Drainage evolution in a Holocene landscape that hosted a ‘lost river’ system in the Punjab-Haryana plains, NW India

Abstract The Sutlej river, one of the important tributaries of the Indus river, debouches into the Punjab-Haryana plains and makes a conspicuous change in its flow direction i.e., from southwest to west. This anomalous flow of the Sutlej river has given rise to a large interfluve between the Indus and Ganga river systems, in which an ephemeral Ghaggar river flows towards southwest that terminates inland. This study investigates the large interfluve between the Sutlej and the Yamuna rivers for its drainage reorganization including the westward deflection of the Sutlej river, using landforms and stream orientation analysis. The drainage network in the area can be divided into two orientation domains - west flowing and south-west/south flowing. Statistical and vector analysis of around 600 drainage vectors (including paleochannels and modelled flow vectors) and more than 9000 slope vectors indicate that the present-day drainage networks and their directivity vary with respect to the paleo-drainage networks as well as the modelled flow patterns. Regional slope deviatory and slope parallel channels point towards a shift of the Sutlej river from south to west in multiple stages. It is suggested that the westward avulsion of the Sutlej river is primarily driven by tectonics of the frontal zone, aided possibly by high magnitude extreme hydro-meteorological events.