Geography Commons^™

Is Field Size An Indicator Of Farm Size In Smallholder-Dominated Croplands?, Sitian Xiong, Protensia Hadunka, Brian P. Mulenga, Kathy Baylis, Philippe Rufin, Lyndon Estes

Geography

Farm size is a key characteristic of agricultural systems, closely linked to farming and land management practices. However, data on farm size are often difficult to obtain, especially in smallholder-dominated regions, and where available, they are rarely spatially explicit. This study examines the use of field size as a proxy for farm size, aiming to identify field size thresholds that can distinguish farms of different sizes. Using household-level data from Zambia’s Crop Forecast Survey, we applied both continuous and categorical methods to quantify the field-to-farm size relationship. Non-parametric Theil–Sen regression revealed a generally linear relationship between log-transformed field and farm …

Evolving U.S. And Chinese International Development Policy: Institutions, Strategies, And Global Impact, Julian Kai Lehto

Social Sciences

This paper is inspired by, and meant to understand, recent changes in global policy towards foreign aid and international development. 2025 saw one of the biggest changes to international development in decades, when President Donald Trump’s new administration made the decision to effectively shut down the United States Agency for International Development (USAID). At the same time, China has been taking on a growing role in foreign aid and development over the last decade. Chinese projects like the Belt and Road Initiative (BRI) have become globally significant. This paper will explore the changing impacts and influence of both the U.S. …

College Of Natural Sciences 2025 Year-End Publication, College Of Natural Sciences

College of Natural Sciences Newsletters and Reports

Page 2 Dean's Message 
Page 3 Department Highlights 
Page 4 One Day for State 
Page 5 Ice cores reveal volcanic eruptions in 13th century 
Page 5 How do our cells interpret stress 
Page 6-7 Faculty Excellence
Page 8 New chemical biology consortium will accelerate cancer research
Page 9 SDSU to combat crop disease, biofilms in new NSF-back project 
Page 9 Science as Art Competition 
Page 10-11 Student Excellence  
Page 12 SDSU researcher developing natural alternative to synthetic dyes
Page 12 Browning Retired
Page 13 Quantum technologies through NSF-backed project
Page 13 NASA Funds CNS Development of Model
Page 14 GGS …

A Framework For Food Reliability In Zambia, Junren Wang, Megan Konar, Sitian Xiong

Student Publications [Scholarly]

Ensuring the reliability of domestic food supplies is increasingly critical given the compounding shocks of production variability, transportation constraints, and demand surges. This study develops a spatially explicit framework for Zambia, introducing the food reliability index to quantify the probability that food requirements exceed supply under stochastic conditions. By integrating probabilistic production estimates with a gravity model of domestic trade, we evaluate reliability dynamics across rural and urban landscapes. We apply this framework to establish a 2020 baseline and project future vulnerabilities to 2050. To address projected deficits, we simulate intervention scenarios, comparing the efficacy of cropland expansion, yield intensification, …

Montana Residents’ Attitudes Towards Tourism – 2025, Carter Bermingham, Megan Schultz, Jayce Beck

Institute for Tourism and Recreation Research Publications

Montana residents maintain a broadly positive outlook on tourism, with 66% agreeing that tourism's benefits outweigh its drawbacks and 72% recognizing the economic value of state-supported tourism promotion. However, resident sentiment remains nuanced: 45% report concerns about overcrowding, and fewer than half (36%) believe increased tourism would improve their personal quality of life — a trend consistent across four consecutive years.

Regional divides are pronounced. Communities near high-visitation destinations such as Glacier National Park and Yellowstone National Park express greater skepticism toward tourism growth, while lower-visitation regions, including Central Montana, Southeast Montana, and Missouri River Country, hold more favorable views …

Automated Machine Learning For High-Resolution Daily And Hourly Methane Emission Mapping For Rice Paddies Over South Korea: Integrating Modis, Era5-Land, And Soil Data, Jiah Jang, Seung Hee Kim, Menas Kafatos, Jaeil Cho, Gayoung Yoo, Sujong Jeong, Yangwon Lee

Institute for ECHO Articles and Research

Agriculture is a major global source of methane (CH4), and accurate emission estimates are essential for refining national greenhouse gas inventories and supporting climate-resilient policies. This study develops a high-resolution estimation framework for CH4 emissions from Korean rice paddies by integrating multi-source datasets, including Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation indices, European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis Version 5 (ERA5)-Land meteorological variables, and Harmonized World Soil Database (HWSD) soil properties. Using CH4 flux observations from four global rice ecosystems (Italy, Japan, South Korea, and USA), we constructed parallel daily and hourly machine learning models using an automated machine …

Beyond Artifacts And Fossils: Exploring The Contributions And Socioeconomic Impacts Of Montana’S Museums And Paleontological Tourism, Emma Keinath-Lopez, Elena Bigart, Glenna Hartman, Kara Grau, Ava Worbets, Melissa Weddell

Institute for Tourism and Recreation Research Publications

This study explores how Montana’s museums, including those along the Montana Dinosaur Trail, influence communities, economies, and visitor experiences in a post-pandemic environment. Through mixed methods—511 visitor surveys at 44 museums and 18 interviews with museum professionals— this research provides a holistic understanding of museum operations, visitor motivations, and community impacts.

A Probabilistic Deep Learning Framework For Retrieving Chlorophyll-A From Hyperspectral Imagery: Integrating Channel Attention And Mixture Density Networks, Wenzhao Li, Surendra Maharjan, Rejoice Thomas, Junde Chen, Hesham Morgan, Michael J. Garay, Olga V. Kalashnikova, Shahryar Fazli, Charles Ichoku, Hesham El-Askary

Mathematics, Physics, and Computer Science Faculty Articles and Research

Accurate monitoring of Chlorophyll-a (Chla) is critical for assessing aquatic ecosystem health, yet ecological complexity often leads to ambiguous spectral signatures in satellite data. Traditional deterministic models assume a one-to-one mapping between spectra and pigments, often failing to capture these high-dimensional analytical challenges. In this study, we propose a novel deep learning architecture, the Channel Attention-Mixture Density Network (CA-MDN), to retrieve Chla from the National Aeronautics and Space Administration (NASA) Earth Surface Mineral Dust Source Investigation (EMIT) hyperspectral mission. The CA-MDN integrates an attention mechanism to dynamically select ecologically relevant spectral bands and employs a probabilistic output layer to quantify …

Relationship Between Vegetation Greenness (Ndvi) And Land Surface Temperature Across Land Cover Types In Ciwidey Sub-Watershed (1990–2020), Syal Syabila, Kuswantoro Marko, Revi Hernina

Jurnal Geografi Lingkungan Tropik (Journal of Geography of Tropical Environments)

Land cover change significantly influences vegetation greenness and land surface temperature (LST), particularly in upstream watershed regions experiencing rapid development. This study aims to analyze changes in vegetation greenness (NDVI), land surface temperature, and their relationship across different land cover types in the Ciwidey Sub-Watershed, Bandung Regency, during 1990–2020. Landsat 5 TM and Landsat 8 OLI images (Path/Row 122/65) acquired in July 1990, 2005, and 2020 were processed using radiometric correction, supervised classification (Maximum Likelihood), NDVI extraction, and mono-window LST algorithm. Land cover classification accuracy was assessed using confusion matrix analysis. Linear regression was applied to evaluate the relationship between …

Temperature And Sex Ratios At Birth, Jasmin Abdel Ghany, Joshua Wilde, Anna Dimitrova, Ridhi Kashyap, Raya Muttarak

Publications, Reports and Presentations

Human sex ratios at birth (SRBs) shape population composition and are closely linked to maternal health and gender discrimination. In the context of environmental change, SRBs may theoretically be skewed by physiological or behavioral responses to exposure to extreme heat. However, evidence for this is limited. In this study, we estimate the effect of prenatal exposure to temperature on birth sex by linking survey data on 5 million live births in 33 sub-Saharan African countries and India with high-resolution temperature data. To distinguish between spontaneous and induced abortions, we exploit sociodemographic differentials, exposure timing, and regional differences in son preference. …

Moment Of Recognizability: Askancing And The Global South, Pedro Lange Churion, Tanu Sankalia

Global Studies Faculty Publications

This article introduces askancing as an epistemic strategy for the Global South to challenge the Global North’s construction of the Global South’s alterity. Askancing is a neologism we propose by engaging with Jacques Lacan’s speculations on the gaze as it pertains to the construction of “the other.” We argue that this strategy of askancing might already be implicit in postcolonial theories, from the notion of the subaltern, through “decoloniality,” to “ecologies of knowledge.” Central to askancing—and contrary to the decolonial call for an epistemic break with modernity—we agree with Dipesh Chakrabarty’s assertion that modernity’s rational discourse is both “indispensable and …

Validating Uas-Based Ndvi Data With Satellite Landsat Imagery For Bald Eagle Habitat Prediction In The Del Rio Springs Ecosystem, Noah Morales, Ronny Schroeder, Elise Anderson

Student Works

Vegetation health is commonly assessed using the Normalized Difference Vegetation Index (NDVI), which can be derived from multispectral sensors operating at different spatial resolutions. Validating NDVI products across sensor platforms is essential to determine their reliability for environmental monitoring and habitat assessment. This research compares NDVI derived from moderate-resolution satellite imagery and high-resolution unmanned aircraft system (UAS) imagery collected over the same study area. Landsat imagery, provided through the joint USGS–NASA mission, was used to represent satellite-based vegetation patterns, while high-resolution multispectral data were acquired using a MicaSense sensor mounted on a UAS to capture fine-scale vegetation detail.

NDVI values …

Satellites, Urban Heat, And Environmental Justice: Community As The Bridge Between Analysis And Action, Joshua B. Fisher, Ambar Rivera, Ava Cison, Ashley Agatep, Kainani Tacazon, Sophia Spiegleman, Alison Mckenery, Rio E. Fisher, Reginald Archer, Jason A. Douglas

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Heat waves are increasing in frequency, intensity, magnitude, and duration, causing a disproportionate impact on marginalized communities exposed to urban heat islands. Newly emerging spaceborne thermal sensing instruments, such as ECOSTRESS and Hydrosat, now have the capabilities to measure urban surface temperatures accurately at the block level (< 100 m) and with enough frequency to capture transient heat waves (daily to subweekly). Such data are critical for monitoring and informing policy and mitigation efforts, such as resurfacing, green space, cooling stations, and medical mobilization. These serve to advance environmental justice and reduce health risks—and deaths—among the most vulnerable: minority, low-income, elderly, those with physical- and mental-health preconditions, unhoused, children, and outdoor workers. While scientists have increasingly used satellite data to quantify urban heat islands and risks to communities, there remains a significant gap in action resulting from such analyses—a figurative and literal “valley of death.” Reviewing over 500 scientific publications, we identify a critical lack of engagement with the communities being analyzed (10.9%; n = 58); yet, community engagement is key to bridging such analysis with subsequent action. Here, we demonstrate how participatory community engagement directly with data and analysis leads to increased policy changes and mitigation efforts. Our framework has immediate implications for how scientists may augment their work and thought processes to achieve …

Prediction Of Methane Gas By Using Hyperspectral Imageries And Remote Sensing Techniques, Aysha Ali Alharmasi Alhajeri

Thesis/ Dissertation Defenses

Greenhouse gases is important for sustaining life on earth as well as in mitigating climate change. Methane (CH4) is considered as one of the most important critical gases for the global climate change and have significant influences on our life. Accordingly, the prediction of this greenhouse gas emissions is very important for avoiding the climate change effects and to maintain environmental sustainability. The objective of this study is to explore the potential applications for remote sensing to predict methane levels in the Earth’s atmosphere with a combination of local ground data and data from hyperspectral satellite imagery. By using hyperspectral …

Artemisinin Partial Resistance Mutations In Zanzibar And Tanzania Suggest Regional Spread And African Origins, 2023, Sean V. Connelly, Julia G. Muller, Mohamed Ali, Billy E. Ngasala, Wahida Hassan, Bakari Mohamed, Kyaw L. Thwai, Jacob M. Sadler, Jacob Marglous, Abebe A. Fola, Abdallah Zacharia, Shija J. Shija, Safia Mohammed, Dominick C. Msolo, Hamza Said, Editruda E. Peter, Melic Odas, Isaack J. Rutha, Mwanaidi Nwange, Karamoko Naire, Shazia Ruybal-Pesántez, Robert Verity, Rebecca Crudale, Varun Goel, Barbara B. Choloi, Anders Björkman, Jeffrey A. Bailey, Jessica T. Lin, Jonathan J. Juliano

Faculty Publications

Artemisinin partial resistance, driven by Plasmodium falciparum K13 mutations, threatens malaria control. Zanzibar is vulnerable to artemisinin partial resistance spread but lacks recent molecular surveillance. We sequenced samples in Zanzibar and mainland Tanzania collected from 2022 to 2024. K13 mutations were found in 2 of 1440 participants (P441L, A675V) in Zanzibar and 6 of 3762 (R561H, P441L) in mainland Tanzania. Based on whole genome sequencing data, K13 mutations appear to be of African origin with regional spread. Frequent parasite importation appears to maintain partner drug mutation frequencies similar to the mainland, where artemether-lumefantrine selects for mutations favoring artesunate-amodiaquine sensitivity. Ongoing …

Beyond "Place Matters": Making Spatial Analysis Accessible With Dashboard-Driven Geography, Stephen Borders

Public Health

This article presents an instructional module that uses Tableau to teach spatial thinking and policy geography through an analysis of Supplemental Nutrition Assistance Program (SNAP) participation. Tableau’s ability to integrate custom spatial files with demographic and health data makes it an accessible platform for introducing geographic inquiry without requiring specialized GIS expertise. The lesson guides instructors through building maps, bullet charts, and scatterplots that highlight gaps between eligibility and enrolment, while connecting food insecurity to health outcomes. By lowering technical barriers, Tableau provides a pedagogical bridge that helps educators foster spatial literacy in diverse classroom contexts.

This article was published …

Post-Wildfire Water Quality And Aquatic Ecosystem Response In The U.S. Pacific Northwest: Science And Monitoring Gaps, Sara Wall, Jana E Compton, Ashley A. Coble, Beth M. Haley, Jiajia Lin, Allison Myers-Pigg, Justin Reale, Katie Wampler, Kevin D. Bladon, Kurt Carpenter, Heejun Chang, Multiple Additional Authors

Geography Faculty Publications and Presentations

An increase in the occurrence of large, high severity wildfires in the western Pacific Northwest (PNW), USA, has created an urgent need for science to better inform forest management and policy decisions to maintain source water quality in the region. The western PNW faces similar challenges to other regions with shifting wildfire regimes and large population centers reliant on surface water from forested catchments. However, the uniquely wet and highly seasonal climate of the western PNW suggests that findings from other, more frequently burned regions may not be directly applicable. To identify science, monitoring, and management gaps and opportunities in …

The Hottest Areas In U.S. Cities Are Losing The Most Greenery, Yunjae Ock, Vivek Shandas

Geography Faculty Publications and Presentations

Due to the significantly increasing impacts of urban heat, cities are seeking to expand tree canopy, parks and other forms of greenery to reduce temperatures. Despite these efforts, few studies have examined the relationship between neighborhood-scale thermal conditions and changes in green spaces. The present study drew on high-resolution, near-surface air temperature measurements in 33 U.S. cities to answer two research questions: (1) to what extent did these cities’ greenery change from 2013 to 2022? and (2) did these study areas have an increase in greenery within neighborhoods exhibiting the hottest air temperatures? Results suggest that 72.7% of cities are …

The World's Largest Saddle Dam At Risk: Multisensor Geohazard Analysis And Downstream Impacts, Hesham El-Askary, Hesham Morgan, Surendra Maharjan, Ali Elgendy, Wenzhao Li, Rejoice Thomas, Austin Madson, Cyril Rakovski

Mathematics, Physics, and Computer Science Faculty Articles and Research

The Grand Ethiopian Renaissance Dam (GERD) Saddle Dam, which holds approximately 89% of the main reservoir's live storage, is one of the largest and most critical auxiliary dams globally; its construction on Ethiopia's Blue Nile has consequently raised significant regional and international concerns regarding potential environmental impacts and geohazard risks. This study presents a comprehensive risk assessment of the GERD Saddle Dam by integrating high-resolution satellite data (GRACE, Sentinel-1, Sentinel-2, WorldView-3), hydrological modeling (SWAT), Persistent Scatterer Interferometry (PSI), geospatial analysis, and advanced statistical techniques. The results highlight critical structural vulnerabilities, including groundwater infiltration estimated at approximately 41 ± 6.2 billion …

Understanding The Epidemiology Of Malaria In Zanzibar Through Molecular And Serological Analysis Of Samples Collected During Reactive Case Detection, Vanrun Goel, Wahida Hassan, Caroline Murphy, Barbara B. Choloi, Mohamed Ali, Shija J. Shija, Jeffrey A. Bailey, Anders Björkman, Billey E. Ngasala, Eric Rogier, Jonathan J. Juliano, Jessica T. Lin

Faculty Publications

Background

The Zanzibar archipelago has been a pre-elimination region for malaria thanks to rigorous control interventions, but recent surges in malaria cases have been observed. The contribution of non-falciparum species to the current malaria situation is unknown.

Method

This study investigates the epidemiology of falciparum and non-falciparum malaria species in Zanzibar. Leveraging plasma extracted from dried blood spots (DBS) collected during reactive case detection (RCD) activities across Unguja island from May 2022 to January 2023, we measured immunoglobulin G (IgG) responses to Plasmodium MSP1-19kD antigens using a multiplex bead-based immunoassay. Additionally, active infections were detected using species-specific real-time PCR.

Results …