Modelling tool capability overview
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, the Pitman model-based tools (WRSM-Pitman and SPATSIM-Pitman), and two tools from overseas that are intended for use across various contexts: SWAT, from the United States, and MIKE-SHE, based on a model co-developed by the European Union and then further developed by the Danish Hydrologic Institute. South African modelling tools can have certain advantages from being developed in response to local data availability and South African catchment contexts in terms of ecosystems, soils and geologic types, and climate as well as land and water management practices. However SWAT and MIKE-SHE have been applied globally and have development teams behind them that help update the
| Characteristic | WRSM-Pitman | SPATSIM-Pitman | ACRU | SWAT | MIKE-SHE |
|---|---|---|---|---|---|
| Current curator / developer | Bailey & Pitman Water Resources Ltd | Rhodes University, Institute of Water Resources | University of KwaZulu Natal, Centre for Water Resources Research | Texas A&M University & US Department of Agriculture | Danish Hydrologic Institute (DHI) |
| Free to 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) |
| Developed in South Africa | yes | yes | yes | no | no |
| 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 (subcat), 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 |
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| Timestep | Monthly* | Monthly* | Daily | Daily, sub-daily | Daily, sub-daily (dynamic timestep length, specified by 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 in documentation for system as whole, only for certain process options within it. The many options do steepen the learning curve for use.) |
| Specific development focuses particular to tool |
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