In December 1993, on my second trip to India to work at the National Institute of Hydrology, I met a colleague who confided to me that he was having trouble modeling a dambreach failure^{1} using a wellknown model. He mentioned that his results appeared to be off by a factor of two. I asked him what value of discharge coefficient was he using. He responded: "Greater than 3, as given in Chow." ^{2} I said: "You must be using SI units." To which he responded: "Of course." Then I said: "That is your problem. You are using a discharge coefficient applicable to U.S. customary units. You should be using the SI equivalent, which is roughly about onehalf."
^{1} Ponce, V. M., A. TaherShamsi, and A. V. Shetty. (2003). Dambreach flood wave propagation using dimensionless parameters. Journal of Hydraulic Engineering, ASCE, Vol. 129, No. 10, October, 777782. ^{2} Chow, V. T. (1959). Openchannel hydraulics. McGrawHill, New York.
 
