Physically based modeling of rainfall-triggered landslides: a case study in the Luquillo Forest, Puerto Rico

.Thispaperpresentsthedevelopmentofarainfall triggered landslidemodulewithin an existing physically basedspatiallydistributedecohydrologicmodel.Themodel, tRIBS-VEGGIE (Triangulated Irregular Networks-based Real-timeIntegratedBasinSimulatorandVegetationGen erator for InteractiveEvolution), is capableof a sophisti cateddescriptionofmanyhydrological processes; inpar ticular, the soilmoisturedynamics are resolvedat a tem poralandspatialresolutionrequiredtoexaminethetrigger ingmechanismsofrainfall-inducedlandslides.Thevalidity of the tRIBS-VEGGIEmodel toa tropical environment is shownwithanevaluationof itsperformanceagainstdirect observationsmadewithinthestudyareaofLuquilloForest. Thenewlydeveloped landslidemodulebuildsupon the previousversionofthetRIBSlandslidecomponent.Thisnew moduleutilizesanumericalsolutiontotheRichards’equa tion(present in tRIBS-VEGGIEbut not in tRIBS),which betterrepresentsthetimeevolutionofsoilmoisturetransport throughthesoilcolumn.Moreover,thenewlandslidemodule utilizesanextendedformulationofthefactorofsafety(FS) tocorrectlyquantifytheroleofmatricsuctioninslopestabil ityandtoaccountforunsaturatedconditionsintheevaluation ofFS. Thenewmodelingframeworkcouplesthecapabilitiesof thedetailedhydrologicmodel todescribesoilmoisturedy namicswiththeinfiniteslopemodel,creatingapowerfultool fortheassessmentofrainfall-triggeredlandsliderisk