Memory-Efficient Flow Accumulation (MEFA)

Part of the Memory-Efficient I/O-Improved Drainage Analysis System (MIDAS)

Please cite Cho (2023) when you use this algorithm or the r.flowaccumulation GRASS addon.

Citation: Huidae Cho, July 2023. Memory-Efficient Flow Accumulation Using a Look-Around Approach and Its OpenMP Parallelization. Environmental Modelling & Software 167, 105771. doi:10.1016/j.envsoft.2023.105771. Author's Version.

• Raw data: 30-m NED for the entire Texas
  • 1.8 billion cells including null
  • 773 million cells without null
• Red: MEFA
• Blue and purple: Benchmark algorithms

Predefined flow direction encodings in GeoTIFF: power2 (default, r.terraflow, ArcGIS), taudem (d8flowdir), 45degree (r.watershed)

Custom flow direction encoding is also possible by passing -e E,SE,S,SW,W,NW,N,NE (e.g., 1,8,7,6,5,4,3,2 for taudem).

Requirements

• C compiler with OpenMP support
• GDAL

For Windows, use MSYS2 and OSGeo4W to install GCC and GDAL, respectively.

How to compile MEFA

make

Benchmark algorithms

• MEFA-HP (algorithm index 7)
• HPFA (algorithm index 1)
• FastFlow (Zhou's algorithm)
• AreaD8
• ArcGIS Pro Flow Accumulation

Pre-/post-processing scripts

• 1.import_ned.zip
• 2.prepare_inputs.zip
• 3.run_algorithms.zip
• 4.check_outputs.zip
• 5.analyze_outputs.zip

Data

Input flow direction files

• taud8.tif: AreaD8
• fdr.tif: Other algorithms

Output flow accumulation files

• meac.tif: MEFA
• mefahp.tif: MEFA-HP
• hpfa.tif: HPFA
• ffaczhou.tif: FastFlow
• tauad801.tif: AreaD8
• fac.tif: ArcGIS