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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />MODEL REASONABLENESS AND REFINEMENT <br /> <br />Detailed model verification and reasonableness evaluations are presented in Section <br />V for individual basins, comparative Colorado Unit Hydrograph Procedure (CUHP) <br />modeling for representative tributaries, for regional relations developed by CWCB, <br />and other unit discharge (ets/acre) comparison. It appears the results are <br />reasonable for the tributary watersheds. <br /> <br />Comparison with statistical analysis of the Eldorado Gage and the UDSWMM <br />deterministic model reveals an apparent disparity where the statistical data is much <br />lower. We believe this is explained largely by the flood storage which is taking <br />place in Gross Reservoir and the numerous storages upstream of the Moffatt rail <br />line. To a lesser degree, refining the South Boulder Creek channel routing <br />parameters based on representative field survey sections might reduce (or increase) <br />the UDSWMM model result. <br /> <br />We know the storage exists upstream of the rail line on South Draw, the major <br />tributary above the Eldorado gage. Other storages can be observed on the <br />topographic maps, but we have not documented their characteristic or effect. <br />Further, the Denver operational data illustrates significant storage of flood type <br />events, for example 1969. <br /> <br />Mountain Modelinq <br />.f.'^~ <br />Ti,t" dVI c,~ven ~ regulations wbicb only allow recognition of storage above fixed <br />spillways of water supply storage operated by governm~ntal entities, and prOhibit( <br />recognition of storages such as those formed by rail lin~the,ie are only two <br />choice~~~'1JI'\.~c ~:f,"_P~~jQ> GcbS~ '~S-I'rv"". 1..fA.b..~.....,-b/ <br /> <br />1.a) <br /> <br />Make institutional arrangements to either preserve the operational practices <br />of Denver Water which result in flood storage, or explore other institutional <br />arrangements and improvements which would enhance storage at GrosS:- lUJ'IV'-v>,\-- <br />Investigate characteristics, needed physical improvement, and make <br />institutional arrangement with the BNRR to preserve or enhance 'this st~rage. . . <br />b (. .kj ,t.'; 1'Vv. <br />~""~""~( <br /> <br />Don't rely on the statistical data at the Eldorado'if'-li't represents the result of <br />inadvertent and unreliable storage. 1\ <br /> <br />b) <br /> <br />Or <br /> <br />2. <br /> <br />As part of either choice the stream routing in SWMM could be refined with field <br />work and further analysis, <br /> <br />1- 13 <br /> <br />