The tide dominated Meghna estuary is characterized by a sequence of distributary channels and islands/chars. While there are a few studies on morphological processes of the Meghna estuary in general, studies on the physical processes of the islands/chars in the estuary are sparse. Close to two million people live on some of these fragile islands and chars. Given the lack of scientific literature on the formation and dynamic processes of the islands/chars, the chapter analyzes time-series historical maps and satellite images in an attempt to fill the knowledge gap. The study reconstructed the history of the Meghna estuary and islands and chars using maps and satellite images, recorded various noticeable events in the estuary and islands, and identified related drivers. Thereafter, the processes of formation of islands/chars and the time required for this in different physical environments were verified. The dynamics of the islands/char formation include the processes of erosion/accretion, increase/decrease in size, changes in shape, and migration of islands/chars.@en

This paper presents a hydraulic and morphological analysis of the Lower Jamuna in Bangladesh with a focus on two key bifurcations that are important for stabilization of the Lower Jamuna reach. We used ground measurements, historical data, multispectral satellite images from various sources as well as numerical models. We carried out hydraulic analyses of the changes and their peculiarities, such as flow distributions at the bifurcation and hysteresis of the stage–discharge relationships. We supplemented our analysis by using numerical models to simulate discharge distribution at the bifurcations under various flow and riverbed conditions. We developed an advanced and automated satellite image processing application for the Lower Jamuna, referred to as Morphology Monitor (MoMo), using the Google Earth Engine. MoMo was found to be an effective tool for a rapid assessment and analysis of the changes in deep-channel and sandbar areas. It is also useful for monitoring and assessing riverbank and char erosion and accretion, which is important not only for morphological but also ecological impact assessment. The application can be adapted as an operational tool as well. Furthermore, we assessed the evolution of deep channels at the bifurcations based on regularly and extensively measured bathymetry data. The analysis was carried out in complement with morphological modeling, particularly for short-term prediction. In this paper we present the major findings of the analysis and discuss their implications for adaptive river management.@en