Rapid Erosion Process of Soft Rock Riverbed - Taan River as an Example

Rapid Erosion Process of Soft Rock Riverbed - Taan River as an Example

Severe erosion of rock riverbed occurred in several rivers in Taiwan. Continuous terrain variation in the main channel by rapid riverbed erosion could pose a great threat to the functions and the safety of crossriver infrastructures, as well as ecological sustainability of the river system, among other problems. Proper countermeasures to deal with rapid bedrock erosion attract much attention.
During the 921 earthquake, one channel section of the Taan River was significantly uplifted (up to 10 meters vertically). The length of the uplifted section is 1 kilometer long and 500 meters wide. After the occurrence of uplifting, the riverbed in this river section starts to show severe river-bed incision in just a few years. Unusually rapid incision of the bedrock provides a rare chance to look into the mechanism and processes of rock erosion due to sudden landform uplift by nature. Hence, this uplifted section is selected as a study site to explore the mechanism and process of rock riverbed erosion.

Historical aerial orthophotos of rapid erosion reach of the Taan River

(1) 1999/12/10

(1) 1999/12/10

(2) 2002/06/11

(2) 2002/06/11

(3) 2005/10/27

(3) 2005/10/27

(4) 2007/10/30

(4) 1999/10/03

Location of rapid erosion reach in the Taan River

Location of rapid erosion reach in the Taan River

Longitudinal thalweg profiles of historical surveyed data of the Taan River

Longitudinal thalweg profiles of historical surveyed data of the Taan River

Historical profiles of cross-section No. 45 of the Taan River

Historical profiles of cross-section No. 45 of the Taan River