The climate change-induced variability in hydrological cycles directly affects regional water resources management. For improved multiple multi-objective reservoir operation, an integrated modeling system has been developed by incorporating a global optimization system (SCE-UA) into a distributed biosphere hydrological model (WEB-DHM) coupled with the reservoir routing module. The reservoir storage change is estimated from the difference between the simulated inflows and outflows; while the reservoir water level can be defined from the updated reservoir storage by using the H-V curve. According to the reservoir water level, the new operation rule can be decided. For optimization: (1) WEB-DHM is calibrated for each dam’s inflows separately; (2) then the calibrated WEB-DHM is used to simulate inflows and outflows by assuming outflow proportional to inflow; and (3) the proportion coefficients are optimized with Shuffle Complex Evolution method (SCE-UA), to fulfill an objective function towards minimum flood risk at downstream and maximum reservoir water storage for future use. The GSMaP product offers hourly global precipitation maps in near real-time (about four hours after observation). Aiming at near real-time reservoir operation in large river basins, the integrated modeling system takes the inputs from both an operational global quantitative precipitation forecast (JMA-GPV; to achieve an optimal operation rule in the assumed lead time period) and the GSMaP product (to perform current operation with the obtained optimal rule, after correction by gauge rainfall). The newly-developed system was then applied to the Red River Basin, with an area of 160,000 km2, to test its performance for near real-time dam operation. In Vietnam, three reservoirs are located in the upstream of Hanoi city, with Hoa Binh the largest (69% of total volume). After calibration with the gauge rainfall, the inflows to three reservoirs are well simulated; the discharge and water level at Hanoi city are also well reproduced with the actual dam releases. With the corrected GSMaP rainfall (by using gauge rainfall), the inflows to reservoirs and the water level at Hanoi city can be also reasonably reproduced. The study aims at achieving an optimal operation rule in the lead time period (with the quantitative precipitation forecast) and then using it to perform current operation (with the corrected GSMaP rainfall). At Hanoi, there are relatively low flows in July, but high floods in August 2005. Results show that with the actual operation, dangerous water level in Hanoi was observed; while with the lead-time operation, the water level in Hanoi can be obviously cut down, and maximum water storage is also achieved for Hoa Binh reservoir at the end of flood season.