AUTOMATIC CASCADE NUMBERING OF UNIT ELEMENTS IN DISTRIBUTED HYDROLOGICAL MODELS

New procedures were developed to identify river-course networks in a Digital Elevation Model of a watershed. The procedures allow the assignation of a sequential number to each river-course segment that must be followed in a cascade algorithm to route the runoff through the watershed model, when the kinematic wave equation is going to be utilized. Likewise, the developed algorithm allows for the identification of the triangular planar units forming the contributing area of each river-course segment, as well as the assignation of a sequential number that must be followed in a cascade model in order to route the overland flow. The methodology has four parts: the first analyses the existing slope relationships between neighbouring planes. The second generates a data structure for the river-course segments. The third defines the calculus sequence which must be followed by the river-course segments.to route the runoff in a cascade model. The fourth part defines which triangular unit areas are constituents of the contributing area of each river-course segment. The computer code was tested using information from a small artificial and a large real watershed model. The results, concenrning only the identification of the river-course and ridge networks, show agreement with known solutions. © 1990.