|
<br />"
<br />
<br />
<br />
<br />
<br />Acknowledgments
<br />
<br />The author is grateful to the various canal companies in the study area
<br />who contributed a portion of their direct-flow water right to provide the
<br />water necessary for the controlled-test release of September 22, 1975. The
<br />Colorado Division of Water Resources, Office of the Division Engineer,
<br />cooperated in the planning of the controlled-test release and provided
<br />personnel who assisted with the collection of streamflow data during the
<br />release. Many helpful suggestions regarding the study were made by Charles
<br />L. Thomson, Manager of the Southeastern Colorado Water Conservancy District.
<br />
<br />HYDROLOGIC MODEL FOR ROUTING RESERVOIR RELEASES
<br />
<br />Historically, streamflow data for the Arkansas River have been collected
<br />at a minimum of 13 locations along the study reach. Eight continuous-record
<br />gaging stations on the main stem and numerous rating-flume stations on
<br />diversion ditches are currently in operation.
<br />
<br />Available streamflow data are inadequate for determining transit losses
<br />for releases from Pueblo ~eservoir. Prior to the beginning of storage in
<br />Pueblo Reservoir in 1974, releases were made from reservoirs located about
<br />150 river miles upstream from Pueblo and the release volumes were difficult
<br />to distinguish from the natural flow downstream from Pueblo. Moreover,
<br />releases usually do not provide adequate data because of changing hydrologic
<br />conditions in the study reach. Consequently, transit losses are best
<br />investigated by theoretical methods using a hydrologic model.
<br />
<br />A hydrologic model is a mathematical simulation of the response of a
<br />hydrologic system to various stresses placed on it. An example of such a
<br />stress is the passage of a reservoir release through a stream system. By
<br />employing a digital computer, the numerous calculations necessary to describe
<br />the hydrologic response of the system can be rapidly performed. Thus, the
<br />computer model, following calibration with observed data, can be used to
<br />simulate the effects of various hydrologic conditions.
<br />
<br />Modification of Original Computer Model
<br />
<br />A computer model that simulates the hydrologic response of a river reach
<br />to reservoir releases passing through it was developed and tested using data
<br />for the Arkansas River upstream from the Colorado Canal (Luckey and Living-
<br />ston, 1975). The assumption was made that this model could also simulate
<br />stream hydrographs of reservoir releases in the study reach from Pueblo
<br />Reservoir to John Martin Reservoir. To adequately define the hydrologic
<br />system and to improve model response, this reach was subdivided into six
<br />sub reaches as shown on figure 1. The name and river-mile location of the
<br />streamflow-gaging stations and diversion canals shown on figure I are listed
<br />in table 1. In order to adapt the original computer model for the somewhat
<br />different hydrologic response of the study reach to reservoir releases,
<br />several modifications were made, as described in the following sections.
<br />
<br />4
<br />
<br />. _~ ." .; - : . .;. ~ :-" c-~,,,,~;;,,,,,.,..,.,.,,,~---,,;', -:- ,:--.' -~, ";,' .
<br />
<br />. -',;-~,:;,,:-:>::,,:,~;:,;<;:,,;~,-:-':-:,:....,:..'-;:'
<br />. ._,.'..,...........,..
<br />
|