Difference between revisions of "Modelling tool capability overview"

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{| class="wikitable"
 
{| class="wikitable"
 
|+
 
|+
−
Critical differences of structural options in the reviewed modelling tools
+
Differences structural options in the reviewed modelling tools
−
| colspan="4" style="text-align:center"|'''components of the catchment and concept of a subcatchment'''
+
| colspan="3" style="text-align:center" width="450"|'''components of the catchment and concept of a subcatchment'''
 
''affects how the river is defined and the location of the outlet''
 
''affects how the river is defined and the location of the outlet''
 
|-
 
|-
−
|semi-distributed subcatchments, each with an outlet
+
|colspan="1" width="150"|semi-distributed subcatchments, each with an outlet
 
streamflow is directed to a particular channel unit (or catchment outlet)
 
streamflow is directed to a particular channel unit (or catchment outlet)
  
Line 222: Line 222:
  
 
semi-distributed land units
 
semi-distributed land units
−
|land areas (modules) draining into a river network,
+
|colspan="1" width="150"|land areas (modules) draining into a river network,
 
streamflow estimates available at each module outlet
 
streamflow estimates available at each module outlet
  
 
lumped land units
 
lumped land units
−
| colspan="2" |flow paths defined by the topography and material of individual land units/cells
+
| colspan="1" width="150"|flow paths defined by the topography and material of individual land units/cells
 
streamflow estimated at each cell and between cells and vertical units
 
streamflow estimated at each cell and between cells and vertical units
  
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distributed land units
 
distributed land units
 
|-
 
|-
−
|SPATSIM-Pitman
+
|colspan="1" width="150"|SPATSIM-Pitman
  
 
ACRU
 
ACRU
Line 239: Line 239:
 
SWAT
 
SWAT
 
|WRSM-Pitman
 
|WRSM-Pitman
−
| colspan="2" |MIKE-SHE
+
| colspan="1" width="150"|MIKE-SHE
 
|-
 
|-
−
| colspan="4" style="text-align:center" |'''scale of representation'''
+
| colspan="3" style="text-align:center" width="450"|'''scale of representation'''
 
''affects how the process is calculated and the meaning of parameter values''
 
''affects how the process is calculated and the meaning of parameter values''
 
|-
 
|-
 
|subcatchment
 
|subcatchment
 
|HRU
 
|HRU
−
| colspan="2" |grid cell
+
| colspan="1" width="150"|grid cell
 
|-
 
|-
−
|ACRU
+
|colspan="1" width="150"|ACRU
  
 
SPATSIM-Pitman
 
SPATSIM-Pitman
 
WRSM-Pitman
 
WRSM-Pitman
−
|SWAT
+
|colspan="1" width="150"|SWAT
  
 
ACRU
 
ACRU
 
MIKE-SHE
 
MIKE-SHE
−
| colspan="2" |MIKE-SHE
+
| colspan="1" width="150"| MIKE-SHE
 
|-
 
|-
−
| colspan="4" style="text-align:center"|'''land cover type discretisation and representation'''
+
| colspan="3" style="text-align:center" width="450"|'''land cover type discretisation and representation'''
 
''affects whether the land cover is explicitly represented and the ability to pinpoint/track specific impacts of a land cover type on the water balance''
 
''affects whether the land cover is explicitly represented and the ability to pinpoint/track specific impacts of a land cover type on the water balance''
 
|-
 
|-
−
| colspan="2" |no restrictions
+
| colspan="2" width="225" |no restrictions
 
explicitly represents multiple land uses  
 
explicitly represents multiple land uses  
−
| colspan="2" |considerable restrictions
+
| width="225"|considerable restrictions
 
does not fully represent multiple land uses
 
does not fully represent multiple land uses
 
|-
 
|-
−
| colspan="2" |ACRU
+
| colspan="2" width="225"|ACRU
  
 
MIKE-SHE
 
MIKE-SHE
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SWAT
 
SWAT
 
WRSM-Pitman
 
WRSM-Pitman
−
| colspan="2" |SPATSIM-Pitman
+
| width="225" |SPATSIM-Pitman
 
|-
 
|-
−
| colspan="4" style="text-align:center" |'''connections between landscape units'''
+
| colspan="3" style="text-align:center" width="450"|'''connections between landscape units'''
 
''affects the flow of water between land units before reaching the outlet''
 
''affects the flow of water between land units before reaching the outlet''
 
|-
 
|-
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catchment outlet)
 
catchment outlet)
−
| colspan="2" |interaction of flow between subcatchments
+
| colspan="1" |interaction of flow between subcatchments
 
(i.e. subcatchment to subcatchment interactions then routing to catchment outlet)
 
(i.e. subcatchment to subcatchment interactions then routing to catchment outlet)
 
|-
 
|-
 
| colspan="2" |ACRU (unless a riparian zone is added)
 
| colspan="2" |ACRU (unless a riparian zone is added)
 
SWAT
 
SWAT
−
| colspan="2" |SPATSIM-Pitman
+
| colspan="1" |SPATSIM-Pitman
  
 
WRSM-Pitman
 
WRSM-Pitman
 
MIKE SHE
 
MIKE SHE
 
|-
 
|-
−
| colspan="4" style="text-align:center"|'''aquifer representation and connectivity'''
+
| colspan="3" style="text-align:center"|'''aquifer representation and connectivity'''
  
 
''determines the spatial scale of  groundwater flows''
 
''determines the spatial scale of  groundwater flows''
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|subcatchment scale
 
|subcatchment scale
 
|HRU scale
 
|HRU scale
−
| colspan="2" |3D modelling mesh  
+
| colspan="1" |3D modelling mesh  
 
(user-defined grid cells)
 
(user-defined grid cells)
 
|-
 
|-
 
|no regional aquifer water exchanges between subcatchments
 
|no regional aquifer water exchanges between subcatchments
 
|no flow between subcatchments
 
|no flow between subcatchments
−
| colspan="2" |all units can interact
+
| colspan="1" |all units can interact
 
|-
 
|-
−
|distributed MIKE-SHE
+
| colspan="1" |distributed MIKE-SHE
  
 
SWAT
 
SWAT
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WRSM-Pitman  
 
WRSM-Pitman  
 
|ACRU (with the exception of version 3)
 
|ACRU (with the exception of version 3)
−
| colspan="2" |distributed MIKE-SHE
+
| colspan="1" |distributed MIKE-SHE
 
|-
 
|-
 
| colspan="2" |No channel transmission
 
| colspan="2" |No channel transmission
−
| colspan="2" |Channel transmission
+
| colspan="1" |Channel transmission
 
(contributes and redistributes water to the unsaturated zone, not the aquifer)
 
(contributes and redistributes water to the unsaturated zone, not the aquifer)
 
|-
 
|-
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SPATSIM-Pitman
 
SPATSIM-Pitman
 
WRSM-Pitman
 
WRSM-Pitman
−
| colspan="2" |SWAT
+
| colspan="1" |SWAT
 
|-
 
|-
−
| colspan="4" |'''channel representation and connectivity'''
+
| colspan="3" style="text-align:center" width="450"| |'''channel representation and connectivity'''
 
''affects the interactions with the channel network''
 
''affects the interactions with the channel network''
 
|-
 
|-
 
| colspan="2" |hydrodynamic model with limited hydraulic features
 
| colspan="2" |hydrodynamic model with limited hydraulic features
  
−
less options and opportunities for interactions with the channel network
+
fewer options and opportunities for interactions with the channel network
−
| colspan="2" |full hydraulic model
+
| colspan="1" |full hydraulic model
  
 
more options and opportunities for interactions with the channel network
 
more options and opportunities for interactions with the channel network
−
(trade off: increases model complexity, computational demands, and run-times)
+
(trade-off: increases model complexity, computational demands, and run-times)
 
|-
 
|-
 
| colspan="2" |ACRU
 
| colspan="2" |ACRU
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SPATSIM-Pitman
 
SPATSIM-Pitman
 
WRSM-Pitman  
 
WRSM-Pitman  
−
| colspan="2" |SWAT
+
| colspan="1" |SWAT
 
|-
 
|-
−
| colspan="4" style="text-align:center"|'''reservoir representation and connectivity'''
+
| colspan="3" style="text-align:center"|'''reservoir representation and connectivity'''
  
 
''affects the setup demand &'' ''accessibility of water storage for irrigation and inflows into the storage''
 
''affects the setup demand &'' ''accessibility of water storage for irrigation and inflows into the storage''
 
|-
 
|-
−
| colspan="2" |Can include farm dams within a subcatchment
+
| colspan="1" |Can include farm dams within a subcatchment
  
  
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''(practical and useful feature in some landscapes)''
 
''(practical and useful feature in some landscapes)''
−
|Implied reservoir within the catchment
+
|colspan="1" |Implied reservoir within the catchment
  
 
an internal water storage unit (ponds) are used to imply reservoirs,
 
an internal water storage unit (ponds) are used to imply reservoirs,
  
 
ponds cannot be used as a water supply for irrigation, ponds can act as flood control structures with outflow rules
 
ponds cannot be used as a water supply for irrigation, ponds can act as flood control structures with outflow rules
−
|Does not include farm dams within a subcatchment
+
|colspan="1" |Does not include farm dams within a subcatchment
  
  
 
each small dam needs to be input separately ''(intensive task)''
 
each small dam needs to be input separately ''(intensive task)''
 
|-
 
|-
−
| colspan="2" |ACRU
+
| colspan="1" |ACRU
  
 
SPATSIM-Pitman
 
SPATSIM-Pitman
 
WRSM-Pitman
 
WRSM-Pitman
−
|SWAT
+
|colspan="1" |SWAT
−
|MIKE SHE
+
|colspan="1" |MIKE SHE
 
|}
 
|}

Revision as of 04:21, 26 May 2021

A set of commonly used modelling tools in South Africa was reviewed for the WRC “Critical catchment model inter-comparison and model use guidance development” project. This set included the major tools developed in South Africa, ACRU and the Pitman model-based tools (WRSM-Pitman and SPATSIM-Pitman), as well as two tools that were developed in the northern hemisphere, but have been used globally, SWAT and MIKE-SHE. Locally developed modelling tools can have certain advantages from being designed with the South African context in mind, both in terms of data availability and local climate characteristics, ecosystems, soils and geologic types, as well as land and water management practices. SWAT and MIKE-SHE have resourced development teams behind them that continually update the tools and adapt them to make use of developing globally available data sources, such as remotely sensed data, and generally improved access to greater computing power. This suite of tools covers a diversity of model structure and algorithm type options.

The two tables below summarise basic information about the tools in this set: the first gives intended uses and broad structural characteristics and the second gives an overview of modelling capabilities across the tools that are likely to be in demand for many typical use-cases.

Background & basic characteristics of reviewed modelling tools
Characteristic WRSM-Pitman SPATSIM-Pitman ACRU SWAT MIKE-SHE
Developed in South Africa yes yes yes no no
Current curator / developer Bailey & Pitman Water Resources Ltd Rhodes University, Institute of Water Resources (IWR) University of KwaZulu Natal,

Centre for Water Resources Research (UKZN-CWRR)

Texas A&M University &

US Department of Agriculture (USDA)

Danish Hydrologic Institute (DHI)
Free access yes yes yes yes no
Version reviewed WRSM-Pitman version 2.9 SPATSIM GWv3 Global Options Threaded model ACRU 4 SWAT & ArcSWAT 2012 MIKE-SHE & MIKE Hydro River, version 2017
Reference documents Theory manual: (Bailey, 2015);

User manual: (Bailey and Pitman, 2016)

Theory papers: (Hughes, 2004, 2013; Kapangaziwiri, 2007);

User manual: (Hughes, 2019)

Theory manual: (Schulze, 1995);

User manuals: (Clark et al., 2012; Schulze and Davis, 2018)

Theory manual: (Neitsch et al., 2011);

User manuals: (Arnold et al., 2012)

Theory manuals:(DHI, 2017a, 2017b);

User’s manuals:(DHI, 2017d, 2017c)

Intended spatial scale

(catchment or model area)

Local to regional:

no suggested min-max model size

Local to regional:

10-10,000’s of km2, more typical:

100-1,000’s km2

Field to regional:

no suggested min-max model size

Field to regional:

no suggested min-max model size

Field to regional:

no suggested min-max model size

Spatial discretisation Modules ('runoff' modules/subcatchments,

special sub-areas, channels, reservoirs) linked by routes

Subcatchments + limited internal sub-area types HRUs within subcatchments HRUs within subcatchments Fully distributed (gridded)

OR

combinations of grids and zones for

different process calculations within subcatchments

(if all process zones align, would act like HRUs)

Intended subcat size < 1,000 km2 Intended subcat size 5-50 km2;

HRU size < 30km2

Timestep Monthly* Monthly* Daily Daily, sub-daily Daily, sub-daily

(dynamic timestep length,

can vary across processes)

Intended modelling applications (as documented):
Water balance estimation yes yes yes yes yes
Design hydrology (flood peaks) yes yes yes
Supply planning (general) yes yes yes yes yes
Reservoir yield yes yes yes yes yes
Irrigation planning yes yes yes yes
Groundwater recharge yes yes yes yes yes
Groundwater-surface water (GW-SW) interactions & pumping impacts yes yes yes
Land cover change impacts yes yes yes yes yes
Climate change impacts yes yes yes yes yes
Application limitations (as documented) Not for peak flow, flood assessment, or design hydrology Not for peak flow, flood assessment, design hydrology Not represent deep GW processes - not for GW pumping impact Not represent deep GW processes (None listed for the modelling system

as whole, only for certain process

representation options.)

Specific development focuses particular to tool
  • Flexible network for tracking managed system transfers,
  • GW-SW interaction,
  • IAP & plantation forestry water use
  • Parsimony,
  • Uncertainty assessment,
  • GW-SW interactions
  • Land cover type representation,
  • Crop & irrigation detail,
  • IAP & plantation forestry water use
  • Land cover type representation,
  • Crop & irrigation detail,
  • Coupling to GIS tools
  • Spatial discretisation & fine scale processes,
  • GW-SW interaction,
  • Coupled hydraulic channel model with overbank flood process representation


The table below gives an overview of a range of capabilities of the modelling tools under review. This summary is supported by more detailed comparison of the structural and process algorithm differences between the modelling tools. Comparing the capabilities of a modelling tool to the needs of a modelling exercise is a critical step in tool selection. When a modelling tool lacks a capability that would be desirable, but not critical for the exercise, there may be ways to adapt the model set-up to account for this, such as adjusting parameter values for implicit representation of a feature or process the tool does not include explicitly.

Modelling tool capabilities overview
Capability WRSM-Pitman SPATSIM-Pitman ACRU SWAT MIKE-SHE
Climate (rain & ET demand)
Spatially variable across model domain yes yes yes yes yes
Spatially variable within subcatchment (limited) no yes no yes
Inter-annual variability in ET demand no yes yes yes yes
Land cover & change
Processes explicitly linked to land cover (limited) (limited) yes yes yes
Multiple land cover types included (limited) (limited) yes yes yes
Cover has explicit location in subcatchment (limited) no (limited) (limited) yes
Cover can vary over model run timespan yes no (limited) no (limited)
Irrigation + dynamic demand & supply yes yes yes yes yes
Potential direct ET from GW (deep root) yes yes (limited) (limited) yes
Peak flows & flooding
Max daily or subdaily peak flow est. no no yes yes yes
Explicit impacts of channel capacity on flow (limited) (limited) (limited) (limited) yes
Calculation of flooded area extent (limited) no (limited) (limited) yes
Flood water subject to infiltration, ET, etc (limited) no yes no yes
Reservoirs, dams & channel flow modification
Reservoirs explicitly modelled yes yes yes yes yes
Facility to represent many small dams no yes yes (limited) no
Abstractions & external inputs yes yes yes yes yes
Internal transfers between model units yes no yes yes (limited)
GW representation & GW-SW interactions
Dynamic, 2-way, GW-SW exchange yes yes no yes yes
GW table elevation predicted (limited) (limited) no (limited) yes
GW pumping included yes yes no yes yes
Wetlands & riparian zones
Wetland processes included yes yes yes yes yes
On-channel wetlands yes yes yes yes yes
Off-channel wetlands (fed by channel spill) yes yes yes no yes
GW fed (receive GW from surrounding) (limited) (limited) (limited) (limited) yes
Other catchment & vegetation processes
Sediment movement no no yes yes yes
Water quality no no yes yes yes
Crop yield no no yes yes no
Uncertainty & parameter calibration
In-built tools for uncertainty, parameter sensitivity, & auto-calibration (batch runs) no yes no no yes
Differences structural options in the reviewed modelling tools
components of the catchment and concept of a subcatchment

affects how the river is defined and the location of the outlet

semi-distributed subcatchments, each with an outlet

streamflow is directed to a particular channel unit (or catchment outlet)


semi-distributed land units

land areas (modules) draining into a river network,

streamflow estimates available at each module outlet

lumped land units

flow paths defined by the topography and material of individual land units/cells

streamflow estimated at each cell and between cells and vertical units


distributed land units

SPATSIM-Pitman

ACRU

SWAT

WRSM-Pitman MIKE-SHE
scale of representation

affects how the process is calculated and the meaning of parameter values

subcatchment HRU grid cell
ACRU

SPATSIM-Pitman WRSM-Pitman

SWAT

ACRU MIKE-SHE

MIKE-SHE
land cover type discretisation and representation

affects whether the land cover is explicitly represented and the ability to pinpoint/track specific impacts of a land cover type on the water balance

no restrictions

explicitly represents multiple land uses

considerable restrictions

does not fully represent multiple land uses

ACRU

MIKE-SHE

SWAT WRSM-Pitman

SPATSIM-Pitman
connections between landscape units

affects the flow of water between land units before reaching the outlet

outflows routed to the catchment

(i.e. subcatchment units to

catchment outlet)

interaction of flow between subcatchments

(i.e. subcatchment to subcatchment interactions then routing to catchment outlet)

ACRU (unless a riparian zone is added)

SWAT

SPATSIM-Pitman

WRSM-Pitman MIKE SHE

aquifer representation and connectivity

determines the spatial scale of groundwater flows

subcatchment scale HRU scale 3D modelling mesh

(user-defined grid cells)

no regional aquifer water exchanges between subcatchments no flow between subcatchments all units can interact
distributed MIKE-SHE

SWAT

SPATSIM-Pitman

WRSM-Pitman

ACRU (with the exception of version 3) distributed MIKE-SHE
No channel transmission Channel transmission

(contributes and redistributes water to the unsaturated zone, not the aquifer)

ACRU

MIKE-SHE

SPATSIM-Pitman WRSM-Pitman

SWAT
|channel representation and connectivity

affects the interactions with the channel network

hydrodynamic model with limited hydraulic features

fewer options and opportunities for interactions with the channel network

full hydraulic model

more options and opportunities for interactions with the channel network (trade-off: increases model complexity, computational demands, and run-times)

ACRU

SWAT

SPATSIM-Pitman WRSM-Pitman

SWAT
reservoir representation and connectivity

affects the setup demand & accessibility of water storage for irrigation and inflows into the storage

Can include farm dams within a subcatchment



farm dams can be used as a water supply for irrigation

(practical and useful feature in some landscapes)

Implied reservoir within the catchment

an internal water storage unit (ponds) are used to imply reservoirs,

ponds cannot be used as a water supply for irrigation, ponds can act as flood control structures with outflow rules

Does not include farm dams within a subcatchment


each small dam needs to be input separately (intensive task)

ACRU

SPATSIM-Pitman WRSM-Pitman

SWAT MIKE SHE
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