Research

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

This new NSF-funded project (2018-2022, PI Dr. Katrina Mullan) will quantify feedbacks among land use, climate, soil moisture, surface water availability, 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, socioeconomic surveys, and agent based models 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.

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, Kris Taniguchi, Napoleon Gudino-Elizondo.

 

 

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

Telemetry provides the opportunity for real-time monitoring of water quality, especially in remote locations. In this cooperative project between SDSU and the San Diego River Park Foundation (SDRPF), members of the Biggs Lab have installed water quality sondes and pressure transducers to measure stream level on Boulder Creek and report the data in real-time via HPWREN. See the Online Data and Summary Story.

Groundwater change and water quality in the Mexicali Valley

These projects mapped changes in groundwater levels and water quality and how they have changed in the Imperial and Mexicali Valleys from 1980-2018, a period when land use and water management changed dramatically. The results of this project will help identify areas that are sensitive to future land use change, and where water quality impairs agricultural production. Students involved:  Rodney Feddema (MS), Sarah Roberts (MS).

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).

*Messina, A. M., & Biggs, T. W. (2016). Contributions of human activities to suspended sediment yield during storm events from a small, steep, tropical watershed. Journal of Hydrology, 538, 726–742. http://doi.org/10.1016/j.jhydrol.2016.03.053

Storlazzi, C. D., Cheriton, O. M., *Messina, A. M., & Biggs, T. W. (2018). Meteorologic, oceanographic, and geomorphic controls on circulation and residence time in a coral reef-lined embayment: Faga’alu Bay, American Samoa. Coral Reefs. http://doi.org/10.1007/s00338-018-1671-

* indicates student co-author