Mapping saltwater intrusion with an airborne electromagnetic method in the offshore coastal environment, Monterey Bay, California

Goebel, Meredith; Knight, Rosemary; Halkjær, Max

doi:10.1016/j.ejrh.2019.100602

Cited by 35 publications

(22 citation statements)

References 13 publications

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“…The AEM method is particularly advantageous for watershed to regional-scale salinity studies as it provides high-resolution resistivity information with greater spatial coverage than is practically feasible with well data or ground-based geophysical surveys. AEM surveys have been used to evaluate groundwater salinity for various hydrogeologic scenarios that include studies of coastal aquifers and saltwater intrusion (Christensen & Halkjaer, 2014;Delsman et al, 2018;Faneca Sànchez et al, 2012;Fitterman & Deszcz-Pan, 1998;Goebel et al, 2019;Haider et al, 2015;Jørgensen et al, 2012;Kirkegaard et al, 2011;Schamper et al, 2013;Siemon et al, 2015;Teatini et al, 2011;Viezzoli et al, 2010), salinity mapping in irrigated and arid regions (Cresswell et al, 2004;Cresswell et al, 2007;, the location of brines Dugan et al, 2015), and the shallow occurrence of produced water from oil and gas production (Paine, 2003;Paine et al, 1997;Paine & Collins, 2003;Smith et al, 1992;Thamke & Smith, 2014). equations in light of other hydrogeologic properties can be assessed (e.g., Gillespie, Davis, Stephens, et al, 2019;Stephens et al, 2019).…”

Section: Salinity Mapping Using Aem Datamentioning

confidence: 99%

“…Other approaches involve resistivity thresholding or the development of linear regressions based on local correlations between bulk resistivity and TDS (e.g. Ball et al, 2020; Cresswell et al, 2004; Fitterman & Deszcz‐Pan, 1998; Goebel et al, 2019; Paine et al, 2009). However, bulk resistivity is influenced by factors beyond salinity, leading to uncertainty and spatial variability in these regressions.…”

Section: Introductionmentioning

confidence: 99%

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Probabilistic Categorical Groundwater Salinity Mapping From Airborne Electromagnetic Data Adjacent to California's Lost Hills and Belridge Oil Fields

Ball

Davis

Minsley

et al. 2020

Water Resources Research

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Growing water stress has led to emerging interest in protecting fresh and brackish groundwater as a potential supplement to water supplies and raised questions about factors that could affect the future quality of fresh and brackish aquifers. Limited well infrastructure, particularly in regions where elevated salinity has led to limited historical groundwater development, hinders traditional mapping of salinity distributions through groundwater sampling. This paper presents a quantitative salinity mapping approach of the upper 300 m using high-resolution, regionally comprehensive resistivity models derived from Bayesian inversion of an airborne electromagnetic survey adjacent to the Lost Hills and Belridge oil fields in the southwestern San Joaquin Valley of California. Using local water quality observations as an interpretational foundation, a probabilistic approach yields maps of fresh, saline, and brackish groundwater while quantifying joint uncertainty inherited from the geophysical data and interpretational relations. Saline and fresh regions are mapped with relatively high confidence in many locations, while areas of lower confidence, particularly at depth, can be mapped as their most probable salinity category while reflecting the relative uncertainty in the interpretation. These maps identify a stratified salinity structure, where saline water commonly occurs in the surficial aquifer overlying fresher groundwater in the Tulare aquifer, separated by regional confining clay layers. Downgradient of unlined surface water diversions, recharge of imported surface water results in relatively fresh groundwater throughout the depth of investigation. Plain Language Summary Salinity, a measure of salt concentration, can impact the potential use of groundwater. Salinity can be difficult to map using wells alone, especially where groundwater development has been limited in the past. Dissolved salts are excellent conductors of electricity, and resistivity measurements are commonly used to estimate salinity where wells are not available. Uncertainty in estimating salinity from resistivity data can be introduced into the interpretation by two sources: (1) how well we can estimate salinity from resistivity and (2) how accurately we can measure resistivity. We present a method for mapping salinity that accounts for both sources of uncertainty using regional-scale, high-resolution airborne geophysical data, leading to spatially comprehensive 3-D maps of likely fresh (low salt) and saline (high salt) groundwater. The method is applied in the southwestern San Joaquin Valley of California adjacent to the Lost Hills and Belridge oil fields. Shallow groundwater is shown to have relatively high salinity in much of the study area, and a clay layer protects lower salinity water in the underlying Tulare aquifer. Leaking surface water canals have imported relatively fresh water into the area, resulting in fresher groundwater downgradient of the canals.

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Section: Salinity Mapping Using Aem Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Probabilistic Categorical Groundwater Salinity Mapping From Airborne Electromagnetic Data Adjacent to California's Lost Hills and Belridge Oil Fields

Ball

Davis

Minsley

et al. 2020

Water Resources Research

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“…CalAm maintains that its slant wells would extract seawater and brackish water only, with no impact to local potable groundwater, based on superposition modeling with the MODFLOW-based North Marina Groundwater Model [36]. The City of Marina disagrees with CalAm's conclusion, citing a study by Goebel et al [76] that used airborne electromagnetic sensing to reveal a more nuanced, connected patchwork of brackish and freshwater zones existing within the intruded boundary used by CalAm's analysis [77]. The contested risk to local aquifers contributed to the Marina Planning Commission's decision to deny CalAm's coastal development permit [67], and it also prompts environmental justice concerns since the City of Marina lies outside CalAm's service area where project benefits would be experienced [66].…”

Section: Mpwsp Desalination Pwm Expansionmentioning

confidence: 99%

Integrated Water Management at the Peri-Urban Interface: A Case Study of Monterey, California

Gile

Sciuto²,

Ashoori

et al. 2020

Water

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Climate change, drought, and chronic overdraft represent growing threats to the sustainability of water supplies in dry environments. The Monterey/Salinas region in California exemplifies a new era of integrated or “one water” management that is using all of the water it can get to achieve more sustainable supplies to benefit cities, agriculture, and the environment. This program is the first of its kind to reuse a variety of waters including wastewater, stormwater, food industry processing water, and agricultural drainage water. This study investigates the partnerships, projects, and innovations that shape Monterey’s integrated water network in order to better understand the challenges and opportunities facing California communities as they seek to sustainably manage peri-urban water supplies. Water reuse in the Monterey region produces substantial economic and environmental benefits, from tourism and irrigation of high-value crops to protection of groundwater and increases in environmental flows and water quality. Water resource managers in other communities can learn from Monterey’s success leveraging local needs and regional partnerships to develop effective integrated water solutions. However, key challenges remain in resolving mismatched timing between water availability and demand, funding alternative water supplies, and planning effectively under uncertainty. Opportunities exist to increase Monterey’s recycled water supply by up to 50%, but this requires investment in seasonal storage and depends on whether desalination or additional recycling forms the next chapter in the region’s water supply story. Regulatory guidance is needed on seasonal subsurface storage of tertiary-treated recycled water as distinct from potable recharge. By increasing the supply of recycled water to Monterey’s indirect potable use system, the region’s potential need for seawater desalination may be delayed as much as 30 years, resulting in cost and energy savings, and giving the opportunity to resolve present planning concerns.

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“…Where this groundwater supports vegetation, this also increases knowledge of vegetation hydrological tolerances. AEM data are most valuable where targets are resolved through electrical conductivity contrasts, such as land salinization and saltwater interface and freshwater lens mapping (e.g., [24][25][26]). Another common application of AEM data is the production of regolith and aquifer thickness maps, where bedrock and aquitards form conductivity contrasts (e.g., [27,28]).…”

Section: Introductionmentioning

confidence: 99%

An Assessment of Water Sources for Heritage Listed Organic Mound Springs in NW Australia Using Airborne Geophysical (Electromagnetics and Magnetics) and Satellite Remote Sensing Methods

Rutherford¹,

Ibrahimi

Munday

et al. 2021

Remote Sensing

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Discrete phreatophytic vegetation associated with organic mound springs is present in several places in the semi-arid Walyarta Conservation Park (Park) in northern Western Australia. The mound springs are heritage listed, having significant cultural and environmental significance. Increased industrial (mining and agriculture) development in the region, coupled with a growing demand for groundwater to support these developments, requires an enhanced understanding of how the springs operate and the source of water that sustains their presence. The springs are broadly believed to be situated on geological faults and receive groundwater from artesian sources. However, their association with deeper geological structures and aquifer systems, the focus of this study, is not well understood. This study employed regional- and finer-scale airborne geophysical data, including electromagnetics (AEM) and magnetics, to constrain the sub-basin-scale hydrogeology of the West Canning Basin in Western Australia and to detail tectonic deformation, sedimentological and hydrological processes. The AEM data were inverted using 1- and 2D methods to better define structural discontinuities in the Park, and the results identified the location of faults and other geological structures that were coincident with spring locations. A complementary analysis of spatiotemporal patterns of green vegetation was undertaken using remote sensing data. A model for the extent of green vegetation (in percent), calculated using a constrained linear spectral unmixing algorithm and applied to a select Landsat Thematic Mapper ™ image archive, showed the persistence of green vegetation aligned with interpreted fault systems through extended dry periods. These geophysical and remotely sensed datasets demonstrate that in the Park, the sedimentary aquifers and landscapes are highly compartmentalized and that this constrains aquifer distribution, groundwater quality and the location of wetlands and phreatophytic vegetation. Integrating key information from these datasets allows for the construction of a three-dimensional model that predicts the nature and extent of the critical zone which sustains perennial groundwater discharge within mound springs, drainages and wetlands and provides a framework to assess discharge rates, mixing and, ultimately, sensitivity to changed water availability.

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Mapping saltwater intrusion with an airborne electromagnetic method in the offshore coastal environment, Monterey Bay, California

Cited by 35 publications

References 13 publications

Probabilistic Categorical Groundwater Salinity Mapping From Airborne Electromagnetic Data Adjacent to California's Lost Hills and Belridge Oil Fields

Probabilistic Categorical Groundwater Salinity Mapping From Airborne Electromagnetic Data Adjacent to California's Lost Hills and Belridge Oil Fields

Integrated Water Management at the Peri-Urban Interface: A Case Study of Monterey, California

An Assessment of Water Sources for Heritage Listed Organic Mound Springs in NW Australia Using Airborne Geophysical (Electromagnetics and Magnetics) and Satellite Remote Sensing Methods

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