Vulnerability evaluation on rice production in response to sea-level rise in Vietnam Mekong Delta

在实地调查、历史数据分析和与越南研究人员讨论的基础上，对越南湄公河三角洲（VMD）海平面上升及其导致的海水入侵对水稻生产的脆弱性进行了综合评价。作为脆弱性指数，我们定义了在可用水资源和天气条件下可能种植期与需要种植期的差值。我们发现该指数可以反映过去水稻的种植状况。并根据气候变化情景和湄公河流量变化对作物年历、收获面积和产量的变化进行了预测。汛期和少雨年上游地区和沿海地区的收获面积将减少。然而，在其他地区，收获面积和产量的增加弥补了减少。无论空间变化如何，总种植面积变化不大，而高温对产量的影响较大。因此，湄公河流域水稻总产量将比目前水平下降11%。

We conducted an integrated evaluation for impacts of sea-level rise and the consequent sea water intrusion on rice production in the Vietnamese Mekong Delta (VMD) in terms of the vulnerability, based on the field survey, historical data analysis and discussion with Vietnamese researchers. As a vulnerability index, we defined the difference between possible cropping period and required one under the available water resources and weather condition. We found the index could indicate the past rice cultivation status. We also made projections on the changes of crop calendar, harvested area and yield based on climate change scenario and changes in river discharge of Mekong river. It is projected that the harvested area would decrease in upstream region and coastal region at flooded year and small rainfall year. In the other regions, however, the increases in harvest area and yield compensate for the decrease. Changes of total cultivation area would be small irrespective of spatial variation, while yield would change largely due to high temperature. Consequently, total production of rice in VMD would decrease by 11% relative to present level.