Key Point of Bridge Damage Caused by Glacial Debris Flows along International Karakorum Highway, Pakistan

Glacial debris flows along International Karakorum Highway (KKH) connecting northern Pakistan with China, are always causing so extreme threats to a majority of bridges built along KKH. So the improvement project of KKH has been being carried out by China Road & Bridge Corporation in 2008. However it is necessary to collect the detailed data about the damages to bridges and obtain the most dangerous key position. The series of field investigations from 2008 to 2011 demonstrate that the damages are classified into four categories: deposition under bridge, abrasive erosion, impact on piers or abutment and collapse due to buoyancy. Statistics indicate deposition under bridge is the most dominant damage whereas the most serious damage is the impact on piers or abutments. Therefore a case study on key point is made for the typical bridge subjected to impact from Ghulkin glacial debris flow. Finally prevention measures are given.

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Evaluation of Rainfall-Triggered Debris Flows under the Impact of Extreme Events: A Chenyulan Watershed Case Study, Taiwan

Water ◽

10.3390/w13162201 ◽

2021 ◽

Vol 13 (16) ◽

pp. 2201

Author(s):

Jinn-Chyi Chen ◽

Wen-Shun Huang

Keyword(s):

Debris Flow ◽

Extreme Events ◽

Debris Flows ◽

Extreme Rainfall ◽

Extreme Rainfall Event ◽

Extreme Rainfall Events ◽

Hourly Rainfall ◽

Central Taiwan ◽

The Impact

This study examined the conditions that lead to debris flows, and their association with the rainfall return period (T) and the probability of debris flow occurrence (P) in the Chenyulan watershed, central Taiwan. Several extreme events have occurred in the Chenyulan watershed in the past, including the Chi-Chi earthquake and extreme rainfall events. The T for three rainfall indexes (i.e., the maximum hourly rainfall depth (Im), the maximum 24-h rainfall amount (Rd), and RI (RI = Im× Rd)) were analyzed, and the T associated with the triggering of debris flows is presented. The P–T relationship can be determined using three indexes, Im, Rd, and RI; how it is affected and unaffected by extreme events was developed. Models for evaluating P using the three rainfall indexes were proposed and used to evaluate P between 2009 and 2020 (i.e., after the extreme rainfall event of Typhoon Morakot in 2009). The results of this study showed that the P‒T relationship, using the RI or Rd index, was reasonable for predicting the probability of debris flow occurrence.

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IMPACT OF EARTHQUAKE ON DEBRIS FLOWS — A CASE STUDY ON THE WENCHUAN EARTHQUAKE

Journal of Earthquake and Tsunami ◽

10.1142/s1793431111001212 ◽

2011 ◽

Vol 05 (05) ◽

pp. 493-508 ◽

Cited By ~ 16

Author(s):

NING-SHENG CHEN ◽

GUI-SHENG HU ◽

MING-FENG DENG ◽

WEI ZHOU ◽

CHENG-LIN YANG ◽

...

Keyword(s):

Debris Flow ◽

Wenchuan Earthquake ◽

Debris Flows ◽

Key Factors ◽

Land Form ◽

Earthquakes In China ◽

The Impact ◽

Debris Flow Initiation ◽

Stable Stage

This paper describes a study about the impact of earthquakes on debris flows with a focus on the Great Wenchuan Earthquake 2008 in China. The land form, precipitation, and source material are the three key factors for debris flow initiation in the Wenchuan surrounding area. Classifications and examples of four types of debris flow initiation triggering (gully triggering, slope triggering, liquefaction triggering, and gully erosion triggering) have been presented. The initiation mechanisms are attributed to hydraulic and geomechanical aspects. The actual debris flow cases linked with the Great Wenchuan Earthquake and other earthquakes in China have been used to illustrate the increased magnitudes of debris flows due to a large amount of loose materials created by the seismic actions. The critical precipitation for debris flows is reduced by the earthquake. It is predicted that the impact of the Great Wenchuan Earthquake on the local debris flows would be significant in the next 5–6 years, and much less in the following years (up to 20 years). Finally, the debris flow system will reach a relative stable stage. This prediction is based on the historical observations at other earthquake areas and the qualitative analysis on debris flow initiation mechanisms.

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EVALUATING GLACIER DYNAMICS USING TEMPORAL REMOTE SENSING IMAGES: A CASE STUDY OF HUNZA VALLEY, NORTHERN PAKISTAN

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-2-w13-1781-2019 ◽

2019 ◽

Vol XLII-2/W13 ◽

pp. 1781-1785

Author(s):

M. Shafique ◽

B. Faiz ◽

A. Bacha

Keyword(s):

Satellite Images ◽

Temporal Dynamics ◽

Drainage Network ◽

Northern Pakistan ◽

Remote Sensing Images ◽

Landsat Images ◽

Glacier Dynamics ◽

Landsat Satellite ◽

The Impact

<p><strong>Abstract.</strong> Glaciers are the major source of water for drainage network. Northern Pakistan is hosting some of the largest and longest glaciers. Studies evaluating the temporal dynamics of glaciers in Pakistan shows contradictory results of retreat, stable of advancing behavior. Aim of the present study is to evaluate the temporal dynamics in three glaciers in northern Pakistan, using Landsat satellite images. The Landsat images for the years of 1977, 1999, 2001, 2007, 2009 and 2014 shows retreat in selected Hispar, Birpu and Bualtar glaciers. To evaluate the impact of weather indicators of the glaciers dynamics, the temporal glaciers inventories were compared with the rainfall and temperature for the corresponding years. This study should assist to understand the glaciers dynamics and future climate of the region.</p>

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