[8pt] Leveed area being inundated by branch

[CarsonPruitt-NOAA]

HUC 01080205 branch 7703000014 is inundating behind a levee system in Hartford, CT.

[mluck]

src/mask_dem.py has been modified so that a levelpath that crosses through a levee-protected area is only able to inundate the levee-protected area within the catchment of the levelpath (not the entire levee-protected area). Compared with the initial image in this issue, the image below shows branch inundation only within the levelpath catchment (highlighted in yellow), resulting in much less inundation in the levee-protected area. Note that the levee-protected areas upstream of the levelpath are completely masked as they are outside of the levelpath catchment, but this is consistent with the fact that we mask branch 0. Inundation is based on 100yr recurrence flows.

A closer view of the branch inundation (blue) in the levelpath catchment (yellow) in the levee-protected area (dotted).