Regional Hydrological Impacts of Climatic Change—Hydroclimatic Variability
(Proceedings of symposium S6 held during the Seventh IAHS Scientific Assembly at Foz do Iguaçu, Brazil, April 2005). IAHS Publ. 296, 2005, 273–282.

Recent trend in spatiotemporal variation of rainfall over India—an investigation into basin-scale rainfall fluctuations


Indian Institute of Tropical Meteorology, Dr Homi Bhabha Road, Pashan, Pune 411 008, India

Abstract In recent years a new perspective has been added to India’s hydrological and water resources research with the formulation of the Master Plan "Interbasin Water Transfer—Interlinking of Rivers of India". The issue of rainfall fluctuations over and across the country needs to be addressed amicably in the planning process of the programme. Using highly quality-controlled data from 316 widely distributed raingauge stations, spatiotemporal features of annual, seasonal and monthly rainfall for the whole of India and its 11 major and 31 (including west coast drainage) minor river basins are reported in this paper. Spatial features of the rainfall for the whole country were studied by examining expansion/contraction of rainfall zones under specified rainfall conditions over the period 1871–2001. Broadly, from around the 1940s, a westward shift, larger variability and declining tendency is seen in the rainfall over the country. To understand temporal features across the country, basin-scale area-averaged rainfall series (1813–2001) have been subjected to time series analysis. Basins in central India (Sabarmati, Mahi, Narmada, Tapi, Godavari and Mahanadi) have been experiencing reduced rainfall from about the 1960s, while in others—Indus from 1954, Ganga from 1993, Brahmaputra from 1988, Krishna from 1953 and Cauvery from 1929—there has been an upward trend in rainfall. The recent trend in rainfall across India is believed to be due to global warming; a possible mechanism is suggested.

Key words basin rainfall studies; global warming; India; instrumental period rainfall series; rainfall spatiotemporal variation; RS-GIS in hydrometeorology