Image Credit: NASA Landsat
Research
The focus of my research is to explain how river systems evolve, shape landscapes, and respond to our rapidly changing world. I use a blend of theoretical modeling, remote sensing, laboratory flume experiments, and geologic field techniques to quantify fluvial processes in targeted research topics, summarized below.
1. Evolution of Deltaic Landscapes
Comprising only one percent of Earth’s land surface, river deltas are home to more than ten percent of the human population and some of the most biodiverse ecosystems on Earth. Deltaic landscapes are highly dynamic, and at the largest scale grow through repeated construction of depositional lobes punctuated by sudden, catastrophic changes in the river’s course to the shoreline called river avulsions. River avulsions have been responsible for dangerous floods and civil unrest over human history, but also nourish wetlands with sediment and build land to counter land loss due to sea-level rise and coastal subsidence. Some examples of my work can be found here:
Chadwick AJ, Steele S, Silvestre J, & Lamb MP (2022). More extensive land loss expected on coastal deltas due to rivers jumping course during sea-level rise. Proceedings of the National Academy of Sciences 119(31).
Chadwick AJ, Lamb MP, Ganti V (2020). Accelerated river avulsion frequency on lowland deltas due to sea-level rise. Proceedings of the National Academy of Sciences, 117(30).
Chadwick AJ, Lamb MP, Moodie AJ, Parker G, Nittrouer J (2019). Origin of a preferential avulsion node on lowland river deltas. Geophysical Research Letters, 46(8).
2. River Channel Mobility
River systems are inherently mobile, and over decades to centuries sweep across floodplains to shape Earth’s lowland environments, construct the sedimentary record, and regulate the terrestrial organic carbon cycle. Three billion people live along river corridors worldwide and rely on rivers for food, water, and energy. A quantitative understanding how rivers migrate is crucial for the sustainable management of water resources and erosion hazards, and represents an important pillar of my research. Some examples of my work can be found here:
Chadwick AJ, Steel E, Williams‐Schaetzel RA, Passalacqua P, Paola C (2022). Channel migration in experimental river networks mapped by particle image velocimetry. Journal of Geophysical Research: Earth Surface, 127.
Chadwick AJ, Steel E, Passalacqua P, Paola C (2022). Differential bank migration limits the lifespan and width of braided river threads. Water Resources Research, 58(8)
3. Linking Rivers to the Critical Zone
I am interested in how river systems are linked to the Critical Zone—Earth’s porous near-surface layer where rock, soil, groundwater, and living organisms interact. Biogeochemical weathering in the Critical Zone creates sediments and solutes, which are then redistributed across the landscape by surface-water runoff and groundwater aquifers. This production and transport carry important consequences for Earth’s carbon cycle, the availability of clean and potable water, and the sustainable arability of farmlands. Some examples of my work can be found here:
Steel E, Paola C, Chadwick AJ, Hariharan J, Passalacqua P, Xu Z, Michael, HA, Brommecker H, & Hajek EA (2022). Reconstructing subsurface sandbody connectivity from temporal evolution of surface networks. Basin Research, 34, 1486– 1506. https://doi.org/10.1111/bre.12668
Xu Z, Hariharan J, Passalacqua P, Steel E, Chadwick AJ, Paola C, Paldor A, Michael HA (2022). Effects of geologic setting on contaminant transport in deltaic aquifers. Water Resources Research 58.
Douglas MM, Li GK, Fischer WW, Rowland JC , Kemeny PC, West AJ, Schwenk J, Piliouras AP, Chadwick AJ, Lamb MP (2022). Organic carbon burial by river meandering partially offsets bank-erosion carbon fluxes in a discontinuous permafrost floodplain. Earth Surface Dynamics, 10(3).
