We will divide the original site of 20 ha into two subscatchments, one NasHyd of 12 ha and one StandHyd of 8 ha.
Duplicate the scenario “Existing” by clicking the Duplicate button on the Project Manager. Rename the new scenario as “Post”. Adjust the scenario layout as below. Note that a StandHyd is added to represent the new development and the Background image is changed to the image “…/data/background/Post.png”.
Select the NasHyd and change its AREA to 12 ha in the Properties tab. Then, select the StandHyd and change its parameters as below. Please note that the AREA of the StandHyd is 8 ha.