This paper presents peak discharge numerical modeling of the Keser watershed for disaster risk mitigation and water resources management for an emergency action plan (EAP) for the Tugu dam. Several formulations for calculating peak discharge associated with the information on flood design in Indonesia are regulated in SNI 2415:2016 regarding the procedure of flood discharge calculation and design. This information on peak discharge/flood design is important and related to water structure dimensions, risk, costs, and reliability. The complexity of watershed conditions affects the hydrograph shape and volume, therefore this hydrograph performance analysis is needed to identify the best model of the current synthetic unit hydrograph (SUH). In this study, the performance of Nakayasu, Gamma 1, and Snyder synthetic unit hydrograph (SUH) will be analyzed and compared with the numerical modeling using the Hec-Ras 2D hydrodynamics model and observed data in the Keser watershed. The observed peak discharge data obtained 2.95 m3/s that occurred by precipitation unit (1 mm). From the calculation results, the peak discharge value using the Nakayasu method is 3,379 m3/s, while the Gamma 1 and Snyder methods obtained 3,276 and 3,158 m3/s. The results of the numerical model with Hec-Ras 2D v6.3 obtained a peak discharge hydrograph value of 3.019 m3/s. Thus, from the three SUH formulas and Hec-Ras calculations, the closest approach to the observed data results is the Hec-Ras 2D v6.3 with a peak discharge error of 2.36%.