Rice is the most important crop for food security and livelihoods of the rural population in Bihar, India. In spite of good soil and water resources, rice water productivity (WP) is very low in Bihar. Trends in WP and key factors influencing WP over 20 years (1991–2010) in 11 Bihar districts were analysed using panel data to help elucidate reasons for low WP values. The annual average rice yield of 938 kg/ha, WP of 0.22 kg/m³, and marginal physical productivity (MPP) of 249 g/m³ are very low in Bihar compared to both the national average for India and other rice growing areas in the world. Rice WP and MPP were higher for the garma (dry) season than for the kharif (monsoon) season. Temporal analysis showed that WP was slowly declining in most districts, while spatial analysis showed a significant variation in WP across the districts. Regression analysis showed that the availability of irrigation facilities, occurrence of flood and drought, and cropping intensity had significant influence on rice WP. Causes for temporal and spatial changes in WP are highlighted and actions to improve rice WP in Bihar are suggested.

A water vulnerability analysis is made of how sensitivity characteristics of the Ganges–Brahmaputra–Meghna (GBM) River basin may affect adaptive capacity. A co-riparian ‘country perspective’ highlights the importance of local level management actions. Results reveal that vulnerabilities in India and Bangladesh stem from hydrological and ecological factors, but are more linked to poverty and underdevelopment in Nepal. Poor political governance and underinvestment in the water sector add to vulnerability in Bangladesh and Nepal. Overall, Bangladesh is the most sensitive country while Nepal has the least capacity to adapt.