Abstract:
Flooding is one of the major natural disasters all around the globe that cause a high
damage to the infrastructure, agriculture and human lives. In recent years the intensity
and frequency of floods have been increasing arguably as a result of climate change.
Such damages can be minimized if reliable information about flooding events is readily
available for relevant authorities and land owners. Hydrodynamic flood models play an
important role in producing inundation maps which then can be used in flood risk
assessment and management. In developed countries, there can be seen many
applications of flood modelling where as in Sri Lanka flood modelling is still a
developing area. Advanced determining methods of flooding scenarios consist of
construction of a physically based 2D hydrodynamic model. The model is then
calibrated and validated using historical flood data. In the process of preparation of the
flood model, a reliable Rainfall Runoff model should be developed. The accuracy of the
flood model largely depends on the accuracy of the Rainfall Runoff model since the
Rainfall Runoff model addresses the catchment characteristics of the area.Gin river is
one of the main sources of water supply in southern region of Sri Lanka having a
catchment area of 932 km2. The upper basin area of the Gin river had experienced
severe floods in years 2003 and 2008 where in 2003 flood 17 lives were lost. With the
availability of a reliable flood model, better planning and managing can be done to
minimize the damages from floods. This paper presents the development of the validated
Rainfall Runoff model which is a prerequisite to the development of 2D flood model. A
Sacramento model integrated with Muskingum routing method is used in development
of the Rainfall Runoff model.
