For the outdoor water demand calculation, how should areas be handled if there are multiple layers covering the same area - e.g. tree canopies covering an area with large shrubs and groundcover below? Should these areas be counted as multiple beds, or should the worst case species factor for all 3 types of vegetation be used?
If there are multiple layers, separate them into different zones with the calculation. The square footages applied to each should be based on the area at ground-level, since that best corresponds to water usage.
For example, if a landscaped area is covered with a tree canopy, and under the trees there are planting beds, these should be counted as separate zones. The tree zone would only include the area around the tree base, and the Kmc for the tree might assume significant exposure to sun (since it's the top layer). The planting bed zone would include the area with the beds, and the Kmc might be lower because the plants are shaded by the tree. In both cases, the appropriate Ks should be used.