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Execution of StateMod in check mode also creates an initial output request file (rg.xou). This file <br />may be hand edited to request only select data be extracted and available for reporting. During <br />Phase lb efforts, all output were requested and reviewed during model calibration. <br />Results -Historical Simulation <br />The Phase lb model includes model execution in simulation mode using historical diversions as <br />demands. In addition, historical end of month (EOM) contents at modeled reservoirs are used as <br />EOM targets. Model representation of the Rio Grande Compact, which is administered by <br />Division 3 through a complex routine involving forecasted inflows, has been simplified by for <br />Phase 1 analysis by representing the Compact as a diversion demand with zero consumption at <br />the lowest point on the Rio Grande: the demand for this "diversion point" is simply the historical <br />flows at the CO - NM state line; the water right is the most senior in the basin; and the returns <br />from this diversion are modeled as occurring immediately. <br />As described above, calibration efforts during the historical simulation runs focused on three <br />areas: comparison of historical observations to modeled 1) stream flows at gage locations; 2) <br />diversions; and 3) reservoir EOM contents. Each of these comparisons are discussed below. The <br />referenced Attachments illustrate these comparisons graphically. <br />Modeled Stream Flows <br />Attachment 1 illustrates comparisons of modeled stream flows to historical observations at <br />several key stream gages. As shown, these comparisons are very favorable and demonstrate less <br />than 1% deviation in the model results from historical gaged flows. Comparisons at individual <br />gages represented in the model are shown in Table 3. <br />The results shown in Table 3 demonstrate a considerable improvement in model calibration over <br />Phase la model results. Most notable are stream comparisons at gages located on Trinchera Creek <br />below Smith Reservoir (ID 8243500) and Conejos River near LaSauces (ID 8249000). <br />Calibration of stream flows at the Trinchera Creek and Conejos River gages improved by roughly <br />10 percent and 8 percent, respectively. By contrast, calibration at the stream flow gage on <br />Culebra Creek At San Luis (ID 8250000) was less favorable using the Phase lb model. This is <br />likely due to problems with assignment of return flow locations of aggregated structures, but may <br />also be a result of the data filling techniques used for structures on Culebra Creek. <br />Modeled Diversions <br />The historical simulation model runs, shortages are defined as the difference between the amount <br />of water historically diverted by ditches and the amount of water delivered in the simulation. The <br />amount of water delivered will never be greater than the amount diverted, but can be less. The <br />reasons for under-delivery, or shortage, can include insufficient water rights (legal supply), <br />insufficient hydrology (physical supply) and inaccurate data (streamflows, diversions, efficiency, <br />return flows, etc.). In most instances, modeled shortages are a result of insufficient wet water, <br />although historical diversions under "free-river" conditions can also create modeled shortages. <br />The question of sufficient water rights can be addressed in StateMod through the addition of "free <br />water rights" -junior priorities which allow ditches to divert under very higher river flows. <br />Insufficient supply is addressed by re-examining hydrology input files, re-configuring the model <br />network, and/or adjusting operating rules to make additional supply available. Calibration of the <br />C:Acdss\Task7-8.doc Phase lb Model March 17, 2000 -Page 6 of 10 <br />