River deltas are valuable resources that support biodiversity and human habitation. Despite this we do not have a global census of deltas nor do we know the conditions that promote their formation. We surveyed 5399 river mouths greater than 50  m wide and found that 2174 (40  %) create a delta. The conditions that lead to delta formation are high sediment input and low wave and tide conditions. These results can be used to understand how deltas will adapt to environmental changes.

Assessing the impact of glaciation at the Earth's surface requires simultaneous quantification of the impact of climate variability on past glacier fluctuations and on bedrock erosion. Here we present a new approach for evaluating post-glacial bedrock surface erosion in mountainous environments by combining two different surface exposure dating methods. This approach can be used to estimate how bedrock erosion rates vary spatially and temporally since glacier retreat in an alpine environment.

We performed seven physical experiments to explore terrace formation and sediment export from a braided alluvial river system that is perturbed by changes in water discharge, sediment supply, or base level. Each perturbation differently affects (1) the geometry of terraces and channels, (2) the timing of terrace formation, and (3) the transient response of sediment discharge. Our findings provide guidelines for interpreting fill terraces and sediment export from fluvial systems.

We mapped eight monsoon-related (> 100 m²) and large (> 0.1 km²) landslides in the Nepal Himalayas since 1970. Adding inventories of Holocene landslides, giant landslides (> 1 km³), and landslides from the 2015 Gorkha earthquake, we constrain the size–frequency distribution of monsoon- and earthquake-induced landslides. Both contribute ~50 % to a long-term (> 10 kyr) total erosion of ~2 mm yr^-1, matching the long-term exhumation rate. Large landslides rarer than ¹⁰Be sampling time drive erosion.

Clast imbrication, which is a depositional fabric where clasts overlap each other similar to a run of toppled dominoes, is one of the most conspicuous sedimentary structures in coarse-grained fluvial deposits. However, the conditions leading to this fabric have been contested. Here, we calculate the hydrological conditions for various stream gradients. We find that clast imbrication most likely forms where channel gradients exceed a threshold and where upper flow regime conditions prevail.