Alladi Ramakrishnan Hall

Drainage networks and the Brownian web

Rahul Roy

Indian Statistical Institute (ISI), Delhi

River basin geomorphology is a very old subject of study initiated byHorton (1945). Various statistical models of drainage networks have been proposed; each such model being a random directed graph with its own nuances. In recent years physicists have been interested in these models because of the commonality of such branching networks in many areas of statistical
physics (see Rodrıguez-Iturbe and rinaldo (1997) for a detailed survey). We discuss the geometric features of one such model and also study its scaling limit. The scaling limit of this model is the Brownian web, which has lately been the focus of extensive study by probabilists. Using this scaling limit we formalize Hack’s law, which is a proportionality relation between
the length and the watershed area of a river.