Understanding the Effect of Unsaturated Hydraulic Conductivity of Surface Soils on Landslide Triggering: A Case Study in Yahalabedda Landslide Risky Area, Sri Lanka

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dc.contributor.authorShanika, K.K.A.
dc.contributor.authorNirujan, B.
dc.contributor.authorWijewardana, Y.N.S.
dc.contributor.authorHerath, H.M.S.K.
dc.contributor.authorGalagedara, L.W.
dc.date.accessioned2021-02-05T07:20:50Z
dc.date.available2021-02-05T07:20:50Z
dc.date.issued2020
dc.description.abstractHydraulic conductivity (K) is one of the most important soil properties for rainfallinduced landslide triggering. Yahalabedda receives higher rainfalls in Northeast and Southwest monsoon seasons and considered a potential landslide risky area in Sri Lanka. The objective of this study was to evaluate the unsaturated K (Kunsat) of surface colluvium soils using a minidisk tension infiltrometer together with relevant basic soil properties. Field investigations were conducted at three soil depths; 0, 30, and 60 cm of a prepared soil profile in September 2019. The infiltration test was conducted at each soil depth using three tension levels of -0.03, -0.02, and -0.01 m. The Kunsat has been calculated using the Kunsat = C1/A, where C1 is the slope of the curve of the cumulative infiltration versus the square root of time, and A is a value relating the van Genuchten parameters for a given soil type to the suction rate and radius of the infiltrometer disk. Kunsat increased with the soil profile depth for each tension value. Kunsat values for -0.03 m tension, are 1.35 × 10-6, 2.62 × 10-6 and 7.77 × 10-6 m s-1 ; for -0.02 m tension, are 2.13 × 10-6, 3.91 × 10-6 and 1.02 × 10-5 m s -1 and for -0.01 m tension, are 4.23 × 10- 6, 7.86 × 10-6 and 1.42 × 10-5 m s-1 for 0, 30 and 60 cm depths, respectively. Kunsat increases with decreasing the tension values at each depth as expected. 0 and 30 cm depths show nearly the same bulk density (1.0 g cm-3 ), while the 60 cm depth shows higher bulk density (1.1 g cm-3 ). The soil texture is clay loam for the entire soil profile while the uniformity coefficient (Cu) is higher (6.8) in upper soil resulting in a lower chance to interlock between soil particles and higher pore spaces. As the Kunsat increases with the depth, more water will be percolated to deeper soils resulting in the increasing soil weight in deeper soils and the landslide risk. The study reveals that the Yahalabedda area has a threat to landslide triggering in rainy seasons. Keywords: Minidisk tension infiltrometer, Hydraulic conductivity, Infiltration, Landslide risky soilsen_US
dc.identifier.isbn9789550481293
dc.identifier.urihttp://www.erepo.lib.uwu.ac.lk/bitstream/handle/123456789/5808/proceeding_oct_08-264.pdf?sequence=1&isAllowed=y
dc.language.isoenen_US
dc.publisherUva Wellassa University of Sri Lankaen_US
dc.relation.ispartofseries;International Research Conference
dc.subjectEnvironmental Scienceen_US
dc.subjectEcologyen_US
dc.subjectSoil Scienceen_US
dc.subjectLandslideen_US
dc.titleUnderstanding the Effect of Unsaturated Hydraulic Conductivity of Surface Soils on Landslide Triggering: A Case Study in Yahalabedda Landslide Risky Area, Sri Lankaen_US
dc.title.alternativeInternational Research Conference 2020en_US
dc.typeOtheren_US
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