An experiment in subjective graphical quantile estimation applied to the generalized extreme value distribution

Fitting flood prediction curves by eye to the data of return period plots i s an intuitive approach to estimating n-year flood discharge magnitudes fro m single-site data. However, the subjective nature of this "procedure" mean s that it is unlikely to be adopted as a recognized flood estimation techni que. An experiment with a group of volunteers demonstrates that some indivi duals are capable of subjectively fitting generalized extreme value curves to yield flood quantile estimates from simulated data with an accuracy comp arable to probability weighted moments. This encourages the development of alternative formal flood estimation procedures based on some form of patter n recognition. Such procedures might mimic the more talented individuals' a pproach to curve fitting, without the disadvantage of subjectivity.