In recent, abnormal phenomena in nature occurs due to climate change, which result in increase of flood frequency and rainfall intensity by change of meteorologic and hydrological factors. Especially, flood inundation in urban watershed frequently happens on casualties expected and property damage. Scientific and technological adaptation are acutely needed for unexpected damage in nature, and that, it is considerably important to develop proper model of hydrological forecasting over the short periods and to build a real-time watershed monitoring system. One of important things for solving a variety of problems is to connect real-time watershed monitoring system with short term hydrologic forecasting model. In this research, Suyoung stream in Busan was determined as a study area. After that, real-time watershed monitoring system at ten minute interval has been established for flood warning and forecast in the field. The data from this system was applied to short-term hydrologic forecasting model based on the artificial neural network. When flood happens in urban, input data of forecasting model on each rainfall event was used. In conclusion, after establishing the model being possible to forecast water level from 10 to 60 minutes at 10 minute interval, as a result of simulating the model, the model performances are considerably good as RMSE 0.02~0.6 and more than 0.9. It makes possible effectively to manage the watershed in urban.