SPDSS_Task1_Research-ID-StudyPeriod

• Title: SPDSS Task 1 - Research and Identify Appropriate Study Period
• Description: The objective of this task was to verify or refine the recommended study period as follows: 1. Review the availability and reliability of digitized data required for the development of DSS components; 2. Determine that the period includes wet, dry, and average periods; represents the long-term average hydrology of the basin; and allows for cost-effective modeling efforts; 3. Document study periods used in other modeling efforts in the South Platte Basin.
• Decision Support - Doc Type: Task Memorandum
• Date: 10/26/2003
• DSS Category: Surface Water
• DSS: South Platte
• Basin: South Platte
• Contract/PO #: C153954
• Grant Type: Non-Reimbursable
• Bill Number: SB01-157, HB02-1152, SB03-110, HB04-1221, SB05-084, HB06-1313, SB07-122
• Prepared By: Leonard Rice Engineering

Land Use Data
An assessment of available land use data in the South Platte, North Platte, and Laramie
River basins was performed in the SPDSS FS. The assessment of land use data in
SPDSS FS found that numerous data sources for current and historic land use are
available. Comprehensive maps of irrigation structures, canals, and ditches are being
developed under SPDSS data collection tasks. The 2001 irrigation season will be used to
represent current irrigated acreage, and coverages will be developed for several historic
periods. Agricultural statistics will be used to estimate irrigated acreage between historic
coverages and from 2001 through the most current year of available data. This data is
expected to be adequate from 1950 to present.
Approach and Results -Verify Hydrology
Streamflow Considerations
The study period used for water resources planning purposes should reflect the long-term
variations in hydrology for the basins and their major tributaries and including wet, dry,
and average periods. To verify that the SPDSS FS selected study period is a true
representation of temporal and spatial conditions, seven indicator streamgage stations
were selected and evaluated for the available period of record through calendar year
2002. Data from each of the streamgage stations were compared to one another and to
the Palmer Drought Severity Index (PDSI), an indicator of climatic conditions, to confirm
accurate representation of conditions within the selected study period.
The seven USGS or DWR Streamflow indicator gages selected for this process are
presented in Table 2. The locations of the selected indicator stations within the basin are
presented on Figure 1. Selection of an indicator gage was based on the following criteria:
1. Location such that the analysis included complete spatial coverage of the basins
and subbasins;
2. Long-term period of available records, as determined and documented in Table
B-1 of the SPDSS FS;
3. Completeness of records, as determined and documented in Table B-1 of the
SPDSS FS; and
4. Minimum upstream influence due to storage, imports, or major diversions.
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