Indo-Gangetic river systems, monsoon and malaria

Abstract

The history of the Indo-Gangetic river systems from the late nineteenth to the early twentieth centuries can be reconstructed from the meticulous official records of the survey, meteorological and medical departments of the British Government of India. In contrast with the grand sweep of the geological evidence, these records indicate a complex narrative of floods, droughts and channel shifts. Similarly, the cumulative growth of the Ganges–Brahmaputra and Indus deltas was overprinted by the effects of the annual monsoon cycle on precipitation, temperature and winds. Malaria, the principal vector-borne disease of the Indian subcontinent, and the deadliest, displayed epidemiological types that ranged between the extremes of stable–endemic to unstable–epidemic as defined in the classic theory of equilibrium of George Macdonald. Variations in its transmission, incidence and prevalence were closely tied to the different deltaic environments of the Bengal and Indus basins and to the short-sightedness of many irrigation and related engineering schemes.