Abstract

The aim of this study was to carry out a detailed soil survey to determine soil types and their influence on landslide occurrence in Bududa District in eastern Uganda. Four transects were chosen following zones with and without landsides. Soil profile description and classification was done using FAO methods. Infiltration rates were measured as described by Landon in 1991. Results show that the soil types are those conditioned by topography and tropical climate namely Nitisols, Cambisols, Lixisols, Ferralsols, Leptosols, Gleysols, and Acrisols. Soil type was not significant in landslide occurrences. However soil texture in the horizons was significant in some of the landslides especially in the western zone. One factor that was common to all soils sampled in the western side was the same soil texture of clay down the profile and the subsequent absence of landslides in the surroundings of the profiles. In the eastern zone soil profile horizon is significant in some of the landslides but in the shallow landslides the slope and the shallow depth which creates a discontinuity between the saprolite and the rock causing water stagnation is the main influence. The clay minerals present are high plasticity clays; Kaolinite and Illite. The infiltration rate of the top soils is generally rapid in the top soils, allowing fast flow of water into the deeper horizons.

Key words: Soil types, soil horizon, infiltration, landslides, Bududa district.