Hydrological modelling

This chapter deals primarily with hydrological flood modelling. Its history began in the mid-nineteenth century with the ‘Rational Method’ for peak flows attributed to Thomas Mulvany. Many different models have been developed, varying greatly in scope and level of detail, and are used for different purposes including science-driven testing of ideas to problem-oriented applied studies. But all represent greatly simplified analogies or visions of the real world. The chapter is concerned with non real-time flow forecasting. It follows a broad classification of models of increasing complexity into metric-, conceptual- and physics-based. The simplest are black-box, data-driven or metric models, which rely solely on observed relationships and have limited or no representation of physical processes. A generation of topographically oriented models has evolved, starting from TOPMODEL to more recent models such as TOPKAPI and Grid-to-Grid which achieve a parsimonious representation of the dominant component processes