Characteristic analysis of large-scale loess landslides: a case study in Baoji City of Loess Plateau of Northwest China

H B Wang,J S Shi,S R Wu,B Li,B Zhou

doi:10.5194/nhess-11-1829-2011

Abstract

Abstract. Landslides are one of the most common geologic hazards in the Loess Plateau of northwest China, especially with some of the highest landslide densities found in Shaanxi and adjacent provinces. Prior to assessing the landslide hazard, a detailed landslide inventory map is fundamental. This study documents the landslides on the northwest Loess Plateau with high accuracy using high-resolution Quickbird imagery for landslide inventory mapping in the Changshou valley of Baoji city. By far the majority of landslides are in loess, representing small-scale planar sliding. Most of the large-scale landslides involve loess and bedrock, and the failure planes occurred either along the contacts between fluvial deposits and Neogene argillites, or partially within the bedrock. In the sliding zones of a large scale landslide, linear striations and fractures of the soils were clearly developed, clay minerals were oriented in the same direction and microorganism growths were present. From the analysis of microstructure of sliding soils, it is concluded that the Zhuyuan landslide can be reactivated if either new or recurring water seepage is caused in the sliding surface. It can be concluded that most landslides are attributed to the undercutting of the slope associated with gullying, and numerous ancillary factors including bedrock-loess interface, slope steepness, vegetation cover and land utilization.

Highlights

1 Introduction In China, loess mantles about 631 000 km2, equivalent to about 6.6 % of the total area (Liu, 1985), of which almost half is found on the Loess Plateau of Shaanxi Province
Wang engineering circles, loess is known as a “problem soil”, because of its catastrophic failure on reaching certain critical moisture content
Landslides are one of the most common geologic hazards in the Loess Plateau, especially with some of the highest landslide densities found in Shaanxi and adjacent provinces

Summary

Introduction

In China, loess mantles about 631 000 km, equivalent to about 6.6 % of the total area (Liu, 1985), of which almost half is found on the Loess Plateau of Shaanxi Province. Landslides are one of the most common geologic hazards in the Loess Plateau, especially with some of the highest landslide densities found in Shaanxi and adjacent provinces. Historical records leave no doubt that the environment in this region is a harsh one, with unpredictable and violent monsoonal rainfall and frequent earthquake shaking. These principal triggers, together with a thick mantle of unconsolidated loess over mountainous bedrock terrain, render this undeveloped area subject to landsliding, causing property damage and fatalities. To reduce the number of casualties and damage to property caused by landslides, factors that affect landslide occurrence should be well understood and the spatial location of landslides mapped

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Results

Conclusion