RAT-SWOT

The SWOT Plugin integrates with RAT to enable estimation of reservoir storage change, evaporation, and outflow using SWOT-derived surface water observations. It leverages the Hydrocron API to extract surface area and water surface elevation time series for reservoirs and lakes.

The plugin requires a set of parameters in the configuration file. Outputs are organized methodically into sub-directories inside the final_outputs/swot/ directory.

Note

The SWOT plugin currently supports three estimation methods:
- elevation_based
- sarea_based
- elevation_sarea_based

Each method differs in how SWOT data (area/elevation) and AEC (Area–Elevation Curve) are utilized to estimate storage change.

Parameters

The following parameters are required to enable the SWOT plugin in the PLUGINS section of the configuration file. The requirement is specified with regard to the running of SWOT plugin. If you don't want to run SWOT plugin, then leave the parameters blank or comment them.

  • swot :

    Required parameter

    Description : Flag that specifies whether to run SWOT plugin during RAT run. Accepted values are True or False or only_swot. If only_swot is specified, then only the SWOT plugin will run and not the default TMSOS.

    Syntax :

    PLUGINS:
    swot: True

  • swot_prior_lake_shpfile :

    Required parameter

    Description : Path to the shapefile containing SWOT prior lakes. It should have unique ID field corresponding to the SWOT lake ID.

    Syntax :

    PLUGINS:
    swot_prior_lake_shpfile: absolute/path/to/data/lakes/swot_prior_lakes.shp

  • swot_prior_lake_shpfile_column_dict :

    Required parameter

    Description : Dictionary specifying column mapping for unique ID of lake/reservoir identifiers. The unique ID must match with SWOT lake ID as it is used by hydrocron API to extract SWOT data.

    Syntax :

    PLUGINS:
    swot_prior_lake_shpfile_column_dict:
        id_column: lake_id

Estimation Methods

The plugin computes storage change, evaporation, and outflow using one of the following methods:

  1. elevation_based:
    Uses SWOT elevation data and the AEC (Area–Elevation Curve) to estimate storage change.

  2. sarea_based:
    Uses SWOT surface area data and the AEC (Area–Elevation Curve) to estimate storage change.

  3. elevation_sarea_based:
    Uses both SWOT area and elevation data to estimate storage change, without relying on AEC.

Outputs

The plugin writes results to: 

final_outputs/
└── swot/
    ├── elevation_based/
    │   ├── dels/
    │   ├── elevation/
    │   ├── sarea_swot/
    │   ├── evaporation/
    │   └── outflow/
    ├── sarea_based/
    │   ├── dels/
    │   ├── elevation/
    │   ├── sarea_swot/
    │   ├── evaporation/
    │   └── outflow/
    └── elevation_sarea_based/
        ├── dels/
        ├── elevation/
        ├── sarea_swot/
        ├── evaporation/
        └── outflow/
  • dels/ → Storage change time series of reservoirs
  • elevation/ → Water Surface Elevation time series of reservoirs
  • sarea_swot/ → Water Surface Area time series of reservoirs
  • evaporation/ → Evaporation time series of reservoirs
  • outflow/ → Outflow time series of reservoirs

Tip

Each method’s directory contains parallel outputs, enabling easy comparison between methods.

Example Configuration Block

PLUGINS:
    swot: True
    swot_prior_lake_shpfile: absolute/path/to/data/lakes/swot_prior_lakes.shp
    swot_prior_lake_shpfile_column_dict:
        id_column: lake_id