Natural levees are the elevation boundary between a river and its floodplain. By looking at how sediment is transported (ie. deposited and eroded) on levees, I want to better understand the sediment and organic matter fluxes to floodplains. The knowledge of how sediment transport shapes floodplain topography will allow for a more precise quantification of sediment and organic matter storage. Additionally, this research will look at the impact of flooding on the floodplain, which is important for infrastructure and resource development.
We are interested in understanding how water availability changes across the Annapurna Himalayas, Nepal. To do this we are using four-year water isotope time series data from the Kali Gandaki River. Water molecules have different isotopic characteristics that vary based on several physical processes such as re-evaporation of water from earth surface, moisture source pathways and precipitation amount. By analyzing the trends in water isotope values, we can better understand the river water sources on both sides of the mountain front.
The Trinity River, Texas, is contained within terrace walls that were formed during Pleistocene sea-level fall. Past research has postulated that there were three distinct sea level fall and lateral migration periods of the river as these terraces were formed. Using a new high resolution elevation map produced from airborne lidar (Light Detection and Ranging) over a 80km linear section, we use a statistical approach to assess if each group of terraces is unique and produced by separate external events (allogenic signal). We find that we cannot rule out that terraces were created through continuous internal processes (autogenic signal) as sea level fell. This research helps develop new metrics to determine if a river terrace belongs to a series of terraces formed during an external change to the river or to a continuous evolution of the river valley as the overall sea-level falls.
Deltas have an important characteristic, the avulsion node — a point along which a river abandons its current channel and builds out the delta at a different location. One hypothesis is that this location of an avulsion is tied to the region where hydraulics of the river are influenced by sea level. Our research revealed that the avulsion occurs in this region due to the increased amount of erosion and deposition compared to other regions of the river. As an undergrad at Caltech, we showed this using a physical experiment of a delta with variable flow (low flow and floods). This research highlights the importance of variable flow on natural deltas that are managed by flood controls, for example, the Mississippi River delta and Huang He (Yellow) River delta.