The development and shifts of individual lobes suggest a stepwise northward movement of the delta system, which is discussed in relation to a stepwise activity of regional fault systems. Based on geometry, steep clinoforms and the development of beach ridges, the delta is classified as mostly river-dominated with significant influence of wave-reworking processes. We present a detailed description of the depositional architecture of five individual lobes of these deltas in the Austrian part of the central Vienna Basin based on the integration of 3D seismic surveys and well-log data, covering an area of about 600 km². The first deltas of the Paleo-Danube formed around 11.5 Ma ago along the northwestern margin of the Vienna Basin, during a lowstand of Lake Pannon. This highlights that autocompaction is an important process that determines the resilience of these low‐lying landforms to climate change. Our simulations show that compaction is the primary process governing the elevation and geomorphological evolution of these landforms. We showcase the model capabilities by simulating three long‐term depositional processes at different spatial scales: (a) vertical growth of a tidal marsh, (b) infilling of an oxbow lake, and (c) progradation of a delta lobe. The number of FEs gradually increases to accommodate newly deposited sediments and each FE changes its shape, that is, becomes compressed, following sediment compaction. A Lagrangian approach underlies the model by means of an adaptive mesh. The model input consists of sedimentation varying in time, space and sediment type. The model couples a groundwater flow and a compaction module that interact in a time‐evolving domain following landform aggradation. We present a novel finite element (FE) simulator that quantifies the impact of natural compaction on landform evolution in a three‐dimensional setting. However, this process is generally oversimplified in morphological simulators. Consequently, they often experience significant compaction due to their own weight, that is, autocompaction, which creates an important feedback within the geomorphological evolution of the landform. The body of these landforms consists of unconsolidated sediments with high porosity and compressibility. These dynamic environments host vulnerable ecosystems with an essential role for biodiversity conservation, coastal protection and human activities. Natural environments such as coastal wetlands, lowland river floodplains, and deltas are formed by sediment, transported by watercourses and the sea, and deposited over century to millennium timescales.
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