Determining Surface Water Availability in Oregon: Program Overview and Updates

Transcription

1 Determining Surface Water Availability in Oregon: Program Overview and Updates Jordan Beamer, OWRD Mellony Hoskinson, OWRD Ken Stahr, OWRD AWRA Meeting Portland, OR 11/9/2017

2 Figures: OWRD, 2012 Water is a Finite Resource Surface water (both supply and demand) in Oregon is not uniformly distributed in space or time. Summer streamflows in most Oregon basins (w/o storage) are often insufficient to meet all instream and out-of-stream demands. Location Timing

3 Figure: OWRD, 2013 Supply Shortfalls not Shared Equally Water law - Prior Appropriation Doctrine - having a water right does not guarantee use of water every year As water use increases in a basin, OWRD needs to: Ensure existing users get their water a reasonable amount of time Determine if any surface water is available for new appropriation

4 Figure: Cooper, 2002 Need for State-wide Allocation System State Legislature 1989 decision Commission directed OWRD establish the Water Availability Program in order to: Establish standards to evaluate if water is available for further use Establish water availability database based on standards Use database to evaluate applications for new uses of surface water The Water Availability Reporting System (WARS) developed and put into operational use in the mid-1990s (Cooper, 2002)

5 The Water Allocation Policy Policy defines over-appropriated as when the expected demands exceed the streamflow that would occur naturally at least 80% of the time. This definition ensures that a new user has use of water a reasonable amount of time, i.e. at least 80% of the time. It doesn t protect instream values so that a stream with no instream water right would have no flow 20% of the time at full appropriation.

6 Water Availability Calculation Statewide data-driven / statistical approach Surface water accounting equation: Natural Streamflow Existing Uses = Available Water Computed on monthly basis for 50% and 80% exceedance natural streamflow levels; positive values indicates water is available Water availability calculated statewide on monthly basis for ~2300 Water Availability Basins (WABs)

7 Figure: Cooper, 2002 Nested Basins (WABs) Water availability is calculated at the pour point of each WAB. Calculation for a nested WAB is considered with others in the same stream network. For water to be available at any upstream point, it must be available at all points of calculation downstream.

8 WARS - Winter Snapshot

9 WARS - Summer Snapshot

10 Water Availability Program Updates Improve functionality and resolution Update input datasets, including: Satellite-based evapotranspiration (ET) Current streamflow patterns Projected future streamflow and demand Figures: Vano et al., 2015 (left); Huntington et al., 2015 (right)

11 Updating Natural Streamflow Natural Streamflow (NSF) is estimated in one of three ways: Continuous measurements Miscellaneous measurements Prediction equations Corrections (add-backs) applied to measurements depleted by consumptive uses (CU): Natural Streamflow = Gaged Streamflow + Consumptive Uses Gages w/ long-record in undeveloped basins = increased certainty in NSF

12 Updating NSF Gaged Streamflows Long-term, index gaging stations the backbone of our NSF dataset ID new index gaging stations 30+ yr record, minimal upstream diversions/storage

13 Count Publish Gaged Streamflow Records Stations with Published and Unpublished Data unpublished records published records Water Year

14 Prelim Results - Base Period Comparison Monthly median gaged streamflows for two base periods at 12 index gaging stations compared Changes in annual volumes generally <10%; some significant shifts in timing of streamflows

15 Updating NSF - Consumptive Uses Need to estimate actual water consumption from irrigation Irrigated acreage for 1990 from Ag Census and OSU extension data Consumptive use based on # of irrigated acres Crop type Irrigation method Crop water requirements from Cuenca et al., 1992 No longer reported Figure: Broad and Collins, 1996

16 Use of Remote Sensing for Actual Consumptive Use Energy balance models METRIC (Allen et al., 2007) and SSEBop (Senay et al., 2013) use remote sensing to see actual CU at the basin- and field-scale. Average Actual Crop ET (METRIC) Potential Crop ET (ETDemands)

17 NASA-ROSES/OpenET Project Project Title: Operational Remote Sensing of Agricultural Water Use in Cooperation with Western State Water Resource Agencies for Improved Water Management Problem: remote sensing approaches often too resource intensive ($$) for operational uses by state water agencies Project partners: Project goal: to develop software tools, ET and CU maps and databases for in-house use by agency staff Expected results: generate 10 years of ET and CU maps in study area, summarize to monthly time series at field and watershed scale

18 Figure: Cooper, 2002 Updating NSF - Prediction Equations Gaged NSF = Gaged SF + Upstream CU Developing regional regression equations involves relating gaged NSF and basin characteristics (McCarthy et al., 2016) Correct ungaged NSF with gaged data Elevation 30m DEM Nov mean precip - PRISM Soil permeability - STATSGO

19 Summary Updating WARS addresses the critical issue of improving water quantity information outlined in the 2016 Monitoring Strategy Determining natural streamflows accurately relies on a robust stream gaging network with continued operation of climate-index gaging stations in minimally developed basins Agricultural consumptive use rates will come from satellite imagery with highly accurate calculations and a long archive Utilize forecast estimates such as climate predictions to predict future streamflow and water demand

20 Questions? Jordan Beamer Surface Water Hydrologist Oregon Water Resources Department Salem, OR Credit: L. Hillman Nehalem River, May 2017

21 References Allen, R. G., Tasumi, M., & Trezza, R. (2007a). Satellite-based energy balance for mapping evapotranspiration with internalized calibration (METRIC) Model. Journal of irrigation and drainage engineering, 133(4), Broad, T., and Collins, C., 1996, Estimated water use and general hydrologic conditions for Oregon, 1985 and 1990: U.S. Geological Survey Water-Resources Investigations Report , 166 p. Cuenca, R.H., 1992, Oregon crop water use and irrigation requirements: Corvallis, OR, Oregon State University Extension Miscellaneous 8530, 184 p. Cooper, R.M Determining Surface Water Availability in Oregon. Open File Report SW Oregon Water Resources Department. Salem, OR. 158 p. Huntington, J.L., Gangopadhyay, S., Spears, M., Allen, R. King, D., Morton, C., Harrison, A., McEvoy, D., and A. Joros West-Wide Climate Risk Assessments: Irrigation Demand and Reservoir Evaporation Projections. U.S. Bureau of Reclamation, Technical memorandum No , 196p., 841 app. Available at McCarthy, Peter M., Roy Sando, Steven K. Sando, and DeAnn M. Dutton Methods for Estimating Streamflow Characteristics at Ungaged Sites in Western Montana Based on Data through Water Year USGS Numbered Series G. Scientific Investigations Report. Reston, VA: U.S. Geological Survey. Oregon Water Resources Department, Oregon s Integrated Water Resources Strategy. 154 p., Available at: Senay, G.B, Bohms, S., Singh, R.K., Gowda, P. H., Velpuri, N.M., Alemu, H., Verdin, J.P., Operational Evapotranpiration Mapping Using Remote Sensing and Weather Datasets: A New Parameterization for the SSEB Approach. Journal of the American Water Resources Association, 49(3), DOI: /jawr Vano, J. A., B. Nijssen, and D. P. Lettenmaier Seasonal hydrologic responses to climate change in the Pacific Northwest, Water Resour. Res., 51, , doi: /2014wr