Drainage network characterization based on confluence organization and tortuosity

Automatic drainage network characterization provides basic information on lithology. Thus, a new Tortuosity and Confluence Organization (TACO) index, based on the notion of confluence density coupled with the calculation of tortuosity, is proposed. This index can be used to compare thinned riverbeds as they appear on topographic maps or when extracted from a digital elevation model. This new index distinguishes meanders with a high degree of tortuosity from linear and parallel structures or meanders with low tortuosity. The distinction between meanders and linear patterns from dendritic arrangements depends on the number of confluences observed in a moving window. The tested area belongs to the Coatzacoalcos basin, which presents the configurations considered by this index. Results show that the meander configuration has values lower than 80, linear patterns have values around 100, and dendritic configurations are between 120 and 200. Thus, this index can be used to map a region according to the drainage network configuration.