Aquifer mapping in Kent and Sussex
Counties, Delaware: A key to
understanding groundwater sources
A Presentation to the
2013 Region 3 Source Water Protection Meeting
June 6, 2013
Pete McLaughlin, Amanda Lawson, and Jaime Tomlinson
Delaware Geological Survey, University of Delaware
• Your challenge: Identifying drinking water sources
and protecting these source waters from
contaminants
Where Source Water Protection Meets Geology
• An understanding the source aquifer and
groundwater flow within it allows delineation of
source water assessment boundaries
• An understanding of subsurface geology is necessary
to accurately characterize the ground water source
• Key geologic aspects:
– Aquifer delination (geographic, depth)
– Aquifer hydrologic characteristics
– Nature of associated confining units
Starting Premise
Accurate Understanding of Aquifer
Geology
is essential to
Accurate Understanding of
Groundwater Occurrence
Geology controls where the groundwater is,
where it goes, and how much we get
The Idea: A Project
• Identify and delineate the aquifers of
southern Delaware (Kent and Sussex Counties)
the are sources of public drinking water
• Determine where these aquifers are used as
drinking water sources and the magnitude of
withdrawals
• Conducted by DGS, supported by DNREC
Outline
1. Objectives and Background
2. Aquifers of Southern Delaware
3. Water Use in Southern Delaware
• Goal: To establish an up-to-date summary of the
groundwater resources of Kent and Sussex
Counties, Delaware
• Incentives:
The last comprehensive report on groundwater availability and aquifers in Sussex County
was published more than 40 years ago
(Sundstrom and Pickett, 1968)
Reported aquifers in state, federal, and SWAPP
databases are not always correct
• Benefit: The results of this work will support
source water protection, well permitting, and
water supply planning programs in Delaware
Kent + Sussex Groundwater Use
100
90
80
MGD
70
60
50
40
30
20
10
0
1985
1990
1995
2000
Data from USGS (http://water.usgs.gov/watuse/data/2005/ )
2005
Kent + Sussex Population
350000
300000
250000
200000
150000
100000
50000
0
1985
1990
1995
Data from USGS (http://water.usgs.gov/watuse/data/2005/ )
2000
2005
Kent + Sussex Groundwater Use
if 130K
population growth
100
in
2030
90
80
70
60
MGD
+ 13?
MGD
50
PLUS
more irrigation
40
30
20
10
0
1985
1990
1995
2000
2005
Objectives
Primary purpose: Updated summary of the ground-water
resources of Kent and Sussex Counties, Delaware, in two parts:
• Aquifer geology:
– to compile geological cross-sections highlighting the
correlation of aquifers
– to construct structural contour and isopach maps of the
aquifers
– to acquire new data in areas where geological control is
lacking, including new drilling and geophysical logging
• Hydrology:
– to compile data on water use in Sussex County,
– to characterize the hydrologic characteristics of each aquifer,
– summarized these within the updated aquifer framework.
Objectives
Recent related work:
• Confined aquifer mapping for Kent County (McLaughlin and
Velez, 2006)
• Unconfined aquifer mapping for Sussex County (Andres and
Klingbeil, 2006)
Strategy:
• use selected, high-quality data;
• establish carefully documented methodologies for
estimation/interpretation where high-quality data are lacking;
• identify issues where a lack of adequate data indicates a need
for further study (project will not address organizational/
quality control issues of all potentially available data).
Geology
&
Hydrology
Geology: Formations
Geology: Aquifers
Geology Methods & Data
• Stratigraphic picks for tops and bottoms of
aquifers (and formations)
• Assembled stratigraphic picks database of
14000 records plus another 2300 records of
sites where picks not made or were
redacted
• Stratigraphic picks database includes app.
6600 wells with stratigraphic picks and
records of app. 2100 others evaluated but
not suitable for picks
Geology Methods & Data
• Dense coverage of picks in
Delaware
• Extended picks into MD
and NJ to minimize edge
effects at borders
Geology
Methods & Data
• Drilled test holes at 10 locations where
availability of confined aquifer data was sparse
• Holes ranged from 600 to 840 ft depth
• Cuttings sample were collected, lithologic logs
were created, and geophysical logs (gammamultipoint electric) were recorded
• Benefit: High quality deep confined aquifer picks
Unconfined Aquifer Methods & Data
• New picks for Kent County;
for Sussex used data and
maps of A&K-2006
• Utilized geophysical logs,
geologist logs, and driller logs
– maximize data volume given
degree of local variation
• Well ranking system
– 1 = Geophysical log and a
descriptive log
– 2 = Geophysical log only
– 3 = Descriptive log only
– 4 = Poor quality log
– 5 = Unable to make pick
Unconfined Aquifer Methods & Data
example: block Md42
• Can we take single driller logs
face value?
• Aim for consistency, esp. with
geologist & geophysical logs
Unconfined Aquifer Methods & Data
• Created Kent County unconfined aquifer grids
1. Reviewed drillers logs in detail, aggressive
accept/reject approach emphasizing consistency
2. Elevation of Base Unconfined grid created using
Radial Basis Function method in ArcGIS Geostatistical
Analyst
3. Unconfined Thickness grid computed from surface
DEM and base elevation grid
4. Final grids corrected for 3-dimensional constraints
(topography)
• Created a K-S unconfined grid by stitching new Kent
unconfined elevation grid and existing A&K-2006
Sussex unconfined elevation grid
Unconfined
Aquifer
Elevation
Grid:
Kent County
Unconfined aquifer & geology
•Common scattered beds
of clayey silt
•Silt to fine sand over
medium to coarse sand in
upper 5-25’
•Rare discontinuous
clayey silt beds
•Heterogeneous coarse to
fine sand, gravelly sand,
and pebble gravel
Unconfined Aquifer, Sussex County
Klingbeil and Andres, 2006
•
•
•
•
•
Thickness map
Elevation of base
Transmissivity map
> 4200 data points
Used drillers’ and
geophysical logs
Unconfined
aquifer
•
•
•
•
Thickness map
Elevation of base
> 1600 data points
Splice with Sussex
map
Unconfined
aquifer
Kent + Sussex
Confined Aquifer Methods & Data
• Picks mostly from geophysical logs, a smaller
number from lithologic logs with highconfidence data
• Depths converted to elevation by subtracting
from well elevation
significant elevation data QC required
• Values exported from stratigraphic database
and imported into ArcGIS as point data
Confined Aquifer Methods & Data
• Gridding utilized Radial Basis Function
(multiquadric) method in ArcGIS
Geostatistical Analyst
• Used 100 m grid resolution
• Grids made for each confined aquifer of:
– top aquifer from picks
– base aquifer from picks
– aquifer thickness by grid math
Confined Aquifer Methods & Data
Grid QC work
• Grids checked against intersection with overlying
and underlying surfaces
– in some cases, dummy or projected values used to
ensure non-intersecting grid position in sparse data
areas
• Grid surfaces are cut-away where overlying surface
occurs lower
– most significant case: base of unconfined aquifer
occurring below top of base of a confined aquifer, which
means normally confined sand unit is not confined there
Mount Laurel aquifer
Rancocas aquifer
Piney Point aquifer
Lower Calvert sand
sand unit below the Cheswold sand
Cheswold sand
Example of how to represent an aquifer in 3D context
Cheswold sand
accurate in 3 dimensions
not represented on grid where based unconfined is lower
somewhat simplified
represented to updip limit of presence regardless of
elevation of base unconfined
“Federalsburg” sand
Frederica sand
Milford sand
middle Choptank sand
upper Choptank sand
Manokin aquifer
Manokin aquifer
simplified, unconfined not accounted for
Manokin
aquifer
subcrop
Implications for
Recharge and
Source Water
Protection
Pocomoke aquifer
Pocomoke aquifer
simplified, unconfined not accounted for
Pocomoke
aquifer
subcrop
Implications for
Recharge and
Source Water
Protection
Groundwater
Use
Groundwater Use Methods & Data
Groundwater Use Calculations
Public
Industrial
Irrigation
Domestic
Livestock
Metered/
Reported
Metered/
Reported
Estimated
Estimated
Estimated
Irrigated acres
Population outside
public-served areas
Livestock populations
for big systems
X
+
Estimated
Estimated water use
by crop type and soils
For smaller systems
calibrated to
Assumed usage rates
per user type
Known usage for
metered irrigation
X
Population or size of
facility served
X
socioeconomic-based
per capita coefficient
Calibrated to
Known usage in
similar public served
areas
X
Average water
use/type of livestock
Compilation of Water Use Data
Theoretically:
• Reported Water Use (large users, allocations)
– large public
– industrial & thermoelectric
– irrigation (ag & golf course)
• Non-Reported Water Use (smaller users)
–
–
–
–
–
smaller public
domestic self-supplied
livestock
lawn self-supplied
other minor types
Groundwater Use Data
Well location data
• DGS WATSYS Oracle database, includes
multiple regular dumps of DNREC well
database
• SWAPP database dump used for
list/locations/depths of public wells
Groundwater Use Data
2004-2008 Water Use Database with ~42,000 records and 930+ wells
Compilation of Water Use Data
In reality, in this study:
• Well data, reported
– large public
– industrial & thermoelectric
• Well data, estimated
– small public (CWS, TNC, NTNC)
– golf course (some reported)
• Area data, estimated by census block
– domestic self-supplied
– irrigation (agricultural)
– livestock (poultry)
– lawn self-supplied
Groundwater Use Methods & Data
Reported Use: Public & Industrial
• Categories:
– Public (446 wells)
– Industrial Self-Supplied (62 wells)
• Approach
– Compiled and cleaned up monthly water use data
– Subtotal annual water use for 2004-2008
– Verified locations and fixed as needed
– Verified screen depths and fixed as needed
Groundwater Use Methods & Data
Reported Use: Public & Industrial
Groundwater Use Methods & Data
Census Data vs. Water Use Relationships
for Census-Based Water Use Estimates
•
•
Used public wells and service areas (block or subblock) with principally domestic use
Examined reported pumping vs census factors used in Horn et al., 2007 USGS New Hampshire
Seacoast water use report; 5 selected:
Gallons Per Capita Daily
Variables
Coefficients
BldYrWtAvg
-0.006891889317145660
HHSizeWtAvg
-0.217913102554659000
HouseValWtAvg
250
200
150
0.000001850164162435
100
HsgDensityWtAvg
0.000113449101106628
PopDensityWtAvg
0.000030698704019032
Intercept
4.933770428394450000
50
•
•
•
•
•
•
y = 0.8504x + 17.495
R² = 0.7072
-
50
100
150
200
250
Subblock percentages derived from basis of percentage of parcels plus extensive manual editing
Use the census populations, for calculation of the calibration data, gallons pumped per day per person (from reported pumpage)
Use the normal log of the weighted average GPCD (gallons per capita daily) for each pumping network to plot against the five census factors selected from the NH study, and do a multiple
regression to determine the correlation coefficent for each -- so we have correlations of census factors (which includes population-based numners like pop density and household density
to water use that includes more-than-census
then I take those coefficients and use them to calculate resident-population-based modeled water use for each census block/subblock (latter where a block is divided) -- so that is also
based on real population
then I calculate expected peak population addition and annualized average summer population addition (on basis of average 66 days occupancy) and scale up the water use from that
population numbers based on that block’s coefficient-based GPCD
then those total block/subblock water use calcs are subtotaled (resident plus vacationer use modeled together) for each service polygon and then into each pumpage network (group of
polygons) so that actual pumpage can be correlated to modeled pumpage
Groundwater Use Data
2010 and 2000 census data for populations and demographics
13,218 census blocks
in Kent & Sussex
Groundwater Use Methods & Data
Estimated Use: Public Community
• Public Community
(178 wells)
– Estimated total water
use for system on
basis of census-based
water use
determinations
– Split the system use
totals among the
wells in the system
(usually 1, 2, or 3
– no basis for
estimation of
different pumping by
year
will update CWS NR map
Groundwater Use Methods & Data
Estimated Use: Public Community & Non-Community
• Public Non-Transient Non-Community (69 wells)
• Public Transient Non-Community (154 wells)
Water Use estimated
either by:
• direct factor by
facility type,
including size
• population served
with a factor for
facility type
Groundwater Use Methods & Data
Estimated Use: Public Non-Community
will update NCNT map
will update NCT map
Non-Public System Water Use
•
•
•
•
•
Self-Supplied Domestic
Irrigation (crops)
Irrigation (golf courses)
Irrigation (lawns – separate self-supplied)
Livestock (poultry)
a quick summary of those methods...
Groundwater Use Methods & Data
Estimated Use: Self-Supplied Domestic
• Basis: Population by Census Block, not wells
– Utilized previously described method of estimating
water use via five census- and pump-data-based
coefficients
Groundwater
Use Data
Ag-related data
• Irrigation: 2,400+
irrigation polygons
• Livestock: 2,600+ chicken
houses
Groundwater Use Methods & Data
Estimated Use: Irrigation
• Approach: Build a model to estimate irrigation
– Method: KanSched irrigation scheduler using nearest
weather station data
– Input:
• Irrigated areas catalogued by James Adkins (UD Ag) via 2008
aerial photography
• Climate (precipitation , evapotranspiration) nearest each irrigated
area
• Crop Type in each irrigated area (National Agricultural Statistics Service
2008 Cropland Data Layer)
• Soil Type (water capacity) predominant in each climate polygon
(USDA NRCS)
Groundwater Use Methods & Data
Estimated Use: Irrigation
Groundwater Use Methods & Data
Estimated Use: Livestock (Poultry)
Chicken house numbers:
• 2611 houses in Kent and Sussex
Counties likely/possibly active
Chicken house sizes:
• Majority of existing houses around
50 x 500 (use as average)
Water Use estimate for average house:
• 374,000 gallons/house/yr drinking
• 201,600 gals/house/yr cooling
Groundwater Use Methods & Data
Estimated Use: Lawn Irrigation (“Ag”)
Approach:
• identify how many lawn wells per census block
(1074 wells in 177 blocks)
• calculate water use per household (not per
capita) per month in those blocks
• assume in summer months that lawn watering
can add 50% to baseline water use on basis of
public data
• calculate lawn watering ag water use for each
block by number wells x 0.5 x 3 months
Viola system: Public example
600000
500000
400000
300000
VIOL
200000
100000
2008-09
2008-05
2008-01
2007-09
2007-05
2007-01
2006-09
2006-05
2006-01
2005-09
2005-05
2005-01
2004-09
2004-05
2004-01
0
Groundwater Use Methods & Data
Reported & Estimated Use: Golf Course Irrigation
28 golf course wells on basis of allocations
• A minority of courses reported reliably -- 8 of 28 wells
• 11 of 28 wells did not report data any year
• 9 of the 17 reported something (but 5 only reported
once)
Approach:
• For wells with reported data, subtotaled monthly
reported pumpage for annual totals (though some look to
have questionable accuracy)
• Where not reported, assume the 1.5 x full allocation was
pumped every year and divided it between wells
How much from which aquifer?
• The above steps get us to how much water is
being pumped
a. from a well; or
b. in an area
• However, if we are concerned about the
source of drinking water, or volumes of
groundwater withdrawals, we need to identify
the relevant aquifers
Hydrology and Water Use
Meet Geology
Well A
Well B
Reported in X
Well C
Emphasis
Correct Aquifer Assignment
• Grids compared with database of screen depths
• Water use and hydrological characteristics assigned to aquifer where
screened instead of reported aquifer
Water Use Analysis
Aquifers:
• Geographic trends in water
use by aquifer
• Totals of water use by aquifer
Frederica
Cheswold
Piney Point
2006 pumping
0 or no data
0 - 20 MG
20 - 50 MG
50 - 60 MG
60 - 120 MG
> 120 MG
Approach: Analysis of screen
depths to aquifer depths
Piney Point
Groundwater Use Methods & Data
Aquifer Assignment: Well Specific Usage
Types: Public, Industrial, Golf Course
1. Tabulate well sources: elevation of well, top screen depth,
bottom screen depth, and convert depths to elevations
• where well elevation missing, sample DEM
• where top and bottom of screen is missing, use hole depth
and/or top and bottom of gravel pack
• cross compare DGS, DNREC, SWAP databases for these data
2. Determine aquifer depths using grids. At the location of
each well, “sample” (pick depth) from the grid of the elevation
of the top and base of each aquifer; so each well location has
13 pairs of aquifer elevation values
Groundwater Use Methods & Data
Aquifer Assignment: Well Specific Usage
Types: Public, Industrial, Golf Course
3. Compare screens to aquifers. Run an ArcMap script OR a
series of Excel formulas that compares the top and bottom
screen elevations (or proxies) to the sampled top and bottom
of each aquifer
• where all screen falls between top and bottom of one
aquifer – easy! assign aquifer
• where the screen crosses two aquifers or falls between
aquifers (all or in part), further investigation is needed
• there is no grid for “confined Columbia” so that is usually a
manual interpretation for screens between highest
confined and base unconfined.
Groundwater Use Methods & Data
Aquifer Assignment: Non-Well Specific Usages
None include Public Water Supply wells
Use
Source
Aquifers
Domestic selfsupplied
Clusters of domestic Sample grids at
screen depths by
block center point
census block
By proportion in
each aquifer in
block
Irrigation
Clusters of irrigation Sample grids at
screen depths by
block center point
census block
By proportion in
each aquifer in
block; many in
multiple aquifers
Poultry
Clusters of ag well
Sample grids at
depths near chicken block center point
house by census
block
By proportion in
each aquifer in
block
Lawn
All very shallow
One aquifer
All unconfined
aquifer
Cross-Reference
Water Use Results
Summary by Use
Kent
MGD
Sussex
MGD
Total
MGD
USGS
2010
USGS
2000
Public Reported (high use yr)
11.0
15.2
26.2
Public Reported (low use yr)
10.1
12.7
22.8
25.24
23.05
Public Non-Reported (estimated)
0.58
1.23
1.81
Domestic self-supplied (model)
4.24
7.37
11.61
5.73
10.79
Industrial self-supplied (high use yr)
1.35
6.96
7.66
Industrial self-supplied (low use yr)
0.83
5.56
6.66
7.29
9.41
Irrigation: Ag (model high use 2007)
19.12
71.69
90.82
53.84
33.82
Irrigation: Ag (model low use 2006)
5.62
44.53
50.16
Irrigation: Golf Course (median rpt+est)
0.17
2.00
2.17
-
-
Ag: Lawn wells (estimated)
0.008
0.022
0.03
-
-
Ag: Livestock (estimated)
0.7
3.6
4.3
1.44
3.63
Total (high end)
37.2
108.1
144.6
Total (low end)
94.5
81.2
22.2
77.0
99.5
USE
updated 6/5/13
Public Water Supply – Reported
• Project & County Totals
calculated
– number of wells and
volumes by year tabulated
– water use volumes
calculated by aquifer
– water use can be displayed
by map, symbolized or
subtotaled by census block
• Strengths & Weaknesses of
Data & Analysis
– based on fairly complete,
error-checked reported data
– well construction
information generally good
by combining DNREC and
DGS information
Public Reported
• app. 25 MGD in public water system reported water use
• app. 11 MGD in Kent
• app. 14 MGD in Sussex
2004
2005
2006
2007
2008
Kent (gallons)
3,674,429,787
3,864,285,976
3,844,692,303
4,016,520,959
3,973,377,535
Sussex (gallons)
4,644,680,600
4,973,593,996
5,129,326,570
5,540,338,394
4,788,754,001
Total (gallons)
8,319,110,387
8,837,879,972
8,974,018,873
9,556,859,353
8,762,131,536
Kent (MGD)
10.07
10.59
10.53
11.00
10.89
Sussex (MGD)
12.73
13.63
14.05
15.18
13.12
Total (MGD)
22.79
24.21
24.59
26.18
24.01
updated 6/5/13
prev
Public Reported
gallons/yr
• annual variations largely reflect water use and not just reporting irregularities
Kent
MTL
2004Total
2005Total
2006Total
2007Total
2008Total
Wells
Sussex
2004Total
2005Total
2006Total
2007Total
2008Total
Wells
Total
2004Total
2005Total
2006Total
2007Total
2008Total
Wells
MTL
RAN
PPT
CHE
FED
FRE
MIL
COLC
UNC
3,103,400
89,883,100
1,573,605,207
1,228,865,848
200,669,900
464,507,284
-
10,200
102,426,920
3,988,300
81,144,800
1,350,243,658
1,214,445,008
286,381,800
466,941,906
-
29,500
424,314,004
5,661,500
85,727,000
1,162,468,238
1,459,185,900
317,876,500
487,375,165
-
24,200
260,576,500
14,574,000
76,593,300
1,321,510,728
1,342,726,900
310,287,543
562,429,300
1,074,300
3,400
447,395,720
13,280,800
72,259,100
1,210,682,194
1,307,237,897
342,731,500
521,403,500
444,200
-
529,244,400
1
5
35
57
13
28
3
1
17
CHE
FED
FRE
MIL
UCH
MAN
POC
COLC
UNC
41,000
56,117,000
181,312,400
272,280,000
49,302,900
659,818,897
982,162,847
738,642,128
1,730,794,428
65,000
66,601,000
203,569,500
240,599,000
54,953,690
776,326,175
1,156,997,485
870,109,521
1,641,169,625
76,000
56,210,000
224,952,000
200,765,000
45,707,710
597,426,413
1,493,379,037
774,076,509
1,776,174,901
29,025,600
56,589,000
180,262,500
217,728,000
49,744,260
700,885,276
1,440,677,701
970,932,087
1,810,128,250
45,088,700
54,124,000
185,565,700
142,164,000
48,898,500
669,536,800
1,234,207,714
750,262,936
1,614,352,851
1
1
15
4
3
27
84
55
98
PPT
CHE
FED
FRE
MIL
UCH
MAN
POC
COLC
RAN
UNC
3,103,400
89,883,100
1,573,605,207
1,228,906,848
256,786,900
645,819,684
272,280,000
49,302,900
659,818,897
982,162,847
738,652,328
1,833,221,348
3,988,300
81,144,800
1,350,243,658
1,214,510,008
352,982,800
670,511,406
240,599,000
54,953,690
776,326,175
1,156,997,485
870,139,021
2,065,483,629
5,661,500
85,727,000
1,162,468,238
1,459,261,900
374,086,500
712,327,165
200,765,000
45,707,710
597,426,413
1,493,379,037
774,100,709
2,036,751,401
14,574,000
76,593,300
1,321,510,728
1,371,752,500
366,876,543
742,691,800
218,802,300
49,744,260
700,885,276
1,440,677,701
970,935,487
2,257,523,970
13,280,800
72,259,100
1,210,682,194
1,352,326,597
396,855,500
706,969,200
142,608,200
48,898,500
669,536,800
1,234,207,714
750,262,936
2,143,597,251
1
5
35
58
14
43
7
3
27
84
56
115
Public Reported
MGD
• Kent: Cheswold and Piney Point are largest sources for reported public use (1/3 each)
• Sussex: Unconfined (1/3) and Pocomoke (1/4), then confined Columbia and Manokin
Kent
2004Total
2005Total
2006Total
2007Total
2008Total
% (2007)
Sussex
2004Total
2005Total
2006Total
2007Total
2008Total
% (2007)
Total
2004Total
2005Total
2006Total
2007Total
2008Total
% (2007)
prev
MTL
0.009
0.011
0.016
0.040
0.036
0.2
MTL
0.009
0.011
0.016
0.040
0.036
0.4
RAN
0.246
0.222
0.235
0.210
0.198
1.9
PPT
4.311
3.699
3.185
3.621
3.317
32.3
CHE
3.367
3.327
3.998
3.679
3.581
32.8
FED
0.550
0.785
0.871
0.850
0.939
7.6
FRE
1.273
1.279
1.335
1.541
1.429
13.7
MIL
0.000
0.000
0.000
0.003
0.001
0.0
COLC
0.000
0.000
0.000
0.000
0.000
0.0
UNC
0.281
1.163
0.714
1.226
1.450
10.9
CHE
0.000
0.000
0.000
0.080
0.124
0.5
FED
0.154
0.182
0.154
0.155
0.148
1.0
FRE
0.497
0.558
0.616
0.494
0.508
3.3
MIL
0.746
0.659
0.550
0.597
0.389
4.0
UCH
0.135
0.151
0.125
0.136
0.134
0.9
MAN
1.808
2.127
1.637
1.920
1.834
12.9
POC
2.691
3.170
4.091
3.947
3.381
26.5
COLC
2.024
2.384
2.121
2.660
2.056
17.9
UNC
4.742
4.496
4.866
4.959
4.423
33.3
PPT
4.311
3.699
3.185
3.621
3.317
13.9
CHE
3.367
3.327
3.998
3.758
3.705
14.4
RAN
0.246
0.222
0.235
0.210
0.198
0.8
FED
0.704
0.967
1.025
1.005
1.087
3.8
FRE
1.769
1.837
1.952
2.035
1.937
7.8
MIL
0.746
0.659
0.550
0.599
0.391
2.3
UCH
0.135
0.151
0.125
0.136
0.134
0.5
MAN
1.808
2.127
1.637
1.920
1.834
7.4
POC
2.691
3.170
4.091
3.947
3.381
15.1
COLC
2.024
2.384
2.121
2.660
2.056
10.2
UNC
5.023
5.659
5.580
6.185
5.873
23.7
Public Non-Reported
Community: 1.31 MGD (479,735,667)
• Kent: 0.45 MGD (163,685,332)
• Sussex: 0.87 MGD (316,050,335 gals)
Non-Community Transient: 0.387 MGD (141,382,833 )
• Kent: 0.083 MGD (30,419,500 gals)
• Sussex: 0.304 MGD (110,963,333 gals)
Non-Community Non-Transient: 0.111 MGD (40,381,517 gals)
• Kent: 0.047 MGD (17,115,000 gals)
• Sussex: 0.064 MGD (23,266,517 gals)
Total: 1.81 MGD (661,500,017 gals)
• Kent: 0.58 MGD (211,219,832)
• Sussex: 1.23 MGD (450,280,185)
PWSEstPumpage w rev
Public Community Non-Reported
• Project & County Totals
calculated
– number of wells tabulated
– water use volumes calculated
by aquifer
– water use can be displayed by
map, symbolized or subtotaled
by census block
• Strengths & Weaknesses of
Data & Analysis
– census-based methodology for
service area, same coefficients
as used for domestic
will update CWS NR map
Public Community Non-Reported
Kent
Gallons/yr
PPT
CHE
FED
FRE
MIL
BLU
COLC
UNC
UNK
2,914,383
97,202,376
8,874,870
6,111,715
43,311,611
431,521
3,750,855
4,376,882
1,653,373
0.008
0.266
0.024
0.017
0.119
0.001
0.010
0.012
0.005
3
29
8
5
5
1
2
5
2
FRE
MIL
ORA
BLU
MAN
POC
COLC
UNC
UNK
20,476,085
23,890,467
6,436,395
6,403,838
60,989,226
46,273,035
91,805,834 101,990,388
21,557,640
0.056
0.065
0.018
0.018
0.167
0.127
0.252
0.279
0.059
5
8
4
2
18
22
33
36
11
MGD
Well Count
Sussex
Gallons/yr
MGD
Well Count
Kent+Sussex
Gallons/yr
MGD
Well Count
prev
PPT
CHE
FED
FRE
MIL
ORA
BLU
MAN
POC
COLC
UNC
UNK
2,914,383
97,202,376
8,874,870
26,587,800
67,202,078
6,436,395
6,835,359
60,989,226
46,273,035
95,556,689 106,367,270
23,211,013
0.008
0.266
0.024
0.073
0.184
0.018
0.019
0.167
0.127
0.262
0.291
0.064
3
29
8
10
13
4
3
18
22
35
41
13
Public Non-Transient Non-Community
• Project & County Totals
calculated
– number of wells tabulated
– water use volumes
calculated by aquifer
– water use can be displayed
by map, symbolized or
subtotaled by census block
• Strengths & Weaknesses
of Data & Analysis
– based on facility type, so a
leap of faith in assumed
water use (per capita user
or per facility size)
will update NCNT map
Public Non-Transient Non-Community
Kent
Gallons/yr
PPT
CHE
FED
FRE
MIL
UNC
UNK
8,575,000
1,725,000
980,000
2,765,000
1,125,000
2,080,000
600,000
0.023
0.005
0.003
0.008
0.003
0.006
0.002
2
3
4
12
1
5
1
MGD
Well Count
Sussex
CHE
Gallons/yr
MGD
Kent+Sussex
Gallons/yr
MGD
Well Count
prev
FRE
MIL
ORA
BLU
150,000 1,155,000
540,000
22,000
125,000
MAN
POC
COLC
UNC
UNK
835,833 5,760,000 5,509,100 8,916,667 1,587,500
0.000
0.003
0.001
0.000
0.000
0.002
0.016
0.015
0.024
0.004
Well Count
1
2
2
1
1
6
5
9
23
4
PPT
CHE
FED
FRE
MIL
ORA
BLU
MAN
POC
COLC
980,000 3,920,000 1,665,000
22,000
125,000
8,575,000 1,875,000
UNC
UNK
835,833 5,760,000 5,509,100 10,996,667 2,187,500
0.023
0.005
0.003
0.011
0.005
0.000
0.000
0.002
0.016
0.015
0.030
0.006
2
4
4
14
3
1
1
6
5
9
28
5
Public Transient Non-Community
• Project & County Totals
calculated
– number of wells tabulated
– water use volumes calculated
by aquifer
– water use can be displayed by
map, symbolized or subtotaled
by census block
• Strengths & Weaknesses of
Data & Analysis
– based on facility type, so a
leap of faith in assumed water
use (per capita user or per
facility size)
will update NCT map
Public Transient Non-Community
Kent
PPT
Gals/yr
CHE
FED
FRE
MIL
COLC
UNC
1,675,000 14,446,500
1,260,000
5,969,000
1,000,000
2,010,000
1,959,000
MGD
Well Count
MGD
Well Count
prev
2,800,000 31,119,500
0.005
0.040
0.003
0.016
0.003
0.006
0.005
0.008
0.085
4
16
3
9
1
3
6
4
46
FRE
MIL
ORA
BLU
Gals/yr
2,525,000
2,860,000
1,030,000
60,000
0.007
0.008
0.003
0.000
0.003
0.069
0.067
0.145
0.008
0.309
5
4
1
1
2
28
23
44
5
113
Well Count
Gals/yr
Total
Sussex
MGD
Kent+Sussex
UNK
PPT
MAN
POC
COLC
UNC
UNK
1,100,000 25,263,666 24,418,833 52,771,000
CHE
FED
FRE
MIL
ORA
BLU
1,675,000 14,446,500
1,260,000
8,494,000
3,860,000
1,030,000
60,000
MAN
POC
Total
2,751,500 112,780,000
COLC
UNC
1,100,000 25,263,666 26,428,833 54,730,000
UNK
Total
5,551,500 143,899,500
0.005
0.040
0.003
0.023
0.011
0.003
0.000
0.003
0.069
0.072
0.150
0.015
0.394
4
16
3
14
5
1
1
2
28
26
50
9
159
Domestic
Self-Supplied
• Total & County
estimates by year
– MGD
– per person
• Map of Use By Block
• Table of Use By Aquifer
• Strengths &
Weaknesses of Data &
Analysis
– complete inventory of
all active wells not
available
– census-based water-use
coefficient is calibrated
to public domestic use
Domestic Self-Supplied
Kent
1,546,648,769 gallons/yr = 4.24 MGD
60,604 self-supplied residents
69.9 gals/pp/day
Sussex
2,690,000,000 gallons/yr = 7.37 MGD
96,451 self-supplied residents (plus up to 15,339 average
non-resident population in self-supplied housing in summer)
76.4 gals/pp/day
Domestic Water Use Census Block Totals on Pivot
Domestic Self-Supplied
unconfined aquifer is largest source, supplying more than 2/3 of domestic self-supplied water
Kent
PPT
RAN
CHE
FED
FRE
MIL
ORA
BLU
COLC
UNC
Total
Gallons
69,334,051
31,074,968
236,148,160
56,375,442
72,318,972
33,450,555
1,560,151
10,394,432
28,499,827
1,007,493,785
1,446,241,324
MGD
0.190
0.085
0.647
0.154
0.198
0.092
0.004
0.028
0.078
2.760
3.96
Percent
4.8
2.1
16.3
3.9
5.0
2.3
0.1
0.7
2.0
69.7
Sussex
CHE
FED
FRE
MIL
ORA
BLU
MAN
POC
COLC
UNC
Total
Gallons
2367688.981
527600.3932
24623640.96
17846720.59
4025907.085
4048993.959
104657505.8
166550668.6
552609112.5
1812726044
2,689,983,883
MGD
0.006
0.001
0.067
0.287
0.049
0.011
0.011
0.456
1.514
4.966
7.370
Percent
0.1
0.0
0.9
0.7
0.1
0.2
3.9
6.2
20.5
67.4
Kent +
Sussex
RAN
PPT
CHE
FED
FRE
MIL
ORA
BLU
MAN
POC
COLC
UNC
Total
Gallons
31,074,968
69,334,051
238,515,849
56,903,043
96,942,613
51,297,276
5,586,058
14,443,426
104,657,506
166,550,669
581,108,939
2,820,219,829
4,136,225,207
MGD
0.085
0.190
0.653
0.156
0.266
0.141
0.015
0.040
0.287
0.456
1.592
7.727
11.332
Percent
0.8
1.7
5.8
1.4
2.3
1.2
0.1
0.3
2.5
4.0
14.0
68.2
Groundwater Use Totals
So, these results allow us to chop-slice-and-dice
water use data/estimates from many angles
• Project Total
• County Totals
• By Block
• By Aquifer
• By Use
• By Year
USE
Kent
MGD
Sussex
MGD
Total
MGD
Public Reported (high use yr)
11.0
15.2
26.2
Public Reported (low use yr)
10.1
12.7
22.8
Public Non-Reported (estimated)
0.58
1.23
1.81
Domestic self-supplied (model)
4.24
7.37
11.61
Industrial self-supplied (high use yr)
1.35
6.96
7.66
Industrial self-supplied (low use yr)
0.83
5.56
6.66
Irrigation: Ag (model high use 2007)
19.12
71.69
90.82
Irrigation: Ag (model low use 2006)
5.62
44.53
50.16
Irrigation: Golf Course (median rpt+est)
0.17
2.00
2.17
Ag: Lawn wells (estimated)
0.008
0.022
0.03
Ag: Livestock (estimated)
0.7
3.6
4.3
Total (high end)
37.2
108.1
144.6
Total (low end)
22.2
77.0
99.5
Groundwater Use Totals
Summary by Aquifer
MTL
0.02
0.04
RAN
PPT
CHE
FED
FRE
MIL
MCH
UCH
MAN
0.02
0.12
1.52
0.58
2.57
1.18
1.38
0.77
7.75
7.06 10.86 57.12
0.04
0.08
0.02
0.22
0.08
0.04
0.14
0.26
1.04
0.21 3.621 3.758 1.005 2.035 0.599
0.136
POC
1.92 3.947
COLC
2.36
UNC
UNK
Irrigation (2007)
4.3
Livestock
0.03
Lawn (self-supp)
2.75
Golf
Public
Reported(2007)
2.66 6.185
0.008 0.266 0.024 0.073 0.184 0.018 0.019 0.167 0.127 0.262 0.291 0.064
0.023 0.005 0.003 0.011 0.005
0.005
0.085
0.19 0.653 0.156 0.266 0.141 0.015
0.02
0.54
0.02
Non-Community
Non-Transient
Non-Community
0.003 0.069 0.072 0.15 0.015
Transient
Domestic Self
0.04 0.287 0.456 1.592 7.727
Supplied
0.002 0.016 0.015
0.04 0.003 0.023 0.011 0.003
Community NR
0.89
2.17
0.02
0.03 0.006
3.69
Industrial (2007)
0.06
0.38
4.05
6.80
2.01
5.06
2.16
1.42
1.11 11.28 14.89 17.84 82.27 0.085
Total MGD
0.04
0.25
2.71
4.55
1.35
3.39
1.45
0.95
0.74
Percentage
preliminary sum of maximum estimates
7.55
9.96 11.94 55.07
0.06
Groundwater Use Totals
By Census Block
• Tabular Form
• Map Form
Summary and Wrap-Up
Starting Premise
Accurate Understanding of Aquifer
Geology
is essential to
Accurate Understanding of
Groundwater Occurrence
Geology controls where the groundwater is,
where it goes, and how much we get
For Kent and Sussex Counties, this project highlights
where Source Water Protection intersects Geology
• Understanding Aquifers. We started with
identification of aquifers in boreholes and then
mapping aquifers in Kent and Sussex Counties
• Tabulating Water Use. We brought water use into
the picture by tabulating all records of water use
from Kent and Sussex Counties, and by estimating
water use where complete, high-quality data were
not available
• Identify Groundwater Sources. We identified the
sources of public drinking water (and water for other
uses) by projecting well screen depths onto digital
aquifer grids
Benefits
• Protection. The results will contribute to accurate
delineation of these public water supply resources,
and potential groundwater flow pathways, to
support source water protection efforts in Delaware
• Permits. The geologic products will also support
identification of aquifers for well permitting
• Planning. The water use products will be useful for
water supply planning efforts, such as the current
Kent-Sussex focus of Delaware’s Water Supply
Coordinating Council
Funding by:
Thank you