Delineating channels and rivers

[SorooshMani-NOAA]

Delineating channels for mesh generation requires multiple related features. Right now the existing channel refinement finds the regions smaller than a "width" either based on domain shape (or based on extracted shape from the DEM at a given level), then it applies refinement in that detected region. Although this might be helpful, it's not exactly what is needed:

• Find thalweg of rivers and channels from DEM (similar to the work done by VIMS folks)
• Generate quad/curvilinear mesh that follows thalweg
  • Generate curvilinear for a specified region
  • Detect where to generate curvilinear and auto detect corners
• Specification of elements per width or length of channels
• etc.