A bilevel modeling framework to analyze the institutional gap between research and operation practices – Case on the Three Gorges Reservoir pre-impoundment problem

•Institutional gap (IG) is defined to quantify the deviation between centralized and hierarchical decision making.•IG results from centralized model neglecting hierarchical interaction between flood control and refill rule makers.•IG is highly related to preference setting in centralized optimizations.•With specific preference settings, Pareto optimal solutions dominate the bilevel solution but are impractical.