As for the dry streams in Jeju island, there are virtually no researches on the analysis of 2 dimensional flow of stream, and the 1 analysis executed by river maintenance basic plan was the only on in practice. In addition, dry streams in island areas tend to show the characteristics of mountain stream and abrupt flood runoff, so they require field observation suitable for flood runoff characteristics, establishment of data and analysis of flow utilizing it.
In this study, the water surface elevation and water velocity upon flood runoff were observed on Han stream a dry stream of Jeju island, and after the water surface elevation and water velocity at the cross-section used at establishment of river maintenance basic plan and those at the cross-section of actual terrain were compared with the use of HEC-RAS and the HEC-GeoRAS based GIS, the 1 dimensional analysis model, the lateral hydraulic characteristics and curved channel of stream were analyzed by applying SMS-RMA2 a 2 dimensional model.
The results of analysis using HEC-RAS model and HEC-GeoRAS model indicated that the distribution ranges of water surface elevation and water velocity were similar, but the water surface elevation by section showed difference of 0.7～2.18 EL.m and 0.88～1.16 EL.m respectively, and water velocity also showed differences of maximum 1.58m/sec and 2.67m/sec. SMS-RMA2 analysis was done with the sphere of Muifa the typhoon as boundary condition, and as a result, water velocity distribution was found to be 1.440 through 3.626 m/sec, and the difference of lateral water velocity in No. 53 and 61 the curved channel of stream was analyzed to be 1.222 and 1.181 m/sec.
In conclusion it is anticipated that the flow analysis of 2 dimension model of stream can reflect the hydraulic characteristics by the stream curved channel or width and shape, and can be applied effectively in the establishment of river maintenance basic plan or management and designing of stream.