Flood risk analysis and mapping of Penaranda River using geomorphological and past flood approach.

Flooding is a normal and naturally occurring phenomenon. Past experience have shown that large investments in the construction of structural flood control facilities have not always resulted in an overall reduction in flood losses and destruction. Moreover, the effectiveness of flood mitigation by flood control facilities is limited and takes considerable time to materialize. Even after the completion of a flood control project, floods exceeding the design value of the structure or project can still cause considerable damage. Considering the limited effectiveness of conventional structural measures, it is evident that optimum benefit can only be obtained when both structural and non-structural measures are combined to mitigate and decrease recurring losses due to flood. Flood risk mapping is a good example of a non-structural, flood mitigating measure. Other forms of flood loss prevention include statistical techniques and monitoring the progress of a typhoon. Flood Risk Mapping is a type of flood loss prevention management system, which uses mapping to estimate the impact of extent of a potential flood on an area. It is meant to satisfy the following type of questions: Given the occurrence of a flood of a specific magnitude in this locality, what will the extent of damage be like? What areas will be under water? Flood risk mapping can be based on known, recorded events or on prehistoric events. In the study, a pilot area was selected which is Peñaranda River and two methods are used and applied. Geomorphological Approach which is based on the susceptibility of each landforms in flooding and Past Flood Approach which is based on past records of flooding and rainfall