This Resource serves to explain and contain the methodology and results of the United States Geological Survey (USGS) Hydro-Climatic Data Network 2009 (HCDN-2009) freshwater supply key indicator analysis for my thesis. For more information, see my thesis at the USU Digital Commons.

Freshwater availability in the state can be summarized using streamflow, reservoir level, precipitation, and temperature data. Climate data for this study have a period of record greater than 30 years, preferably extending beyond 1950, and are representative of natural conditions at the county-level.

A limited number of USGS HCDN-2009 streamflow gages were found that can represent statewide conditions, are unimpaired (which produces natural hydrographs), and have measurements that extend as far back as water year 1915, making them suitable for this study. USGS HCDN-2009 streamgage data for Utah are available and downloaded as tab-separated files from the USGS National Water Information System: Web Interface. To relate HCDN-2009 streamflow measurements as water supply indicators to every five-year annual USGS irrigation withdrawal and acreage data, they were summarized at water year timesteps. Annual summations of each daily average cubic feet per second measurement over each water year (1 OCT – 30 SEP) were calculated. This gives an annual volume of streamflow at each gage for each available water year. For the known periods of time when there were measurement malfunctions, USGS models and approves data to fill these gaps.

Freshwater availability key indicators were non-parametrically separated per temporal/spatial delineation into quintiles representing Very Wet/Very High/Hot (top 20% of values), Wet/High/Hot (60-80%), Moderate/Mid-level (40-60%), Dry/Low/Cool (20-40%), to Very Dry/Very Low/Cool (bottom 20%). Each quintile bin was assigned a rank value 1-5, with ‘5’ being the value of the top quintile, in preparation for the Kendall Tau-b correlation analysis. These results, along with USGS irrigation withdrawal and acreage data, were loaded into R. State-level quintile results were matched according to USGS report year. County quintile results were matched with corresponding USGS irrigation withdrawal and acreage county-level data per report year for all other areas of interest.

See Word file for an Example PRISM Analysis, made by Alan Butler at the United States Bureau of Reclamation, which was used as a guide for this analysis.