Agricultural land and water use has modified natural flow regimes in the western US. Understanding the effect of agricultural water use on streamflow is critical to effective water management and is often limited by the available data record. This investigation evaluates agricultural water use and streamflow in the Smith River watershed (SRW), a semi-arid agricultural watershed located on the eastern slope of the northern Rocky Mountains in west-central Montana. Questions motivating this study include: (1) Has agricultural water use modified streamflow on the Smith River? (2) What aspect of agricultural activity in the Smith River watershed is having the greatest effect on streamflow? (3) What hydrologic properties of the watershed determine streamflow sensitivity to agricultural land and water use? Three approaches are employed to address these questions: (1) construction of an annual water budget, (2) comparison of streamflow to current and historic agricultural water use intensity, and (3) simulation of watershed processes using a precipitation-runoff model. Based on the mean-annual water budget estimate of the SRW, 12 percent of mean-annual streamflow in the Smith River is consumed by irrigation water use. The hydrologic effects of increased irrigated area detected with linear regression analyses of streamflow and agricultural water use include decreased seasonal flows in April, May, and June; increased late-summer flows in August and September; and increased low-flow volumes. Numerical hydrologic model simulations demonstrate that dominant precipitation-runoff processes in the watershed cannot be adequately represented without including agricultural water use.
| Identifer | oai:union.ndltd.org:MONTANA/oai:etd.lib.umt.edu:etd-03142013-102142 |
| Date | 23 May 2013 |
| Creators | Stanley, Andrea |
| Contributors | Andrew Wilcox, Marco Maneta, Anna Klene, Kyle Blasch |
| Publisher | The University of Montana |
| Source Sets | University of Montana Missoula |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.umt.edu/theses/available/etd-03142013-102142/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Montana or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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