Spatial temporal regional modeling of local rainfall pattern effect on slopes in Hulu Kelang
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Date
2015
Authors
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Publisher
Universiti Teknologi Malaysia
Abstract
Hulu Kelang is a slope failure prone area near to Kuala Lumpur. Urban development has caused numerous slope failures and mudflow events in this region. To minimize losses incurred by slope failures, a development of spatial temporal regional modeling of local rainfall pattern effect on the plant covered slope was employed in this study. Four approaches were considered in this research, i.e: (1) identification of the spatial factors that may affect the slope failure in Hulu Kelang area and their relative importances; (2 ) spatial qualitative and quantitative modeling of slope failure susceptibility assessments; (3) rainfall-induced slope failure modeling under spatial and spatiotemporal rainfall conditions, and (4) improved spatial temporal regional modeling of rainfall induced slope failure incorporating effect of plant cover. Evaluation of spatial factors affecting slope stability was carried out by using both qualitative and quantitative methods. The results show that the quantitative models produced a more reliable susceptibility map than the qualitative methods that involve a considerable amount of generalizations in the analysis. The analysis of the spatial factors using the quantitative models also shows that plant cover plays an important role in the stability of the slopes in Hulu Kelang. On the other hand, the analysis of spatiotemporal factors shows that the slope failure occurrences have good correlations with local rainfall patterns. These observations signified the importance of correlating the initiation of slope failure occurrences with alteration in plant cover and rainfall infiltrations in the study area. In this regard, this study attempted to develop a spatial temporal regional modeling of local rainfall pattern effect on the plant covered slope in Hulu Kelang area. Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability analysis method (TRIGRS) was revised and improved for analyzing rainfall-induced slope failures under the local rainfall distribution model. Two patterns of rainfall conditions, the monthly average rainfall during two monsoons and the critical rainfall thresholds for triggering shallow slope failure in Hulu Kelang area were considered for analyzing the effect of rainfall patterns on the slope failures. The results show that the improved TRIGRS model without the consideration of plant cover has yielded an overestimation of the slope failure susceptibility. A further improved TRIGRS model was then developed by incorporating rainfall distribution model and the plant cover characteristics on the slope stability analysis. The improved model incorporating these two parameters shows that the slope failure susceptibility produced with the inclusion of plant cover effect was comparable with the historical slope failure incidents in Hulu Kelang.
Description
Thesis (Ph.D (Civil Engineering - Geotechnics))
Keywords
Slopes (Soil mechanics)—Data processing, Slopes (Soil mechanics)—Malaysia, Hillside planting