A coupled stability and eco-hydrological model to predict shallow landslides

Knowledge of spatio-temporal dynamics of soil water content, groundwater and infiltration processes is of considerable importance for the understanding and prediction of landslides. Rainfall and consequent water infiltration affect slope stability in various ways, mainly acting on the pore pressure distribution whose increase causes a decrease of the shearing resistance of the soil. For such reasons rainfall and transient changes in the hydrological systems are considered the most common triggers of landslides. So far, the difficulty to monitor groundwater levels or soil moisture contents in unstable terrain have made modeling of landslide a complex issue. At the present, the availability of sophisticated hydrological and physically based models, able to simulate the main hydrological processes, has allowed the development of coupled hydrologicalstability models able to predict when and where a failure could occur. In this study, a slope-failure module, with capability to predict shallow landslides, implemented into an ecohydrological model, tRIBS-VEGGIE (Triangulated Irregular Network (TIN)-based Real-time Integrated Basin Simulator with VEGetation Generator for Interactive Evolution), is presented. The model evaluates the stability dynamics in term of factor of safety consequent to the soil moisture dynamics, strictly depending on the textural soil characteristics and hillslope geometry. Failure criterion used to derive factor of safety equation accounts for the stabilizing effect of matric suction arising in unsaturated soils. The eco-hydrological framework allows also to take into account the effect of vegetation with its cohesive effect as well as its weight load. The Mameyes basin, located in the Luquillo Experimental Forest in Puerto Rico, has been selected for modeling based on the availability of soil, vegetation, topographical, meteorological and historic landslide data. A static analysis based on susceptibility mapping approach was also carried out on the same area at a larger spatial scale, providing the hot spot of landsliding area. Application of the model yields a temporal and spatial distribution of predicted rainfall-induced landslides. Moreover, stability dynamics have been assessed for different meteorological forcing and soil types, to better evaluate the influence of hydrological dynamics on slope stability

Parameter Uncertainty in Shallow Rainfall-triggered Landslide Modeling at Basin Scale: A Probabilistic Approach

This study proposes a methodology to account for the uncertainty of hydrological and mechanical parameters in coupled distributed hydrological-stability models for shallow landslide assessment. A probabilistic approach was implemented in an existing eco-hydrological and landslide model by randomizing soil cohesion, friction angle and soil retention parameters. The model estimates the probability of failure through an assumed theoretical Factor of Safety (FS) distribution, conditioned on soil moisture content. The time-dependent and spatially distributed FS statistics are approximated by the First Order Second Moment (FOSM) method. The model was applied to the Rio Mameyes Basin, located in the Luquillo Experimental Forest in Puerto Rico

A coupled stability and eco-hydrological model to predict shallow landslides

4openopenARNONE, Elisa; NOTO, Leonardo; Lepore, C; Bras RLArnone, Elisa; Noto, Leonardo; Lepore, C; Bras, R

Modeling the hydrological and mechanical effect of roots in shallow landslide analysis

5siopenopenARNONE, Elisa; CARACCIOLO, Domenico; NOTO, Leonardo; Preti, F; Bras, RLArnone, Elisa; Caracciolo, Domenico; Noto, Leonardo; Preti, F; Bras, R

Prevalence of pfmdr1, pfcrt, pfdhfr and pfdhps mutations associated with drug resistance, in Luanda, Angola

<p>Abstract</p> <p>Background</p> <p>Malaria is the infectious disease causing the highest morbidity and mortality in Angola and due to widespread chloroquine (CQ) resistance, the country has recently changed its first-line treatment recommendations for uncomplicated malaria, from CQ to artemisinin combination therapies (ACT) in adults, and sulphadoxine/pyrimethamine (S/P) in pregnant women. Loss of SP sensitivity is, however, progressing rapidly in Africa and, in this study, were investigated a number of molecular markers associated to CQ and S/P.</p> <p>Methods</p> <p>Blood samples were collected from 245 children with uncomplicated malaria, admitted at the Pediatric Hospital Dr. David Bernardino (HPDB), Angola, and the occurrence of mutations in <it>Plasmodium falciparum </it>was investigated in the <it>pfmdr1 </it>(N86Y) and <it>pfcrt </it>(K76T) genes, associated with CQ resistance, as well as in <it>pfdhfr </it>(C59R) and <it>pfdhps </it>(K540E), conferring SP resistance.</p> <p>Results</p> <p>The frequencies of <it>pfmdr1 </it>mutations in codon 86 were 28.6% N, 61.3% Y and 10.1% mixed infections (NY). The frequency of <it>pfcrt </it>mutations in codon 76 were 93.9% K, 5.7% T and 0.4% mixed infections (KT). For <it>pfdhfr </it>the results were in codon 59, 60.6% C, 20.6% R and 18.8% mixed infections (CR). Concerning <it>pfdhps</it>, 6.3% of the isolates were bearers of the mutation 540E and 5.4% mixed infections (K540E).</p> <p>Conclusion</p> <p>The results of this epidemiologic study showed high presence of CQ resistance markers while for SP a much lower prevalence was detected for the markers under study.</p