Speaker: George Allen, Texas A&M University

Title: A Global View of Rivers and Streams

Abstract: The turbulent surfaces of rivers and streams are natural hotspots of gaseous exchange with the atmosphere. At the global scale, the total river-atmosphere flux of trace gasses such as carbon dioxide depends on the proportion of Earth's surface that is covered by the fluvial network, yet the total surface area of rivers and streams is poorly constrained. We built a global database of planform river hydromorphology and used a statistical approach to show that global river and stream surface area at mean annual discharge is 773,000 ± 79,000 km2 (0.58 ± 0.06%) of Earth's nonglaciated land surface, an area 44 ± 15% larger than previous spatial estimates. Rivers and streams therefore likely play a greater role in controlling land-atmosphere fluxes than is currently represented in global carbon budgets. Ongoing developments in the fields of surface hydrology and remote sensing of rivers will also be discussed.

Short Bio: Dr. George Allen is an Assistant Professor of Physical Geography at Texas A&M University. Dr. Allen is the head of the Global Rivers Group in the Department of Geography and is faculty of the Texas A&M Water Program. He studies surface water resources using remote sensing, geospatial analysis, models, and fieldwork. His work focuses on characterizing river systems at the global scale, including fluvial geomorphology, flood hazards, and river-atmosphere biogeochemical interactions. Dr. Allen received his B.S. from UC Davis in Geology, his M.S. and Ph.D. in Geological Sciences from UNC Chapel Hill. He did a postdoc at the Caltech Jet Propulsion Laboratory before joining the Texas A&M Faculty in 2018. His research is motivated by a desire to promote the conservation, management, and understanding of surface water resources worldwide.