Factors Affecting United States Geological Survey Irrigation Freshwater Withdrawal Estimates In Utah: USGS HCDN-2009 Streamgages Analysis Results

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.

本资源用于阐释并收录本学位论文中针对美国地质调查局（United States Geological Survey, USGS）2009年水文气候数据网络（Hydro-Climatic Data Network 2009, HCDN-2009）淡水供给关键指标分析的方法与结果。如需获取更多信息，可通过USU Digital Commons查阅本人学位论文。
该州的淡水供给能力可通过径流、水库水位、降水与气温数据进行概括。本研究使用的气候数据记录时长超过30年，优先选取覆盖1950年之后的序列，且需代表县级尺度的自然水文气候条件。
本研究筛选出少量符合要求的USGS HCDN-2009径流监测站：其数据可代表全州水文条件、未受人类活动干扰（可生成自然水文过程线）且监测序列最早可追溯至1915年水文年，完全适配本研究需求。犹他州的USGS HCDN-2009径流监测数据可从美国地质调查局国家水信息系统（USGS National Water Information System: Web Interface）获取，以制表符分隔文件格式下载。为将作为淡水供给指标的HCDN-2009径流监测数据，与每五年一期的美国地质调查局灌溉取水量及灌溉面积数据进行关联，本研究将径流数据按水文年时间步长进行汇总：计算每个水文年（10月1日至9月30日）内逐日平均流量（立方英尺/秒）的年度总和，由此得到各监测站在对应可用水文年的年径流总量。对于已知的监测故障时段，美国地质调查局会通过建模并经审核的数据填补这些缺失值。
淡水供给关键指标将通过非参数方法，按时间/空间划分维度划分为五分位组，分别对应：极湿/极高/高温（数值前20%）、偏湿/偏高/偏热（60%-80%分位）、中等/中值水平（40%-60%分位）、偏干/偏低/偏凉（20%-40%分位）以及极干/极低/极凉（数值后20%）。为开展肯德尔tau-b相关分析，为每个五分位组赋予1至5的秩值，其中‘5’代表最高五分位组。将上述结果与美国地质调查局灌溉取水量及灌溉面积数据一并导入R语言软件。全州尺度的五分位结果将按照美国地质调查局报告年份进行匹配；县级尺度的五分位结果则按报告年份，与对应研究区域的县级美国地质调查局灌溉取水量及灌溉面积数据进行匹配。
可参考由美国垦务局（United States Bureau of Reclamation）艾伦·巴特勒（Alan Butler）制作的PRISM气候数据分析示例Word文档，本研究的分析流程即以该示例为参考指南。