For a full list of all papers, see Google Scholar page here or Biggs cv here.

Current research projects

Rural Heat Islands and Farmworking Communities

Urban heat islands have received much attention in climate change adaptation, but mapping and adapting to rural heat islands (RHIs) is also critical for California’s climate action and environmental justice. Farmworking communities are vulnerable to heat stress, especially in the hot desert of the Imperial Valley.

We propose to map rural heat islands and to co-produce knowledge on heat stress exposure and dissemination strategies with the farmworker community of Imperial Valley, California.

*** Seeking PhD and MS students for this project!  Please contact for details. ***

Automated mapping of cropping intensity at global scales

This USGS-funded project (PI Dr Prasad Thenkabail) aims to map cropping intensity (single, double, triple cropping) at global scales using Google Earth Engine and machine learning techniques.

*** Seeking PhD and MS students for this project!  Please contact for details. ***

Coupled land-water-climate-human dynamics in the Amazon Basin

This NSF-funded project (2018-2022, PI Dr. Katrina Mullan, U Montana) quantifies feedbacks among land use, climate, water, and human well-being and behavior in the Brazilian Amazon. The project will couple models of climate (Dr. Fernando de Sales, SDSU) with land surface models, hydrological data and models (Biggs), socioeconomic surveys, and agent-based models of human decisions to quantitatively link the hydroclimate, humans, and land cover outcomes.  See SDSU media coverage here and on page 10 here.  See the project website here, and project resources here.  Brazil-wide Water Resources Network ProfAgua aqui.

Sustainable agriculture and water in California

This USDA-funded project (PI Dr. Lluvia Flores-Renteria, Biology) aims to recruit students for the agricultural workforce and provide skills in sustainable agriculture.  The water resources component focuses on irrigated agriculture and the water use of different crops in California using remote sensing and water balance methods.

Plastic and anthropogenic debris mapping and modeling

Plastic and other anthropogenic debris are a threat to marine and freshwater ecosystems, and present hazards by blocking drainage and increasing flood hazard.  We have projects in the US and Mexico designed to help map, monitor, and model the mass balance of anthropogenic debris.

Figure credit: Elena Aguilar

Real-time Water Quality Monitoring

Impaired water quality threatens human health and ecosystems.  Contamination events, including from sewer system overflows, can be difficult to predict, and yet there are few real-time water quality monitoring stations in the San Diego-Tijuana Border region.  We are developing systems to monitor water quality in real-time, including proxies for bacteria concentrations, using telemetry and advanced water quality monitoring systems.  See the Online Data and Summary Story.  In 2019 we installed a system on the San Diego River at Mission Trails and in 2021 in the Tijuana Estuary to monitor tryptophan, an indicator of bacteria. See the data collected to date at

Land Use Change, Crop water use and Water Resources

Water scarcity both drives and is impacted by land cover change. This series of projects aims to map crop water use and land cover change in irrigated agricultural regions, including applications in India, Southern Africa, California and on the US-Mexico border, and to document the major drivers of those changes through mixed methods approaches that integrate remote sensing for automated mapping of crop water use (evapotranspiration) and land cover, quantitative survey data, and qualitative interviews. Applications in California and on the US-Mexico border are supported in part through the  NOAA CREST program.  Students involved:  Yelena Granovskaya, Joel Kramer, Gabriela Morales, Alex Messina, Nadine Barham, Gabriela Morales.


Biggs, T. W., Marshall, M., & *Messina, A. (2016). Mapping daily and seasonal evapotranspiration from irrigated crops using global climate grids and satellite imagery: Automation and methods comparison. Water Resources Research, 52(9), 7311–7326.

Hess, T. M., Sumberg, J., Biggs, T., Georgescu, M., Haro-Monteagudo, D., Jewitt, G., … Knox, J. W. (2016). A sweet deal? Sugarcane, water and agricultural transformation in Sub-Saharan Africa. Global Environmental Change, 39, 181–194.

Biggs, T. W., Gangadhara Rao, P., & Bharati, L. (2010). Mapping agricultural responses to water supply shocks in large irrigation systems, southern India. Agricultural Water Management, 97(6), 924–932. Retrieved from

Research tools

SDSU General Guidelines for research safety here.
SDSU guidelines for safety in field research here.

Prior research

Click here to see prior research projects, including groundwater quality in the Imperial Valley, mapping socioeconomic conditions along the US-Mexico border, and others.

ENVS498 projects Fall 2023