In several decades, understanding and predicting the flood discharge at mountain and ungaged region have been of great concern to the hydrologists an water resources engineers n real fields. Even f Several methodologies and approaches relating geomorphological aspects of those basins have been developed and applied to solve that questions, it is still in the stage of progress in this field due to its difficulties obtaining appropriate geomorphological information and systemizing the geomorphological approaches to traditional approaches. Moreover, the flash flood prediction and warning system at the ungaged regions have been interested in the hydrological fields recently because of its high frequent occurrence and serious damage features caused by climate change ans land use practice over the world. The flash flood problems have been known as one of challengeable topics, otherwise the related researches may not be satisfied until now. In this study, we developed two model system which can consider both the flood hydrograph analysis based on geomorpho-hydrological theory called Open Source GIS-based Geomorpho-hydrological Watershed Modeling System(OSG²WMS) and can be applicable to the flash flood warning scheme called Flash Flood Prediction model in Ungaged Basins(F²PUB). In addition to adapting GCUH process in G² WMS, we developed the modified geomorpho-hydrological unit hydrograph method called Korea-GCUH(K-GCUH) which contained the watershed and river characteristics of own Korean mountain regions and can be applied simply with basic river characteristics without complex geophysical analysis by Open Source GIS.