The ability to determine the responses to changes in external or controlling factors in the form of cause-and-effect relations is the corner stone for management of a lake system. It is well recognized that understanding of the mean circulation of a lake is important for many ecological and management issues. This book is concerned with the distribution of surficial sediment and variation of water quality parameters under major influences of wind forcing and major rivers inflows in Lake Abaya, the largest Ethiopian Rift Valley Lake. Spatial and temporal variability of physical parameters are presented and the interrelationships between variables are discussed. The results were interpreted in terms of the direction and magnitude of wind forcing, nature of sediment distribution, bathymetry, and major inflow that determine possible pattern and strength of circulation. The observed spatial and temporal variability of physical variables allowed estimating general circulation pattern. Lake Responses to External Forcing will be of particular interest to researchers and professionals actively involved in lake hydrodynamics and management.