Complex Hydro-policy Modeling with RiverWare for Collaborative Multi-objective River System and Hydropower Planning and Operations

Decision making for operating and planning in multi-objective river basins requires a modeling tool with detailed representation of both physical processes and operating policy. RiverWare is a hydro-policy model that combines an extensive library of physical process algorithms with fully customizable policy to drive the model solution. RiverWare offers two mathematical approaches for modeling policy, both resolving conflicting objectives via priorities. In Rulebased Simulation, prioritized rules set values of decision variables given logic that considers the current state of the system, then physical process algorithms simulate the effects throughout the system. Higher priority rules dominate the effects of lower priority rules. RiverWare’s Optimization uses a preemptive linear goal programming solution. At each priority a policy objective is formulated as either a traditional objective function or a set of soft constraints that get converted to an objective function to minimize the violations. After optimizing at each priority, the objective function value is locked-in before moving to the next priority, reducing the feasible solution space. Lower priority objectives cannot degrade higher priority objectives. Both solution approaches utilize the RiverWare Policy Language, a rich scripted language with a syntax-directed graphical editor that allows fully customized, complex policies. Two example applications illustrate how these two approaches are used effectively to make decisions with different logical structures of the policies that drive their operations. Bonneville Power Administration uses RiverWare to optimize 19 GW of hydropower capacity while meeting a range of high-profile environmental obligations on the Columbia River system in the northwestern United States. In the drought-plagued Colorado River Basin in southwestern United States, RiverWare’s Rulebased Simulation is used for collaborative planning and operations, and has been an essential modeling platform for negotiating many water-sharing agreements among the seven basin states and Mexico, with intense participation of a multitude of stakeholders.