Status and sustainability challenges of agricultural water usage in Bangladesh

Maintaining sustainability in agricultural water usage is a critical concern particularly when the burgeoning population demands more food while adverse climate change impacts water availability. Despite this, the climate-water-crop nexus is still poorly understood in many regions throughout the globe. This study was conducted to quantify current agricultural water use in Bangladesh, one of the most climate-vulnerable countries, and to assess its sustainability challenges. The number of crops, cropping area, yield, water use, long-term daily rainfall, daily river stage and weekly groundwater level data were collected and statistically analyzed. This study revealed that the two most drought-prone northwest divisions export virtual water embedded in agricultural produce at 14086 Mm3/yr, whereas two urbanized divisions import 18477 m3/yr, to or from the national water-use budget. Only rice production consumed ~88% of the total water used in agriculture, and the dry season rice had higher water demand than the wet season rice. The water use sustainability in the two most water-exporting divisions is at great stake because total rainfall in July is decreasing significantly (2.90 mm/yr) in one division and the number of rainless days in August is significantly increasing (0.033 day/yr) in other division. Irrigated rice production will also face water scarcity because the dry season water level in both rivers (63%) and observation wells (92%) shows a declining trend. The ratio of green (rainfed) to blue (irrigation) water use in the country was estimated at 2.5, which needs to be increased