Disentangling the impacts of water deficit and lack of irrigation infrastructure on critical food supplies such as rice in countries like Bangladesh remains a challenge. In this paper, we explore this challenge using North Bengal as a case study site over 1979–2018. We characterise crop water surplus/deficit with meteorological and soil moisture data and analyse the coherence of these timeseries with rice production in the study region. We then examine the trends, periodicities and degree of coherence between crop water surplus/deficit, irrigation, and rice production. Our results indicate an almost constant water deficit during winter and maximum water deficits in the pre-monsoon and post-monsoon periods. Critically, crop water surplus shows a significantly decreasing trend since 1979 during the monsoon period. We find that the correlation between crop water surplus/deficit, while strongly correlated with meteorological drought, weakens over time. This is suggestive of the important role that irrigation development has played over this period. Although the severity and frequency of water deficits have increased during the study period, possibly as a result of climate change or variability, rice production has decoupled from this trend and is instead positively correlated with irrigation. Despite this encouraging finding, it is unknown if technological progress will continue and whether there will be sufficient extractable groundwater and surface water to meet increasing irrigation demand in the future. Our finding of a long-term increase in water deficit underscores the likely future challenges in these critical rice growing regions for the people of Bangladesh, should this trend continue. The future sufficient rice production in the region will likely rely on the availability of reliable and affordable fuel or electric power to operate irrigation systems and a proactive and vigilant approach to agricultural water security in a variable and changing climate.

在孟加拉国等国家，消除缺水和缺乏灌溉基础设施对大米等关键粮食供应的影响仍然是一项挑战。在本文中，我们使用北孟加拉邦作为 1979-2018 年的案例研究地点来探索这一挑战。我们用气象和土壤水分数据来描述作物水分过剩/不足，并分析这些时间序列与研究区域水稻产量的一致性。然后，我们检查作物水分过剩/短缺、灌溉和水稻生产之间的趋势、周期性和一致性程度。我们的结果表明冬季几乎恒定的缺水量和季风前和季风后时期的最大缺水量。至关重要的是，自 1979 年以来，在季风期间，作物水分盈余呈显着下降趋势。我们发现，作物水分过剩/缺水之间的相关性虽然与气象干旱密切相关，但随着时间的推移而减弱。这暗示了灌溉发展在这一时期发挥的重要作用。尽管在研究期间缺水的严重程度和频率有所增加，可能是由于气候变化或变异性的结果，但水稻产量已与这一趋势脱钩，而是与灌溉呈正相关。尽管有这一令人鼓舞的发现，但尚不清楚技术进步是否会继续，以及是否有足够的可提取地下水和地表水来满足未来日益增长的灌溉需求。我们对水资源短缺长期增加的发现强调了如果这种趋势继续下去，这些关键水稻种植区未来可能对孟加拉国人民带来挑战。该地区未来充足的稻米生产可能依赖于可靠和负担得起的燃料或电力的可用性来运行灌溉系统，以及在多变和不断变化的气候中采取积极和警惕的农业用水安全方法。