Analysis of post-fire suspended sediment sources by using colour parameters

Abstract After a wildfire, total or partial removal of vegetal biomass and changes in physicochemical soil properties lead to an increase in overland flow and sediment yield. Eventual damage must be counteracted urgently by identifying erosion hotspots and by implementing post-fire management programmes and sampling campaigns. In this context, the sediment source fingerprinting technique is widely used to determine the origin of suspended sediments in catchments and to evaluate the effectiveness of sediment management programmes. It traditionally relies on the use of physical, biochemical and geochemical properties as tracers. However, measuring these tracers in the laboratory is often expensive and time-consuming. Colour tracers have been shown to greatly reduce time and cost, especially if a normal office scanner is used for measurements. Here we explored whether colour parameters can be used to investigate suspended sediment origin in burned catchments. To this end, sediment and ash were mixed artificially to verify colour linear additivity and ash influence on colour parameters. Colour parameters were then used for source ascription of suspended sediment samples (n = 9) collected during two years after a fire in a small Mediterranean catchment (Mallorca, Spain). In addition, reflectance-derived colour parameters were compared with those obtained using a normal office scanner. The close correlation between most chromatic indexes (obtained using both methods; p