Rainfall Thresholds for Prediction of Landslides in Idukki, India: An Empirical Approach

Idukki is a South Indian district in the state of Kerala, which is highly susceptible to landslides. This hilly area which is a hub of a wide variety of flora and fauna, has been suffering from slope stability issues due to heavy rainfall. A well-established landslide early warning system for the region is the need of the hour, considering the recent landslide disasters in 2018 and 2019. This study is an attempt to define a regional scale rainfall threshold for landslide occurrence in Idukki district, as the first step of establishing a landslide early warning system. Using the rainfall and landslide database from 2010 to 2018, an intensity-duration threshold was derived as I = 0.9D-0.16 for the Idukki district. The effect of antecedent rainfall conditions in triggering landslide events was explored in detail using cumulative rainfalls of 3 days, 10 days, 20 days, 30 days, and 40 days prior to failure. As the number of days prior to landslide increases, the distribution of landslide events shifts towards antecedent rainfall conditions. The biasness increased from 72.12% to 99.56% when the number of days was increased from 3 to 40. The derived equations can be used along with a rainfall forecasting system for landslide early warning in the study region.

[1]  Davide Tiranti,et al.  Application of the MoniFLaIR early warning system for rainfall-induced landslides in Piedmont region (Italy) , 2010 .

[2]  M. Rossi,et al.  The rainfall intensity–duration control of shallow landslides and debris flows: an update , 2008 .

[3]  Bernard W. Silverman,et al.  Density Estimation for Statistics and Data Analysis , 1987 .

[4]  S. L. Gariano,et al.  An algorithm for the objective reconstruction of rainfall events responsible for landslides , 2015, Landslides.

[5]  Paweł Prokop,et al.  Impact of the Darjeeling–Bhutan Himalayan front on rainfall hazard pattern , 2017, Natural Hazards.

[6]  N. Satyam,et al.  Probabilistic approach toward Darjeeling Himalayas landslides-A case study , 2018 .

[7]  N. Satyam,et al.  Rainfall thresholds for the prediction of landslides using empirical methods in Kalimpong , Darjeeling , India , 2017 .

[8]  D. P. Kanungo,et al.  Rainfall thresholds for prediction of shallow landslides around Chamoli-Joshimath region, Garhwal Himalayas, India , 2014, Landslides.

[9]  Neelima Satyam,et al.  Probabilistic rainfall thresholds in Chibo, India: estimation and validation using monitoring system , 2019, Journal of Mountain Science.

[10]  N. Casagli,et al.  A Regional-Scale Landslide Warning System Based on 20 Years of Operational Experience , 2018, Water.

[11]  Samuele Segoni,et al.  Quantitative comparison between two different methodologies to define rainfall thresholds for landslide forecasting , 2015 .

[12]  Samuele Segoni,et al.  Brief communication: Using averaged soil moisture estimates to improve the performances of a regional-scale landslide early warning system , 2017 .

[13]  John L. Innes,et al.  Debris flows , 1983 .

[14]  Ikuo Towhata,et al.  Early warning system using tilt sensors in Chibo, Kalimpong, Darjeeling Himalayas, India , 2018, Natural Hazards.

[15]  S. Balakrishnan,et al.  Climatic control on clay mineral formation: Evidence from weathering profiles developed on either side of the Western Ghats , 2005 .

[16]  F. Noverraz,et al.  Influence of climate change on large landslides : assessment of long-term movements and trends , 2001 .

[17]  S. L. Kuriakose,et al.  Modelling the runout of a debris flow of the Western Ghats, Kerala, India , 2009 .

[18]  S. L. Kuriakose,et al.  History of landslide susceptibility and a chorology of landslide-prone areas in the Western Ghats of Kerala, India , 2009 .

[19]  Fausto Guzzetti,et al.  Rainfall thresholds for possible landslide occurrence in Italy , 2017 .

[20]  Fausto Guzzetti,et al.  Rainfall thresholds for the possible occurrence of landslides in Italy , 2010 .

[21]  C. J. Westen,et al.  Estimating temporal probability for landslide initiation along transportation routes based on rainfall thresholds. , 2009 .

[22]  A. Pasuto,et al.  Rainfall as a trigger of shallow mass movements. A case study in the Dolomites, Italy , 1998 .

[23]  S. Sreekumar.  Techniques for slope stability analysis: Site specific studies from Idukki district, Kerala , 2009 .

[24]  Chandra Shekhar Jha,et al.  Deforestation and land use changes in Western Ghats, India , 2000 .

[25]  Samuele Segoni,et al.  Updating and tuning a regional-scale landslide early warning system , 2013, Landslides.

[26]  Samuele Segoni,et al.  Rainfall thresholds for the forecasting of landslide occurrence at regional scale , 2012, Landslides.

[27]  Abhirup Dikshit,et al.  Estimation of rainfall thresholds for landslide occurrences in Kalimpong, India , 2018, Innovative Infrastructure Solutions.

[28]  M. Martina,et al.  Probabilistic rainfall thresholds for landslide occurrence using a Bayesian approach , 2012 .

[29]  Samuele Segoni,et al.  Updating EWS rainfall thresholds for the triggering of landslides , 2015, Natural Hazards.

[30]  S. L. Kuriakose,et al.  Physically-based dynamic modelling of the effect of land use changes on shallow landslide initiation in the Western Ghats of Kerala, India , 2010 .

[31]  Pietro Aleotti,et al.  A warning system for rainfall-induced shallow failures , 2004 .

[32]  Fausto Guzzetti,et al.  The impact of landslides in the Umbria region, central Italy , 2003 .

[33]  S. Sorooshian,et al.  Geometrical Characterization of Precipitation Patterns , 2011 .

[34]  L. Starkel,et al.  Extreme rainfalls in Eastern Himalaya and southern slope of Meghalaya Plateau and their geomorphologic impacts , 2007 .

[35]  Samuele Segoni,et al.  Landslides triggered by rainfall: A semi-automated procedure to define consistent intensity-duration thresholds , 2014, Comput. Geosci..

[36]  Giovanni B. Crosta,et al.  Regionalization of rainfall thresholds: an aid to landslide hazard evaluation , 1998 .