Regional estimation of flood quantiles: Parametric versus nonparametric regression models

Abstract

A recent trend in regional frequency analysis is to consider floating regions where only basins that are sufficiently similar to the design site are considered for information transfer. Similarity is measured in some suitable metric of catchment characteristics. This paper discusses the analogy between this idea and nonparametric regression. Some of the techniques developed recently in the area of nonparametric regression are employed to develop improved regional flood estimators. The additive model used here to a large extent overcomes the curse of dimensionality often associated with nonparametric regression on multivariate predictor space. The application of the proposed methodology to selected areas of the United States suggests that there can be substantial gains over the traditional log linear models currently employed.