Research

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

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

This NSF-funded project (2018-2022, PI Dr. Katrina Mullan, U Montana) will quantify feedbacks among land use, climate, soil moisture, surface 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.  We are currently seeking applicants for this research at both the MS and PhD levels.  Please contact tbiggs@sdsu.edu or fdesales@sdsu.edu.  See SDSU media coverage here and on page 10 here.  See the project website here.

Ye Mu, Trent Biggs, Douglas Stow & Izaya Numata (2020). Mapping heterogeneous forest-pasture mosaics in the Brazilian Amazon using a spectral vegetation variability index, band transformations and random forest classification, International Journal of Remote Sensing, 41:22, 8682-8692, DOI: 10.1080/2150704X.2020.1802529

De Sales, Fernando, Thais Santiago, Trent W. Biggs, Katrina Mullan, Erin O. Sills, and Corrie Monteverde (2020). Impacts of protected area deforestation on dry‐season regional climate in the Brazilian Amazon. Journal of Geophysical Research: Atmospheres, 125, e2020JD033048.

Land cover, runoff and erosion in Tijuana, Mexico

This series of projects, funded by the US EPA, aimed to map and model land cover, runoff and erosion from urbanized watersheds in Mexico that drain to the ecologically-valuable Tijuana Estuary.  Projects included measurement and modeling of runoff and sediment load, mapping of gully and channel erosion, and mapping land cover and socioeconomic status.  Students involved:  Garrett McGurk, Ben Downing, Kris Taniguchi (PhD 2018), Napoleon Gudino-Elizondo (PhD 2018).

 

 

Stable isotopes for detection of runoff sources and evaporation

Stable isotopes of water (18O and D) can be used for both source identification and quantification of evaporation rates.  We have used isotopes to estimate evaporation fractions in high elevation-lakes in the Himalaya (funded by WWF-India), and are currently using them to separate dry weather flows in San Diego into local and imported (Sierra Nevada, Colorado River) sources, funded by the County of San Diego.

Biggs, T. W., Lai, C.-T., Chandan, P., *Lee, R. M., *Messina, A., Lesher, R. S., & Khatoon, N. (2015). Evaporative fractions and elevation effects on stable isotopes of high elevation lakes and streams in arid western Himalaya. Journal of Hydrology, 522(0), 239–249. http://doi.org/10.1016/j.jhydrol.2014.12.023

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 http://sdwaterquality.sdsu.edu/.

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.

 

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. http://doi.org/10.1002/2016WR019107

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. http://doi.org/http://dx.doi.org/10.1016/j.gloenvcha.2016.05.003

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 http://www.sciencedirect.com/science/article/B6T3X-4YJCTMK-1/2/94fb2a6a5321f73c294d33692cc1ec4c

Land-Based Pollution of Coral Reefs, American Samoa

Sediment and nutrient loading impacts the health of coral reefs.  This series of projects funded by NOAA and NFWF quantified the sources of sediment in a watershed draining to a sediment-impacted reef, and documented the impact of mitigation activities on sediment load.  Students involved:  Alex Messina (PhD, 2016), Greg McCormick (MS 2016), Sean Quezada (MS)

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.