Decades of delta avulsion (i.e. channel abrupt jump) study has not resolved what the main controls of delta avulsion are. Using computer model, integrated with field observation, analytical and laboratory-made delta, we found that the sediment load, itself is controlled by the steepness of river upstream of a delta, controls the timing of avulsion. We can now better understand the main cause of abrupt channel changes on deltas, a finding that aids flood risk management in river deltas.

Estimating the sizes of flood events is critical for flood-risk management and other activities. We used data from several sources in a statistical analysis of flood size for rivers in the Philippines. Flood size is mainly controlled by the size of the river catchment, along with the volume of rainfall. Other factors, such as land-use, appear to play only minor roles in flood size. The results can be used to estimate flood size for any river in the country alongside other local information.