Planform geometry and relief characterization of drainage networks in high-relief environments: An analysis of Chilean Andean basins

Drainage network types give indications of the landscape evolution processes and the lithologic and structural conditions that produced them. Moreover, drainage network attributes affect the hydrologic response of basins. Several network types have been identified through visual inspection and, more recently, through quantitative methods developed and applied primarily on relatively low-relief regions. These methods have not been tested in high-relief environments where other factors can control network evolution and other network types may exist. In this work, we study the occurrence of network types in high-relief environments and their potential identification through quantitative classification methods. We analyze 29 high-relief basins in the Chilean Andean region. After exploring the contextual properties (geological, climatic and landcover) of these networks, we calculate several metrics describing their horizontal and vertical attributes and benchmark them against those for network types in low-relief regions. Results show that the high-relief networks have three different types (herringbone, barbed, and high-relief pinnate), which differ in terms of their contextual properties as well as their horizontal and vertical attributes. Classification trees built using only vertical attributes have accuracies of 93% and 84% when differentiating among the high- and low-relief networks, respectively. Furthermore, an overall accuracy of 91% is reached when classifying the entire set of high- and low-relief networks with a combination of vertical and horizontal attributes. Overall, we conclude that classification of drainage patterns through vertical and horizontal attributes is feasible and more accurate than with horizontal attributes alone.