Morphology of river deltas at active tectonic margins
Delta morphology is impacted by upstream and downstream boundary conditions that operate over a range of spatial and temporal scales. Here, we explore the effect of a particular boundary condition, episodic tectonic subsidence, on delta dynamics using field data collected from the Selenga River Delta, Russia and analytical models.
Bankfull channel geometry in sand-bed rivers
For gravel-bed rivers, channel geometry adjusts so that the average fluid shear stress slightly exceeds the critical stress of mobility for the median bed sediment size. However, for sand-bed streams, fluid stress is usually up to an order of magnitude greater than the critical stress of mobility for sand, hence large uncertainties exist for relations that predict hydraulic geometry. Here, we explore the possibility that bank properties may control hydraulic geometry of rivers by analyzing a global data set, including the Selenga River Delta, Russia.
Flow partitioning in distributary channel networks
Partitioning of water and sediment discharge at a river bifurcation are complex processes. Distributary network of a river delta often contains numerous bifurcations, therefore making prediction of flux distribution very difficult. Here, we develop a graph model to predict flow partitioning in a delta network solely based on remote sensing data. This framework is applied to multiple deltas worldwide, by which predictions are in agreement with field data.
Recognizing river channel patterns in the rock record
Distinguishing between single-thread and braided river patterns is straightforward in modern environment as they can be directly observed or predicted using hydrological data. However, distinguishing channel patterns in the rock record has proven to be difficult, as only remnants of the river channels are preserved and they only account for a small fraction of the overall record. Identifying channel patterns in the ancient is important for predicting the quality and heterogeneity of groundwater and hydrocarbon reservoirs. Here, we develop a novel set of metrics for distinguishing river types using distributions of the dimensions of river channels and channel belts, measured from modern rivers using remote sensing data.