Weiwei Zhan

Weiwei Zhan

Assistant Professor at University of Central Florida

Geomorphological Surveys of Successive Landslide Dams

less than 1 minute read

Earthquakes can not only cause immediate slope failure but also affect slope stability and landscape evolution in the short and long terms. Through the extensive field surveys in the earthquake-impacted area, I found an interesting near-fault slope unit where at least three landslide events occurred and dammed the river in the past. From the hazard assessment and prevention perspective, it is important to explore landslide hazard management at such successive sliding and dam sites. I collected multi-temporal remote sensing images and terrain data through unmanned aerial vehicle (UAV) surveys and conducted geomorphological and geological surveys. I concluded that this site is a good example of multiple reactivations of a prehistorical giant landslide under different triggering conditions: a reactivation of an older landslide during a strong earthquake, and a second reactivation during a rainfall event several years later. Meanwhile, I proposed a generalized framework for assessing landslide dam cascading hazards, including landslide volume estimation, empirical landslide dam stability evaluation, GIS-based barrier lake volume estimation, and dam-breach flooding parameter estimation.


You May Also Enjoy

Geomorphological Precursors for Landslide Early Detection

Early detection of rockslides at high-elevation and well-vegetated slopes remains challenging. This study used satellite and unmanned aerial vehicle (UAV) optical remote-sensing (ORS) images to track evidence of slope deformation and examine potential geomorphological precursors of five large rockslides in China. All the surveyed landslides had cracks or scarps and rockfalls within the landslide source area before the onset of rapid sliding. These precursors can be identified in ORS images taken several years or decades before the rapid slope failure, which provides sufficient time for the landslide early detection in practice. Local topography affects the spatial locations of cracks or scarps. Rockfalls within the landslide source area tend to locate at “key blocks” where slope mass provides forces resisting sliding. The rockfall area ratio, defined as the accumulated area of rockfalls over the landslide source area, ranged from 0.33 to 0.92 before rapid slope failure. The landslides developed on anti-dip and igneous rock slopes show a more significant rise of rockfall area ratio before the slope failure than the landslides on dip slopes. Given the broad availability of ORS data, this study could shed light on the ORS- based landslide early detection and landslide kinematics study.

Empirical Modeling of Landslide Mobility

Landslide-impacted area is another crucial element for individual landslide hazard assessment for slope units close to infrastructure and community. Rock avalanche is a high-mobility type of landslide that can travel a few to tens of kilometers and move a mass of a million to billion cubic meters.

Geomorphological Precursors for Landslide Early Detection

Early detection of rockslides at high-elevation and well-vegetated slopes remains challenging. This study used satellite and unmanned aerial vehicle (UAV) optical remote-sensing (ORS) images to track evidence of slope deformation and examine potential geomorphological precursors of five large rockslides in China. All the surveyed landslides had cracks or scarps and rockfalls within the landslide source area before the onset of rapid sliding. These precursors can be identified in ORS images taken several years or decades before the rapid slope failure, which provides sufficient time for the landslide early detection in practice. Local topography affects the spatial locations of cracks or scarps. Rockfalls within the landslide source area tend to locate at “key blocks” where slope mass provides forces resisting sliding. The rockfall area ratio, defined as the accumulated area of rockfalls over the landslide source area, ranged from 0.33 to 0.92 before rapid slope failure. The landslides developed on anti-dip and igneous rock slopes show a more significant rise of rockfall area ratio before the slope failure than the landslides on dip slopes. Given the broad availability of ORS data, this study could shed light on the ORS- based landslide early detection and landslide kinematics study.