Combined Rainfall Runoff models¶
The runoff from a number of catchments, constituting parts of a larger catchment, can be combined into a single runoff series. Each of the sub- catchments must be specified separately by name, model type, parameters etc. The combined catchment can be defined only after the sub-catchments have been created. The combined catchment is defined in the group for combined catchments, which is activated when selecting combined catchment. The sum of the contributing areas of the sub-catchment has to match the area of the combined catchment.
The runoff from the combined catchment is calculated by applying a contributing factor to the runoff of each contributing catchments. The factor corresponds to the contributing area of the sub-catchment compared to the entire area of the combined catchment.
For example the Combined catchment has an area of 100 km2, Catchment A of 300 km2 and Catchment B of 400 km2. However Catchment A contributes only to 60 km2 and Catchment B to 40 km2 in the Combined catchment. Hence the contributing factor for Catchment A and Catchment B will be respectively 0.2 (= 60/300) and 0.1 (= 40/400).