| The Aspinall Unit is comprised of three reservoirs that lie on the western slope of Rocky Mountains and regulate approximately 50% of the Gunnison River Basin drainage. Since its completion in 1977, the Unit's primary objectives have been generation of hydropower, storage for consumptive use, flood prevention, and recreation. Currently, an Environmental Impact Statement (EIS) is being prepared to benefit endangered fish species found in the Gunnison River, focusing on habitat management by prescribing beneficial flows. Thus, the implication of this additional demand/objective is of importance to water managers.;Southwestern water management and planning are increasingly discussed topics, given the recent, unprecedented drought (1999-2004). While this period marked the worst drought on record for the Colorado River Basin, paleo reconstructed flows dating back to the 1500's suggest that such events are not uncommon. As a result, when assessing the impact of the recommended fish flows (RFF) on pre-existing objectives, it is important to consider a wide range of hydrologies that include extended periods of drought and surplus.;This work aims to develop synthetic hydrologies that can be used to assess the implications of meeting the RFF on current operations of the Aspinall Unit through the following steps. Stochastic flow sequence generation techniques based on observed data only are first investigated, followed by approaches to incorporate paleo data. The selected methods are then employed to generate synthetic traces which are eventually used as inputs to a Decision Support System (DSS) model of the Gunnison Basin. In order to be used as such, these traces are disaggregated from an annual single site value to intervening flows throughout the basin at a monthly timestep. Last, a DSS model is developed and employed to demonstrate the usefulness of the stochastic flow sequences. |
