... introduced above, Gia Vong – a river basin in Quang Tri was taken as a case study (Figure 3.1). The basin has an area of about 275 km2, a perimeter of 111.9 km and an average rainfall of 2500 ... much easier and quick to find the best overall parameters than the traditional trial -and- error method. Keywords: Rainfall-runoff, event data, auto- calibration, trial -and- error, searching space. ... peak flow of observation is much higher than that of simulation. This can be attributed to both of the large interval of rainfall data and the changes of basin characteristics. The calibrated...