weir3a5.sharpcrest()the procedures of Hulsing, Harry, 1967, Measurement of peak discharge at dams by indirect methods: U.S. Geological Survey Techniques of Water-Resources Investigations, Book 3, Chapter A5, 29 p.,NAis the empty set and will error out.weir.sharpcrest(..., type=c("TWRI3A5", NA))data.frame() is returned.weir3a5.sharpcrest