Tracing and visualisation of contributing water sources in the LISFLOOD-FP model of flood inundation (within CAESAR-Lisflood version 1.9j-WS)

Abstract

Abstract. We describe the formulation of a simple method of water source tracing for computational models of flood inundation and demonstrate its implementation within CAESAR-Lisflood. Water source tracing can provide additional insight into flood dynamics by accounting for flow pathways of each model boundary condition. The method developed is independent of the hydraulic formulation used, allowing it to be implemented in other model codes without affecting flow routing. In addition, we developed a method which allows up to three water sources to be visualised in the RGB colour space, while continuing to allow depth to be resolved. The number of water sources that may be traced is limited only by the computational resources. We show the application of the methods developed for example applications of a major flood event, a shallow estuary, and Amazonian wetland inundation. A key advantage is that the method is independent of the hydraulic formulation, meaning that it is relatively straightforward to add to existing finite-volume codes, including those based on or developed around the LISFLOOD-FP method. This method enables water tracing with a minimal computational overhead, allowing users of the LISFLOOD-FP method to address environmental issues relating to water sources and mixing, such as water quality and contamination problems.