Groundwater Resources Program Regional Groundwater Evaluation

Transcription

1 Groundwater Resources Program Regional Groundwater Evaluation Appalachian Plateaus Aquifer System Kurt McCoy, David Nelms Mark Kozar Richard Yager David Ladd USGS Virginia Water Science Center USGS West Virginia Water Science Center USGS New York Water Science Center USGS Tennessee Water Science Center

2 11 Appalachian Plateaus Regional GW Availability Study Objectives 1. Computing estimates of hydrologic budget components 2. Establishing a regional hydrogeologic framework 3. Defining the largest flow system of relevance An opportunity to expand knowledge of subsurface resources to include water

3 Framework for GW Availability at a Regional Scale-- Principal Aquifers Source: U.S. Geological Survey National Atlas of the United States; 8

4 PRIMARY INTENT 1. To improve datasets for adaptive management of drinking-water resources, aquatic ecosystems, and continued energy resource development. 2. A better understanding of groundwater availability in the Appalachian Plateaus thus plays a central role in sustained economic development of the region.

5 Vital Resource Regional Perspective Groundwater Withdrawals - Prolific aquifers of the United States Source: Maupin and Barber, 2005 Groundwater withdrawals - Appalachian Plateaus aquifers ~ 500 MGD

6 Water Availability Issues Existing and potential for WATER- QUALITY degradation at a regional scale Localized shortages during periods of extended DROUGHT

7 Precipitation Evapotranspiration Groundwater Discharge Runoff How do the various components of the water budget respond to climate variability? Photo courtesy of NPS Big South Fork River NRA

8 Methods of Hydrologic Budget Computation Soil-Water Balance Model ( ) (Westenbroek and others, 2010) INPUTS: Daily Precip, Temperature, Land Use, AWC, Soil Group Base-flow separation (PART) (USGS-GW Toolbox) Independent methods that permit Model Calibration

9 Scale-Dependent Variability Data from 849 USGS stream gages Baseflow variability decreases with drainage area Large basins integrate climate Homogenize basin characteristics

10 Climate-Dependent Variability

11 Climate-Dependent Variability

12 Climate-Dependent Variability

13 MAJOR FINDINGS PART I 1. Wide range of basin characteristics in 86,000 mi2 area equates to high spatial variability in water budgets. 2. Climate variation results in annual conditions that differ up to a factor of two or more from long-term averages. 3. Regional bias towards higher unit discharge in eastern highlands. 4. Orographic effects in Garrett County moderate water budget variability (High Precip, Low Temps)

14 Historical Variability in Water Budget Components

15 Historical Variability in Water Budget Components PRECIPITATION, INCHES PER YEAR YOUGHIOGHENY RIVER NEAR OAKLAND, MD PRISM Climate Group, Oregon State University, accessed 1 Nov 2012

16 Historical Variability in Water Budget Components Groundwater Dominant Runoff Dominant Relative proportioning of water budget components

17 Historical Variability in Water Budget Components Synthesize data from 849 gages 1. Plot all data on one plot Normalized anomaly = Value - mean Standard deviation 2. Regional response to climate trends +1 sdev Mean - 1 sdev

18 Precipitation 849 anomalies 10-year moving average Stream flow LEGEND Annual average all sites Base flow Runoff Base flow index YELLOW LINE WINDOW bump 2. Stream flow and base flow negative to positive anomaly 3. Runoff unchanged 4. BFI goes positive, but no 1970 bump

19 Historical Variability in Water Budget Components

20 Historical Variability in Water Budget Components 77 Index Gages 60 or more years of record ( ) No more than 20% missing record Basin boundaries in GAGES-II

21 1930baseflow Base flow Magnitude of change Sens Slope

22 Base Flow Index Magnitude of change Sens Slope

23 MAJOR FINDINGS PART II 1. Long-term (80-yr) trends are positive 2. Short-term trends (40-yr) around 1970 step change are negative 3. BFI is consistently increasing and appears independent of climate trends 4. Spatial patterns of change are mixed, but are generally consistent with prevailing climate patterns and land-use changes.

24 Appalachian Plateaus Regional GW Availability Study Visit Us Please!! Study Information Latest Research Update Online Data Portal