Foreword ...................................................... iii
Executive Summary ............................................... 1
Background and Major Issues .................................. 1
Groundwater Budget ........................................... 2
Climate Trend Evaluation ..................................... 2
Groundwater Monitoring Evaluation ............................ 3
Introduction .................................................... 3
Purpose and Scope ............................................ 4
Study Area Characteristics ................................... 4
Climate ................................................... 4
Population ................................................ 8
Land Use .................................................. 8
Water Use ................................................. 8
Geologic Setting .......................................... 8
Hydrogeologie Units ...................................... 10
Previous Investigations ..................................... 13
Methods Overview ............................................... 13
Numerical Model ............................................. 13
Data Compilation ............................................ 14
Modifications to the Numerical Model ........................ 14
Development of the Hydrologie System ........................... 14
Predevelopment Conditions ................................... 14
Postdevelopment Conditions .................................. 15
Groundwater Availability, a Water-Budget Perspective ........... 17
Regional Water Budget ....................................... 20
Principal Aquifer Water Budgets ............................. 25
Local Area Water Budgets .................................... 28
Climate Trends and Potential Future Effects on Groundwater
Availability ................................................ 32
Hydroclimate Data Processing and Analysis ................ 32
Climate Simulation Development ........................... 35
Climate Trend Scenarios and Simulated Water Levels ....... 36
Evaluation of Regional Groundwater-Level Monitoring
Network ..................................................... 37
Existing Monitoring Networks ............................. 37
Network Analysis ......................................... 37
Groundwater-Flow Model Improvements ......................... 40
Challenges for Future Groundwater Availability
Determinations-Limitations and Lessons Learned ................. 40
Scaling Regional to Local Issues ............................... 42
Acknowledgments ................................................ 43
References ..................................................... 43
Appendixes 1-3 ................................................. 49
Appendix 1 Effects of Natural-Climate Trends on Interannual
to Multidecadal Timescales ......................... 50
Appendix 2 Singular Spectrum Analysis ......................... 52
Appendix 3 Extrapolated 30-Year Precipitation Values
Interpolated Spatially across the Mississippi
Embayment Regional Aquifer Study Area .............. 58
Figures
1 Map showing location of the study area and Coastal Plain
physiographic province sections ............................. 5
2 Map showing streams simulated in the study area ............. 6
3 Graphs showing cumulative departure from average
precipitation within the study area and at selected
locations, showing dry and wet periods for the study area ... 7
4 Map showing land use within the Mississippi embayment ....... 9
5 Graph showing cumulative groundwater pumpage by aquifer
used in the Mississippi Embayment Regional Aquifer Study
model ...................................................... 10
6 Cross-sectional view of hydrogeologie units within the
study area with predevelopment conceptual water movement ... 11
7 Map showing simulated predevelopment streamflow leakage .... 16
8 Diagram showing predevelopment groundwater-flow budget of
the alluvial and Tertiary systems, in acre-feet per year ... 17
9 Maps showing comparison of A 1929 and B, 2006
potentiometric surface of the Grand Prairie area ........... 18
10 Cross-sectional view of hydrogeologie units within the
study area with postdevelopmentflow (2006) conceptual
water movement ............................................. 19
11 Diagram showing postdevelopment groundwater-flow budget of
the alluvial and Tertiary systems in acre-feet per year .... 20
12 Graphs showing groundwater-flow budget of the MERAS model
A seasonal after 1986, spring/summer depicted by large net
pumpage and fall/winter depicted by small net pumpage; B,
average annual ............................................. 21
13 Graph showing cumulative change in groundwater storage by
aquifer .................................................... 22
14 Map showing water-level change from predevelopment to 2007
in the A Mississippi River Valley alluvial aquifer and B,
the middle Claiborne aquifer ............................... 23
15 Pie charts showing percent area for water-level change
groups from predevelopment to 2007 in the Mississippi
River Valley alluvial aquifer and the middle Claiborne
aquifer .................................................... 25
16 Graphs showing groundwater-flow budget of the alluvial
aquifer A seasonal after 1986, spring/summer depicted by
large net pumpage and fall/winter depicted by small net
pumpage; B, average annua .................................. 26
17 Graphs and pie chart showing groundwater-flow budget of
the middle Claiborne aquifer ............................... 27
18 Graphs showing groundwater-flow budgets of local areas ..... 29
19 Pie charts showing predevelopment groundwater-flow
interactions with adjacent hydrogeologie units within
local areas ................................................ 30
20 Pie charts showing postdevelopment groundwater-flow
interactions with adjacent hydrogeologie units within
local areas ................................................ 31
21 Graphs showing demonstration of hydroclimate
data-processing steps using A total monthly precipitation
time series, B, monthly cumulative departure (MCD), and C,
normalized departure series ................................ 33
22 Graph showing average annual (2-year or more)
precipitation values used in the MERAS model and selected
meteorological stations including extrapolated
precipitation data from 2008 to 2038 ....................... 34
23 Graph showing specified net recharge at selected locations
including extrapolated net recharge from 2008 to 2038 ...... 34
24 Graph showing relation between fractional change in
pumping from 2005 and fractional change in precipitation
at Memphis, Tennessee, from 2005 ........................... 35
25 Pie charts showing percent area for water-level change
groups from predevelopment to 2038 in the Mississippi
River Valley alluvial aquifer and the middle Claiborne
aquifer (dry and wet scenarios) ............................ 36
26 Maps showing water-level change of the dry scenario from
predevelopment to 2038 in the A, Mississippi River Valley
alluvial aquifer and B, the middle Claiborne aquifer ....... 38
27 Map showing results of 0PR-PPR showing the relative
importance of spring 2007 water-level observations in the
middle Claiborne aquifer ................................... 41
1-1 Graphs showing interactions between the positive and
negative phases of the A, multivariate El Nino/Southern
Oscillation (ENSO) index, B, Pacific Decadal Oscillation
(PD0) index, and C, Atlantic Multidecadal Oscillation
(AMO) index cumulatively affect United States climate
and, in turn, surface and groundwater resources ............ 50
2-1 Graphs showing statistically significant reconstructed
components based on the Chi-squared significance test
from the singular spectrum analysis for time series of A,
precipitation at meteorological stations, 6, streamflow
at streamflow-gaging stations, and C, groundwater levels
at wells from the study area indicate that all time
series contain variations that are consistent with El
Nino Southern Oscillation (2 to 6 years), Pacific
Decadal Oscillation (10 to 25 years), and greater than
Pacific Decadal Oscillation (greater than 25 years)
periods, which are indicated by the gray shading.
Additional variations with periodicities of 6 to 10
years were observed in all three types of hydrologie
time series ................................................ 57
3-1 Maps showing the extrapolated 30-year precipitation
values interpolated spatially across the Mississippi
Embayment Regional Aquifer Study area are shown as A,
2-year average extrapolated annual precipitation (in
inches) and as 6, deviation of the 2-year average
extrapolated annual precipitation from the average
observed annual precipitation (in percent) for the time
period 2008 to 2038 ........................................ 58
Tables
1 Correlation of hydrogeologie units across States within
the Mississippi Embayment Regional Aquifer Study ........... 12
2-1 Summary of the period and percent variance for
reconstructed components from the singular spectrum
analysis ................................................... 53
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