The hydrologic model FESHM was introduced and its applicability was investigated in an attempt to analyze the rainfall-runoff relationships of urban small watersheds and to hereafter predict the environmental changes. Basic data on rainfall, water level, geomorphological characterisitics and land use were obtained from Yeonwha stream watershed located in Chonju-si Dukjin-dong. WL-5 for simulation of subshed WS#1(136.7 ha) with urban district and WL-1 for total watershed WS#5 (278.78 ha) were selected as gaging points. The main results gained through applications were summarized as follows. 1. Direct runoff ratio caalculated from a simple separation method for WS#5 WS#1 was 20~39%, 38~62%, respectively. 2. Simulations for the runoff estimation were carried out for each watershed using 5 rainfall events, the simulation errors had the range of 2~30%, 0~63% and 0~120 minutes for the runoff volume, peak flow and peak time, respectively. 3. The effect of landuse change by urbanization was tested to WS#1, runoff volume before development was estimated as from tenth to twentieth against after development.