Nearshore Wave Direction Gage

by William R. James, Mathematical Statistician; Conservation Div., U.S. Geological Survey, Reston, Va.; formerly, Chf., Geological Engrg. Branch, Engrg. Development Div., U.S. Army Coastal Engrg. Research Center, Fort Belvoir, Va.,
Robert J. Hallermeier, Oceanographer; Coastal Processes Branch, Research Div., U.S. Army Coastal Engrg. Research Center, Fort Belvoir, Va.,

Serial Information: Journal of the Waterways, Harbors and Coastal Engineering Division, 1976, Vol. 102, Issue 4, Pg. 379-393

Document Type: Journal Paper


Bow wave formation can cause large variation in peak water level around a thin circular pile in shallow-water waves. The symmetry of this variation might be used to measure wave direction on a crest-by-crest basis. This paper empirically examines the resolution possible in objectively estimating the symmetry point of data sets consisting of small numbers of peak-water-level measurements made around a pile in laboratory wave action. Data sets for several types of single incident crests, in wave action of steepness such that 0.007≤H/≤0.05, were analyzed by three different estimation methods. For example, with 10 peak water level measurements (36° spacing around the pile), one estimation method gave directions within a range of 2.8°, on the average, for all test crests. The results indicate that four water-level sensors embedded in a vertical pile at 60° spacing might be used to measure the direction of single nearshore wave trains to a point within ±3° over a 120° range, in an instrument that can be made fully automatic.

Subject Headings: Wave measurement | Water level | Piles | Nearshore | Symmetry | Wave action | Wave crest | Spacing

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