The wealth of professional experience gained in recent years clearly confirms hydraulic intuition that flood drainage systems (FDS) often display distinct hydraulic characters. This seems remarkable in a background where the FDS configurations are potentially unlimited owing to (a) geomorphological diversity and hydrometric complexity and (b) multi-purpose utilitarian functions and subsequent attributes (such as land use, environment, public perception), Since conflicts are inevitable in these systems, a problem-solving procedure based on hydraulic modelling and holistic appraisals has been developed. This paper argues that such a problem-solving procedure may be enriched by identification of hydraulic characters to offer a sense of direction for obtaining insights into the complexities of the FDS, Together with the case studies presented in the companion paper (Paper 11321(1)), this paper presents a review of prevailing hydraulic characters in the background of current open channel flow modelling practices. Based on the dominance of spatially-distributed storage and dynamic effects and features such as distributive and locally-governed effects, the following hydraulic characters were identified: attenuating, storing, responsive, retarding, spatially-distributed, inertial, distributive and locally-governed systems.