Water supply and history: Harappa and the Beas regional survey

Introducing the methods of archaeoclimatology, the authors measure the relative locus of the monsoons, the intensity of winter rains and the volume of water in the rivers in the Upper Indus, in the region of Harappa. They also note the adoption of a multi-cropping agricultural system as a possible strategy designed to adjust to changing conditions over time. They find that around 3500 BC the volume of water in the rivers increases, and the rivers flood, implying annual soil refreshment and the consequent development of agriculture. By contrast, from around 2100 BC the river flow begins to fall while the winter rains increase. This time-bracket correlates nicely with the brief flourishing of Harappa. The locally derived evidence from Harappa combined with the Beas survey data provide a model for understanding the abandonment of settlements in the Upper Indus and possibly the wider civilisation.