Many coastal systems show relatively strong vertical stratification.
This is particularly likely to be the case for systems with relatively large amounts of freshwater input. We can modify the basic water budget calculations illustrated in Figure 1 of the section dealing with water and salt budget calculations. Figure 1 presents a modified version of the single-layer budgetary models presented in that section. The calculations illustrated here are actually very similar to the single-box calculations. The notation retains the convention that positive flow is into the system, so in a stratified system with freshwater inflow, V R will be a negative quantity.