ABSTRACT
The increase in number and magnitude of landslides in Dessie town has led to examine the relationship between slope instability and seasonal rainfall in the area. The variation in moisture content of soil materials at different periods, the rate of daily precipitation, the amount of cumulative precipitation recorded up to the date of analysis, and the mean annual rainfall were variables used to derive a simple equation which is supposed to be useful to determine the likelihood of landsiding. The increase in pore water pressure at potential slip planes due to an increase in rainfall has also been assessed, although owing to irregularity in nature of subsurface materials, groundwater flow and distribution was found to be complex. Stability analysis which took into account some external factors and back analysis techniques assured the sensitivity of materials of the site for an anomalous increase in the level of subsurface water.
