Humboldt State University



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dc.contributor.advisor Van Kirk, Robert en Peterson, Kimberly en 2011-08-31T19:23:16Z en 2011-08-31T19:23:16Z en 2011-08 en
dc.identifier.uri en
dc.description Thesis (M.S.)--Humboldt State University, Environmental Systems: Mathematical Modeling, 2011 en
dc.description.abstract Watersheds throughout the western U.S. are experiencing changes to traditional irrigation practices and land use, resulting in changes to surface and groundwater hydrology. Teton Valley, in eastern Idaho and western Wyoming, is typical of western alluvial-fill valleys bounded by mountain ranges, in this case the Teton Range to the east, the Big Hole Mountains to the west, and the Snake River Range to the south. The primary water supply is snowmelt from the Teton Range, which flows to the Teton River in six major tributaries. In the late 19th century, homesteaders began diverting water from these tributaries for irrigated agriculture, which has been the dominant land use for the last century. Prior to the 1970s, conveyance occurred in earthen canals, and application occurred via flooding and other direct methods. In the late 20th century, most surface application was converted to sprinkler application, although most conveyance still occurs in the earthen canals. I developed an analytical model to investigate surface flows in the tributaries, as well as groundwater recharge, under five water management scenarios: the natural system (no irrigation), historical flood irrigation, actual 1979-2008 irrigation practices, 90% of irrigated land using sprinkler application (current condition), and future potential replacement of earthen canals with pipelines. I found that surface flow through the tributaries was highest under the natural scenario, at 73% of total inflow, and lowest under the flood irrigation scenario at 46%. Under the three irrigation scenarios that use canal conveyance, 46% to 49% of the water diverted was recharged to the shallow aquifer. Irrigation efficiencies for these scenarios averaged 45% to 48%. Irrigation greatly increased groundwater recharge compared to the natural state, altering the hydrologic regime of a system naturally dominated by surface runoff from snowmelt. Replacing the canal system with pipelines could shift the hydrologic regime closer to the natural state and increase the amount of water available for direct crop use by 80% but decrease groundwater recharge by about 45%. Regardless whether diverted water is used for agriculture or other uses associated with land development, I found that changes in the conveyance system, not in application methods, have the greatest potential effect on hydrologic regimes. Depending on the resources being considered, such as spring discharge diverted by downstream irrigators or surface flow for aquatic species, these effects could be positive or negative. en
dc.description.sponsorship U.S Department of Agriculture: Cooperative State Research, Education and Extension Service. en
dc.language.iso en_US en
dc.publisher Humboldt State University en
dc.subject Teton Valley en
dc.subject Hydrologic modeling en
dc.subject Surface water en
dc.subject Groundwater en
dc.subject Irrigation efficiency en
dc.title An analytical model of surface water/groundwater interactions in a western watershed experiencing changes to water and land use en
dc.type Masters Thesis en
dc.description.program Mathematical Modeling en

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