UPPER KLAMATH BASIN GROUND-WATER STUDY

 
Traditional use of numerical models in solving management problems has involved the simulation of a few plausible management scenarios among an infinite number of possible options. Resource managers then must then compare the simulated results of this limited set of scenarios, and chose the one with the least negative impacts. This traditional usage does not necessarily identify the optimal scenario. In addition, the traditional usage may have emphasized the effects of water use on one valued resource, whereas commonly objectives involve the need to evaluate effects on several valued resources. Methods are now available by which ground-water models can be used with optimization methods to identify management schemes that meet multiple resource allocation objectives under various hydrologic and economic constraints. Using these methods, an infinite number of management scenarios are effectively evaluated rather than the few that could be evaluated using traditional methods.

 
The coupling of ground-water models with optimization procedures requires two mathematical models: one, a ground-water flow model, and the other, a model containing economic or hydraulic evaluations of flow-model outcomes run under a set of constraints. The coupled models are designed to reach optimal solutions to stated objectives which can be couched in economic terms (e.g. minimize the cost of water), or hydraulic terms (e.g. maximize the pumping available to supplement streamflow) while honoring constraints (e.g. ground-water discharge to the lake is not reduced by more than 10 percent). Recent developments which allow for the optimization of several objectives at the same time have been very useful in other parts of the United States for dealing with conjunctive-use management of SW/GW systems- systems where management schemes need to address conflicting objectives.
 

The cooperating agencies will be consulted to define potential management objectives in the basin as well as the limitations (constraints) on development of water resources. These objectives and constraints will be expressed in mathematical form and used to test the coupled optimization model. From this work, a set of optimal management solutions will be identified for consideration by water-resource management agencies in the basin as part of their planning and policy making missions.

 

The management solutions identified using the optimization model will be compared with results of management scenarios evaluated in phase III. For a valid comparison, the same management objectives underlying the scenarios defined for simulation in phase III, should be used in the optimization model with appropriate constraints. Examples of comparisons that might be made are: 1) locations and pumping rates of wells determined with the optimization model versus those defined in the scenario, 2) simulated changes in spring and stream flow using the optimal solution versus the scenario, or 3) simulated changes in ground-water levels using the optimal solution versus the scenario. Such comparisons would evaluate the potential for improvement in present management schemes in addition to serving as an illustration of the utility of the optimization procedures.