Task 2 of LimnoTech's 2022 Task Order 5, to develop an abstract base class all for terrain analysis functions. This will encapsulate all uses of TauDEM and GDAL system calls such that alternative terrain analysis “engines” (with different library dependencies) could be called in its place without altering core package code.

• Develop an abstract base class all for terrain analysis [and geospatial analysis] functions
• Implement TauDEM and GDAL as the first “terrain analysis engine” of this abstract base class

Task 2a adds selection and implementation of an alternative “terrain analysis engine” of the new abstract base class, aiming to provide similar or the same functionality with a “lighter weight” and more accessible installation pathway. We will specifically:

• Implement pysheds as an optional terrain analysis engine, after confirming capabilities and in consultation with USGS
• Implement the following terrain analysis functions as “core”:
  • AreaD8 is the primary “core” function
• Optionally implement the following additional functions, in consultation with USGS, after exploring end-user use cases and determining their availability within pysheds:
  • DinfDecayAccum (D-Infinity Decaying Accumulation)
  • D8HDistTostrm (D8 Distance to Streams)
  • D8FlowPathExtremeUp (D8 Extreme Upslope Value)