The application of process-based hydrological models requires the estimation of a number of soil hydraulic properties that are difficult time-consuming and costly to measure. This would have severely limited the use of these models had it not been for the development of pedotransfer (PTFs). PTFs are regression equations that relate readily available, easily measured soil physical and chemical data either directly or indirectly to soil hydraulic properties. The great majority of work in the development of PITS has been in the USA and Europe and therefore the soils used have been American or European. The problem comes in trying to apply PTFs in other areas such as sub-Saharan Africa. This paper describes on-going work at a number of locations in Tanzania that is attempting to evaluate the ability of PTFs to accurately predict soil hydraulic properties. Results are presented which compare PTF-predicted soil hydraulic properties with these measured by the instantaneous profile drainage method. Results indicate that PTFs developed in the USA and Europe do not reliably predict the hydraulic properties of the tested Tanzanian soils. The factors responsible for this and the techniques currently being considered for adapting PTFs for use in Tanzania are discussed.
Young, M.D.B., Gowing, J.W., Hatibu, N., Mahoo, H.F., and Payton, R.W. 1999. Assessment and development of pedotransfer functions for semi-arid sub-Saharan Africa. Physics and Chemistry of the Earth, Part B: Hydrology, Oceans and Atmosphere, 24(7): 845-84 [doi:10.1016/S1464-1909(99)00091-X]