Following is the appearance of the Soil Layers tab of the Catchment Coefficients dialog:
There are five different types of soil coefficients: Hydrology, Initial Concentrations, Adsorption, Mineral Composition, and Inorganic Carbon. When each type is selected, the spreadsheet changes to show those coefficients. The spreadsheet contains one row for each soil layer. To change the number of soil layers, place the cursor in the box in the upper left and change the number. There must be at least one soil layer but no more than five soil layers.