SWSI Implementation Update with Attachments

Home Browse Search

DRAFT SWSI Methodology for Estimating Available Water Supply The Colorado, Gunnison, Yampa, White, and San Juan/Dolores Basins have existing ? CDSS datasets and models. For these basins, the StateMod water resources planning model and supporting datasets will be used to estimate physically and legally available water. The datasets for the Rio Grande are still being revised, but it is expected that they will be available to use as part of this task. For those basins without developed CDSS datasets-Arkansas, South Platte, and North Platte-information for physically and legally available flows will be gathered from existing sources and studies. While the physical availability of water can be evaluated using historic observations, the legal availability of water is only a portion of the observed flows and will in general be determined by using some type of model or analysis tool that accounts for the Prior Appropriation Doctrine and operational policies in effect in the basin. In those basins with CDSS datasets, the StateMod data will be used to estimate available flows. In addition, the CDSS datasets contain naturalized flows, or baseflows, for the basin. River flows could be evaluated at selected locations with the appropriate water supply summary. These locations will be established as the project evolves. It is anticipated that up to five key locations will be identified within each basin, based upon such factors as hydrologic delineations, basin administration practices, location • of future water demands, and superior conditional decrees. Methodology for Basins with Existing CDSS Datasets CDSS datasets and StateMod models have been developed for the Colorado, Gunnison, Yampa, White, San Juan/Dolores, and Rio Grande River Basins. The StateMod model represents the hydrological, structural, and administrative feature of the river basin. Model datasets contain all necessary time-series data and information to simulate the allocation and distribution of water according to the Prior Appropriation Doctrine. Direct flow, instream flow, storage and operational rights, and permitted well rights are simulated as a function of water availability, priority, decreed amount, demand, structure capacity, and location. The current CDSS modeling system focuses on datasets in the following configurations: Historical Dataset ("H"). Simulate historical events. This case is used to estimate naturalized flows and to calibrate physical parameters of the models (e.g., by adjusting delay tables for diversion return flows and verifying the estimated streamflow time series). The historical diversions are used as demands. For reservoirs in the historical dataset, the end of month content is set to zero for the time before the reservoir existed, effectively eliminating the reservoir from the model during that period. Water rights can also be turned on and off during the ? modeling period. The results from this dataset are mainly used to validate and 2 S:\TASK 8 8 9 SUPPLY AND DEMAND\SWSIWATERSUPPLVMETHODOLOGY_1-13-04.DOC