Advances in Geophysical Tools for Estimating Hydrologic Parameters and Processes Kamini Singha Hydrologic Science and Engineering Colorado School of Mines

With contributions from: Andrew Binley, Fred Day-Lewis, Tim Johnson, Niklas Linde, Burke Minsley, Dale Rucker, Frédéric Nguyen, Jonathan Nyquist, Adam Pidlisecky, Lee Slater, Remke Van Dam, Jan van der Kruk Motivation Need to quantify the operation of aquifer parameters controlling flow and transport • To determine availability of water for removal • To assess risk & create schemes for contaminant cleanup hydraulic contaminant conductivity concentration high Z Z

Y low X [Singha, CSM] X Motivation

The problem…

[Hartman et al., JCH, 2007]

[British Geological Survey, 2004]

[Binley, Lancaster] [British Geological Survey, 2004] Motivation

We have these:

[Binley, Lancaster] Motivation

Or we might be lucky and have one of these: [LeBlanc et al., 1991, WRR, Large-scale natural gradient tracer test in sand and gravel, Cape Cod, Massachusetts, 1, Experimental design and observed tracer movement] Advantages of

Geophysics offers advantages over conventional sampling to the hydrologist because of:

High data sampling density Relative lower cost of measurements Minimally invasive Larger measurement volume

[Binley, Lancaster] spatial extents spatial small over information high resolution chartprovide the near of end this approaches Acquisition

SCALES OF INVESTIGATION Scale of measurement

Laboratory or Local Regional Point

~10-4 to 10-1 ~10-2 to 102 ~101 to 104 m Measurements ~10 Logging (G,H) Wellbore High Moderate Low High Moderate - (G,H) Core 3 to 1~10 RELATIVERESOLUTION measurements (G,H) (G,H) measurements Crosshole and well tests (H)well tests and - 1 to 10 ~10 to to 10 10 (G) Geophysics Surface [Rubin and Hubbard,2005,[Rubin and Airborne/Satellite (G, H) 2

m spatial extents spatial large over information low resolution chartprovide the near of end this approaches Acquisition

Hydrogeophysic s]

History

Early geophysical studies concentrated on defining lithological boundaries and other subsurface structures.

[Zohdy, 1965, GW, Geoelectrical and seismic refraction investigations near San Jose, California] Moving Forward with Static Images

• Can distinguish lithologic units in some geologic settings • Characteristics of GPR reflectors differs with depositional environment

[Jol and Smith, 1991, CJES, Ground Penetrating Radar of Northern Lacustrine Deltas]

History

• During the 1990s there was a rapid growth in the use of geophysics to provide quantitative information about hydrological properties and processes.

• Much of this was driven by the need to gain information of direct value to hydrological models, particularly given the developments of ‘data hungry’ stochastic tools.

[Tiedeman and Hsieh, 2004, WRR, Evaluation of longitudinal dispersivity estimates from simulated forced- and natural- gradient tracer tests in heterogeneous aquifers] [Binley, Lancaster] Common Geophysical Tools Used in Hydro

Method Property of Interest Gravity Density Seismics Seismic velocity Direct-current resistivity Electrical conductivity Induced polarization Chargeability Electromagnetic induction Electrical conductivity Ground-penetrating radar Dielectric permittivity Some Hydrologic Problems Where Geophysics Can Help

• Determining preferential pathways • Quantifying movement of conductive contaminants • Monitoring gas transport • Exploring -surface water exchange • …

A few applications… Imaging preferential pathways: GPR

Surface radar reflectance for a 0.9 x 2.0 m area

Higher moisture Higher

Before water release

Higher moisture Higher Water released to After addition of 26.5 liters flow down slope from a shallow trench. [Nyquist et al., in prep] [Nyquist, Temple] Fractured Rock: ER

4 h injection @ 15 m depth 38 g/L NaCl @ 500 L/h ? ? ? ? ? ? ?

4.5 hours

[Robert et al., 2012, Geophysics, A salt tracer test monitored with surface ERT to detect preferential flow [Nguyen, Liege] and transport paths in fractured/karstified limestones] Hydrofacies from GPR & direct-push data

Coupling high-res characterization tools to improve flow and transport simulations at MADE site: • Full-resolution 3D GPR • Direct-push K measurements (HRK)

[Dogan, Van Dam, Bohling, Butler, Hyndman, 2011, GRL, Hydrostratigraphic analysis of the [Van Dam, MSU] MADE site with full-resolution GPR and direct-push hydraulic profiling] Enhanced gold recovery: ER

(A) 8:48am (1.6 hrs) (B) 10:29am (3.3 hrs) (C) 12:09pm (5.0 hrs)

N

111.2 110.1 111.2 110.1 111.2 110.1 111 111 111

60 60 60

30 30 30

102.1 101.1 80 102.1 101.1 80 102.1 101.1 80 50 50 50

(D) 2:04pm (6.9 hrs) (E) 4:13pm (9.0 hrs) (F) 11:51pm (16.7 hrs)

110.1 111.2 111.2 110.1 111.2 110.1 111 111 111

60 60 60

30 30 30

102.1 101.1 80 102.1 101.1 80 102.1 101.1 80 50 50 50 * Distance data are in meters Imaging subsurface injection of 800 gpm using 150 [Rucker, Crook, Winterton, McNeill, Baldyga, electrodes on surface and within 6 boreholes. Isopleths Noonan, and Fink, in review, NSG] represent 3, 6, and 12% change in resistivity from [Rucker, HGP] background conditions (prior to injection) Geothermal applications: ER Heated water (48°C) was injected for 70 hours at the rate of 87 L/h in Thermography a 10.5°C aquifer.

Observed (o) and modeled (-) temperature log

[Hermans et al., 2012, Geophysics, A shallow geothermal experiment [Nguyen, Leige] in a sandy aquifer monitored using electric resistivity tomography] How is free-phase carbon gas distributed in peatlands? (GPR)

? Shrubs & trees

? Forested Crest [Parsekian, Comas, Slater, and Glaser, 2011, JGR, Geophysical evidence for the lateral distribution of Sturgeon River Bog, MN free phase gas at the peat basin scale in a large [Slater, Rutgers] northern peatland] Mineral soil contact

[Slater, Rutgers] [Slater, Rutgers] Effective rooting depth: ER Time-lapse ER for soil moisture dynamics

reveals rooting depth  May differences of forest 10m and grassland.  August 50m Volumetric moisture

Data enables improved root parameterization in global climate and landscape hydrology models.

[Jayawickreme, Van Dam, Hyndman, 2008, GRL, Subsurface imaging of vegetation, climate, and root- zone moisture interactions ] [Van Dam, MSU] Infiltration Pond Study: ER

~100m

~300m

[Pidlisecky, Cockett, Knight, 2012, VZJ, The development of electrical conductivity probes for studying processes: advances in data acquisition and analysis]

[Pidlisecky, Calgary] Time

[Pidlisecky, Calgary] In some cases it is difficult to get access to what we want to look at even with conventional methods

[Binley, Lancaster] Groundwater-Surface Exchange: FLIR

• Thermographic images collected in Kansas to explore gw-sw exchange

[Loheide and Gorelick, 2005, RSoE, A High-Resolution Evapotranspiration Mapping Algorithm (ETMA) with Hydroecological Applications at Riparian Restoration Sites] Tracer lingering in hyporheic zone: ER 3. Porewater sampling of frozen core confirms tracer

1.Well breakthrough curves

2. Electrical evidence of tracer along stream flow direction

[Toran, Nyquist, Fang, Ryan, and Rosenberry, 2012, HP, Observing heterogeneity in hyporheic flow with electrical resistivity and subsurface well sampling during a stream tracer test] [Nyquist, Temple] Some Questions About Exchange Controls 1. How seasonally and spatially consistent is the size of the hyporheic zone? 2. How are changes controlled by valley- scale morphology and gradient?

[Singha, CSM] Tracer Injections During Baseflow Recession

33 L/s 15 L/s 7 L/s 4 L/s

[Ward, Fitzgerald, Gooseff, Voltz, Binley, Singha, 2012, WRR, Hydrologic and geomorphic controls on hyporheic exchange during baseflow recession in a headwater mountain stream] 33 L/s 7 L/s 4 L/s Depth, 3 h in m

Distance, in m 6 h

% Change 12 h in Bulk Cond 24 h

48 h

+6 h

+24 h

[Singha, CSM] Many, many applications

• Mapping depth to rock, lithologic changes • Monitoring changes in soil moisture, injection of ionic compounds quantify clogging of infiltration ponds, fracture patterning, operation of parameters controlling flow and transport • Imaging carbon gas • Exploring changes in temperature in the subsurface • Quantifying hyporheic zone extent • … We also spend a lot of time trying to figure out what

goes on in a small part of the ground …

Depth Depth (m)

[Binley et al., JoH, 2002] [Singha and Gorelick, WRR, 2005] [Binley, Lancaster] … when lots of folk need to know what is happening at a larger scale.

[Binley, Lancaster]

Hanford 300 Area

East from the Hanford 300 Area

Contamination legacy: 241 metric tons of copper 117 metric tons of fluorine 2060 metric tons of nitrate 33 and 59 metric tons of uranium

[Slater et al., 2010, WRR, Use of electrical imaging and What is the spatial and distributed temperature temporal variability in sensing methods to characterize surface water– exchange between groundwater exchange uranium contaminated regulating uranium transport groundwater and river at the Hanford 300 Area] water? [Slater, Rutgers]

Figure 1: ERI-IP boat track locations (white); FO-DTS cable (red); high resolution ERI- IP survey (green). Yellow line indicates the suggested U contributing area to the Columbia River (Fritz et al., 2007); Orange contour lines are for Uranium concentration (ug/L) (PNNL - 16435) 300 Area Geology & Exchange Pebble to boulder size TemperatureImprovements Measurements in hydrogeological in the area with exchangegravelsCorrelation and interbeddedCoefficient between Temperature and River Stage 6 0 framework required along corridor sands 4of surface-water/groundwater [Higher -0.1K ~ 100 m/day] exchange 2 -0.2 aquifer/river interaction is 0 -0.3

Temp (°C) Temp increasingly considered to exert a -2dominant control AND IMPART -0.4 COMPLEXITY on transport at the Coefficient Correlation -4 -0.5 60 site65 70 60 65 70 Julianday Julianday Interpolated River Stage) 0.6

0.4

0.2 Highly heterogeneous, 0 granule to cobble size River Stage (m) Stage River -0.2 gravels interbedded

-0.4 with fine sand and silt. 60 65 70 [Lower K – 0.2 m/day,] [Slater, Rutgers] Julianday GW-SW exchange: DTS, ER, IP

• Spatial geometry of Hanford and Ringold Units

• Identification of focused exchange: temperature anomalies at low stage; correlation between stage and temperature occur where Hanford unit thickest; exchange muted/absent where Hanford is thinnest

DTS data

Inverted image at 7 m locally-incised paleochannels? [Slater, Rutgers] a b c Winter CC * Summer CC <1 -0.6 -0.3 0 -0.25 0.25 0.75 250 * 1-2 5 13.5 24 16 25 34 2-3 o Winter T ( C) Summer T (oC) 3-4 Deep H-R contact, 4-5

temperature 500 5-6 6-7 anomalies and stage- temperature 7-8 8-9 correlation coincide 9-10

with known uranium 750 10-11 >11 seeps (but there Hanford Formation appear to be others) Thickness (m)

1000 Shallow H-R

contact, no

temperature

anomalies, and no 1250

known uranium

seeps

1500 [Slater, Rutgers] • 37 Even bigger: airborne geophysics Airborne resistivity: ~ 100 km / hour

Easting, in km

Ground-based resistivity ~ 1 km /day

Lake talik permafrost

Distance, in km

[Minsley, USGS] Informing groundwater models in Nebraska As of 2007 NE is the top irrigator in the US surpassing CA and TX irrigators.

Cost of irrigating from wells in NE in 2008: $43/ac TX: $105/ac, CA: $114/ac [2008 Farm and Ranch Irrigation Survey, USDA, National Agricultural Statistics Service]

2004 passage of LB962, meant to strike a balance between water supply and water demand in the state's river basins, put a cap on new irrigation development across much of the state.

[Minsley, USGS] [Abraham et al., 2012, Airborne Electromagnetic Mapping of the Base of Aquifer in Areas of Western Nebraska, US Geological Survey Scientific Investigations Report, 2011-5219]

[Minsley, USGS] Permafrost Mapping

[Minsley et al. 2012, GRL, Airborne Electromagnetic Imaging of Discontinuous Permafrost]

[Minsley, USGS] Geophysical monitoring of seawater intrusion

[Fitterman and Deszcz-Pan, 1998, EG, Helicopter EM mapping [Minsley, USGS] of saltwater intrusion in EvergladesFitterman National and Park, others, Florida] 1998- Resistivity & Induced Polarization GPR 0

-5

-10 0 5 10 15 20 25 30 35 40 45 50 55 60 0

-5

-10 0 5 10 15 20 25 30 35 40 45 50 55 60

Ground Conductivity Push rod 90 Local sampling logs 80 and geology

70 24 23 22 60 21 20 19 50 18 17 16 40 15 14 13 30 12 11 10 9 20 8 7

10

0 0 10 20 30 40 50 60

How do we bring all these data together to form one

[Binley, Lancaster] consistent, improved model of the system? A Problem

• Geophysical methods image rock properties not necessarily related to hydraulics • Need appropriate relation to use geophysical information quantitatively • How do we relate geophysical parameters to hydrologic properties? State of The Practice Hydrogeophysical studies often use a lab-scale or field-local petrophysical relation to estimate the parameter of interest in the field

truth geophysical hydrologic parameter parameter data estimate rock collection physics & inversion

[Singha, CSM] A Large Inverse Problem… Minimize data misfit and model misfit

d m 2 2 Wd (F(m) d) Wm (m m0 ) where α is a trade off parameter between model misfit and data misfit that determines the relative contribution of each misfit type

Problem: may have 1000s of data and 10s of

[Singha, CSM] 1000s of parameters Impact of Variable Resolution

Nugget CORRELATION

[Day-Lewis, Singha and Binley, 2005, JGR, The application of petrophysical models to radar and electrical resistivity tomograms: resolution dependent limitations] A big challenge

Geophysical data that is (sometimes) linked to our hydrological property of interest.

We may have multiple datasets measuring different geophysical properties at different support volumes and at different resolution and accuracy.

But we will also have other hydrological, hydrogeological and geochemical data together with a starting conceptual model of our site. Alternate Parameterizations: GPR w/ 1600 data

[Pidlisecky, Singha and Day-Lewis, 2011, GJI, A novel parameterization for improved time-lapse tomographic imaging of hydrologic processes] Alternate Parameterizations: GPR w/ 100 data

[Pidlisecky, Singha, Day-Lewis, 2011 GJI] Advances in Inversion Techniques Ray Based Methods Waveform Methods

Input data: Input data: • First arrival times • Significant parts of wavefields • First cycle amplitudes • Inversion based on Maxwell’s Eq. Observed data

3

4

first-cycle amplitude 5

6

7 first-arrival [m]depth Receiver 8 full-waveform first arrival full-waveform times 9

first cycle 80 90 100 110 120 130 140 150 160 Time Time [ns] amplitudes Time [ns] inexpensive, coarse structures detailed sub-wavelength structures, more expensive

[van der Kruk, Julich] Advances in Inversion Techniques Ray-based Inversion Results

VelocityVelocity - Full-waveform - Traveltime Inversion Inversion ConductivityConductivity - -First Full-waveform Cycle Amp. Inversion Inversion

5 5

6 6

7 7

Depth [m] Depth

Depth [m] Depth [m] Depth Depth [m] Depth

8 8

9 9

1 2 3 4 5 6 1 2 3 4 5 6 Distance [m] Distance [m]

60 65 70 75 80 85 90 95 2 0.4 3 0.64 5 60.8 7 8 9 10 1 151.2 20 25 v [m/ s] [mS/m]

[van der Kruk, Julich] Advances in Inversion Techniques Full-Waveform Inversion Results

Velocity - Full-waveform Inversion Conductivity - Full-waveform Inversion

5 5

6 6

7 7

Depth [m] Depth [m] Depth

8 8

9 9

1 2 3 4 5 6 1 2 3 4 5 6 Distance [m] Distance [m]

60 65 70 75 80 85 90 95 2 3 4 5 6 7 8 9 10 15 20 25 v [m/ s] [mS/m]

[van der Kruk, Julich] Advances in Inversion Techniques Crosshole GPR full-waveform inversion: Characterization of waveguides that act as preferential flow paths within aquifer systems

Velocity

5

6

7 Depth [m] Depth

8

9

1 2 3 4 5 6 Distance [m]

60 65 70 75 80 85 90 95 [-] v [m/r μs]

[Klotzsche, van der Kruk, Meles, Vereecken, 2012, Geophysics, Crosshole GPR full-waveform inversion of waveguides acting as preferential flow paths within aquifer system] [van der Kruk, Julich] Joint Inversion: Cross Gradients To assure structural resemblance of the inverse models, the objective function is formulated as where

and

[e.g., Gallardo and Meju, JGR 2004; Tryggvason and Linde, GRL

2006; Linde et al., WRR 2006; Linde et al., Geophysics 2008; Doetsch et al., Geophysics 2010; Doetsch et al., GRL 2010] [Linde, Lausanne]

Application to geophysical and hydrological data

[Lochbühler [Lochbühler al., in et prep]

Methods • crosshole GPR traveltime tomography • hydraulic tomography (HT) = multilevel crosshole slugtests > hydraulic conductivity K = diffusivity x specific storage > peak arrival times and attenuation data • Tracer mean arrival time inversion > temporal moments of breakthrough curves [Linde, Lausanne] Conclusions

• Many applications of geophysical tools to hydrologic problems • Some issues • Not measuring hydrologic parameters directly • Resolution varies • Rock physics are uncertain • Working on how to scale up—fundamental to watershed-scale work, support of large-scale observatories • How do we capitalize on time-lapse changes?