The Ullion Creek is a tributary of the Tinée River in the south east of France. Its 12 km² catchment is very steep, ranging from 2087 m.a.s.l. to 356 m.a.s.l. at the confluence with the Tinée. The creek channel is confined between steep hillslopes until the confluence and has a very uniform longitudinal slope of 11.0\% along the modelled reach. The Tinée River has conversely a catchment of about 600 km² at the confluence. It has an average longitudinal slope of about 1.1%.

On the 2nd and 3rd October 2020, the Alex Storm hit the region triggering extreme rainfalls and catastrophic floods with high sediment transport. The rainfall estimated from the combination of weather radar and rain gauges was higher than 500 mm on the Ullion Creek catchment within less than 24 h. A large landslide occurred in a former diffuse gullying area and fed suddenly the creek with an unlimited amount of sediment. The sediment was transported mainly as bed load, at least in the downstream part of the basin according to videos taken by local dwellers. A massive deposition occurred in the creek bed, elevating the bed level by about 7 m on average. An alluvial fan that was formed at the confluence dammed and diverted the main river to the opposite bank, thus resulting in the erosion of about 300m of the main road.

Two digital terrain models (DTM) where obtained from LiDAR data, the first dating from 2018 (LiDAR2018@MNCA) and the second dating from two days after the event (LiDAR2020@IGN). A total volume of bed material deposit of about 330,000 m^3 was estimated from the difference between both DTM within the extend of the alluvial fan deposit and of the 1.5km terminal reach of the creek.

This dataset contains the Iber+ model of the event that used the initial DTM. The Iber+ model should be run with the executables provided by CEA & GARCIA-FEAL 2023, "Iber+ executables (V3.2b)", https://doi.org/10.57745/UFEK4L.

Iber+, 3.2