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10.6 Runoff models
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Models are not discussed in any detail in this publication. Two of the runoff models used
in South Africa to simulate yields are the ACRU (Agricultural Catchments Research Unit)
Model developed at the Department of Agricultural Engineering, University of Natal,
Pietermaritzburg (Schulze, 19891*; and the Pitman Monthly Runoff Model (Pitman,
19731** developed at the then Hydrological Research Unit of the University of the
Witwatersrand. The Computing Centre for Water Research maintains a list of certain
models used in South Africa for various hydrological, engineering, irrigation and water
quality modelling purposes. Selected programs are available from the Centre. A recent
report published by the Water Research Commission and the Department of Water Affairs
and Forestry, contains a useful overview of some 62 models used in this country. Several
other models are also listed* * * .
*
***
See Schulze, R.E., 1989. ACRU: background, concepts and theory, WRC Report No. 154/1/89,
Water Research Commission, Pretoria, various pages, and Schulze, R.E., George, W.J., lynch, 5.0.
and Angus, G.R., 1989. ACRU - 2.0: user manuat, WRC Report No. 154/2/89, Water Research
Commission, Pretoria, various pages. Note that the model has been revised and that updated
documentation is available. See Schulze, R.E., 1995. Hydrology and agrohydrology: a text to
accompany the ACRU 3.00 agrohydrological modelling system, WRC Report No. TT 69/95, Water
Research Commission, Pretoria, various pages, as well as Smithers, J. and Schulze, R., 1995. ACRU
agrohydrological modelling system: user manual version 3.00, WRC Report No. TT 70/95, Water
Research Commission, Pretoria, various pages.
See Pitrnan, W.V., 1973. A mathematical model for generating monthly river flows from
meteorological data in South Africa, HRU Report No. 2173, Hydrological Research Unit, University of
the Witwatersrand, Johannesburg, various pages. Note that the Pitrnan Model has been restructured.
The updated version, the Water Resources Simulation Model (WRSM90) was written to run on a PC.
(For an urban perspective see Green, I.R.A. and Stephenson, D., 1986. Urban hydrology and
drainage: comparison of urban drainage models for use in South Africa, WRC Report No. 115/6/86,
Water Research Commission, Pretoria, 265 p. + app., as well as Stephenson, D., Green, I.R.A. and
Lambourne, J.J., 1986. Urban hydrology and drainage: review, WRC Report No. 11511/86, Water
Research Commission, Pretoria, 119 p. + app. An important series of 12 urban catchment
publications (including the executive summary), is also available from the Water Research
Commission, PO Box 824, Pretoria, 0001. An example is given here: Stephenson, D., 1993. Effects
of urbanization on catchment water balance, 1. Analysis of effects of urbanization on runoff, WRC
Report No. 18311/93, Water Research Commission, Pretoria, 78 p.).
See CSIR Environmental Services, 1995. Procedures to assess effluent discharge impacts, WRC
Report No. TT 64/94, Water Research Commission and the Department of Water Affairs and Forestry,
Pretoria, 352 p.