$(15$ pt$)$ Hydrographs $-$ A watershed has been delineated for a point of interest and posted as Watershed.pdf$.$

$($a$)$ Sketch the longest flow path.

$($b$)$ Discuss what would happen to the time of concentration if this watershed were to have $40\backslash \%$ impervious land use added in area A$.$

$($c$)$ Sketch the shapes of the hydrographs that you would expect at the point of interest for the original watershed and the watershed with added impervious area. Describe how these hydrographs are different and why.

$($d$)$ Identify a stormwater BMP that could be designed so that the hydrograph for the developed watershed looks more like the original hydrograph at the point of interest. $($Use the PA Stormwater BMP Manual$)$