The People’s Republic of China’s creation of artificial islands in the South China Sea (SCS) represents a challenge for cartographers and geospatial scientists due to the rapid development of new geographic features in a politically opaque realm. The sudden construction of these islands enhances Chinese political control over the region at great cost to the existing environment, ecology, and natural habitat. When geospatial scientists must assess the impact of such features without direct access, creative solutions combining remote sensing, geographic information system, and environmental and social science can still provide powerful analyses. Indirect techniques are required to overcome such a data-scarce environment, as this study relies solely on the imagery of island feature construction in late 2017. The case study demonstrates a unique pedagogy of shadow analysis applied to structures on the islands, examining potential data gathering techniques for newly created features relevant to environmental impact assessments. This novel methodology is tested on radar arrays on three key islands in the SCS’s Spratly chain, examining political motivation as a driver for human interaction with the environment. While overcoming data sourcing limitations, the study quantifies tower heights and provides a method of measurement for constructed features on the islands. This study outlines the potential for geospatial science to create data where it is otherwise denied, providing narrative solution to the common problem of limited data or data access for the newest man-made geographic features.

Introduction

The history of Earth has entered the Anthropocene age, wherein human development and behavior now leaves marked changes in geological structures and formation. This impact stretches from the microscopic to the monumental, as industrial mankind exerts ever greater control over its environment. The slow and steady use of hydrocarbon energy sources has raised atmospheric carbon levels, thus leaving deposits in ice and stone for millennia to come. However, megastructures and large-scale construction works have created more striking changes to the surface of the earth. Modern engineering has mastered the ability to construct impenetrable dams, carve tunnels and canals through bedrock, and create dry land in the middle of the ocean. The geological impact of many of these phenomena is most pronounced in the People’s Republic of China (PRC), where megastructures and carbon-based energy fuel the development of the world’s most populace economy. In the South China Sea (SCS), however, the PRC has taken these same tools to task on geopolitical issues. Artificial island construction in the SCS has shocked international onlookers, largely due to the ability of construction to outpace spectators’ monitoring ability. The speed and secrecy of the island-building has greatly limited data availability, impeding research into the impact on the environment, ecology, and geography of these islands. In such circumstances, environmental scientists must turn to geospatial scientists and some nonstandard methods to gather data for the analysis of new man-made features.

Island Construction

The SCS can be defined by three facets: a unique and diverse ecology, an abundance of natural resources, and the geopolitical competition to control these resources. The region is home to a unique and wide range of local fauna, with 571 known species of reef corals and a “remarkable and unexpected diversity” of aquatic life, and a variety of vital migratory fishes like tuna (Huang et al. 2014). The value of this ecology is matched by natural resources in the SCS, not only commercial fisheries but often petroleum. Midrange estimates put the amount of petroleum beneath the seabed of the SCS at 11 billion barrels, with 190 trillion cubic feet of natural gas (EIA 2013). And for every barrel untapped under the SCS, the value can be magnified by the volume of oil and other goods transported and traded across its waters. As one of “the most enduring maritime trade route[s] in history,” the waters of the SCS transported $3.37 trillion—or 21% of all global trade—in 2016 (China Power Team 2017; Gao and Jia 2013). To govern the distribution and access to such resources and territory, the United Nations Convention on the Law of the Seas (UNCLOS) grants nations local areas of sea to control and exploit without competition. These Exclusive Economic Zones (EEZs) are vital to nations as means to control fisheries, extract undersea oil, and manage trade. In the case of the SCS, disputed competition over EEZ claims led the PRC to reinforce assertions through military might and island building—all at the cost of ecological integrity.

While initially unnoticed, Chinese island construction in the SCS slowly spread through the 2010s from the Paracel chain of reefs, just south of the island of Hainan, toward the further—and more contentious—Spratly chain between Vietnam, the Philippines, and Malaysia (figure 1). Using dredging ships to pour subsurface sand atop existing reefs, the PRC navy layered earthen works to quickly create new islands and atolls at the center of the SCS. As highlighted in work by the Center for Strategic and International Studies (CSIS) and their Asian Maritime Transparency Initiative (AMTI), the PRC rapidly developed new artificial landmasses to serve as future military outposts (figure 2). This unilateral action was made difficult to monitor through secrecy in planning and operation, meaning that many new dredging and dumping sites went unnoticed until construction had already begun. The speed of these unannounced projects left researchers and monitoring groups on their backfoot and caught many regional actors unaware and unprepared for the environmental and geopolitical ramifications of China’s militarized EEZ assertions.

Figure 1.

Competing claims and natural resources. Source: The Brookings Institute; Reuters.

Figure 1.

Competing claims and natural resources. Source: The Brookings Institute; Reuters.

Figure 2.

Subi Reef, an artificial island built by the People’s Republic of China. July 2016. Source: CSIS Island Tracker.

Figure 2.

Subi Reef, an artificial island built by the People’s Republic of China. July 2016. Source: CSIS Island Tracker.

As the new islands lay in maritime territory claimed by multiple countries—each with varying levels of validity—the construction became an international issue. The Chinese claim under their “Nine-Dash Line” effectively demanded control of the entire SCS, regardless of its geographic distance to the Chinese mainland. More relevant claims from the Philippines and Vietnam contended for various portions of the SCS, with Malaysia, Brunei, Indonesia, and Taiwan all involving themselves in the issue along different proposed territorial boundaries and different interpretations of international law. A 2013 legal action found that the Philippines sued China for violation of territorial integrity under guidelines from UNCLOS. In the eyes of many international observers, the construction was harming the ecosystems of Philippine and global territory. The PRC continued construction heedless of the outcome, ultimately ceding the case in 2016. With some deft political maneuvering to diffuse the issue, China managed to continue their geological manipulation without any penalty enforcement (Sofaer 2016). Economic concerns outweighed the Philippines’ interest in halting Chinese territorial violations, and the geographic truth of Philippine maritime boundaries was undermined by geopolitical realism. This case result revealed how long-standing human borders could be upended just as easily as piles of muck beneath the water’s surface, invalidating both human and geological terrain through the island-building process.

Beyond international law and economic maneuvering, the dredging involved in island building created serious ecological harm. At face value, the Chinese construction seized existing reefs and atolls—natural fixtures in their environment—and irrevocably destroyed them to build artificial surfaces suitable for human construction. While the loss of these features is hard to quantify, the dredging process is easier to measure. Research focused on the SCS has shown this upturned sediment to muddy pristine waters and clog microorganism photosynthesis across a “cumulative area impacted by dredging exceeding 1,200 km2” (Smith et al. 2019). This is a point of great concern toward the volume and duration of dredging in PRC island construction. But beneath the surface as well, the sediment itself is vital to the existing ecology. Dredging for artificial islands has long been known to disturb and destroy coastal sediment with effects on “plankton, bottom fauna, fishes and on larvae and young stages of sea animals in general” (de Groot 1979). These smaller fish feed up the food chain, where the SCS reefs were central to ecology that “also function[ed] as biological ‘roadside cafes’ for migratory fish, including tuna” (Ives 2016) who would eat, breed, and develop successive generations in the Pacific. While research in the SCS has not yet been performed on the topic, the environmental impact and pollution of heavy construction itself must also be considered. The loss of these reefs has yet unforeseen downstream effects, but these concerns were not shared by PRC military engineers.

As construction of each island pushed onward, the PRC began the process of militarizing the sites. Built often as harbors, the new islands housed docks and shipyards for military vessels. Airfields were built along straight lengths of new earth on various islands, whereas smaller islets were left as monitoring outposts. To understand the purpose of each island—and to evaluate the permanence of this new environmental impact—a geospatial investigation was required to gather information on the new features, hinting at how they might grow or change in the future and what ecological damage this might create.

Shadow Analysis

With the new islands in place, there was a clear need to analyze the geographic, environmental, and geopolitical effects of their construction and continued ecological damage. Considering the construction value of the new islands to the PRC, and the military impact as a core driver of Chinese construction, the surface facilities identified themselves as a key point of investigation. Understanding how the new buildings and military posts had been constructed and positioned could reveal much about the current and future construction implications. The bunkers, airfields, storage units, and radar towers would have immense value when analyzing the political and military uses of the islands and therefore indicate how things were constructed and whether the construction was even complete. Measuring building size and shape, construction material, and position would then allow for an environmental impact assessment. The patterns of these facilities might also foreshadow where the PRC might build future islands, show PRC prioritization of various resources or areas, and what level of ecological damage they were willing to induce. All of these hypothetical analyses required data in an environment with denied public access, therefore relying upon a combination of techniques to acquire information about the island facilities.

Measuring Man-Made Objects

Shadow analysis—the indirect measurement, or mensuration, of object sizes, shapes, and heights using trigonometry based on object shadows and the angle of the sun—stood out as a tool to acquire data on the radar systems. The methodology for shadow analysis uses basic trigonometry to compare the varying lengths of an object’s shadow as the sun illuminates the object from different angles. Shadow analysis is immensely useful, as it requires only a single image of a target object with basic metadata about the image capture. In denied environments where little information about an object is known, “an obvious starting point for height estimation is the sun shadow” (Wegner et al. 2014). While the shadow can be measured using aerial or orbital imagery of a target object, knowledge of the date, time, and location of the image can be used to find the angle at which the sun shone during image capture. Shadow analysis can also be used for a wide variety of environmental and ecological studies, from the measurement of glaciers and landslide spillage volumes to changing heights of sea cliffs or depth of canyons. When it is difficult to gain direct access to a feature, be it by distance or hazard, shadow analysis provides researchers with a valuable measuring tool.

In the case of SCS island construction, CSIS/AMTI had previously identified many PRC structures through imagery analysis of the islands, noting the presence of radar towers, airfields, hangars, and other sites (figure 3). With these identifications, the shadow analysis technique was applied to commercially available imagery from the DigitalGlobe Foundation, focusing on objects present on the three largest artificial islands in the Spratly chain—Subi, Mischief, and Fiery Cross Reefs (Luttrull 2018). Shadow lengths were measured, and trigonometry was applied to calculate the building heights using the sun elevation angle at the time of image capture (figure 4). The radar towers were of particular interest, as they stood out on multiple corners of the islands and were visually some of the tallest built structures (table 1).

Figure 3.

CSIS Identification of island features, with inlay of radar array.

Figure 3.

CSIS Identification of island features, with inlay of radar array.

Figure 4.

Example of shadow measurement in multispectral imagery. Source: Satellite image(s) courtesy of the DigitalGlobe Foundation.

Figure 4.

Example of shadow measurement in multispectral imagery. Source: Satellite image(s) courtesy of the DigitalGlobe Foundation.

Table 1.

Tower Height Measurements and Height Calculations.

Tower Height Measurements and Height Calculations.
Tower Height Measurements and Height Calculations.

The resulting building heights and their impacts were visualized in a geographic information system (GIS) to create maps and image graphics. The GIS data were then ready for analysis in conjunction with other known and measured environmental damage exhibited on the islands. Although laborious and unorthodox, the methodology was able to create data on the fly, helping to understand the extent of PRC island building and heavy construction. The data it created were prone to some level of error due to the manual measurement and mensuration of imagery and therefore would not be appropriate for advanced analytics. Nonetheless, the geodata were accurate enough for visualization and thematic mapping—especially as more reliable data did not yet exist. Considering that the methodology only required basic GIS software, there was still opportunity to improve the existing methods and expand the variety of examinable features on the new islands—for example, how deep the port berthings were constructed, and therefore what kinds of heavy ships might now frequent those waters. With such foundational GIS data created, environmental assessments could then be made to estimate how much damage was caused and what other effects may come into play as construction moved toward completion.

Conclusion

This case is defined by the predetermined constraints and limitations of data availability. The tense geopolitical reality of SCS militarization has reduced the ability of environmental researchers to study the impact of island building, and alternative methods like shadow analysis are one of the few tools available to measure what is being constructed on the new islands and how construction might continue. As human environmental impact increases in pace and extent, alternative methods to standard GIS can be used to develop data in data-scarce environments. Not all these scenarios occur in denied areas; however, the added difficulty of undisclosed construction is an ideal backdrop to test data generation methodologies in the harshest of settings. These methodologies are especially complex—in this case relying on trigonometry, remote sensing techniques, and background knowledge of regional geopolitics—and therefore require more trial and error than more straightforward investigative studies. Understanding the human rationale was also necessary to appropriately identify what features to measure and what metrics were geospatially relevant, so that the correct data could be passed to environmental scientists. As mankind develops ever-increasing ability to change our geological environment with ease, even minor strategic or economic goals can drive decisions with permanent geographic ramifications. Geospatial scientists will continue to perform a key role in measuring these phenomena and developing the base data upon which environmental science relies.

Case Study Questions

  • Context:

    • How does the situation in the SCS compare to other military-political investigations using GIS?

    • What about island building in the SCS presents a unique problem for geospatial scientists, and what about it presents a unique problem for GIS to solve?

    • What other events or situations function similarly?

    • How can background knowledge of social science help guide a GIS study of human interaction with the environment?

  • Data:

    • What data sources were used in this case?

    • How does data sourcing affect the structure of a project?

    • Why should a GIS analyst be comfortable with as many data types as possible (imagery, relational data, etc.)?

    • How can imagery metadata enable alternative forms of analysis?

  • Methodology:

    • Supposing unlimited data, where could this study’s methodology be improved?

    • How applicable is the use of shadow analysis toward measuring heights of objects a researcher does have direct access to?

  • Results:

    • How was the study affected by limited data, and what was done to account for this?

    • How do political interests affect the environment?

    • How can current facility information inform how island construction might continue?

Acknowledgments

The authors would like to thank the DigitalGlobe Foundation for the provision of high-quality, timely, and well-performing imagery used in this study, and the University of Southern California’s Spatial Science Institute for providing the creative academic space necessary for this research.

Supplemental Material

Appendix A: Data Notes

Appendix B: Labeled Imagery of Tower Sites

References

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Additional Readings

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Shadow Analysis
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Supplementary data