This report reviews the status of water resources and climate trends, and their expected impacts on water-related hazards and associated risks in South Asia, one of the world’s regions most vulnerable to climate change. The monsoon-driven climate combines intense rainfall generating devastating floods that alternate with extensive dry periods.

By altering evapotranspiration and influencing how water is routed and stored in a basin, natural and agrarian ecosystems affect river flow.

Food security in India is tightly linked to rainfall variability. Trends in Indian rainfall records have been extensively studied but the subject remains complicated by the high spatiotemporal variability of rainfall arising from complex atmospheric dynamics. For various reasons past studies have often produced inconsistent results. This paper presents an analysis of recent trends in monthly and seasonal cumulative rainfall depth, number of rainy days and maximum daily rainfall, and in the monsoon occurrence (onset, peak and retreat).

Provision of detailed continuous long-term hydrological time series data for any river basin is critical for estimation, planning and management of its current and future water resources. Most of the river basins in India are data poor, including its iconic river – Ganga (Ganges).