The Huanghe (Yellow River) delta, China, is one of the most dynamic and heavily urbanized coastal landscapes in the world. We aim to utilize the ancient record of human-landscape interactions and an unrivaled pace of present-day fluvial dynamics to inform frameworks for the management of river and deltaic landscapes globally. Science here includes integrating field observations and numerical models, to evaluate fluvial-deltaic and landscape development. Because the Huanghe carries an exceptionally high sediment load, the drivers of change for this system are internal, so that boundary conditions of the basin exert minimal influence of the stratigraphy. This project is a multi-investigator, cross-disciplinary and integrative effort that includes researchers from around the world.
The sedimentary dynamics of active rift-basin margins are rarely evaluated based on studies from modern dispersal systems, despite the abundance of stratigraphic information regarding these systems preserved in the rock record. The Selenga River delta of Lake Baikal (Siberia, Republic of Buryatia, Russian Federation) provides an opportunity to evaluate the interplay between sedimentology and tectonics for shaping fluvial-deltaic stratigraphy. Here, a 30-million year old shelf-edge deltaic system has produced > 9 km of sediment deposit. We are analyzing hydrology and sediment transport across the topset and foreset of the Selenga River delta to evaluate how sustained tectonic subsidence influences sediment transport and the preservation of deposits. This project represents an excellent opportunity to evaluate the interplay between internal and external (i.e., “autogenic” versus “allogenic”) drivers on the production of fluvial-deltaic stratigraphy.
The Western Irish Namurian Basin (~ 310 m.a.) is considered to be a shelf-edge deltaic system, with sediment transport connections between delta and deep-water deposits. Our aims here are to evaluate the physical processes of dispersal across the wide-range of sedimentary environments preserved within this basin, and evaluate linkages to the stratigraphy of the system. This information helps inform about the importance of sediment transport processes in modern systems, by identifying the strata signatures of adjusting morphodynamic conditions pervasive in all sedimentary basins.
Texas Gulf Coast:
Our work on the Texas Gulf Coast evaluates sediment dispersal, accumulation patterns, and delta dynamics. Research efforts include evaluating the role of large woody debris for damping wave stress and helping preserve the Brazos River delta. Additionally, numerical modeling efforts have explored the interactions of Holocene sea-level rise and hydrodynamics for the Trinity River system, which provides a natural laboratory for linking fluvial morphodynamics to stratigraphy produced by sea-level rise, because the sediments occupying the Trinity incised valley are well-constrained in terms of timing of deposition and facies distribution.
Mississippi River delta:
Sediment transport properties are intimately linked to hydrodynamics, so it is only natural to evaluate how properties of water discharge vary in time and space across a fluvial-deltaic system. With its exceptionally low river slope, the Mississippi River possesses a long (> 500 km) reach where water flow velocity decelerates during low and moderate water discharge conditions. This “backwater” effect has important controls on the transport sediment, both for grain size and style (e.g., bedload versus suspended load). Our group focuses on evaluating the movement of sand from the delta apex to the distal channel edges found in the Gulf of Mexico. This work has important implications for efforts to restore the deltaic wetlands of Louisiana, via controlled water and sediment diversions to the surrounding topset.
Active learning in the classroom: