crestone Creek at Baca NWR near Crestone, CO

Looking upstream (east) at U.S. Geological Survey (USGS) streamgage 08227510 North Crestone Creek at Baca NWR near Crestone, CO; USGS hydrologist is servicing the streamgage.

Credit: Michael Kohn, USGS

One of the two sites in the San Luis Valley is on North Crestone Creek draining the west slope of the Sangre de Cristo Mountains and supplying water to Baca NWR in Colorado. North Crestone Creek is a high elevation mountain stream where traditional monitoring equipment in the stream channel is difficult to operate and maintain and has failed due to effects from flooding, sediment and debris, and washing out. The second site is on the Rio Grande flowing through Alamosa NWR in Colorado at New Ditch, an important water diversion structure for the refuge. This very wide and shallow stream reach experiences changing channel conditions during floods, making it difficult to monitor. 

Near-field remote sensing technology has advanced in recent years with the advent of non-contact radars that measure and transmit stream stage and velocity in real-time. Data collected with non-contact radars can be used to compute streamflow at a cross section using an efficient algorithm based on the probability concept. Comparisons with traditional streamgage technology has shown that stage- and velocity-radar streamgages can produce continuous time series of mean velocity, stage, and streamflow that compare favorably to stage-discharge streamgages and can be computed in the absence of historical data while reducing the operational cost of maintaining a streamgage. Non-contact radars are also installed above the wetted-channel, which means they won’t be damaged by high-flow events and will remain operational even when the channel cross section changes. The advantages of stage and velocity radars combined with the probability concept include (1) improved safety, (2) reduced operational costs, (3) improved data delivery, and (4) increased operational efficiency. This technology has broad application throughout U.S. Fish and Wildlife Service Regions 5 and 7 as a low-cost, efficient streamflow monitoring system that could be moved from one site to the next with relative ease.


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