Difference between revisions of "Water balance outputs across tools"

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! scope="col" style="width:15em" colspan="2" rowspan="2" |Flux or storage
 
! scope="col" style="width:15em" colspan="2" rowspan="2" |Flux or storage
! colspan="6" | '''Tool output and/or calculation approach'''
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! colspan="6" | '''''Tool output and/or calculation approach'''''
 
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! scope="col" style="background: #F2CEE0; width:8em" |WRSM-Pitman </br><small>(Sami GW)
 
! scope="col" style="background: #F2CEE0; width:8em" |WRSM-Pitman </br><small>(Sami GW)

Latest revision as of 09:50, 4 December 2023

Modelling tools differ in the hydrological processes, or water balance elements (fluxes and storages), that they calculate individually, save, and allow users to export for further analyses. The table below covers what each software tool outputs, meaning what can be saved as a timeseries of flow rates, fluxes, or storage volumes or depths, and for what spatial scale or modelled units these can be output (e.g. output for each grid cell, HRU, subcatchment, or catchment total). Output file formats are covered here.

The spatial scales at which the software can output values gives an indication of how much external calculation work a user may need to do in order to find out about a flux or store of particular interest. For example, we often wish to know the ET water use of a particular vegetation type, likely to compare with another type. ACRU and SWAT will output AET components for individual HRUs, however if there are multiple HRUs of the same land cover type within the model type, these tools will not compile an area-weighted average for the cover type across the whole modelled area. The user would need to do that manually outside the tool using the individual HRU outputs. MIKE-SHE can do this compilation within the software as the user can specify a polygon that covers the full area of a cover class and the tool will compile fluxes for that polygon.

Note: The table differentiates between the case in which a tool does not output its calculation of a certain flux or storage (Output = "no") and the case in which the tool does not explicitly model the listed process ("not modelled"), meaning it's not part of the model's calculations. In the case when a tool does model a process, but does not output the results of this calculation, the user could potentially consult the tools' user guide and attempt to calculate the process themselves using the algorithm that is applied in the software and other components that can be output. In cases where a calculation would be relatively simple, and based only on other outputs covered in the table, the calculation approach has been given in the table.
For cases where the tool does output a flux but uses a different name for it that has been used in the table row heading, this has been noted in brackets below. For more terminology comparison across tools, see further coverage here.
Some of the fluxes listed in the table are net totals of component fluxes which are also listed in the table (e.g. total AET or total evaporation & transpiration = canopy interception evaporation + AET from soil + AET from GW + evaporation off water bodies, where applicable). Some tools model and output each separately and may or may not output each individually. Some provide outputs of the total and the components, some just the components and the user would need to sum them if the total was of interest. Some calculate a total of some or all in a single step and output the total.

Flux or storage Tool output and/or calculation approach
WRSM-Pitman
(Sami GW)
SPATSIM-Pitman
(Hughes GW)
ACRU4 SWAT2012 MIKE-SHE,

semi-distributed,
more conceptual

MIKE-SHE,

fully-distributed,
more physical

AET total Output
no *

calculate:
precip – runoff
– Δ soil storage
– Δ GW storage
(works for long-term average, not monthly due to recharge lag)

no *

calculate:
ET output (includes canopy interception)
+ AET from GW (external calculation)

no *

calculate:
canopy evap.
+ AET from soil

no *

calculate:
AET from soil
+ AET from GW

YES YES
Scale (runoff module) (subcatchment) (HRU) (HRU) grid cell, polygon, catchment grid cell, polygon, catchment
Canopy interception evaporation Output no YES YES
not modelled
YES YES
Scale subcatchment HRU grid cell, polygon, catchment grid cell, polygon, catchment
AET from soil Output no YES YES YES YES YES
Scale subcatchment HRU HRU, subcatchment, catchment grid cell, polygon, catchment grid cell, polygon, catchment
AET from GW Output no no not modelled

(exception: riparian HRU approximation)

YES
(‘Revap’)
YES YES
Scale HRU subcatchment aquifer, catchment grid cell, polygon, catchment, (aquifer layer or all)
Evaporation from surface water body Output no YES YES YES YES YES
Scale water body water body water body (includes river reaches) water body (includes river reaches), surface ponding: grid cell, polygon, catchment water body (includes river reaches), surface ponding: grid cell, polygon, catchment
Runoff (RO) total Output YES YES YES YES YES YES
Scale runoff module, route (any scale) subcatchment HRU, subcatchment, catchment HRU, subcatchment, catchment river cross section river cross section
Surface runoff Output
no *

calculate:
RO total – interflow – aquifer RO

YES
no *

calculate:
“Quickflow” – “DelayedStormflow”

YES YES YES
Scale runoff module subcatchment HRU HRU, subcatchment, catchment grid cell, polygon, catchment grid cell, polygon, catchment
Interflow Output YES YES
(‘soil moisture runoff’)
YES
(‘DelayedStormflow’)
YES
(‘Lateral Q’)
YES YES
(saturated zone, upper layer)
Scale runoff module subcatchment HRU HRU, subcatchment, catchment subcatchment interflow reservoir grid cell, polygon, catchment
Aquifer to channel Output YES YES YES YES YES YES
Scale runoff module subcatchment HRU, subcatchment HRU, subcatchment, catchment subcatchment aquifer, catchment grid cell, polygon, catchment, (aquifer layer or all)
Channel to aquifer Output YES YES not modelled no YES YES
Scale river module subcatchment channel to "bank store", not output, need to back-calculate for reach river reach river reach; grid cell, polygon, catchment (aquifer layer)
Aquifer GW flow, into or out of a model unit, remaining as GW Output no YES not modelled
no *

GW can ‘leave’ catchment by recharging an inactive deep aquifer

no *

GW can ‘leave’ catchment by recharging an inactive deep aquifer or ‘dead storage’

YES
Scale subcatchment (subcatchment) (subcatchment) grid cell, polygon, catchment, (aquifer layer or all)
Water body storage Output YES YES YES YES YES YES
Scale water body water body water body water body, surface ponding: grid cell, polygon, catchment water body, surface ponding: grid cell, polygon, catchment
Soil profile storage Output YES YES YES YES YES YES
Scale runoff module subcatchment soil layer in HRU HRU, subcatchment, catchment grid cell, polygon, catchment grid cell, polygon, catchment
Aquifer storage Output YES no YES YES YES YES
Scale runoff module HRU, subcatchment HRU, subcatchment subcatchment aquifer, catchment grid cell, polygon, catchment, (aquifer layer or all)
Percolation out of soil storage Output YES
(‘total recharge’ - lagged to aquifer, excess becomes interflow)
YES
(same as aquifer recharge below)
YES
(same as aquifer recharge below)
YES
(lagged to aquifer)
YES
(goes to 'interflow store')
YES
(same as aquifer recharge below)
Scale runoff module subcatchment HRU HRU, subcatchment grid cell, polygon, catchment grid cell, polygon, catchment
Aquifer recharge Output YES
(‘aquifer recharge’)
YES YES
(B-horizon soil ‘SaturatedFlow’ + ‘UnsaturatedFlow’)
YES YES YES
Scale runoff module subcatchment HRU, subcatchment HRU, subcatchment subcatchment aquifer, catchment grid cell, polygon, catchment, (aquifer layer or all)