J. D. Quinn, P. M. Reed, M. Giuliani, A. Castelletti, J. W. Oyler, and R. E. Nicholas
Water Resources Research (6 June 2018)
Abstract Multi?reservoir systems require robust and adaptive control policies capable of managing evolving hydroclimatic variability and human demands across a wide range of time scales. This is especially true for systems with high intra?annual and interannual variability, such as monsoonal river systems that need to buffer against seasonal droughts while also managing extreme floods. Moreover, the timing, intensity, duration, and frequency of these hydrologic extremes may evolve with deeply uncertain changes in socioeconomic and climatic pressures. This study contributes an innovative method for exploring how possible changes in the timing and magnitude of the monsoonal cycle impact the robustness of reservoir operating policies designed assuming stationary hydrologic and socioeconomic conditions. We illustrate this analysis on the Red River basin in Vietnam, where reservoirs and dams serve as important sources of hydropower production, multi?sectoral water supply, and flood protection for the capital city of Hanoi. Applying our scenario discovery approach, we find that stationary reservoir operations provide robust hydropower performance in the Red River, but that increased mean streamflow, amplification of the within?year monsoonal cycle, and increased interannual variability all threaten their ability to manage flood risk. Additionally, increased agricultural water demands can only be tolerated if they are accompanied by greater mean flow, exacerbating food?flood tradeoffs in the basin. These findings highlight the importance of exploring the impacts of a wide range of deeply uncertain socioeconomic and hydrologic factors when evaluating system robustness in monsoonal river basins, considering in particular both lower order moments of annual streamflow and intra?annual monsoonal behavior.