Flood Plain Modelling of Krishna Lower Basin Using Arcgis, Hec-Georas And Hec-Ras

A flood is an overflow of water that submerges land which is usually dry. Floods can also occur in rivers when the flow rate exceeds the capacity of the river channel, particularly at bends or meanders in the waterway. This results in causing damage to human and property if they are in the natural flood plains of rivers or settled on the banks of rivers. To facilitate the appropriate measures for effective flood mitigation in advance, there is a need to model the flood plain which facilitates to locate the flood plain and its extent for effective flood mitigation measures. By understanding the extent of flooding and floodwater inundation, decision makers are able to make choices about how to best allocate resources to prepare for emergencies and to generally improve the quality of life. This research presents a straightforward approach for processing output of the HEC-RAS hydraulic model, to enable two and three dimensional floodplain mapping and analysis in the ArcView geographic information system. The methodology is applied to a stretch of river Krishna from downstream of Nagarjuna Sagar project to Kummaripalem which is located on upstream of Prakasam Barrage. The flood plain maps are developed for the flows corresponding to 2, 10, 25, 50 and 100 year return periods. The resulting surface model provides a good representation of the general landscape and contains additional detail within the stream channel. Overall, the results of the research indicate that GIS is an effective environment for floodplain mapping and analysis.