Objective analyses and mapping techniques for rainfall fields: An objective comparison

TLDR

Rainfall field estimation has been approached with many methods, including statistically based techniques, to derive point or average values at ungauged sites. This study reviews conventional and recent rainfall estimation techniques and presents a case study in a high‑variability region to assess method sensitivity. The authors classify methods by fundamental principles, optimality criteria, and practical aspects, identify statistical structure functions for regionalized variables, evaluate them using a split‑network validation on independent storm events, and emphasize careful result interpretation and visualization. The authors conclude that a particular method should be adopted, balancing performance with cost‑efficiency.

Abstract

Many methods have been proposed and applied individually to rainfall fields in order to estimate point or average values at ungauged sites. This paper reviews some of the usual as well as some of the more recent techniques. They are classified according to their fundamental principles, optimality criteria, and practical aspects. Some theoretical developments, mostly for the statistically based techniques, are offered, and the practical aspects are mainly directed to the particular case of rainfall fields. A case study is presented for a region with particularly high rainfall variability, providing a good sample of events for testing the sensitivity of the estimation to the different methods used. The identification of statistical structure functions, required by certain methods using regionalized variable concepts, is discussed in detail for the case considered. Method evaluation is based on a classical validation technique that divides the available stations into two separate networks, i.e., a base network is used to perform estimations at the stations of a test network for a set of independent storm events. Careful attention is paid to result interpretation and visualisation. Finally, conclusions are drawn as to which method should be implemented, taking into account cost‐efficiency considerations.