In this paper scalar and vector data are visualised by suited colour scales based on perceptive and uniform colour models. Using opportune colour scales, colour information is created from the two-dimensional scalar data computed at different time steps. Direction and magnitude of computed vector data are represented employing circular colour look-up tables (LKT). In a scientific computing environment focused on analysis and interpretation of physical phenomena, the coloured visualisation of data generated by numerical simulations represents a fundamental fashion of knowledge. The colour, in fact, can help the researcher to analyse and interpret information present in computed data in a fast and immediate way. The colour human perception is a complex process, which includes physiological, psychophysical, psychological and physical aspects. A colour model (colour space) is a way adopted to represent and describe a colour using three co-ordinates. We visualise the results obtained by a finite difference method applied to the solution of 2D shallow water equations for the simulation of water circulation in natural basin: the San Pablo Bay. We show solutions of the two-dimensional shallow water equations (SWEs), that is, solutions of quasi linear hyperbolic partial differential equations, governing the water circulation in a basin with spatial dimensions significantly greater than the water depth.