his research is the first study identifying that a reservoir rule curve can be decomposed into four segments, namely, 1) a descending segment, 2) an escalating segment, 3) transition segment I (the horizontal transitioning segment from descending to escalating segment), and 4) transition segment II (the horizontal transitioning segment from escalating to descending segment). Simulation modeling, serving as an effective tool, identifies four consecutive segments. This study proposes to use critical inflow to better position the reservoir rule curve. We further apply this synthetic critical inflow approach to the case of Feitsui Reservoir and yield results that may lead to . In this research, extensive investigations also render improvements on the synthetic critical inflow approach, which are believed to contribute to a more reliable reservoir rule curve.