Contribution of Irrigation Seepage to Groundwater-Surface Water Interactions on the Eastern Snake River Plain Rob Van Kirk, HSU Department of Mathematics http://www.humboldt.edu/henrysfork/ BSU Geosciences Department, November 30, 2011
Collaborators and funders Current USDA-funded Project Brian Apple, Humboldt State University Dr. J. Mark Baker, Humboldt State University Dr. Yvonne Everett, Humboldt State University Dr. Brad Finney, Humboldt State University Lora Liegel, Humboldt State University Kimberly Peterson, Humboldt State University Dr. Steve Steinberg, Humboldt State University Dale Swenson, Fremont-Madison Irrigation District Kim Ragotzkie, Henry s Fork Foundation Amy Verbeten, Friends of the Teton River Other Collaborators Kevin Boggs, University of Idaho Dr. Gary Johnson, University of Idaho Funders National Science Foundation U.S. Department of Agriculture
Outline Study areas and hierarchy of nested spatial scales 1. Teton Valley tributary basin (400 km 2 ) 2. Henry s Fork upper part of Plain (8,000 km 2 ) 3. Upper Snake R. entire aquifer (93,000 km 2 ) Hydrogeology of Snake River Plain Statement of problem Research approach Results Ecological consequences Conclusions and recommendations
Eastern Snake River Plain and Study Basins
N 50 miles Beartooth Plateau Centennial Mts. Yellowstone Lake Great Salt Lake Bear Lake
N 50 miles Plate Motion 1 in/year Hot Spot
N 50 miles Uplift Zone Hot Spot Bow Wave Uplift Zone
Elevation (feet) Precipitation (inches) Elevation-precipitation relationship across the hotspot. N 50 miles 12,000 10,000 8,000 Old Faithful Hayden Valley Beartooth Plateau Elevation Precipitation 70 60 50 6,000 4,000 Snake R Plain Lamar Valley Billings 40 30 20 2,000 10 0 0 50 100 150 200 250 Distance (miles) 0
N 50 miles Headwaters of a Continent Yellowstone Snake Bear
Upper Snake River Water System Drainage area: 35,800 mi 2 (93,130 km 2 ) Irrigated area: 2.4 M acres (9750 km 2 ) 9 major storage reservoirs; capacity 4 M a-f (5 x 10 9 m 3 )
Eastern Snake Plain Aquifer (ESPA) Boggs et al., 2010, J. Am. Water Res. Assoc. Water budget and water rights accounting close below Thousand Springs.
Water Table Height (ft) Problem 1: Decline in Groundwater Levels 4820 4815 4810 4805 4800 10/1/1961 10/1/1969 10/1/1977 10/1/1985 10/1/1993 10/1/2001 Groundwater level in a monitoring well on the ESPA.
1902 1907 1912 1917 1922 1927 1932 1937 1942 1947 1952 1957 1962 1967 1972 1977 1982 1987 1992 1997 2002 2007 Discharge - Cubic Meter per Second Problem 2: Decline in Aquifer Discharge 200 180 160 140 120 100 80 60 40 20 0 Water Year Thousand Springs Discharge
Research Approach Model flow through linked surface-ground system, including: Diversions from streams into canal system Seepage from canals Seepage from stream channels Seepage due to irrigation application in excess of crop ET Surface return from irrigation system Returns to surface system from aquifers Analyze changes in irrigation practices Estimate water budgets Conduct analyses at multiple spatial scales: Small tributary basins(teton Valley) Intermediate-scale watershed (Henry s Fork) Entire system (Upper Snake River/Eastern Snake Plain Aquifer)
Henry s Fork Watershed Mean ann. precip.: 28.2 inches Min. elevation: 4,820 ft. Max. elevation: 11,400 ft. Canal-irrigated area: 250,000 ac. Canal length: 475 miles Annual water supply: 2.5 M a-f Annual diversion: 1.2 M a-f
Surface lithology of Henry s Fork Precambrian Paleozoic and Mesozoic sedimentary Cenozoic silicic volcanics from Yellowstone hotspot explosive eruptions Quaternary basalts Quaternary alluvium and glacial drift Source: Bayrd 2006 M.S. Thesis, Idaho State University
Field work to measure canal and stream channel loss rates and geometry for model parameterization.
Changes in Irrigation Practices Flood irrigation Sprinkler irrigation
Conversion from flood to sprinkler But, almost all conveyance still occurs in unlined canals.
Annual Volume (acre-feet) Groundwater pumping began in 1950s 350,000 300,000 250,000 200,000 150,000 100,000 50,000 0 1954 1959 1964 1969 1974 1979 1984 1989 1994 1999 Year Annual volume of groundwater pumped by A&B Irrigation District But, GW pumping does not occur in all locations.
Diversion (cfs) 30-year Mean Canal Hydrograph Teton Valley 700 600 500 400 Application Seepage Crop ET Canal Seepage Canal/Sprinkler ET Surface Return 300 200 100 0 1-Oct 1-Nov 1-Dec 1-Jan 1-Feb1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep Date
Diversion (acre-feet) Canal Budget by Year Teton Valley 160,000 140,000 120,000 100,000 Application Seepage Crop ET Canal Seepage Canal/Sprinkler ET Surface Return 80,000 60,000 40,000 20,000 0 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 Year
Diversion (cfs) 30-year Mean Canal Hydrograph HF 4500 4000 3500 3000 2500 Application Seepage Crop ET Canal Seepage Canal/Sprinkler ET Surface Return 2000 1500 1000 500 0 1-Oct 1-Nov 1-Dec 1-Jan 1-Feb1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep Date
Diversion (acre-feet) Canal Budget by Year Henry s Fork 1,600,000 1,400,000 1,200,000 Application Seepage Crop ET Canal Seepage Canal/Sprinkler ET Surface Return 1,000,000 800,000 600,000 400,000 200,000 0 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 Year
Net Gain (acre-feet/yr) River reach gains Henry s Fork Watershed 700,000 600,000 500,000 400,000 Lower HF & Teton HF Ashton-StA Teton Valley 300,000 200,000 100,000 0-100,000 1979 1984 1989 1994 1999 2004
Analysis of Reach Gains in Henry s Fork Watershed Reach gains depend strongly on irrigation recharge, which depends on diversion
Annual aquifer recharge, acre-feet 40000 60000 80000 100000 120000 Natural Flood Actual Sprinkler Pipeline GW recharge under modeled scenarios, Teton Valley Pipeline scenario assumes 100% irrigation efficiency
Effect on GW elevations: Teton Valley
Distribution of Surface Withdrawals Does this scale up to entire Upper Snake? 100% 90% 80% 70% 60% Return via Surface Flow Evaporative Loss Crop Evapotranspiration Return via Groundwater 50% 40% 30% 20% 10% 0% Teton Valley 0.92 M a-f/yr Henry's Fork 1.2 M a-f/yr Upper Snake 8.7 M a-f/yr Water budget for surface water withdrawals
Distribution of Recharge Sources Does this scale up to entire Upper Snake? 100% 90% 80% 70% Direct Precipitation Stream Seepage/Tributary Underflow Irrigation Seepage 60% 50% 40% 30% 20% 10% 0% Teton Valley 0.95 M a-f/yr Henry's Fork 1.2 M a-f/yr Upper Snake 9.0 M a-f/yr Distribution of Recharge Sources to Valley Aquifers
Prediction of Thousand Springs discharge from irrigation seepage Modeling efficiency: 75% Boggs et al. 2010, JAWRA
Ecological Consequences: hydrologic alteration Modeled Teton River flow: irrigation has decreased peak flow and increased base flow
Ecological Consequences: hydrologic alteration Modeled Teton River flow, dimensionless hydrographs Measure GW influence by maximum/minimum ratio
Teton R. Maximum/minimum discharge ratio
1-Oct 1-Dec 1-Feb 1-Apr 1-Jun 1-Aug Discharge (percent of annual) Depth/bankfull width 0.1 0 HF at Rexburg Warm River Trail Creek Groundwater influence and stream channel morphology -0.1-1 0 1 2 3 Distance/bankfull width Stream channel complexity increases with hydrograph max/min ratio (Bayrd 2006) 1.2% 1.0% 0.8% 0.6% 0.4% 0.2% 0.0% HF at Rexburg Warm River Trail Creek
Percent cutthroat trout Max/min Ratio and Trout Species Composition Nonnative rainbow trout displace native cutthroat when max/min ratio is low. 100% 80% 60% South Fork Snake Teton River Linear (South Fork Snake) Linear (Teton River) 40% 20% 0% 0 5 10 15 20 Maximum/minimum ratio during year of spawn
BUT, irrigation seepage maintains
Some conclusions and recommendations Irrigation patterns have driven groundwater-surface water interactions in upper Snake Basin since late 19 th century. Irrigation has transformed upper Snake hydrologic regimes from snowmeltdominated to GW-dominated. Native species and ecosystems have been replaced by nonnatives, but Ecosystem services provided by irrigation-dependent groundwater and wetlands are valued, if poorly understood and under-appreciated. Increases in irrigation efficiency have reduced GW-associated resources, including water supply for downstream users. Irrigation remains single largest source of aquifer recharge. Water management for all uses and values must account for groundwatersurface water interactions and treat both components equally Beware of unintended down-gradient and downstream consequences of wellintentioned water conservation measures.