Non-Contact River Discharge and Precipitation Measurements

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0106391PlantThe US Geological Survey routinely measures river discharge at more than 7000 sites in the United States by monitoring the height, or stage, of the rivers. This requires that the relation between stage and discharge be accurately known. Present methods of acquiring such calibration data place instruments and, often personnel, in the water. At high flow rates such measurements are both difficult and hazardous; at extremely high rates, they cannot be made at all. Yet the need for these measurements is especially acute at very high flow rates in order to monitor and predict flooding conditions. In this proposal we outline research to develop a microwave system capable of remotely measuring river discharge under nearly all flow conditions. Additionally, the system will provide infon-nation on rainfall.Our approach is to construct an array of simple continuous-wave microwave systems and algorithms for analyzing their output in order to obtain river surface velocities and rain rates remotely and continuously. The primary focus of the project will be on the algorithms needed to obtain accurate currents and rain rates since the microwave and data acquisition systems will be relatively simple. Current information is contained in the Doppler shift of the microwaves backscattered from the river while rain rates are related to the intensity of the return from raindrops. The initial application of the prototype system will be long-term measurements from a bridge on the Cowlitz River near Castle Rock, WA. The work will be carried out in collaboration with the USGS, who will mount the antenna of a ground-penetrating radar on a cableway near the bridge. The combined measurements have the potential to yield discharge.This research will provide inexpensive, portable systems for making river discharge and precipitation measurements. Continuous, remote measurements with these systems will improve development and monitoring of international and interstate agreements on allocation of water resources; provide streamflow data to manage and improve water quality; assess changes in the riverine environment that affect the quality of river and riparian habitat; and improve the estimation of flood frequency and flood inundation areas.