Mapping Saltwater Intrusion using Transient ElectroMagnetic Data in Maopa, Central Province, Papua New Guinea

10.26686/wgtn.17142035.v1 ◽

2021 ◽

Author(s):

◽

Ronald Verave

Keyword(s):

Papua New Guinea ◽

Saltwater Intrusion ◽

Groundwater Resources ◽

Cost Effective ◽

New Guinea ◽

Small Island ◽

Mixing Zone ◽

Low Resistivity ◽

Transient Electromagnetic ◽

Tem Method

<p>Saltwater intrusion studies in coastal Papua New Guinea (PNG) are a rarity despite recognized vulnerabilities to salination of coastal groundwater resources. For many seaside communities such as Maopa the threat of salination is exacerbated by high extraction rates by a growing population and the likelihood of the effects of climate change. Saltwater intrusion can be addressed using various methods, including direct water sampling from wells and electrical resistivity measurements. This study advances knowledge of a previous assessment of saltwater intrusion and groundwater in this region that used DC Schlumberger resistivity soundings, through an extensive and cost-effective Transient ElectroMagnetic (TEM) survey. The study aims to map the lateral and vertical extent of salination and the characterization of groundwater in the landward direction over seven lines of TEM soundings along Keakalo Bay. The TEM method proved successful in identifying four main geoelectric layers. The top layer has a highly variable resistivity (range of 5 to 355 Ωm) inferred as the vadose zone. Beneath this layer is a layer of intermediate resistivity (100 Ωm > p ≥ 20 Ωm) characterizing a perched freshwater aquifer with a thickness range of 3.2 to 15 m. An intermediate layer of low resistivity (20 Ωm > p ≥ 3 Ωm) was detected at the boundary separating the freshwater aquifer from the inferred saltwater intrusion. This layer is typically thicker than the freshwater aquifer and is referred to as the mixing zone. The deepest layer constituting the salination zone has a very low resistivity (3 Ωm > p ≥ 0.4 Ωm), occurring at depths of up to 42 m. The depth to the salination zone varied from deep in the middle of the survey area to shallow in the fringes of the survey. This pattern is reflective of surface seawater infiltration marked by mangrove forest in the interior and subsurface infiltration from the coast. Similar depth trends but at shallower depths were also observed for the mixing zone, and the freshwater region. In some cases the mixing area overwhelms the freshwater regions. Layering confirmed groundwater resource and salination patterns as those of basic models reflective of small island hydrology, except that salination and the freshwater boundary were less distinctive due to the relatively high thickness of the dispersion zone. The use of different sounding parameters in line 7 provided useful information about the nature of the deep basement unit and thickness of the overlying unconsolidated quaternary sediment.</p>

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Establishment of an NDE Center at the Papua New Guinea University of Technology: Scope and Objectives

ASME 1997 Turbo Asia Conference ◽

10.1115/97-aa-065 ◽

1997 ◽

Author(s):

Don E. Bray ◽

G. S. Gad

Keyword(s):

Nondestructive Evaluation ◽

Papua New Guinea ◽

Pacific Islands ◽

Solomon Islands ◽

Flaw Detection ◽

Cost Effective ◽

New Guinea ◽

Material Degradation ◽

University Of Technology ◽

South Pacific Islands

Papua New Guinea lies just north of Australia (Fig. 1). It is a developing island nation, with 462,839 km of land area, a population of 3.9 million people, and vast natural resources (Compton’s Interactive Encyclopedia, 1996). It is the largest island in the Oceania region of the world, which also includes Fiji, the Solomon Islands and Vanuatu. Most of these islands share similar resources, and prudent development of the resources requires utilization of nondestructive evaluation (NDE). NDE provides the means for flaw detection and size assessment, as well as evaluation of material degradation such as corrosion and hydrogen attack. These are factors which affect the service life of components and systems. Being aware of the state of degradation of these components and systems will enable cost effective maintenance, and reduce costly and dangerous failures. Recognizing the need for NDE expertise, the Papua New Guinea University of Technology at Lae has initiated a Center for Nondestructive Evaluation. Once operational, the center should serve the entire Oceania region, and provide resources, trained students and expertise that will enable the growth of the NDE industry within that area. It is widely accepted that NDE adds value to a product or process, not just cost. The amount of value is directly related to the engineering education of the personnel making NDE decisions. The growth of the NDE industry in these South Pacific Islands will add to the economy, as well as aid in the further creation of a population of engineers who are well educated in NDE.

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Using an airborne electromagnetic method to map saltwater intrusion in the northern Salinas Valley, California

Geophysics ◽

10.1190/geo2019-0272.1 ◽

2020 ◽

Vol 85 (4) ◽

pp. B119-B131

Author(s):

Ian Gottschalk ◽

Rosemary Knight ◽

Theodore Asch ◽

Jared Abraham ◽

James Cannia

Keyword(s):

Electrical Resistivity ◽

Saltwater Intrusion ◽

Groundwater Resources ◽

Mitigation Strategies ◽

Electromagnetic Signal ◽

Confined Aquifer ◽

Coastal Regions ◽

Low Resistivity ◽

Salinas Valley ◽

Airborne Electromagnetic

Saltwater intrusion can pose a serious threat to groundwater quality in coastal regions. Estimating the extent of saltwater intrusion is vital for groundwater managers to plan appropriate mitigation strategies. The airborne electromagnetic (AEM) method is commonly used to evaluate groundwater resources, but it is challenging to apply in coastal environments because the low resistivity of saltwater-saturated aquifers attenuates the electromagnetic signal quickly and the relationship between electrical resistivity and pore water salinity is complex. However, if successful, the AEM method can supply information to address questions of critical importance in coastal regions. We investigated the extent of, and controls on, saltwater intrusion using the AEM method in the northern Salinas Valley, CA, USA. We collected 635 line-km of AEM data in the study area, the inversion results of which produced estimates of the electrical resistivity of the subsurface, reaching depths of between 50 and approximately 200 m below the ground surface. We have developed a relationship between the AEM electrical resistivity model and groundwater salinity, calibrated from borehole geophysical and water quality measurements, which allowed us to generate images revealing the distribution of saltwater and fresher groundwater in the study area. This fresher groundwater (defined as “a source of drinking water”) was successfully mapped out in the unconfined aquifer (the Dune Sand Aquifer) and the uppermost confined aquifer (the 180-Foot Aquifer) in the study area, illustrating a groundwater recharge process that helps mitigate saltwater intrusion in the 180-Foot Aquifer. Deep, low-resistivity bodies also were mapped, indicating regions where saltwater likely is migrating vertically from the 180-Foot Aquifer into the lower confined aquifer (the 400-Foot Aquifer). The findings from this case study demonstrate the value of acquiring AEM data for investigating the distribution of salinity in coastal aquifers impacted by saltwater intrusion.

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Cost effective seismic acquisition and drilling in the fold thrust belt of Papua New Guinea and implications for exploration in Irian Jaya

10.29118/ipa.1177.g.179 ◽

2018 ◽

Author(s):

R.J. Schroder

Keyword(s):

Papua New Guinea ◽

Cost Effective ◽

New Guinea ◽

Thrust Belt ◽

Irian Jaya ◽

Seismic Acquisition

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Is there an owl species on St Matthias (Mussau) Islands, Papua New Guinea?

10.20938/afo37161165 ◽

2020 ◽

Vol 37 ◽

pp. 161-165

Author(s):

Thierry Quelennec ◽

Marianne Quelennec

Keyword(s):

Papua New Guinea ◽

New Guinea ◽

Small Island

In July 2019, during a short ornithological visit to the St Matthias (Mussau) Islands, Papua New Guinea, we recorded a sound that might have been from an owl on the small island of Emussau close to Mussau. No owl or nightjar is known to occur on these islands. The bird’s call shows similarities but differs from other Melanesian Ninox owl species. Here we describe the call and discuss potential origins.

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Creating and Maintaining a Secure and Safe Environment on a Challenged Civilian University Campus in Papua New Guinea

International conference KNOWLEDGE-BASED ORGANIZATION ◽

10.2478/kbo-2019-0078 ◽

2019 ◽

Vol 25 (2) ◽

pp. 189-196

Author(s):

Garry Sali ◽

Mirzi Betasolo ◽

Eric Gilder

Keyword(s):

Papua New Guinea ◽

Cost Effective ◽

New Guinea ◽

University Campus ◽

Social Psychological ◽

Campus Environment ◽

Security Issues ◽

University Of Technology ◽

Social And Economic Development ◽

The University

Abstract The article introduces the challenges of maintaining effective security (of both personnel and property) on a 220 hectare rural/suburban University campus, The Papua New Guinea University of Technology, located on the outskirts of Lae, the second-largest city in Papua New Guinea, serves as its main port and manufacturing hub. Since the Independence of Papua New Guinea in 1975, the city of Lae, the University (of approximately 3000 students, and 1500 academic, technical, and administrative and staff) and its surrounding communities have faced increasing pressing security issues, some caused by internal (on campus) and others by external (off campus) factors. After a long, politically motivated student boycott in 2016 (which ended up with destruction of varied University properties and the death of a student), the University has endeavoured to create a safe campus environment by employing quantitative modelling predictive techniques, cost-effective technologies and appropriate social-psychological insights aimed at transcending extant tribal mindsets (the country is noted for having over 800 tribes and languages across its widely space geography of 462,840 Km and approximately 7 million population). Tribal conflict is a constant concern for the police and governing authorities, an inhibitor of balanced social and economic development of the resource-rich country.

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