The flash flood at Sitobondo (East Java) on February 9, 2008 had caused many victims and loss of material. Discharge magnitude of this flood cannot determine the extent and return period of flood because water level in the area was not observed. Therefore, in 2007, the Research Center for water Resources had developed a formula to estimate design flood in un-gauged basin by carrying out research on regional watershed characteristics for estimation of design flood in un-gauged catchment...