Section 5 Sediment Transport Module

5.1 Mass Balance

Users can now specify an additional output type massbalance that generates a suite of csv files that report timeseries of all time-accumulated volume and mass fluxes within a model domain, as related to all simulated quantities, other than temperature. This includes the suspended sediment mass transport component for all sediment fractions. Bed load mass transport is currently excluded. Details of this output are provided in Section 2.4 of these Release Notes.

One csv file of timeseries data is generated for each simulated quantity’s mass balance, and each csv file’s headers are therefore unique. The column headers pertaining to suspended sediment are presented and described in Table 5.1, with relevant mass units. Acronyms within column headers include:

  • V = Volumetric quantity
  • A = Areal quantity
  • MF = Mass flux
  • FV = TUFLOW FV output or computed from same
  • NS = Nodestring, encompassing WL, WLS and QN boundary types
  • WQ = Water Quality output or computed from same
  • Q = Q boundary type
  • QC = QC or QC_POLY boundary types
  • PCT = Percent

‘_N’ in the file path refers to sediment fraction number, which increments from 1 upwards to the total number of sediment fractions simulated. One file per sediment fraction is produced.

Table 5.1: Sediment Mass Flux Headers
Column Header Description Units
Sediment <fvc_name>_MASSBALANCE_SEDIMENT_N.csv
TIME ISODATE Time
FV_SED_MASS Instantaneous sediment fraction mass computed from TUFLOW FV state variables. Always a positive quantity. tonnes
FV_MF_QC Accumulated sediment fraction mass fluxes across all QC and QC_POLY boundaries, summed to a single timeseries. Can be a positive or negative quantity. tonnes
FV_MF_Q Accumulated sediment fraction mass fluxes across all Q boundaries, summed to a single timeseries. Can be a positive or negative quantity. tonnes
FV_MF_NS Accumulated sediment fraction mass fluxes across all WL, WLS and QN boundaries, summed to a single timeseries. Can be a positive or negative quantity. tonnes
FV_MF_NETSED Accumulated sediment fraction mass flux of net sedimentation (i.e. settling and erosion) acros the entire domain, summed to a single timeseries. Can be a positive or negative quantity. tonnes
FV_MF_TOTAL Total of accumulated sediment fraction mass fluxes, with individual signs preserved. Can be a positive or negative quantity. tonnes
MF_SED_MASS Estimate of total sediment fraction mass computed from summing previous timestep sediment fraction mass and current timestep sediment fraction mass fluxes. Always a positive quantity. tonnes
MF_PCT_ERROR The percentage error of the different between FV_SED_MASS and MF_SED_MASS. Can be a positive or negative quantity. %
MF_TURNOVERS See explanatory text (Section 2.4). Always a positive quantity. No units