The book contains the impact of tsunami in the Weligama area in Sri Lanka which happened on 26 December 2004 due to the generation of the earthquake off the west coast of Sumetra. This book is an attempt to reduce this natural phenomenon through the understanding of the area at risk incorporating with the land use details. The numerical simulation of tsunami inundation was carried out using ComMIT model with the major input parameters of earthquake source parameters, topography and bathymetry data. The December 2004 Sumatra Earthquake source parameters were used for generation, propagation, and coastal amplification of the tsunami waves and finally the inundation extent and water level was obtained to prepare large scale action maps on tsunami inundation to protect the coastal communities. The GIS tool has been used to incorporate the tsunami inundation depth to identify the hazard and the reliability of model results was compared with the field data and a high resolution QuickBird images. The analysis allows determining the level of vulnerably associated with the coastal belt. This book also discourses for disaster management activities.