Kolkata has no catchment view, and that is a deliberate omission rather than a missing dataset. Catchments are delineated by tracing water downhill across a 30 m elevation model - which needs a hill. Kolkata has about 11 metres of fall across 40 kilometres of delta, against 43 m in Chennai and 338 m in Mumbai, the cities where this view ships. At that gradient the method would draw confident-looking boundaries that the ground does not support, and in any case most of Kolkata's runoff travels through a combined sewer network rather than over the surface. We would rather show no catchments than invent them.