Norfolk Island, like many islands in the subtropical Pacific, is at increasing risk of drought. To test the hypothesis that desalination is the most cost-effective technology for providing potable water during ‘water emergencies’, this study calculated and compared the levelised cost on Norfolk Island of seven ‘centralised’ intervention options and two ‘diffuse’ options for increasing groundwater accessions. Gully dams were the ‘centralised’ intervention option found to have the lowest levelised cost but had the largest percentage reductions in yield (i.e., 39% for 1 ML storage) under a projected drier future climate, greater than twice the percentage reduction in rainfall (16%) but less than the percentage reduction in runoff (44%). Cluster-scale roof-harvested rainwater systems with ‘turkey nest’ earth embankment had the second lowest levelised cost but are probably socially unacceptable due to siting on the community’s premier sporting oval. Desalination had the third lowest levelised cost, followed by the use of existing deep groundwater bores to pump and store water exclusively for use during a water emergency. Although desalination was not the most cost-effective technology, it is likely to be more socially acceptable than the two more cost-effective options. After gully dams, rainwater harvesting intervention options had the second highest proportional reductions in yield under a projected drier future climate (~10%); however, the reductions were less than the percentage reductions in rainfall. The yield from desalination and groundwater were unaffected under a drier future climate projected for ~2060.

中文翻译：

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水，到处都是水，也没有一滴水可以喝？在预测的更干燥的未来气候下提高亚热带岛屿抗旱能力及其产量敏感性的选项

与亚热带太平洋的许多岛屿一样，诺福克岛面临越来越大的干旱风险。为了验证海水淡化是“水紧急情况”期间提供饮用水的最具成本效益的技术这一假设，本研究计算并比较了诺福克岛七种“集中”干预方案和两种增加地下水的“分散”方案的平均成本加入。沟壑水坝是“集中式”干预选项，在预计未来气候更干燥的情况下，发现其平准化成本最低，但产量减少百分比最大（即 1 ML 储存减少 39%），超过降雨减少百分比的两倍（ 16%），但低于径流减少的百分比（44%）。带有“火鸡巢”土路堤的集群规模屋顶收集雨水系统的平准化成本是第二低的，但由于位于社区首屈一指的运动场地上，因此可能在社会上是不可接受的。海水淡化的平准化成本第三低，其次是使用现有的深层地下水钻孔来抽水和储存水，专门用于在水紧急情况下使用。尽管海水淡化不是最具成本效益的技术，但它可能比两种更具成本效益的选择更能被社会接受。在沟壑坝之后，雨水收集干预方案在预计未来气候更干燥的情况下，产量减少比例第二高（约 10%）；然而，减少的幅度小于降雨减少的百分比。