hydrogeological modeling of the pullman-moscow basin basalt aquifer system, wa and id
DESCRIPTION
Hydrogeological Modeling of the Pullman-Moscow Basin Basalt Aquifer System, WA and ID. Joan Wu, Farida Leek, Kent Keller Washington State University John Bush University of Idaho. OUTLINE. Introduction Hydrogeologic Setting Methodology GIS database development Ground-water flow modeling - PowerPoint PPT PresentationTRANSCRIPT
Hydrogeological Modeling of the Pullman-Moscow Basin Basalt
Aquifer System, WA and ID
Joan Wu, Farida Leek, Kent Keller Washington State University
John Bush
University of Idaho
2
OUTLINE
Introduction Hydrogeologic Setting Methodology
GIS database development Ground-water flow modeling
Results and Discussions Summary Position Announcement
3
INTRODUCTION
The aquifer system in the CRBG is the sole water supply source for the Palouse Basin
The continuous water-level decline and the projected future development have led to serious public concerns
PBAC: a multi-stakeholder, multi-agency (city, county, university) organization promoting conservation and sound ground-water management
The 2003 MOA with PBAC: GIS database
4
INTRODUCTION (cont’d)
Past Studies on Hydrogeological Characterization Crosby and Cavin (1960) Foxworthy and Washburn (1963); Jones and Ross
(1972) Bush and colleagues (1998, 2000, 2001, 2003)
Past Studies on Groundwater Modeling Barker (1979), overly conservative Lum et al. (1990), overly optimistic Both models proved inadequate by year 2000
5
INTRODUCTION (cont’d)
Goal To develop a foundation for improved and informed
Palouse Basin groundwater resources assessment and management
Objectives To develop a hydrogeology GIS database for the
Palouse Basin to improve data accessibility and data processing and analysis efficiency
To develop a groundwater flow model for the basaltic aquifer system of the Pullman-Moscow area based on new spatial and temporal data
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HYDROGEOLOGIC SETTING
Palouse loess Saddle Mts. Wanapum basalt Grande Ronde basalt Imnaha basalt Pre-basalt
CRBG
7
HYDROGEOLOGIC SETTING (cont’d)
Palouse loess: rural domestic use Wanapum basalt: major aquifer for Moscow
till 1960’s Grande Ronde basalt: source for more than
90% of water supply, with a recent construction of WSU #8
Occurred during late Miocene and early Pliocene (17–6 mya BP)
Engulfing ~ 1.6×105 km2 of the Pacific Northwest between Cascade Range and Rocky Mt., covering parts of ID, WA, and OR
Over 300 high-volume individual lava flows identified, along with countless smaller flows, with vents up to 150 km long
Eventually accumulating to more than 1,800 m thick
Tectonic origin (Hooper, 1997) Yellowstone hot spot Thinning of continental
lithosphere due to spreading behind Cascade arc
Proximity of fissure vents to tectonic boundary between accreted terranes and lithospheres of old N. Am. Plate
Source: USGS, http://vulcan.wr.usgs.gov/
Source: ND Space Grant Consortium, http://volcano.und.edu/
12
METHODOLOGY:I. GIS DATABASE DEVELOPMENT Data Collection
Well log Groundwater level Pumpage Precipitation Geochemistry
Data Compilation Digitizing into ArcGIS Processing existing and new coverages:
• Topography• Township and range to UTM conversion of well coordinates• Stream network• Land use• Soil• Watershed boundary
Digitizing & Processing Well Data
Well 15/46-31J1 Well 39N/5W-7ad2
A
R 45E R 46E R 6 W R 5 W T 16N T 4 0 N
T 15N T 3 9 N
T 14N T 3 8 N
WASH
ING
TON
IDA
HO
R 46E
6 5 4 7 8 9
T 15N 18 17 16
19 20 21
30 29 28
31 32 33
R 5 W
6 5 4 3 2 1 7 8 9 10 11 12 18 27 16 15 14 13 19 20 21 22 23 24
30 29 28 27 26 25
31 32 33 34 35 36
D C B A
E F G H
M L K J
N P Q R
b a
c d a
Digitizing & Processing Well Data cont’d
17
Data Analysis Plot long-term hydrographs
• Separate vs composite• Their relations with precipitation and pumpage
Build structural contour maps• To depict the shape of stratigraphic horizons
Construct aquifer contour maps• Wanapum• Grande Ronde
Develop hydrogeological cross-sections• Across most of the basin• In various directions
METHODOLOGY:I. GIS DATABASE DEVELOPMENT
RESULTS AND DISSCUSSION:I. GEOSPATIAL DATA ANALYSIS
Composite Hydrograph for Palouse Basin Aquifer
Year1923 1931 1939 1947 1955 1963 1971 1979 1987 1995 2003
Wat
er L
evel
Ele
vatio
n, a
.m.s
.l., f
t
2200
2250
2300
2350
2400
2450
2500
2550
2600
2650
2700
2200
2250
2300
2350
2400
2450
2500
2550
2600
2650
2700
Moscow # 1 Moscow # 2 Private well (Freight)UI # 2Moscow # 3 Moscow-Arden UI-Irrigation UI # 1 Moscow # 7Cemet. well
Private well (Carson) Jones EvelandUSGS
Wanapum
Palouse LoessPullman # 1 Pullman # 2 Pullman # 3 Moscow # 6 Moscow # 9 UI # 4 Pullman # 4 Pullman # 6 WSU # 3 WSU # 4 WSU # 5 WSU # 6 WSU # 7 UI # 3 Pullman # 5 WTESTPullman # 7 Moscow # 8 Grande Ronde
Composite Hydrograph of Wells in the Palouse Basin
Long-term Hydrograph for Pullman and WSU Grande Ronde Wells
Year
1974 1977 1980 1983 1986 1989 1992 1995 1998 2001 2004
Wat
er L
evel
, Ele
vatio
n, a
.m.s.
l., ft
22302235224022452250225522602265227022752280228522902295230023052310
22302235224022452250225522602265227022752280228522902295230023052310
Pullman 3 Pullman 4 Pullman 6 Pullman 5 Pullman 1 Pullman 2 Pullman 7 DOEWSU 3 WSU 4 WSU 5 WSU 6 WSU 7 WTEST
Long-term Hydrograph for Moscow and UI Grande Ronde Wells
Year
1974 1977 1980 1983 1986 1989 1992 1995 1998 2001 2004
Wat
er L
evel
Ele
vatio
n, a
.m.s.
l., ft
22202225223022352240224522502255226022652270227522802285229022952300
22202225223022352240224522502255226022652270227522802285229022952300
Moscow 6 Moscow 8 Moscow 9 UI 3 UI 4
(a)
Year
1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Annu
al P
umpa
ge, M
GY
0
500
1000
1500
2000
2500
3000
3500
Annual precipitation, mm
Pullman pumpageMoscow pumpageTotal pumpagePullman precipitationMoscow precipitation
(a)
0
500
1000
Long-term Groundwater Pumpage from Two Aquifers
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Long-term Hydrographs
Each aquifer has a distinct pattern of water-level fluctuations in relation to pumping, climate, recharge
Wanapum saw its groundwater level recovery since 1960’s when pumping shifted to the Grande Ronde
Relatively more consistent pattern of fluctuation in Grande Ronde wells in Pullman than in Moscow
0.3–0.6 m/yr groundwater level decline observed at both pumping centers
Contour Map of Top Altitude of Wanapum Formation
Contour Map of Top Altitude of Grande Ronde Formation
32
Structural Contour Maps
Wanapum Wanapum basalt is to the NW controlled by NW
trending folds, and dips and thickens E and W away from Pullman
Grande Ronde The top of GR drops in elevation E towards Moscow
and W and NW away from Pullman Substantial lateral changes in the occurrence and nature
of sediments exist between Pullman and Moscow
Potentiometric surface contour map of the Wanapum aquifer (1960s)
Potentiometric surface contour map of the G. Ronde aquifer (1990s)
35
Potentiometric Surface Contour Maps
Wanapum Hydraulic connection between Pullman and Moscow is
weak General groundwater movement is to W and NW
Grande Ronde Piezometric surface shows two cones of depression as
a result of heavy pumping The open shape of cones of depression to the W and
NW is possibly controlled by structural features
METHODOLOGY:II. DEVELOPING A NEW MODEL
41
Water Release from a Confined Aquifer: Water Expansion + Aquifer Compression
Source: http://www.bae.uky.edu/sworkman/AEN438G/theiseq/theiseq.html
42
Unsteady-State Flow in “Ideal” Aquifer: Theis (1935) Equation
Source: http://www.olemiss.edu/sciencenet/saltnet/theisbio.html
“The flow of ground water has many analogies to the flow of heat byconduction. We have exact analogies … for thermal gradient, thermalconductivity, and specific heat…solution of some of our problemsis probably already worked out in the theory of heat conduction…”
43
Unsteady-State Flow in “Ideal” Aquifer: The Solution
“Actually derived by a mathematician friend of Theis, C.I. Lubin.Reportedly, Lubin declined co-authorship of the paper becausehe regarded his contribution as mathematically trivial.” [Fetter, 1994]
44
Groundwater Flow Model Development
Industry standard MODFLOW MODular 3-d finite-difference
groundwater FLOW model Free source codes from the USGS
and GUI versions available
PEST (nonlinear parameter estimator) can be used with MODFLOW for optimal parameterization
Source: http://water.usgs.gov/nrp/gwsoftware/modflow2000/modflow2000.html
45
Comparison of Model Domain and Structure
Barker (1979)Western BC at Union Flat Cr.;One lumped basalt aquifer; “single-layer-cake”
Lum et al. (1990)
Western BC at Snake R.;Palouse Loess + two separate basalt aquifers, layers horizontal
New ModelWestern BC as in Barker (1979);Three model layers with actual top/bottom altitudes
46
Barker (1979) Dirichlet (head) at Union Flat Cr. for lumped aquifer
Lum et al. (1990) Cauchy (weighted head and flux) at Snake R. for all three aquifers
New Model Same as in Barker (1979) but for three distinct aquifers
Comparison of Western Boundary Condition
47
Comparison of Hydraulic Parameterization
Barker (1979)Uniform hydraulic properties within zones:Kh = Kv = 0.03–7.9 m/d, S = 0.005
Lum et al. (1990)
Uniform hydraulic properties within zones of each aquifer:Loess: Kh = 1.5 m/d, Kv = 0.02 m/d
Wanapum: Kh = 0.1–0.2 m/d, Kv = 2.4–3.6×10−4 m/d
Grande Ronde: Kh = 0.1–3.7 m/d, Kv = 3.1–76×10−5 m/d
S = 0.001
New Model Apply inverse modeling to a wealth of historical head data for greatly improved parameterization
Comparison of Hydraulic Parameterization
48
Barker (1979) 17 mm yr−1 uniform across model domain
Lum et al. (1990) 71 mm yr−1 uniform across model domain
New Model
Spatially varying following O’Green (2005):3 mm yr−1 in 33% (near Moscow Mt.),10 mm yr−1 in 37% (Pullman area),actual infiltration in 10% (valleys) of the basin area
Comparison of Recharge Distribution
49
Aerial RechargeRecharge needs: 14 mmWinter wheat consumes up to 90% annual precipitation of 550 mmWinter runoff loss unavoidable from conventionally farmed fieldsLow permeability across Bovill sediment–Wanapum basalt contact in places
Transporting Surface Water from Snake R.Economic feasibility low but of potential
Artificial RechargeOf greatest potential when using streams incised into WanapumGround-water modeling imperative in determining the effectiveness
Given: pumpage needs 2,400 MGY = 9.1×106 m3, basin area 660 km2
Management Alternatives
50
SUMMARY AND CONCLUSIONS
GIS database has in the first time brought together the various scattered data pertinent to PBA hydrogeology and placed it in uniform and easily accessible form
Such database facilitates efficient data retrieval and analysis and allows continuous updating and refinement, forming a solid foundation for future trans-boundary hydrogeolocial investigation
A great deal has been learned from this newly available digital temporal and spatial data
Development of an improve basin-scale groundwater flow model is underway
THANK YOU !
52
Pullman─Moscow Cross-section
Pullman─Moscow Cross-sectionPullman side Less sedimentary interbedding Loess is in direct contact with the basalt Wanapum is unproductive
Moscow side More sedimentary interbeds Wanapum is highly productive Current hydraulic gradient and ground-water flow in
Grande Ronde between Pullman and Moscow is minimal, reflecting good hydraulic connection and lack of dike barrier as suggested by some scientists
53
Long-term Hydrographs Revisit
Relatively consistent pattern of fluctuation in Grande Ronde wells in Pullman Aquifer is shown to have been depressurized!
Greater fluctuation in Grande Ronde wells in Moscow due to Multi-layered sediment system Proximity to low-permeability boundaries created by
non-basaltic rocks Confined nature of aquifer All these factors tend to cause longer recovery period
for the wells to reach equilibrium
54
Pullman─Albion─Colfax Cross-section
Fracture patterns and degree of weathering dominantly control the productivity of wells
Grande Ronde dips eastward towards Colfax with a hydraulic head drop of 150 m
Intrusion of low-permeability pre-Tertiary rocks are considered to form barriers between Pullman and Colfax and cause the drastic change in hydraulic head
Certain previous pump test results may be questionable; substantial ground-water flow from Pullman to Colfax appears unlikely
55
Pullman–Union Flat Creek–Snake River Significant difference (~460 m) exists in hydraulic heads
of the Wanapum and Grande Ronde near the Snake R.; this sudden change in head may be related to the dip of the basalt flows to the NW away from the Snake R.
Cross-sections and potentiometric surface maps suggest a major flow direction of NW along the Snake R.; significant seepage along the canyon walls of the Snake R. from the Grande Ronde aquifer is unlikely
Geochemistry data from previous studies (Larson et al., 2000) also indicates a lack of Grande Ronde discharge to the Snake R.
56
SUMMARY AND CONCLUSIONS (cont’d)
Long-term trends of the hydrographs indicate weak vertical hydraulic connection between the two basalt aquifers, consistent with pervious isotope geochemistry studies
Each aquifer exhibits a distinct pattern of water-level fluctuation as affected by pumping, climate and recharge, with the top basalt aquifer seemingly receiving Holocene precipitation recharge and the bottom aquifer pre-Holocene recharge
57
SUMMARY AND CONCLUSIONS (cont’d)
Potentiometric surface contour maps of the basalt aquifers display a general pattern with the ground-water level dipping S–NW along the ancient basalt flow
Existing structural features (monoclines, anticlines and synclines) tended to create local areas with rapid changes in water levels in the approximate direction of their major axis
Previous modeling studies using Snake R. as a Cauchy boundary and forced high recharge may have been the key causes of the model failures
58
SUMMARY AND CONCLUSIONS
Geologic and hydrogeologic conditions at the two cities of Pullman, WA and Moscow, ID in the Palouse Basin are rather different; yet the hydraulic connection appears strong
The nature and position of stratigraphic units and their inherent spatial heterogeneity together with geologic structures have significant effects on the ground-water flow regime in a fractured complex basalt system, which should be carefully taken into account in future modeling efforts