Estimating Rainfall Thresholds for Landslide Occurrence in the Bhutan Himalayas
| Autor: | Raju Sarkar, Kelzang Dorji, Abhirup Dikshit, Saroj Acharya, Biswajeet Pradhan |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
lcsh:TD201-500
lcsh:Hydraulic engineering shallow landslides 010504 meteorology & atmospheric sciences Geography Planning and Development Landslide Hourly rainfall Aquatic Science 010502 geochemistry & geophysics Monsoon 01 natural sciences Biochemistry rainfall thresholds lcsh:Water supply for domestic and industrial purposes lcsh:TC1-978 Road networks Trade route Early warning system Environmental science Physical geography Bhutan 0105 earth and related environmental sciences Water Science and Technology |
| Zdroj: | Water, Vol 11, Iss 8, p 1616 (2019) |
| ISSN: | 2073-4441 |
| DOI: | 10.3390/w11081616 |
| Popis: | Consistently over the years, particularly during monsoon seasons, landslides and related geohazards in Bhutan are causing enormous damage to human lives, property, and road networks. The determination of thresholds for rainfall triggered landslides is one of the most effective methods to develop an early warning system. Such thresholds are determined using a variety of rainfall parameters and have been successfully calculated for various regions of the world at different scales. Such thresholds can be used to forecast landslide events which could help in issuing an alert to civic authorities. A comprehensive study on the determination of rainfall thresholds characterizing landslide events for Bhutan is lacking. This paper focuses on defining event rainfall−duration thresholds for Chukha Dzongkhag, situated in south-west Bhutan. The study area is chosen due to the increase in frequency of landslides during monsoon along Phuentsholing-Thimphu highway, which passes through it and this highway is a major trade route of the country with the rest of the world. The present threshold method revolves around the use of a power law equation to determine event rainfall−duration thresholds. The thresholds have been established using available rainfall and landslide data for 2004−2014. The calculated threshold relationship is fitted to the lower boundary of the rainfall conditions leading to landslides and plotted in logarithmic coordinates. The results show that a rainfall event of 24 h with a cumulated rainfall of 53 mm can cause landslides. Later on, the outcome of antecedent rainfall varying from 3−30 days was also analysed to understand its effect on landslide incidences based on cumulative event rainfall. It is also observed that a minimum 10-day antecedent rainfall of 88 mm and a 20-day antecedent rainfall of 142 mm is required for landslide occurrence in the area. The thresholds presented can be improved with the availability of hourly rainfall data and the addition of more landslide data. These can also be used as an early warning system especially along the Phuentsholing−Thimphu Highway to prevent any disruptions of trade. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|