Difference between revisions of "Modelling tool capability overview"

From Hydromodel SA Wiki
Jump to navigation Jump to search
m
 
(12 intermediate revisions by the same user not shown)
Line 1: Line 1:
 +
<span id="Capabilities - pg top"></span>
 
A set of commonly used modelling tools in South Africa was reviewed for the [[Model inter-comparison study|WRC “Critical catchment model inter-comparison and model use guidance development” project]].  
 
A set of commonly used modelling tools in South Africa was reviewed for the [[Model inter-comparison study|WRC “Critical catchment model inter-comparison and model use guidance development” project]].  
  
Line 10: Line 11:
 
''More detailed information about the structural options and capabilities of the tools is given across the other tool inter-comparison pages: [[#Model units & connections|Model units & connections]], [[#Process representation across tools|Process representation]], [[#Water balance outputs across tools|Water balance outputs across tools]], [[#Modelling tool user interfaces|User interfaces]], [[#Documentation & support across tools|Documentation & support]], and [[#Applying tools in specific use cases|Specific use cases (e.g. irrigation, farm dams, groundwater pumping, riparian zones, wetlands)]].''
 
''More detailed information about the structural options and capabilities of the tools is given across the other tool inter-comparison pages: [[#Model units & connections|Model units & connections]], [[#Process representation across tools|Process representation]], [[#Water balance outputs across tools|Water balance outputs across tools]], [[#Modelling tool user interfaces|User interfaces]], [[#Documentation & support across tools|Documentation & support]], and [[#Applying tools in specific use cases|Specific use cases (e.g. irrigation, farm dams, groundwater pumping, riparian zones, wetlands)]].''
  
−
== Tool background & intended uses ==
+
== Modelling software tool background & versions covered ==  
−
The modelling software tools and the specific versions of these tools covered here are given in the table below.
 
−
</br>
 
−
</br>
 
−
=== Modelling software tool background & version covered ===
 
 
{| class="wikitable"
 
{| class="wikitable"
 
! scope="col" style="width:15em" | Characteristic
 
! scope="col" style="width:15em" | Characteristic
Line 107: Line 104:
  
  
−
These software tools have different development histories and somewhat different focuses, however all have adapted over time, adding features that allow them to be used in more contexts and have generally overlapping intended applications (see [[#intended use - Table Anchor|table below]]).  
+
These software tools have different development histories and somewhat different focuses, however all have adapted over time, adding features that allow them to be used in more contexts and have generally overlapping intended applications ([[#Intended uses & development focuses summary|see table below]]).  
  
 
The structural options and design of each tool reflect the intended applications as well as the balance struck by the developers between potentially competing concerns and goals, such as achieving parsimony, including detailed representation of land cover differences to estimate the impacts of change, maintaining ease of use of the tool, facilitating quantification of model output uncertainty, ensuring applicability in data limited contexts, etc.   
 
The structural options and design of each tool reflect the intended applications as well as the balance struck by the developers between potentially competing concerns and goals, such as achieving parsimony, including detailed representation of land cover differences to estimate the impacts of change, maintaining ease of use of the tool, facilitating quantification of model output uncertainty, ensuring applicability in data limited contexts, etc.   
  
−
For these reasons, despite the overlap in general intended uses, the tools offer some fairly different modelling strategies (see [[#basic structure - Table Anchor|structure overview]] below). This impacts how they can be applied in specific settings (documented in more detail [[Model units & connections|here]]). For example, all the tools are capable of modelling the impacts of land use change to some degree, however WRSM-Pitman and SPATSIM-Pitman place greater limitations on the number and types of land cover that can be explicitly modelled compared to the other tools.   
+
For these reasons, despite the overlap in general intended uses, the tools offer some fairly different modelling strategies ([[#Model structure overview by tool: spatial & temporal scales|see table below]]). This impacts how they can be applied in specific settings (documented in more detail [[Model units & connections|here]]). For example, all the tools are capable of modelling the impacts of land use change to some degree, however WRSM-Pitman and SPATSIM-Pitman place greater limitations on the number and types of land cover that can be explicitly modelled compared to the other tools.   
  
−
A summary table of some key modelling capabilities across the tools is presented [[#capabilities - Table Anchor|below]].  
+
A summary table of some key modelling capabilities across the tools is presented [[#Modelling tool capabilities summary|below]].  
 +
</br>
 +
</br>
 +
[[#Capabilities - pg top|Back to top of page]]
 
</br>
 
</br>
 
</br>
 
</br>
−
=== Intended uses & development focuses summary ===
+
 
 +
==Intended uses & development focuses summary ==
 
{| class="wikitable"
 
{| class="wikitable"
 
! scope="col" style="width:15em" | Characteristic
 
! scope="col" style="width:15em" | Characteristic
Line 152: Line 153:
 
* Coupled hydraulic channel model & flooding processes
 
* Coupled hydraulic channel model & flooding processes
 
|-
 
|-
−
| style="vertical-align: vertical-align: center;" |'''Intended applications:'''
+
| colspan="6" style="background: #FFFFFF;vertical-align: vertical-align: center;" |<big>  </big>'''Intended applications:'''
−
| style="background: #FFF5FA; vertical-align: center; text-align:center;" |
 
−
| style="background: #FFF7F5; vertical-align: center; text-align:center;" |
 
−
| style="background: #F5FFF5; vertical-align: center; text-align:center;" |
 
−
| style="background: #FFFFF5; vertical-align: center; text-align:center;" |
 
−
| style="background: #F5FCFF; vertical-align: center; text-align:center;" |
 
 
|-
 
|-
 
| style="vertical-align: vertical-align: center;" |''Water balance estimation''
 
| style="vertical-align: vertical-align: center;" |''Water balance estimation''
Line 236: Line 232:
 
| style="background: #F5FCFF; vertical-align: top" |''<small>(None documented for the modelling system as whole, only for certain process options within it. The learning curve for its use and computing power required can pose practical limitations to its application )</small>''
 
| style="background: #F5FCFF; vertical-align: top" |''<small>(None documented for the modelling system as whole, only for certain process options within it. The learning curve for its use and computing power required can pose practical limitations to its application )</small>''
 
|}
 
|}
 +
[[#Capabilities - pg top|Back to top of page]]
 +
</br>
 +
</br>
  
−
== Model structure & capabilities overview across tools ==
+
== Model structure overview by tool: spatial & temporal scales ==
−
 
+
The table below gives a very basic overview of the type of model structure that can be built in each tool.   
−
 
+
</br> More details about the model structure options across tools are presented [[Model units & connections|here]].     
−
The table below gives a very basic overview of the type of model structure that can be built in each tool.  More details about the model structure options across tools are presented [[Model units & connections|here]].     
 
−
 
 
−
 
 
 
{| class="wikitable"
 
{| class="wikitable"
−
|+<span id="basic structure - Table Anchor"> <big>Model spatial & temporal scale overview by tool</big> </span>
 
 
! scope="col" style="width:15em" | Characteristic
 
! scope="col" style="width:15em" | Characteristic
 
! scope="col" style="background: #F2CEE0; width:15em" |WRSM-Pitman
 
! scope="col" style="background: #F2CEE0; width:15em" |WRSM-Pitman
Line 314: Line 309:
  
  
−
Despite having largely overlapping intended uses in general, there is notable diversity in model structure (table above, and more detailed coverage [[Model units & connections|here]]) and in more specific modelling capabilities in this set of tools ([[#capabilities - Table Anchor|table below]]).
+
Despite having largely overlapping intended uses in general, there is notable diversity in model structure (table above, and more detailed coverage [[Model units & connections|here]]) and in more specific modelling capabilities in this set of tools ([[#Modelling tool capabilities summary|table below]]).  
−
 
 
−
Some key points arising from the capabilities comparison are:
 
−
 
 
−
 
 
−
* No one tool had all the capabilities listed.  All the tools have differing sets of advantages over the others.
 
−
 
 
−
 
 
−
* Although both based on the same predecessor model structure and sharing many basic process algorithms, WRSM-Pitman and SPATSIM Pitman have diverged in capabilities across several aspects. These differences are linked to WRSM’s modular network structure compared to the SPATSIM version’s focus on the subcatchment as the primary unit for process representation. For example, a WRSM model can include user-defined artificial water transfers between channel units in a model network, which SPATSIM does not include. SPATSIM includes an uncertainty or stochastic modelling routine, made more straightforward by the more uniform set-up of subcatchments, which WRSM does not include.
 
−
 
 
−
 
 
−
* WRSM-Pitman, SPATSIM-Pitman, and MIKE-SHE model dynamic, two-way exchange between surface water channels and groundwater aquifers (GW-SW exchange): groundwater can flow into the channel or channel water can recharge an aquifer in the model and the direction and magnitude of the exchange is calculated based on the water levels in each in every modelled timestep.
 
−
 
 
−
 
 
−
* Only MIKE-SHE has a fully coupled hydraulic model, allowing it to model channel-floodplain interactions in more detail, including the impact of changes in channel size, shape, depth of incision, etc. Other tools can represent some aspects of overbank flooding and the fate of the flood water, but this is limited to their wetland and riparian zone modules.
 
  
 +
Some key points arising from the capabilities comparison are:</br>
 +
</br>
 +
* No one tool had all the capabilities listed.  All the tools have differing sets of advantages over the others.</br>
 +
</br>
 +
* Although both based on the same predecessor model structure and sharing many basic process algorithms, WRSM-Pitman and SPATSIM Pitman have diverged in capabilities across several aspects. These differences are linked to WRSM’s modular network structure compared to the SPATSIM version’s focus on the subcatchment as the primary unit for process representation. For example, a WRSM model can include user-defined artificial water transfers between channel units in a model network, which SPATSIM does not include. SPATSIM includes an uncertainty or stochastic modelling routine, made more straightforward by the more uniform set-up of subcatchments, which WRSM does not include.</br>
 +
</br>
 +
* WRSM-Pitman, SPATSIM-Pitman, and MIKE-SHE model dynamic, two-way exchange between surface water channels and groundwater aquifers (GW-SW exchange): groundwater can flow into the channel or channel water can recharge an aquifer in the model and the direction and magnitude of the exchange is calculated based on the water levels in each in every modelled timestep. </br>
 +
</br>
 +
* Only MIKE-SHE has a fully coupled hydraulic model, allowing it to model channel-floodplain interactions in more detail, including the impact of changes in channel size, shape, depth of incision, etc. Other tools can represent some aspects of overbank flooding and the fate of the flood water, but this is limited to their wetland and riparian zone modules.</br>
 +
</br>
 +
</br>
 +
[[#Capabilities - pg top|Back to top of page]]
 +
</br>
 +
</br>
  
−
'''It's important to note that this capabilities summary table indicates what is ''technically possible'' within the modelling tools, but it does ''not'' cover the ''practicality and ease-of-use'' of the different features across each tool.'''
+
==Modelling tool capabilities summary==
 +
'''Important note: this capabilities summary table indicates what is ''technically possible'' within the modelling tools, but it does ''not'' cover the ''practicality and ease-of-use'' of the different features across each tool.''' </br>
 
Some things that are possible in a tool become a veritable labour of love to actually achieve, depending on the nature of the model set-up (i.e. how many subcatchments, how many HRUs, etc). </br>
 
Some things that are possible in a tool become a veritable labour of love to actually achieve, depending on the nature of the model set-up (i.e. how many subcatchments, how many HRUs, etc). </br>
−
For example, while different climate inputs ''can'' be specified by HRU in ACRU4, to allow for spatial distribution of rainfall within a subcatchment, operationalising this when there are many HRUs becomes quite unwieldly compared to simply specifying one set of climate inputs for all units in the subcatchment scale. There is no batch-input of climate for other subgroups beyond the subcatchment, and so varying climate within a subcatchment requires manually clicking through three layers of menus each for four different climate inputs for every HRU.  
+
''Example: In ACRU4, different climate inputs '''can''' be specified by HRU, to allow for spatial distribution of rainfall within a subcatchment. However operationalising this when there are many HRUs becomes very time consuming compared to simply specifying one set of climate inputs the whole subcatchment. Applying different climate inputs to different areas within a subcatchment requires manually clicking through three layers of menus each for four different climate inputs for every HRU. There is no batch-input of climate for subgroups of HRUs within a subcatchment.''</br>
 
Various aspects of the user interfaces of the different tools and their implications are covered on a separate page [[Modelling tool user interfaces|here]].  
 
Various aspects of the user interfaces of the different tools and their implications are covered on a separate page [[Modelling tool user interfaces|here]].  
−
 
−
 
 
{| class="wikitable"
 
{| class="wikitable"
−
|+<span id="capabilities - Table Anchor"> <big>Modelling tool capabilities summary </big></span>
 
 
! scope="col" style="width:15em" | Capability
 
! scope="col" style="width:15em" | Capability
 
! scope="col" style="background: #F2CEE0; width:8em" |WRSM-Pitman
 
! scope="col" style="background: #F2CEE0; width:8em" |WRSM-Pitman
Line 348: Line 341:
 
! scope="col" style="background: #CEE6F2; width:8em" |MIKE-SHE
 
! scope="col" style="background: #CEE6F2; width:8em" |MIKE-SHE
 
|-
 
|-
−
| colspan="6" style="vertical-align: vertical-align: center;" |'''Climate (rain & PET)'''
+
| colspan="6" style="background: #FFFFFF;vertical-align: vertical-align: center;" |<big>  </big>'''Climate (rain & PET)'''
 
|-
 
|-
 
| style="vertical-align: vertical-align: center;" |Spatially variable across model domain
 
| style="vertical-align: vertical-align: center;" |Spatially variable across model domain
Line 371: Line 364:
 
| style="background: #F5FCFF; vertical-align: center; text-align:center;" |'''yes'''
 
| style="background: #F5FCFF; vertical-align: center; text-align:center;" |'''yes'''
 
|-
 
|-
−
| colspan="6" style="vertical-align: vertical-align: center;" |'''Land cover & change'''
+
| colspan="6" style="background: #FFFFFF;vertical-align: vertical-align: center;" |<big>  </big>'''Land cover & change'''
 
|-
 
|-
 
| style="vertical-align: vertical-align: center;" |Processes explicitly linked to land cover
 
| style="vertical-align: vertical-align: center;" |Processes explicitly linked to land cover
Line 415: Line 408:
 
| style="background: #F5FCFF; vertical-align: center; text-align:center;" |'''yes'''
 
| style="background: #F5FCFF; vertical-align: center; text-align:center;" |'''yes'''
 
|-
 
|-
−
| colspan="6" style="vertical-align: vertical-align: center;" |'''Peak flows & flooding'''
+
| colspan="6" style="background: #FFFFFF;vertical-align: vertical-align: center;" |<big>  </big>'''Peak flows & flooding'''
 
|-
 
|-
 
| style="vertical-align: vertical-align: center;" |Max daily or subdaily peak flow estimation
 
| style="vertical-align: vertical-align: center;" |Max daily or subdaily peak flow estimation
Line 445: Line 438:
 
| style="background: #F5FCFF; vertical-align: center; text-align:center;" |'''yes'''
 
| style="background: #F5FCFF; vertical-align: center; text-align:center;" |'''yes'''
 
|-
 
|-
−
| colspan="6" style="vertical-align: vertical-align: center;" |'''Reservoirs, dams & channel flow modification'''
+
| colspan="6" style="background: #FFFFFF;vertical-align: vertical-align: center;" |<big>  </big>'''Reservoirs, dams & channel flow modification'''
 
|-
 
|-
 
| style="vertical-align: vertical-align: center;" |Reservoirs explicitly modelled
 
| style="vertical-align: vertical-align: center;" |Reservoirs explicitly modelled
Line 475: Line 468:
 
| style="background: #F5FCFF; vertical-align: center; text-align:center;" |''(limited)''
 
| style="background: #F5FCFF; vertical-align: center; text-align:center;" |''(limited)''
 
|-
 
|-
−
| colspan="6" style="vertical-align: vertical-align: center;" |'''GW representation & GW-SW interactions'''
+
| colspan="6" style="background: #FFFFFF;vertical-align: vertical-align: center;" |<big>  </big>'''GW representation & GW-SW interactions'''
 
|-
 
|-
 
| style="vertical-align: vertical-align: center;" |Dynamic, 2-way, GW-SW exchange
 
| style="vertical-align: vertical-align: center;" |Dynamic, 2-way, GW-SW exchange
Line 498: Line 491:
 
| style="background: #F5FCFF; vertical-align: center; text-align:center;" |'''yes'''
 
| style="background: #F5FCFF; vertical-align: center; text-align:center;" |'''yes'''
 
|-
 
|-
−
| colspan="6" style="vertical-align: vertical-align: center;" |'''Wetlands & riparian zones'''
+
| colspan="6" style="background: #FFFFFF;vertical-align: vertical-align: center;" |<big>  </big>'''Wetlands & riparian zones'''
 
|-
 
|-
 
| style="vertical-align: vertical-align: center;" |Wetland processes included
 
| style="vertical-align: vertical-align: center;" |Wetland processes included
Line 528: Line 521:
 
| style="background: #F5FCFF; vertical-align: center; text-align:center;" |'''yes'''
 
| style="background: #F5FCFF; vertical-align: center; text-align:center;" |'''yes'''
 
|-
 
|-
−
| colspan="6" style="vertical-align: vertical-align: center;" |'''Modelling other related catchment processes'''
+
| colspan="6" style="background: #FFFFFF;vertical-align: vertical-align: center;" |<big>  </big>'''Modelling other related catchment processes'''
 
|-
 
|-
 
| style="vertical-align: vertical-align: center;" |Sediment movement
 
| style="vertical-align: vertical-align: center;" |Sediment movement
Line 551: Line 544:
 
| style="background: #F5FCFF; vertical-align: center; text-align:center;" |no
 
| style="background: #F5FCFF; vertical-align: center; text-align:center;" |no
 
|-
 
|-
−
| colspan="6" style="vertical-align: vertical-align: center;" |'''Uncertainty & parameter calibration'''
+
| colspan="6" style="background: #FFFFFF;vertical-align: vertical-align: center;" |<big>  </big>'''Uncertainty & parameter calibration'''
 
|-
 
|-
 
| style="vertical-align: vertical-align: center;" |Functions/routines for batch runs, uncertainty, parameter sensitivity, & calibration
 
| style="vertical-align: vertical-align: center;" |Functions/routines for batch runs, uncertainty, parameter sensitivity, & calibration
Line 560: Line 553:
 
| style="background: #F5FCFF; vertical-align: center; text-align:center;" |'''yes'''
 
| style="background: #F5FCFF; vertical-align: center; text-align:center;" |'''yes'''
 
|}
 
|}
 +
[[#Capabilities - pg top|Back to top of page]]
 +
</br>
 +
</br>

Latest revision as of 09:59, 1 December 2023

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 major tools developed in South Africa: ACRU and the Pitman model-based tools, WRSM-Pitman and SPATSIM-Pitman. It also included two tools that were developed in the northern hemisphere, but have been used in South Africa and globally: SWAT and MIKE-SHE. Locally developed tools can have certain advantages from being designed with the South African context in mind, both in terms of local data availability and in terms of local climate characteristics, ecosystems, soils, geologic types, and land and water management practices (e.g. landscapes with many small farm dams). 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, but users should be aware there are many many tools available (see more examples)

The tables below summarise basic information about the tools in this set. These tables provide a broad overview, which may be all you need in many instances.

More detailed information about the structural options and capabilities of the tools is given across the other tool inter-comparison pages: Model units & connections, Process representation, Water balance outputs across tools, User interfaces, Documentation & support, and Specific use cases (e.g. irrigation, farm dams, groundwater pumping, riparian zones, wetlands).

Modelling software tool background & versions covered

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 to access yes yes yes yes no*

free student licenses & free/reduced research licenses by arrangement

Version reviewed in wiki WRSM-Pitman version 2.9 SPATSIM GWv3 Global Options Threaded model ACRU 4 SWAT2012; ArcSWAT2012 MIKE-SHE & MIKE Hydro River, version 2019 & 2020
Reference documents consulted

(see documentation links page)

Theory manual:

Bailey, A.K. (2015). WRSM2000/Pitman: Water Resources Simulation Model for Windows - Theory Manual (Water Research Commission).

User manual:

Bailey, A.K., and Pitman, W.V. (2016). WRSM/Pitman User’s Manual: WR2012 Volume 7 (Water Research Commission).

Theory documentation:

Hughes, D.A. (2004). Incorporating groundwater recharge and discharge functions into an existing monthly rainfall–runoff model. Hydrological Sciences Journal 49.

Hughes, D.A. (2013). A review of 40 years of hydrological science and practice in southern Africa using the Pitman rainfall-runoff model. Journal of Hydrology 501, 111–124.

Kapangaziwiri, E. (2007). Revised parameter estimation methods for the Pitman monthly rainfall-runoff model. MSc. Rhodes University.

User manual:

Hughes, D.A. (2019). SPATSIM v3 & IWR version of the Pitman model (IWR Rhodes University).

Theory manual:

Schulze, R.E. (1995). Hydrology and Agrohydrology: A Text to Accompany the ACRU 3.00 Agrohydrological Modelling System (Water Research Commission).

User manuals:

Clark, D.J., Smithers, J.C., Thornton-Dibb, S.L.C., and Lutchminarian, A. (2012). ACRU 4 User Manual: User Interface & Tutorials (Volume 3 of Deployment, Maintenance, & Further Development of SPATSIM-HDSF)

Schulze, R.E., and Davis, N.S. (2018). Practitioners’ Handbook for Undertaking Current and Projected Future Climate Related Risk and Vulnerability Modelling Assessments (an update of the ACRU user manual) (Schulze and Associates).

Theory manual:

Neitsch, S.L., Arnold, J.G., Kiniry, J.R., and Williams, J.R. (2011). Soil and Water Assessment Tool (SWAT) Theoretical Documentation, Version 2009 (Texas Water Resources Institute, Texas A&M University).

User manuals:

Winchell, M., Srinivasan, R., Di Luzio, J., and Arnold, J. (2013). ArcSWAT Interface for SWAT2012: User’s Guide (Texas Water Resources Institute, Texas A&M University).

Arnold, J.G., Kiniry, J.R., Srinivasan, R., Williams, J.R., Haney, E.B., and Neitsch, S.L. (2012). Soil & Water Assessment Tool (SWAT) - Input/Output Documentation, Version 2012 (Texas Water Resources Institute, Texas A&M University).

Theory manuals:

DHI (2019). MIKE SHE Manual, Volume 2: Reference Guide, MIKE 2019 (Danish Hydrologic Institute).

DHI (2019). MIKE 1D: DHI Simulaton Engine for 1D river and urban modelling - Reference Manual, MIKE 2019 (Danish Hydrologic Institute).

User manuals:

DHI (2019). MIKE SHE Manual, Volume 1: User Guide, MIKE 2019 (Danish Hydrologic Institute).

DHI (2019). MIKE Hydro River: User Guide, MIKE 2019 (Danish Hydrologic Institute).


These software tools have different development histories and somewhat different focuses, however all have adapted over time, adding features that allow them to be used in more contexts and have generally overlapping intended applications (see table below).

The structural options and design of each tool reflect the intended applications as well as the balance struck by the developers between potentially competing concerns and goals, such as achieving parsimony, including detailed representation of land cover differences to estimate the impacts of change, maintaining ease of use of the tool, facilitating quantification of model output uncertainty, ensuring applicability in data limited contexts, etc.

For these reasons, despite the overlap in general intended uses, the tools offer some fairly different modelling strategies (see table below). This impacts how they can be applied in specific settings (documented in more detail here). For example, all the tools are capable of modelling the impacts of land use change to some degree, however WRSM-Pitman and SPATSIM-Pitman place greater limitations on the number and types of land cover that can be explicitly modelled compared to the other tools.

A summary table of some key modelling capabilities across the tools is presented below.

Back to top of page

Intended uses & development focuses summary

Characteristic WRSM-Pitman SPATSIM-Pitman ACRU4 SWAT2012 MIKE-SHE
Specific tool development focuses
  • Flexible network for managed systems: many for options transfers, withdrawal points, reservoir locations, etc.
  • Irrigated area representation
  • IAP & plantation forestry water use
  • Groundwater-surface water interaction (vegetation & GW pumping impacts)
  • Parsimony,
  • Uncertainty assessment & stochastic modelling,
  • Groundwater-surface water interaction (vegetation & GW pumping impacts)
  • Detailed land cover type representation,
  • In-built local parameter database for SA vegetation & soil types, supports the level of representation
  • Crop & irrigation detail,
  • IAP & plantation forestry water use, including deep rooted vegetation in riparian areas
  • Detailed land cover type representation,
  • In-built local parameter database for vegetation & soil types - North American focus, some more general, supports the level of representation
  • Crop & irrigation detail with source flexibility,
  • Coupling to GIS tools
  • Flexible spatial discretisation & distribution (climate, land cover, soil, geology, etc),
  • Potential for fine scale process representation
  • Crop & irrigation detail with source flexibility,
  • Groundwater-surface water interaction,
  • Coupled hydraulic channel model & flooding processes
Intended applications:
Water balance estimation yes yes yes yes yes
Design hydrology & flood analyses no no yes yes yes
Supply planning (general) yes yes yes yes yes
Reservoir yield yes yes yes yes yes
Irrigation planning yes (limited) yes yes yes
Groundwater recharge yes yes yes yes yes
GW-SW interactions & GW pumping impacts yes yes no yes yes
Land cover change impacts yes yes yes yes yes
Climate change impacts yes yes yes yes yes
Application limitations
  • Monthly model: not applicable for peak flow, flood assessment, design hydrology
  • No irrigation direct from groundwater
  • Monthly model: not applicable for peak flow, flood assessment, design hydrology
  • No irrigation direct from groundwater
  • Simplified groundwater modelling;
  • Does not model groundwater pumping
  • Highly simplified deep groundwater modelling
 (None documented for the modelling system as whole, only for certain process options within it. The learning curve for its use and computing power required can pose practical limitations to its application )

Back to top of page

Model structure overview by tool: spatial & temporal scales

The table below gives a very basic overview of the type of model structure that can be built in each tool.
More details about the model structure options across tools are presented here.

Characteristic WRSM-Pitman SPATSIM-Pitman ACRU4 SWAT2012 MIKE-SHE
Intended scale of catchment or modelled 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

Timestep Monthly*


A daily version has been developed. Limited use to-date.

Monthly*


A daily version has been developed. Limited use to-date

Daily Daily, subdaily Daily, subdaily*


Calculation timesteps are dynamic and vary by process. All outputs saved for a user-selected step.

Spatial discretisation (model spatial units) Modules connected by routes


(“runoff” modules + special area modules + channel modules create subcatchments)

Subcatchments + limited internal sub-area types HRUs within subcatchments HRUs within subcatchments Grid cells (3D),

with optional calculation simplifications: surface flow modelled for zones, interflow & groundwater modelled for storage reservoirs within subcatchments.

Suggested model unit scales Runoff module:  < 1,000 km2 (none listed) Subcatchments: 5-50 km2

HRUs:  < 30km2

(none listed) (none listed)


Despite having largely overlapping intended uses in general, there is notable diversity in model structure (table above, and more detailed coverage here) and in more specific modelling capabilities in this set of tools (table below).

Some key points arising from the capabilities comparison are:

  • No one tool had all the capabilities listed.  All the tools have differing sets of advantages over the others.


  • Although both based on the same predecessor model structure and sharing many basic process algorithms, WRSM-Pitman and SPATSIM Pitman have diverged in capabilities across several aspects. These differences are linked to WRSM’s modular network structure compared to the SPATSIM version’s focus on the subcatchment as the primary unit for process representation. For example, a WRSM model can include user-defined artificial water transfers between channel units in a model network, which SPATSIM does not include. SPATSIM includes an uncertainty or stochastic modelling routine, made more straightforward by the more uniform set-up of subcatchments, which WRSM does not include.


  • WRSM-Pitman, SPATSIM-Pitman, and MIKE-SHE model dynamic, two-way exchange between surface water channels and groundwater aquifers (GW-SW exchange): groundwater can flow into the channel or channel water can recharge an aquifer in the model and the direction and magnitude of the exchange is calculated based on the water levels in each in every modelled timestep.


  • Only MIKE-SHE has a fully coupled hydraulic model, allowing it to model channel-floodplain interactions in more detail, including the impact of changes in channel size, shape, depth of incision, etc. Other tools can represent some aspects of overbank flooding and the fate of the flood water, but this is limited to their wetland and riparian zone modules.



Back to top of page

Modelling tool capabilities summary

Important note: this capabilities summary table indicates what is technically possible within the modelling tools, but it does not cover the practicality and ease-of-use of the different features across each tool.
Some things that are possible in a tool become a veritable labour of love to actually achieve, depending on the nature of the model set-up (i.e. how many subcatchments, how many HRUs, etc).
Example: In ACRU4, different climate inputs can be specified by HRU, to allow for spatial distribution of rainfall within a subcatchment. However operationalising this when there are many HRUs becomes very time consuming compared to simply specifying one set of climate inputs the whole subcatchment. Applying different climate inputs to different areas within a subcatchment requires manually clicking through three layers of menus each for four different climate inputs for every HRU. There is no batch-input of climate for subgroups of HRUs within a subcatchment.
Various aspects of the user interfaces of the different tools and their implications are covered on a separate page here.

Capability WRSM-Pitman

(+ Sami GW)

SPATSIM-Pitman

(+ Hughes GW)

ACRU4 SWAT2012 MIKE-SHE
Climate (rain & PET)
Spatially variable across model domain yes yes yes yes yes
Spatially variable within subcatchment (limited) no yes no yes
Inter-annual variability in PET 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) yes (limited)
Irrigation, with dynamic demand & supply yes yes yes yes yes
Potential for ET from GW (deep roots) yes yes (limited) (limited) yes
Peak flows & flooding
Max daily or subdaily peak flow estimation no no yes yes yes
Explicit impacts of channel capacity & shape on flow (limited) (limited) (limited) (limited) yes
Calculation of flooded area extent (wetland) no (wetland) (wetland) 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
Lumped representation for many small dams yes yes (limited) (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 (limited) 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 (valley bottom) yes yes yes yes yes
Off-channel wetlands (fed by channel overbank spill) yes yes yes no yes
Groundwater-fed wetlands (direct vs via channel's baseflow) (limited) (limited) (limited) (limited) yes
Modelling other related catchment 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
Functions/routines for batch runs, uncertainty, parameter sensitivity, & calibration no yes no yes yes

Back to top of page

Retrieved from "https://hydromodel-sa-wiki.saeon.ac.za/index.php?title=Modelling_tool_capability_overview&oldid=767"