Analysis of the effect of fluvial and tidal sediment fluxes on bifurcations in river channel networks

Abstract

River deltas are complex areas with intricate channel patterns that deliver water and sediment from source to the coast. The shape and pattern of a delta or river network is prone to changes originating from sediment fluxes of fluvial and tidal origin. These changes can be devastating for the 24% of the world population living in delta areas. Quantification of the influence of these fluvial and tidal sediment fluxes on river channel networks is lacking and a global dataset on distributary networks does not yet exist. In this study, the objective is to identify relationships between delta channel networks and fluvial and tidal sediment fluxes for seven deltas around the world. A river network is derived from the JRC Global Water dataset together with the MERIT Hydro dataset available on the Google Earth Engine platform. The network is used to find the number of bifurcations, river outlets and channel lengths. All rivers are placed on a spectrum from highly fluvial dominated to highly tidal dominated and analysed based on the number of bifurcations, river outlets and channel lengths their place on the spectrum. The study finds that terminal channel length decreases with increasing tidal influence which suggests a decrease in number of bifurcations, this is corroborated by literature. This study lays the groundwork for a global understanding of fluvial and tidal influences on delta morphology, however uncertainties lie in the sample size and vector processing. Future research can build on this research by improving the image processing and increasing the number of deltas for a more reliable result.