ACCURACY OF RADAR WATER LEVEL MEASUREMENTS

摘要

Radar water-level sensors are generating a lot of interest among hydrographers because of theirrnease of installation and low maintenance. However, limited information is available on thernaccuracy and performance of radar sensors in the field. This paper presents test results fromrnrecent field measurements made with radar water-level sensors. Field data collected with twornpulse radars, (Design Analysis Associates H-3611 and the Ohmart Vega Puls 62) and onerncontinuous wave frequency modulated radar (Saab Rosemount) during lake drawdown at HorsernMesa Dam, Arizona, are presented and compared against a conventional float-well system. (Thernuse of firm, trade and brand names in this report is for identification purposes only and does notrnconstitute endorsement by the U.S. Government). Measured radar data were analyzed forrnpossible sources of systematic measurement uncertainty (error) including sensor height abovernwater (air gap), air temperature and surface waves.rnThe Ohmart Vega sensor has a systematic uncertainty from varying air gap. The H-3611 and thernSaab Rosemount sensor do not have an obvious systematic uncertainty from varying air gap.rnNone of the radar sensors have an obvious uncertainty from surface waves when compared withrnthe float-well systems. No systematic uncertainty due to temperature or wind speed was notedrnfor any of the radars. Analysis of the field data indicate that the data measured by the H-3611rnand the Saab Rosemount are not statistically different from that collected by the float-wellrnsystem. For the data measured by the Ohmart Vega, a systematic error of about 0.3 ft over arn35-ft change in water level occurred during the field measurements.