Application for Terrestrial LiDAR on Mudstone Erosion Caused by Typhoons

Yeuan-Chang Cheng,Jiun-Chuan Lin,Ci-Jian Yang

doi:10.3390/rs11202425

Yeuan-Chang Cheng, Jiun-Chuan Lin + Show 1 more

Open Access

https://doi.org/10.3390/rs11202425

Copy DOI

Journal: Remote Sensing	Publication Date: Oct 18, 2019
Citations: 5	License type: CC BY 4.0

Affiliation: National Taiwan University

Abstract

Storms are important agents for shaping the Earth’s surface and often dominate the landscape evolution of mudstone areas, by rapid erosion and deposition. In our research, we used terrestrial scanning LiDAR (TLS) to detect surface changes in a 30 m in height, 60 m in width mudstone slope. This target slope shows the specific erosion pattern during extreme rainfall events such as typhoons. We investigate two major subjects: (1) how typhoon events impact erosion in the target slope, and (2) how rills develop on the hillslopes during these observation periods. There were three scans obtained in 2011, and converted to two observation periods. The permanent target points (TP) method and DEMs of differences were used to check the accuracy of point cloud. The results showed that the average erosion rate was 5 cm during the dry period in 2011. Following the typhoons, the erosion rate increased 1.4 times to 7 cm and was better correlated with the increase in the rainfall intensity than with general precipitation amounts. The hillslope gradient combined with rainfall intensity played a significant role in the geomorphic process. We found that in areas with over 75° gradients with larger rainfall intensity showed more erosion that at other gradients. The gradient also influenced the rill development, which occurred at middle and low gradients but not at high gradients. The rills also created a transition zone for erosion and deposition at the middle gradient where a minimal change occurred.

Highlights

Mudstone shows heterogeneous erodibility in response to soil moisture, especially during extreme rainfall events, because extreme rainfall can increase its water content in a short time, i.e., mudstone is a clay-bearing material and its characteristic allows rapid weathering and erosion [1,2]
Based on the terrestrial scanning LiDAR (TLS) results, we focused on the erosion rate and erosion pattern affected by precipitation
After comparing the digital elevation models (DEMs) of different scans, we obtained the numbers of topographical change of the target slope in two periods (Table 4)

Summary

Introduction

Mudstone shows heterogeneous erodibility in response to soil moisture, especially during extreme rainfall events, because extreme rainfall can increase its water content in a short time, i.e., mudstone is a clay-bearing material and its characteristic allows rapid weathering and erosion [1,2]. The tipping point of mudstone erosion is the wet–dry circle, resulting in slake [5,6,7] and shrinking due to drying-out in the dry season [8,9,10]. This process produces mud cracks and surface crusts that both develop soil piping, rills, and gullies [11,12,13]. Mudstone slopes can more dynamically change than other mother-rock materials during rainfall events and become a battered field for slope erosion processes

Methods

Results

Discussion

Conclusion