When applying the multiple triangle approach to build a stream hydrograph, the run$-$off for increment $2($and beyond$)$ is determined by calculating the run$-$off up to that time increment, and then subtracting the runoff from the prior increments. Why is this necessary? Group of answer choices to account for runoff diverted to other watersheds to account for changing soil conditions without changing the curve number to account for increased interception during the storm to account for changing lag times during the course of the storm