Island Dynamics Research Articles

Assessing the Dynamics of Land Surface Temperature, Vegetation Health and Urban Heat Islands in Lucknow City: A Comprehensive Analysis from 1993 to 2022

Assessing the Dynamics of Land Surface Temperature, Vegetation Health and Urban Heat Islands in Lucknow City: A Comprehensive Analysis from 1993 to 2022

Nonlinear microtearing modes in MAST and their stochastic layer formation

First nonlinear gyrokinetic simulations of microtearing modes in the core of a MAST case are performed on two surfaces of the high-collisionality discharge used in Valovič et al (2011 Nucl. Fusion 51 073045) to obtain the favorable energy confinement scaling with collisionality, . On the considered surfaces microtearing modes dominate linearly at binormal length scales of the order of the ion Larmor radius. While the effect of electron collision frequency is moderate in linear simulations, a strong dependence on this parameter is found in nonlinear simulations at , where r and a are the surface and tokamak minor radius, respectively. The dynamics of magnetic islands generated by microtearing modes is analysed, showing that the radial extent of the stochastic region caused by islands overlapping plays an important role in determining the saturation level of the microtearing mode driven heat flux. Local nonlinear gyrokinetic simulations show that the microtearing mode driven heat flux, , is largely dominated by magnetic flutter and depends strongly on the magnetic shear, . Comparing two surfaces, and , reveals that is negligible at (), with the electron temperature gradient (ETG) driven heat flux, , comparable to the experimental electron heat flux, , while is significantly larger and comparable to and at (). Microtearing modes cause more experimentally significant transport in higher regions and may influence (together with ETG modes) the observed scaling of energy confinement time with collisionality (Valovič et al 2011 Nucl. Fusion 51 073045).

Groundwater mapping and locally engaged water governance in a small island terrain: Case study of Karainagar island, Northern Sri Lanka

AbstractGroundwater is a vital resource under threat in island communities. Karainagar, a 22 km2island, is one of seven islands off the coast of Jaffna in Northern Sri Lanka, with its population of just about 11,000 persons, experiences seasonal water shortage, and salinity in groundwater as twin threats impacting on their lives. This paper reports on a 3‐year study (October 2019 to September 2022) to map groundwater dynamics of Karainagar island spatially and seasonally and discusses the patterns revealed in terms of community needs, policy implications, and governance ideas that could already be considered by relevant authorities and citizens jointly. Thirty‐six dug wells used for drinking, domestic, agricultural, and public purposes were selected, and water level, salinity, and pH changes recorded along with daily rainfall. This paper offers a thorough description of the geography, land use, distribution of wells, and water bodies, followed by discussion of the current status of the groundwater in Karainagar island. Year‐to‐year differences in rainfall pattern resulted in different rates of change and range in water level with a corresponding reverse pattern seen in salinity with some exceptions across the island. Cumulative rainfall required to reach full capacity of wells ranged from 652 to 892 mm over the 3 years with an average figure of 739 mm of rain. This implies that any further rainfall during early phase of the main rainy season is potential surface water for storage and runoff. Practices such as unregulated pumping and construction of tube wells are argued to be contributing to increase in salinity levels with health implications for residents. A participatory governance approach that overcomes limitations of the existing institutional approach is proposed. Its success based on broad stakeholder engagement, improved equity, and transparency when supported by adequate policies and village level aquifer monitoring will enable sustainability of groundwater resources in Karainagar.

Image-based machine learning for monitoring the dynamics of deltaic islands in the Atchafalaya River Delta Complex between 1991 and 2019

Deltaic islands are distinct hydro-environmental zones with global significance in food security, biodiversity conservation, and fishery industry. These islands are the fundamental building blocks of many river deltas. However, deltaic islands are facing severe challenges due to intensive anthropogenic activities, sea level rise, and climate change. In this study, dynamic changes of deltaic islands in Wax Lake Delta (WLD) and Atchafalaya Delta (AD), part of the Atchafalaya River Delta Complex (ARDC) in Louisiana, USA, were quantified based on remote sensing images from 1991 to 2019 through a machine learning method. Results indicate a significant increase in deltaic islands area for the whole ARDC at a rate of 1.29 km2/yr, with local expansion rates of 0.60 km2/yr for WLD and 0.69 km2/yr for AD. All three parts of the WLD naturally prograded seaward, with the western part (WP) and central part (CP) expanding southwestward to the sea, while the eastern part (EP) prograding southeastwards. Differently from WLD, the three parts of AD irregularly expanded seaward under the impacts of anthropogenic activities. The WP and CP of the AD expanded respectively northwestwards and southwestwards, while the EP remained stable. Different drivers dominate the growth of deltaic islands in the WLD and AD. Specifically, fluvial suspended sediment discharge and peak flow events were responsible for the shift in the spatial evolution of WLD, while dredging and sediment disposal contributed to the expansion of AD. Tropical storms with different intensity and landing locations caused short-term deltaic island erosion or expansion. Tropical storms mainly generated erosion on the deltaic islands of the WLD, while causing transient erosion or siltation on the deltaic islands of the AD. In addition, high-intensity hurricanes that made landfall east of the deltas caused more erosion in the AD. Finally, sea level rise, at the current rate of 8.17 mm/yr, will not pose a threat to the deltaic island of WLD, while the eastern part of AD may be at risk of drowning. This study recognizes the complexity of factors influencing the growth of deltaic islands, suggesting that quantitative studies on the deltaic island extent are of critical for the restoration and sustainable management of the Mississippi River Delta and other deltas around the world.

Coral reef island shoreline change and the dynamic response of the freshwater lens, Huvadhoo Atoll, Maldives

Low-lying coral reef islands have been projected to become uninhabitable by the end of the century due to sea level rise, but such projections of vulnerability assume that reef islands are static landforms that flood incrementally with sea level rise. In fact, GIS-based reef island shoreline analyses have demonstrated that reef islands are highly dynamic landforms that may adjust their shorelines in response to changing environmental conditions. However, the vast majority of reef island shoreline analyses have been undertaken in the Pacific Ocean, leaving our understanding of changes in the Indian Ocean more limited. Further, our knowledge of how island dynamics can impact groundwater resources is restricted due to the assumption that islands will exhibit purely erosional responses to sea level rise. Here, we analyse shoreline evolution on 49 reef islands over a 50-year timeframe in Huvadhoo Atoll, Maldives. Additionally, rates of shoreline change were used to undertake numerical modelling of shifts in freshwater lens volume in 2030, 2050 and 2100 in response to changes in recharge. Despite sea level rising at 4.24 mm/year (1969-2019), accretion was prevalent on 53% of islands, with the remaining islands eroding (25%) or remaining stable (22%). Average net shoreline movement was 4.13 m, ranging from -17.51 to 65.73 m; and the average rate of shoreline change (weighted linear regression) was 0.13 m/year, ranging from -0.07 to 2.65 m/year. The magnitudes and rates of reef island evolution were found to be highly site-specific, with island type found to be the only significant predictor of either net shoreline movement or weighted linear regression. Results suggest that freshwater lens volume was substantially impacted by shoreline change compared to changes in recharge whereby accretion and erosion led to large increases (up to 65.05%) decreases (up to -50.4%) in les volume, respectively. We suggest that the capacity of reef islands to both (1) adjust their shorelines, and even accrete, under conditions of sea level rise; and (2) increase their storage of groundwater over the coming decades represents highly valuable geomorphic ecosystem services.

Understanding the Spatial–Temporal Patterns of Floating Islands Impacting the Major Dams of the White Nile

Floating islands in Lake Victoria, the world’s second-largest fresh water lake, disrupt transportation, fisheries, irrigation, and water quality. Despite their impact, the dynamics of these islands remain unexplored. This study investigates island dynamics within the Nalubaale, Kiira, and Bujagali dams in Uganda, exploring the causes of their formation and the subsequent impact on hydropower production. The study collects data of Landsat imagery from 2000 to 2020, CHIRPS precipitation, and Lake Victoria’s water level datasets from 2004, 2010, 2013, 2017, and 2020. The results reveal a strong correlation between precipitation, fluctuating water levels, and floating island formation, with nutrient-rich runoff from municipal waste and agriculture promoting island growth. In addition, rising water levels lead to the dislodging of rocks and soil, contributing to floating island formation, which may manifest with a lag time of up to one month. The analysis shows higher correlations between precipitation, water levels, and floating islands during the long (March–May) and short (September–November) rainy seasons as opposed to drier periods (June–August, December–February). The findings indicate that southeast monsoon winds, which transport floating vegetation, also are essential in influencing island dynamics. Consequently, the major drivers of floating islands in Lake Victoria are identified as precipitation, water level fluctuations and wind variations. Finally, a negative correlation between floating island eutrophication and power production at Kiira and Nalubaale stations suggests that the increased eutrophication caused by the presence of floating islands leads to reduced power output at both Kiira and Nalubaale power stations.

Effects of resistivity and viscosity on dynamic evolution and radial position change of m/n = 3/1 double tearing mode

The effects of the plasma resistivity and viscosity on the dynamic evolution of the m/n = 3/1 double tearing mode (DTM) are studied and analyzed quantitatively using the CLT (Ci-Liu-Ti, which means magnetohydrodynamics in Chinese) code. In this work, we mainly focus on the change in the radial positions and the oscillatory dynamics of the magnetic islands grown on the two rational surfaces. We conduct a systematic investigation on the effect of viscosity on the DTM dynamics, which has rarely been studied before. From the results of the study, it is observed that the time required for entering the explosive phase decreases with decreasing viscosity. In the nonlinear phase, the kinetic energy exhibits an oscillatory behavior due to the magnetic flux injection and magnetic reconnection, and the oscillation amplitude is suppressed for a large viscosity due to dissipation. The effects of the plasma resistivity and viscosity on the change in the radial positions of magnetic islands are systematically explained. The change in the radial positions of magnetic islands occurs in an abrupt growth phase before the kinetic energy reaches its maximum value. Multiple position changes take place with a relatively higher reconnection rate and magnetic flux injection at low viscosity damping. A large range of radial vortices formed as a result of the change in the positions may have a positive effect on the transport.

Monitoring Monthly and Seasonal Dynamics of Subsurface Urban Heat Island and Possible Mitigation Measures in Enugu Metropolis, Nigeria

This study analysed the monthly and seasonal dynamics of subsurface urban heat island in Enugu metropolis, using secondary soil temperature data set that was sourced from the Nigerian Meteorological Agency. The descriptive statistical tool used was the line graph. The study showed that the monthly subsurface urban heat island intensity peaks at 0.6 0 C in May and remains fairly constant from September to February. It also revealed that the seasonal subsurface urban heat island intensity peaks at 0.5 0 C in spring (March, April and May) before staying relatively stable from summer (June, July and August) to winter (December, January and February). From the study, it was clear that the urban heat island effect occurred in the subsurface in Enugu, as it does above the ground. Therefore, this study recommends the creation of gardens and parklands and direct tree planting as part of the mitigation measures to this problem. Keywords: Enugu, mitigation, soil temperature, subsurface, urban heat island, urbanisation DOI: 10.7176/JEES/13-3-03 Publication date: April 30 th 2023

New Aspects of Energy Conversion in Magnetic Island Dynamics: Particle-in-cell Simulation of Multiple Island Coalescence and MMS Observations

Coalescence of multiple magnetic islands is recognized as an effective process to energize particles during magnetic reconnection, while its energy conversion process still remains unclear. Here, a two-dimensional fully kinetic simulation of multiple island coalescence with a small reconnection guide field is studied. In the analysis of energy conversion within a magnetic island, the dot product of is a useful quantity to compare with j · E = w 2, since the average work done by the Lorentz force on the circulating particles is negligible in the island and . A bipolar pattern of w 1 is found at a secondary island when the electrons are in circular motion inside the island. Significant energy dynamo (w 3 < 0) resulting from j ∥ E ∥ is found at the secondary island, which has not been reported before, where the parallel electric field E ∥ is highly correlated with w 3. Moreover, significant energy dissipation (w 3 > 0) due to is seen in the merging region between two coalescing islands. Both types of energy conversions are accompanied by enhancements in j ∥ and the parallel electron temperature T e∥. Three ion-scale magnetic islands (FR1, FR2, and FR3) observed by the Magnetospheric Multiscale spacecraft are compared favorably with the simulated signatures of energy dynamo and dissipation of an evolving secondary island. In particular, FR1 displayed a similar energy dynamo signature as that simulated in an early stage of the secondary island. FR2 and FR3 showed a dominant energy conversion similar to that obtained in a later stage of the secondary island.

Urban Heat Island Dynamics in an Urban–Rural Domain with Variable Porosity: Numerical Methodology and Simulation

Heat transfer and fluid dynamics modeling in porous media is a widely explored topic in physics and applied mathematics, and it involves advanced numerical methods to address its non-linear nature. One interesting application has been the urban-heat-island (UHI) numerical simulation. The UHI is a negative consequence of the increasing urbanization in cities, which is defined as the presence of warm temperatures inside the urban canopy in contrast to the colder surroundings. Furthermore, an interesting phenomena occurs within a UHI context when the city transitions from a heat island to a cold island, matching the increases and decreases of solar radiation over the span of a day, as well as the decrease in the UHI intensity as a result of wind action. The numerical study in this paper had, as its main goal, to reproduce this phenomenon. Therefore, the key elements proposed in this work were the following: A 2D horizontal urban–rural domain that had a variable porosity with a Gaussian distribution centered in the city center. A non-stationary Darcy–Forchheimer–Brinkman model to simulate the flow in porous media, combined with an air–soil heat transport model linked by a balancing equation for the surface energy that includes the evapotranspiration of plants. In regards to the numerical resolution of the model, a classical numerical methodology based on the finite elements of Lagrange P1 type combined with explicit and implicit time-marching schemes have been effective for high-quality numerical simulations. Several numerical tests were performed on a domain inspired by the metropolitan region of Guadalajara (Mexico), in which not only the temperature inversion was reproduced but also the simulation of the UHI transition by strong wind gusts.

Morphodynamic Characteristics of a Complex Anabranching System in the Qinghai‐Tibet Plateau and the Implications for Anabranching Stability

AbstractThe understanding of fluvial processes controlling morphological adjustments and stability of anabranching rivers remains incomplete. Focusing on a complex anabranching system in the Upper Yellow River, this study quantifies the morphological characteristics and lateral dynamics of islands and channels in four reaches over a 56‐km river course from 1986 to 2017. Using five heuristic anabranching structures derived from the studied anabranching system, we estimate sediment transport capacities and assess their implications for the morphodynamics of anabranching rivers. These results show that the system exhibited a highly complex pattern featuring high channel multiplicity and dominance of islands. Over the study periods, the system exhibited an accreting disequilibrium state, which was highlighted by spatiotemporally diverse and dynamic patterns of islands. Morphological changes in islands were dominated by expansion and shrinkage, which caused more areal changes than other modes of change, including coalescence, cleavage, new island formation, and elimination. These processes controlled the creation and elimination of small anabranches, whereas the size and morphology of large channels remained comparatively stable, which maintained the stability of this anabranching pattern. The stability of the anabranching pattern is further supported by estimations of transport capacity in that the main channels transport most sediments and in that excess development of small anabranches promotes sediment deposition within the system. Overall, this study provides new insight into the morphodynamic properties of anabranching rivers, demonstrating that, instead of channel numbers, island dynamics and interactions with channels are controls of the evolutionary processes and stability of anabranching rivers.

Reef islands have continually adjusted to environmental change over the past two millennia

Global environmental change is identified as a driver of physical transformation of coral reef islands over the past half-century, and next 100 years, posing major adaptation challenges to island nations. Here we resolve whether these recent documented changes in islands are unprecedented compared with the pre-industrial era. We utilise radiometric dating, geological, and remote sensing techniques to document the dynamics of a Maldivian reef island at millennial to decadal timescales. Results show the magnitude of island change over the past half-century (±40 m movement) is not unprecedented compared with paleo-dynamic evidence that reveals large-scale changes in island dimension, shape, beach levels, as well as positional changes of ±200 m since island formation ~1,500 years ago. Results highlight the value of a multi-temporal methodological approach to gain a deeper understanding of the dynamic trajectories of reef islands, to support development of adaptation strategies at timeframes relevant to human security.

Can we ignore trait-dependent colonization and diversification in island biogeography?

The application of state-dependent speciation and extinction models to phylogenetic trees has shown an important role for traits in diversification. However, this role remains comparatively unexplored on islands, which can include multiple independent clades resulting from different colonization events. To explore whether assuming no dependence on traits leads to bias in inference on island dynamics, we extend an island biodiversity model, DAISIE (Dynamic Assembly of Islands through Speciation, Immigration, and Extinction) to include trait-dependent diversification simulations, and evaluate the robustness of the inference model which ignores this trait-dependence. Our results indicate that when the differences between colonization, extinction, and speciation rates between trait states are moderate, the model shows negligible error for a variety of island diversity metrics, suggesting that island diversity dynamics can be accurately estimated without the need to explicitly model trait dependence. We conclude that for many biologically realistic scenarios with trait-dependent diversification and colonization, this simple trait-less inference model is informative and robust to trait effects on colonization, speciation, and extinction. Nonetheless, our new simulation model may provide a useful tool for studying patterns of trait variation.

Trophic connectivity between the terrestrial and marine ecosystems of Malpelo Island, Colombia, evaluated through stable isotope analysis

The trophic dynamics of islands with low terrestrial primary productivity often depend on marine allochthonous inputs from nearby donor habitats. For instance, on Malpelo Island, Colombia (4° 00′ 05.63″ N; 81° 36′ 36.41″ W), the Nazca booby Sula granti affects the productivity and trophic dynamics of the terrestrial ecosystem by delivering nutrients, primary in the form guano, chick carcasses, and eggs. This study evaluated the trophic connectivity between the terrestrial and marine ecosystems of Malpelo Island, Colombia based on the isotopic (δ13C and δ15N) assessment of 403 samples (107 terrestrial and 296 marine) collected between 2017 and 2021. Isospaces were estimated based on δ13C and δ15N values, contribution of terrestrial sources in consumer diets (mixing model), 15 N enrichment in C3 plants, and interactions among environments (overlap). δ13C and δ15N values showed a larger terrestrial isospace (134.7‰2) than the marine isospace (117.2‰2). The mixing model indicated that detritusTerrestrial (median: 30.2%) contributed more to the food web than C3 plants (0.2%), reflecting high δ13CMarine content. The high isotopic overlap (> 60%) between terrestrial and marine isospaces suggests a significant trophic connection between environments. These results show the role of the marine ecosystem on the terrestrial ecosystem and the importance of S. granti regarding nutrient transfer between environments. The conservation of this seabird is essential to maintain the balance of this insular ecosystem. Using stable isotopes, this study was able to reveal trophic relationships between ecosystems associated with small oceanic islands that host large seabird colonies but have low primary productivity.

Dynamics of Urban Heat Island and Anthropogenic Emissions in Bekasi before and during COVID-19 Pandemic using Landsat 8 and Sentinel-5P

The rise in temperature in urban areas resulting in UHI formation is thought to be significantly driven by anthropogenic emissions due to human activities. During the COVID-19 pandemic, the Indonesian government issued the Large-Scale Social Restrictions (PSBB) and Community Activities Restrictions Enforcement (PPKM) policy. Bekasi Regency is part of the Jabodetabek megapolitan that applied strict PSBB and PPKM treatment during the pandemic. The decreasing industrial activity and traffic volume are expected to reduce air pollutants and thermal radiation. The research method uses processed satellite imagery from Sentinel 5P to get anthropogenic emissions concentrations (NO2 and SO2) and Landsat 8 to get land surface temperature (LST). The results showed that Bekasi had a slight decrease in the concentration of anthropogenic emissions during COVID-19 pandemic 2020, then increased during COVID-19 pandemic 2021. The areas affected by urban heat islands increased steadily during the COVID-19 pandemic. Therefore, when the concentration of anthropogenic emissions rises, the UHI ascends.

Island settings and their influence on geographical research methods

AbstractThis study presents lessons learned from the application of mixed methods during three field visits to central Mediterranean islands over an eight‐year period to learn about and from visitors who voluntarily paid to experience ecotourism. The study outlines various challenges encountered in research in small island settings. Such challenges include logistical difficulties to reach islands, including those originating from weather conditions, difficulty in practising observation in small communities, sampling dilemmas, different levels of trust and willingness to disclose views among interview participants, lack of standardised data, language barriers that may limit who conducts research on specific islands, and substantial fluctuations in population size throughout the year. Findings show that the choice and application of methods for island research need to be informed by island dynamics; this entails adapting methods and using different data collection techniques to mitigate challenges arising from island settings. The study also outlines the need of more research in the application of mixed methods when studying islands.

Characterizing Temporal Dynamics of Urban Heat Island in a Rapidly Expanding City: A 39 Years Study in Zhengzhou, China

Extreme heat wave weather phenomena have erupted worldwide in recent years. The urban heat island (UHI) effect has exacerbated urban heat waves with serious consequences for urban energy and residents’ health. Therefore, a better understanding of the dynamics of the UHI effect and the influencing factors is needed in the context of carbon neutrality and global warming. This study used long-term observation and statistical data to investigate the urban heat island intensity (UHII) over the past 39 years (1981–2019) and to analyze the temporal changes of the UHI effect and the relationship between the UHI effect and indicators of rapid urbanization in Zhengzhou, China. The results showed that Zhengzhou is warming 2.2-times faster than the global land warming trend of about +0.9 °C from 1981 to 2019. There is a clear phase characteristic of the heat island effect in Zhengzhou, and it offers a rapid upward trend after 2000 and a positive correlation with the urbanization process; it was found that the social and economic conditions of urban expansion in Zhengzhou have a significant relationship with UHII. We also found that the denser the urban built-up area, the more obvious the heat island effect. Compared with other countries, the influence of national policies on urban development is an indirect factor influencing the change of UHI specifically for Chinese cities. This research could provide a reference for understanding the temporal dynamics of UHI in an expanding large city for sustainable urban planning and mitigating urban warming and environmental problems.

Monster-producing Islands: Prospects for island detourning in contemporary times

Colonialism produces monsters thriving in island ecologies, but without a structural/historical treatment of how island monsters are created, how the agential relation between colonisers and natives accentuates the dynamics of interpellation, the island would reveal nothing of its past, the reusable trace that can be interpellated in the present. In the modern-day Philippines, a former colonial object to three foreign aggressions (Spanish, American and Japanese) that spanned almost half a millennium, such reusable trace has recently entered the international streaming platform Netflix. Trese (2021), a Philippine-made anime, navigates the myth of aswang, one of the dominant features of Filipino folklore, which centres on the image of a female, vampire-like monster. This image traces its iterative root in the lost history of the babaylans (female shamans) amid the creation of folk Christianity and diffracted engagements with the Christian indoctrination of the islands. This article navigates this subject and how Trese, among other actants in this play of figuration, is itself interpellated by traces of historical, geographical, and non-human ecologies that, in turn, reflect the fundamental role of liquidity in monster-creation as a material-semiotic intervention. As the discussions expand on the two most essential concepts in Island Studies today, the archipelagic and the aquapelagic, the article deploys the concept of detourning, a critical rhetorical arc that binds the article’s multi-faceted discussions, connections, and combinations, from human to the non-human, thus completing its assessment of the dynamics of islands being interpellated by traces.

Electromigration of Au on Ge(111): Adatom and island dynamics

We have observed the motion of two-dimensional phases of Au on Ge(111) under an electric bias by in operando low energy electron microscopy. Electromigration of Au results in a complex dynamics that depends on the nature of the involved mobile phases: two-dimensional adatom gas or two-dimensional islands. We show that the Au adatoms move at the surface in the direction opposite to the electric current. The wind force induced by the electron flow is measured: the effective valence of Au (${Z}^{*}=\ensuremath{-}82\ifmmode\pm\else\textpm\fi{}15$) is directly deduced from the coverage profile of a Au adatom gas spatially retained by a strong Erlich-Schwoebel barrier at a downhill step edge. The velocity of two-dimensional Au islands versus island size reveals a mass transport by terrace diffusion inside the islands. The energy barrier for diffusion above 820 K is $1.16\ifmmode\pm\else\textpm\fi{}0.08$ eV and it strongly increases up to $3.1\ifmmode\pm\else\textpm\fi{}0.6$ eV below. We attribute this change of regime to a modification of diffusing species from single Au atoms at high temperature to Au clusters at low temperature. The strong shape fluctuations of the 2D islands is consistent with a nearly vanishing line tension of $1.2\ifmmode\pm\else\textpm\fi{}0.4$ meV/nm at 800 K.

Segregation patterns in three-dimensional granular flows.

Flow of size-bidisperse particle mixtures in a spherical tumbler rotating alternately about two perpendicular axes produces segregation patterns that track the location of nonmixing islands predicted by a dynamical systems approach. To better understand the paradoxical accumulation of large particles in regions defined by barriers to transport, we perform discrete element method (DEM) simulations to visualize the three-dimensional structure of the segregation patterns and track individual particles. Our DEM simulations and modeling results indicate that segregation pattern formation in the biaxial spherical tumbler is due to the interaction of size-driven radial segregation with the weak spanwise component of the advective surface flow. Specifically, we find that after large particles segregate to the surface, slow axial drift in the flowing layer, which is inherent to spherical tumblers, is sufficient to drive large particles across nominal transport barriers and into nonmixing islands predicted by an advective flow model in the absence of axial drift. Axial drift alters the periodic dynamics of nonmixing islands, turning them into "sinks" where large particles accumulate even in the presence of collisional diffusion. Overall, our results indicate that weak perturbation of chaotic flow has the potential to alter key dynamical system features (e.g., transport barriers), which ultimately can result in unexpected physical phenomena.