1. Centre IRD d'île de France; 32, avenue Henri Varagnat 93143 Bondy Cedex France
2. School of Bioresources Eng. and Environ. Hydrology; Rabie Sanders Bldg., Univ. of Kwazulu-Natal Scootsville 3209 South Africa
3. Soil Survey and Land Classification Center; National Agric. and Forestry Research Institute; Vientiane Laos