SAPWAT was developed and is maintained by PICWAT, which started off as partnership between Charles Crosby, an agricultural engineer of repute who has specialised in issues related to irrigation water planning and management; Isobel van der Stoep, an agricultural engineer with many years’ lecturing and training experience; and Pieter van Heerden, an agronomist who has been involved in irrigation water requirement planning since 1977. Pieter is still actively involved in the further development and maintenance of SAPWAT 4.

The original SAPWAT was designed by Charles.

Charles has gone into happy retirement and Isobel has left the partnership to further specialise in irrigation water use efficiency and to give her own specialist input to the South African Irrigation Institute (SABI) as Executive Technical Officer.


  • Pieter was awarded the 2011 SABI (South African Irrigation Institute) award for ‘Outstanding contribution to irrigation technology’ for SAPWAT related work.
  • Charles Crosby and Pieter van Heerden were awarded the ICID (International Commission on Irrigation and Drainage) 2011 WATSAVE award for outstanding contribution to water saving and water conservation in agriculture for their contribution in the development and support of SAPWAT 3.

Crop irrigation


The SAPWAT 4 program and documentation contained in this website emanate from research projects financed by the Water Research Commission (WRC) and are approved for release. Although every precaution has been taken to ensure that the information is correct, application of results is at the risk of the user.

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