Estimation of Landslide Importance in Hillslope Erosion Within the Panama Canal Watershed

This paper presents an approach for assessing the regional importance of landslides based on conventional daily-discharge and daily-sediment data from sub-basins within the Panama Canal Watershed. In many wet mountainous regions, sediment yields are controlled by both surficial erosion and deep, landslide erosion. Landslides require that rainfall (and by inference runoff) exceed a threshold. Runoff can be used to derive a parameter termed ‘landslide days’, with a suitable correction factor, to account for evapotranspiration, infiltration, and rainfall patchiness. The approach developed then uses runoff as the driver for a simple surficial-erosion model and landslide days as the driver for a landslide model. In a case study of the Panama Canal Watershed, this model describes spatial and temporal patterns of annual yields with a high degree of efficacy, demonstrating that simple daily data can be used to determine whether a river basin, such as the upper Río Charges basin, might be undergoing substantial landslide-related erosion.