The research on flood design in the river catchment area of Code using synthetic unit hydrograph Gama I is software JanaFlow_Code_14. Flood discharge analysis JanaFlow_Code_14 (QJF) using measured rain data and JanaFlow_Code_14 software. The river debit recorded in the Automatic Water Level Recorder (AWLR) is actual discharge (Qaktual). The result of Qaktual and QJF calculation there is difference of result which is average of underestimed because average of QJF is lower than Qaktual. The biggest difference between Qaktual and QJF occurs on April 22, 2015 with the discharge difference is -16.73 m3/s, and the average difference between Qaktual and QJF is -1.98 m3/s. Factors that influence the results of different discharge calculations are the rain distribution patterns, the river catchment area characteristics, and the use of synthetic unit hydrograph Gama I in JanaFlow_Code_14 calculations.