VELMA Sediment Prototype Output Data Summary

Overview

The VELMA sediment prototype model simulates transfer of detritus leaf and top-layer humus via lateral movement of surface water.

When a VELMA simulation includes the sediment model parameterization, sediment-specific data columns are automatically added in the DailyResults.csv and AnnualResults.csv output files.

Sediment-specific data columns are also automatically added in any CellDataWriter .csv output files specified by CellDataWriter parameterization in the configuration.

No SpatialDataWriter .asc map files are automatically generated, but users may add SpatialDataWriter parameterizations that specify sediment-specific data to their simulation configurations.

Details

Spatially-Explicit Data

The sediment model computes and maintains per-simulation-step ("per-day"), spatially-explicit data for detritus leaf and top-layer humus sediment transportation amounts, as well as the delta (flux) of detritus leaf and humus at each cell.

Type of Value	Meaning
"Lateral In"	The total amount added to the cell, transported (in millimeters) from uphill-adjacent cells during the simulation step.
"Lateral Out"	The total amount removed from the cell and transported (in millimeters) to downhill-adjacent cells during the simulation step.
"Delta"	The cell's ("Lateral In" - "Lateral Out") amount (in milligrams per square meter) for the day.

The spatially-explicit per-step data may be identified with the following keynames:

DETRITUS_LEAF_SEDIMENT_LATERAL_IN
DETRITUS_LEAF_SEDIMENT_LATERAL_OUT
DETRITUS_LEAF_SEDIMENT_DELTA
HUMUS_SEDIMENT_LATERAL_IN
HUMUS_SEDIMENT_LATERAL_OUT
HUMUS_SEDIMENT_DELTA

Users can generate maps of sediment spatial data values by adding SpatialDataWriter parameterizations to their simulation configuration, and using the keynames above as values for the initializeSpatialDataSources parameter.

In CellDataWriter .csv files, cell-specific sediment data values for each simulation step are reported in the following columns:

Detritus_Leaf_Sediment_Lateral_In(mm/day)
Detritus_Leaf_Sediment_Lateral_Out(mm/day)
Detritus_Leaf_Sediment_Delta(mgN/m2/day)
Humus_Sediment_Lateral_In(mm/day)
Humus_Sediment_Lateral_Out(mm/day)
Humus_Sediment_Delta(mgN/m2/day)
Sediment_Humus_T1(gN/m2)

Note: the Sediment_Humus_T1 *data column is only available in CellDataWriter output. It cannot be specified as output data for SpatialDataWriter map output. Its value is the amount of top-layer Humus available in a cell prior to sediment transfer. This value is necessary for VELMA parallel mode runs (and is used by VELMA in that mode), but may otherwise be ignored.

Temporal Data

The sediment model computes per-simulation-step ("per-day") "VSA" and "Loss" values for detritus leaf and humus. These values are computed for the entire watershed and are solely applicable for the watershed's outlet location (i.e. the cell coordinates specified by the simulation configuration's outx and outy coordinates).

Their calculation involves distinquishing between "channel" and "NONchannel" cells. To VELMA, a "channel" cell is any cell whose log(flow accumulation value) meets or exceeds a specified threshold.

VSA is computed as: the sum of all channel-cell Lateral Out amounts, divided by the number of cells in the watershed.

Loss is computed as: the sum of all NONchannel-to-channel Lateral Out amounts, plus VSA, divided by the number of cells in the watershed.

The VSA and Loss values are reported in the DailyResults.csv and AnnualResults.csv files in the following data columns:

Detritus_Leaf_Sediment_VSA(gN/m2/day)_Delineated_Average
Detritus_Leaf_Sediment_Loss(gN/m2/day)_Delineated_Average
Humus_Sediment_VSA(gN/m2/day)_Delineated_Average
Humus_Sediment_Loss(gN/m2/day)_Delineated_Average

VSA and Loss values are only computed for the "final" (outx, outy) outlet cell of a simulation configuration unless the simulation configuration is run using VelmaSimulatorParallelCmdLine.
A simulation configuration run using JVelma or VelmaSimulatorCmdLine will not compute or report sediment VSA and Loss values for sub-reach outlets specified for initialReachOutlets.

Additional Detailed Temporal Data

When the sediment model's enableCategorizedLossTransfersReport parameter is set to true, VELMA reports additional VSA-and-Loss-related values in the results folder's global trace log file (default name "GlobalTraceLog.csv", but user-renamable via the csvTraceLogFileName parameter). The addtional values provide details about how the final detritus leaf and humus VSA and Loss values were calculated. This can be useful for understanding how much of a watershed's overal Loss amounts are due to channel-cell transfers versus NONchannel-cell transfers.

Be aware that this additional data generates one additional row of output per simulation step in the global trace log .csv file and in the global state log .txt file, and that these additional rows are echoed to the simulation's console (whether in JVelma or a command line via stdout). For simulations configured to run for many years (i.e. many steps), this may mean the simulation takes appreciably longer to run, as that additional data is written its console, global state, and global trace. It also means that the global state and global trace log files will be larger.

The column headers for the data reported (from left-to-right) are:

FINEST
doSurfaceStepEnd
iStep
LOSS_TRANSFER_REPORT
Transfer_Count_DetritusLeaf(gN/m2/day)_NONchannel_to_NONchannel
Transfer_Count_DetritusLeaf(gN/m2/day)_NONchannel_to_Channel
Transfer_Count_DetritusLeaf(gN/m2/day)_Channel_to_NONchannel
Transfer_Count_DetritusLeaf(gN/m2/day)_Channel_to_Channel
Transfer_Amount_DetritusLeaf(gN/m2/day)_NONchannel_to_NONchannel
Transfer_Amount_DetritusLeaf(gN/m2/day)_NONchannel_to_Channel
Transfer_Amount_DetritusLeaf(gN/m2/day)_Channel_to_NONchannel
Transfer_Amount_DetritusLeaf(gN/m2/day)_Channel_to_Channel
DetritusLeaf(gN/m2/day)_VSA_TOTAL
DetritusLeaf(gN/m2/day)_LOSS_TOTAL
Transfer_Amount_Humus(gN/m2/day)_NONchannel_to_NONchannel
Transfer_Amount_Humus(gN/m2/day)_NONchannel_to_Channel
Transfer_Amount_Humus(gN/m2/day)_Channel_to_NONchannel
Transfer_Amount_Humus(gN/m2/day)_Channel_to_Channel
Humus(gN/m2/day)_VSA_TOTAL
Humus(gN/m2/day)_LOSS_TOTAL

• The iStep column value is the simulation step value, and matches the Step column value in DailyResults.csv file. Use it to synchronize between records from these two files.

• The FINEST, doSurfaceStepEnd, and LOSS_TRANSFER_REPORT columns are constants that identify the logging level, simulator method, and logging data respectively. The global trace log file may contain many different types of data rows: use these columns to identify and isolate the loss transfer rows.
  Example for a Window Powershell command-line:
  C:\Users\me\VELMA\my_run_results> (Select-String -Pattern ",LOSS_TRANSFER_REPORT," .\GlobalTraceLog.csv).Line

• Transfer_Count_... columns report the number of times that a cell-to-cell transfer of specific category occurred. (Although "Count" columns include units text, but their values are purely integer counts: inluding the units simply reinforces the correspondence with the matching "Amount" columns.)

• Transfer_Amount_... columns report the actual amount transferred for that simulation step for the specific category of cell-to-cell transfer.

• The ..._VSA_TOTAL columns report the row's (..._Channel_to_NONchannel + ..._Channel_to_Channel) amounts.

• The ..._LOSS_TOTAL columns report the row's (NONchanne_to_Channel + ...VSA_TOTAL) amounts.

• The ..._VSA_TOTAL and ..._LOSS_TOTAL column values provide the "standard" ..._Sediment_VSA(gN/m2/day)_Delineated_Average and ..._Sediment_Loss(gN/m2/day)_Delineated_Average values prior to division by the number of cells in the watershed.