ALABAMA GROUNDWATER SUSTAINABILITY: A STRONG SCIENTIFIC FOUNDATION FOR WATER RESOURCE MANAGEMENT AND POLICY TO SECURE ALABAMA S WATER FUTURE

Transcription

1 ALABAMA GROUNDWATER SUSTAINABILITY: A STRONG SCIENTIFIC FOUNDATION FOR WATER RESOURCE MANAGEMENT AND POLICY TO SECURE ALABAMA S WATER FUTURE Marlon Cook

2 Geological Survey of Alabama Groundwater Assessment Program

3 Alabama Water Policy Development Alabama is essentially a raparian rights state. The Alabama Water Resources Act of 1993 created the Alabama Office of Water Resources, which maintains a Certificate of Beneficial Use Program that tracks water use of >100,000 gallons per day. In 2008 Act No created the Permanent Joint Legislative Committee on Water Policy and Management. In 2011 Governor Robert Bentley created the Alabama Water Agencies Working Group (AWAWG) comprised of the: Alabama Office of Water Resources Alabama Department of Environmental Management Alabama Department of Conservation and Natural Resources Alabama Department of Agriculture and Industries Geological Survey of Alabama In 2013, the Alabama Permanent Joint Legislative Committee on Water Policy and Management mandated the Geological Survey of Alabama and the Alabama Office of Water Resources to perform scientific assessments of the state s water resources.

4 Alabama Water Resource Policy and Management Alabama Water Policy? A Clean Slate?

5 Effective Water Management and Policy Must be Based on Sound Scientific Data

6 WHY IS GROUNDWATER IMPORTANT IN ALABAMA? 40% of public water supply by volume is from groundwater sources. 70% of the geographic area of Alabama is supplied by groundwater sources. Source of water-use data, USGS-OWR Estimated Use of Water in Alabama 2005

7 Assessments for Water Resource Management and Policy Development: The Big Picture Effective statewide water management is founded on a number of integrated components that include: Acquisition of fundamental water resources data including: Water Availability Assessments Determine how much water of sufficient quality is available from surface and groundwater sources, current impacts of water production, quantities of sustainable yield, and strategies for future water source development. Consumptive Water Use Assessments Determine how much water is currently used in specified sectors of society, how much water is returned to the environment, forecasts of future water use, and strategies for more efficient water production and use. Instream Flow Assessments Determine how much water should remain in surface channels to support fish and wildlife and the functions of natural hydrologic systems, and impacts of current and future climate and water production. Establish statewide surface-water and groundwater monitoring networks including: A comprehensive water resource monitoring network comprised of strategically located real-time and periodic groundwater level, surface-water discharge, and precipitation monitoring systems, designed to assess climate and water production impacts.

8 State-Wide Groundwater Assessment Areas

9 Groundwater Assessments: HYDROGEOLOGIC COMPONENTS Well location maps (water wells and oil and gas production and test wells will be sources of data for investigations). Hydrogeologic well data (includes well depth, depth to water, pumping rates, and specific capacity). Stratigraphic analyses including mapping and cross sections (includes geophysical log evaluation, well sample analysis, and seismic interpretations). Structure maps (elevation of the top of each assessed aquifer and location of geologic structures that influence water occurrence including fault and fracture identification. Structural investigation will include geophysical log analysis, gravity and magnetics, and seismic acquisition and interpretation). Net potential productive interval isopach maps for all major coastal plain aquifers (net aquifer productive interval isopach maps indicate depositional trends and the water bearing potential of geologic units). Aquifer productivity characteristics includes specific capacity, pumping rates, and depth to water maps. Potentiometric surface/water table, and residual drawdown maps (indicates groundwater flow paths, production impacts, and climatic impacts). Ground-water production impact maps (indicates production stress on each assessed aquifer based on water levels and well contribution area models). Probable sustainable yield maps (based on available aquifer test data). Aquifer recharge estimates (quantitative estimate of recharge for each assessed aquifer including stream base-flow assessments and character of surface- ground-water interaction). Groundwater storage estimates (quantitative estimate of in-situ water storage in individual aquifers.

10 Alabama Water Well Data GSA is the repository for Alabama water well data. More than 125,000 well records including construction, lithologic, pump testing, geophysical logs, and geochemical analyses. Most records are scanned and data is currently being input to excel spreadsheets.

11 Alabama RBDMS-Environmental Database Development The GSA GAP with GWPC and its developers to develop an RBDMS-E database to house Alabama s water well and groundwater research data. These data will be displayed in an interactive mapping system similar to the Alabama OGB. The GSA GAP RBDMS-E Database along with a similar database to be developed for the Alabama Office of Water Resources will provide the foundation for Alabama Water Resource Management and Policy development.

12 Alabama Groundwater Research Statewide Groundwater Assessment Area 1

13 Generalized Stratigraphy Southeast Alabama Major Aquifers Minor Aquifers Potential New Aquifer

14 Stratigraphic Analysis

15 Net Potential Productive Interval Mapping GR Resistivity Nanafalia Formation = 74 ft 75%

16 Net Potential Productive Interval Isopach Map Clayton Aquifer

17 Net Potential Productive Interval Isopach Map Gordo Aquifer

18 Initial Potentiometric Surface Map Clayton Aquifer Pre 1970

19 Current Potentiometric Surface Map Clayton Aquifer

20 Production Impact Map

21 Well capture zone and spacing data for southeast Alabama aquifers Aquifer Range of residual drawdown (feet) Average capture zone area (mi 2 ) Optimum well spacing (miles) Along strike of hydraulic gradient direction Gordo Ripley Clayton Nanafalia Tallahatta Tuscahoma Lisbon Crystal River Up or down gradient direction

22 Components of Groundwater Recharge

23 Aquifer Recharge Areas

24 Aquifer Recharge Unconfined or partially confined recharge for aquifers in the Southeast Alabama pilot project area Aquifer Recharge Area (mi 2 ) Million g/d Gallons/d/mi 2 In/yr Tuscaloosa Group , Eutaw Formation , Cusseta Member Ripley Formation , Ripley Formation , Providence Formation , Clayton Formation , Nanafalia Formation , Lisbon and Tallahatta Formations 1, , Crystal River Formation 1, ,

25 Confined recharge for selected aquifers in the Southeast Alabama pilot project area Aquifer Transvissivity (ft 2 /d) Thickness (ft) Hydraulic Gradient (ft/mi) Gordo Formation 3, Ripley Formation 7, Clayton Formation 10, Nanafalia Formation 4, Recharge (million gal/d) Recharge volumes for unconfined and confined zones of major aquifers in the southeast Alabama project area Crystal River Nanafalia Clayton Aquifer Ripley Cusetta Providence Eutaw Tuscaloosa Group/Gordo 0 50 Confined Recharge Volume Unconfined Recharge Volume Recharge (Mgd)

26 Groundwater in Subsurface Storage When storativity is multiplied by the surface area overlying an aquifer and the average hydraulic head above the stratigraphic top of a confined aquifer, the product is the volume of available groundwater in storage in a confined aquifer (Fetter, 1994): V w = SA h Storativity, related aquifer characteristics, and available groundwater in storage for major confined aquifers in the project area Aquifer Average effective porosity (percent) Confined aquifer area (fresh water) (mi 2 ) Aquifer potential productive interval thickness (ft) Storativity Available groundwater in storage (million ft 3 ) (million gal) Lower Cretaceous 28 2, ,202.4 Coker Formation 32 4, ,196.1 Eutaw and Gordo Formations 36 4, ,102.3 Ripley Formation 30* 4, Clayton Formation and Salt Mountain Limestone 40* 1, Nanafalia Formation 30* 2,

27 GSA GAP Web Site

28 GSA GAP Real-Time Groundwater Monitoring System

29 Real-Time Hydrograph Location: Jefferson County Aquifer: Bangor Limestone Depth of Well: 140 BLS Land Surface Elevation: 642 feet AMSL Period of record for percentiles:

30 Periodic Monitored Wells

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32 For more information: Marlon Cook Director, Groundwater Assessment Program Geological Survey of Alabama