During California’s severe drought from 2011 to 2017, a significant shift in irrigated area from annual to perennial crops occurred. Due to the time requirements associated with bringing perennial crops to maturity, more perennial acreage likely increases the opportunity costs of fallowing, a common drought mitigation strategy. Increases in the costs of fallowing may put additional pressure on another common “go-to” drought mitigation strategy—groundwater pumping. Yet, overdrafted groundwater systems worldwide are increasingly becoming the norm. In response to depleting aquifers, as evidenced in California, sustainable groundwater management policies are being implemented. There has been little modeling of the potential effect of increased perennial crop production on groundwater use and the implications for public policy. A dynamic, integrated deterministic model of agricultural production in Kern County, CA, is developed here with both groundwater and perennial area by vintage treated as stock variables. Model scenarios investigate the impacts of surface water reductions and perennial prices on land and groundwater use. The results generally indicate that perennial production may lead to slower aquifer draw-down compared with deterministic models lacking perennial crop dynamics, highlighting the importance of accounting for the dynamic nature of perennial crops in understanding the co-evolution of agricultural and groundwater systems under climate change.

中文翻译：

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多年生作物动态可能会影响长期地下水位

在加利福尼亚州 2011 年至 2017 年的严重干旱期间，灌溉面积发生了从一年生作物到多年生作物的重大转变。由于与多年生作物成熟相关的时间要求，更多的多年生种植面积可能会增加休耕的机会成本，这是一种常见的干旱缓解策略。休耕成本的增加可能会给另一种常见的“首选”干旱缓解策略——地下水抽取带来额外压力。然而，全球超采地下水系统正日益成为常态。为了应对日益枯竭的含水层，正如加利福尼亚所证明的那样，可持续的地下水管理政策正在实施。几乎没有关于增加多年生作物产量对地下水使用的潜在影响以及对公共政策的影响的模型。一个动态的，加利福尼亚州克恩县农业生产的综合确定性模型是在此处开发的，其中地下水和多年生面积都被视为存量变量。模型情景调查地表水减少和常年价格对土地和地下水使用的影响。结果普遍表明，与缺乏多年生作物动态的确定性模型相比，多年生生产可能导致含水层下降较慢，突出说明了考虑多年生作物的动态性质对于理解气候变化下农业和地下水系统共同进化的重要性. 模型情景调查地表水减少和常年价格对土地和地下水使用的影响。结果普遍表明，与缺乏多年生作物动态的确定性模型相比，多年生生产可能导致含水层下降较慢，这突出说明了考虑多年生作物的动态性质对于理解气候变化下农业和地下水系统共同进化的重要性. 模型情景调查地表水减少和常年价格对土地和地下水使用的影响。结果普遍表明，与缺乏多年生作物动态的确定性模型相比，多年生生产可能导致含水层下降较慢，突出说明了考虑多年生作物的动态性质对于理解气候变化下农业和地下水系统共同进化的重要性.