USE OF UAVS TO ESTABLISH A VISUAL BASELINE OF FLOW CONDITIONS AT USGS STREAM MONITORING SITES

U. S. Geological Survey NWIS stream monitoring sites measure and record stage and discharge data for streams at almost 10,000 different locations across the United States. The data is used widely by local, state, and federal agencies as well as commercial firms and private individuals. Distribution of the data is via a USGS website (http://waterdata.usgs.gov/nwis/sw). When linking to the data-distribution page for a specific gauged stream, an online photo of the site may include a view of the stream at some undefined stage and discharge condition. If flow-characterization studies for the site have been carried out by engineers or scientists due to a flood event or some other stream-flow situation, then photos of the stream depicting clearly defined flow conditions may be provided in the report. Many times, however, these photos are only ground-based because it is not possible to get an aerial view of unique flow conditions due to cost or timing. Thus, air photo documentation of the appearance of a stream at various stages and discharges is sorely lacking for most sites. Available images that are found on Google Earth or via other websites are often random images that do not match a flow that corresponds to any particular event of interest. With the advent and use of UAV’s (unmanned aerial vehicles) for taking still images and videos in a cost-effective and timely manner, the possibility exists for the collection of a visual baseline of flow conditions at many USGS stream monitoring sites. The usefulness of such images is often not fully appreciated until a sequence of images from rising or falling stages is examined. Catching 1, 2, 5, 10, 25, 50, and/or 100-year flow events could help corroborate the ground-based evidence for such an event. The date and time from the UAV image taken at a particular USGS gauge site can be matched to the date and time of the USGS stage and discharge data for the site. A published pdf document can be the means of distributing the sequence of images. Other available aerial images from the past that have an exact date and time stamp can be incorporated into the sequencing. Many of the USGS gauge sites have data that goes back decades. For this study two USGS sites have been chosen to initiate the sequencing. They are the Little Miami River at Oldtown, OH and Massie’s Creek at Wilberforce, OH.