Abstract Many agricultural communities depend on groundwater irrigation as a supplemental or primary water source. However, groundwater resources are finite, and depletion can make continued irrigation inviable. When modeling the economic impacts of future aquifer decline, studies often assume that irrigated cropland will transition uniformly to dryland crop production. In reality, irrigation has allowed crops to be grown across a wider range of soil and climate conditions than can support dryland crop production. Here, we test the agronomic and economic importance of this assumption by mapping the spatiotemporal distribution of anticipated future irrigation losses across the Ogallala or High Plains Aquifer (USA) at annual, 30 m resolution. We then develop a land use suitability model to determine whether these lands would transition to dryland agriculture or pasture use. We find that 22,000 km2 (24 %) of currently irrigated lands in the High Plains Aquifer may be unable to support irrigated agriculture by 2100, and 13 % of these areas are not suitable for dryland crop production due primarily to low quality soils. To quantify the farm-scale and regional-scale economic importance of land use suitability, we selected six case study counties across the aquifer and modeled farm and community-scale economic outcomes (gross revenue and value added, respectively) with and without consideration of land use suitability. We find that not accounting for land use suitability leads to an overestimate of economic benefits in transitioned land by 12–45 %, with variability across counties primarily driven by the distribution of soil capability, dryland crop mix, and local economic factors. Notably, this implies that the economic impacts of land transitions are not directly proportional to area lost but rather mediated by underlying variability in these three factors. Our analyses highlight the importance of considering local biophysical constraints in planning for future land use trajectories. Community and regional land use planning needs to incorporate the possibility that irrigated cropland may transition to non-irrigated pasture production rather than dryland crop production, which can have substantial biophysical and economic impacts.

中文翻译：

---

奥加拉拉含水层从灌溉农业向旱地农业的转变：土地利用适宜性和区域经济影响

摘要 许多农业社区依赖地下水灌溉作为补充或主要水源。然而，地下水资源是有限的，枯竭会使继续灌溉变得无法生存。在模拟未来含水层下降的经济影响时，研究通常假设灌溉农田将统一过渡到旱地作物生产。实际上，灌溉使作物能够在更广泛的土壤和气候条件下种植，而不是支持旱地作物生产。在这里，我们通过以每年 30 m 的分辨率绘制整个奥加拉拉或高平原含水层（美国）的预期未来灌溉损失的时空分布图来测试这一假设的农艺和经济重要性。然后，我们开发了一个土地利用适宜性模型，以确定这些土地是否会转变为旱地农业或牧场用途。我们发现，到 2100 年，高原含水层中 22,000 平方公里（24%）的灌溉土地可能无法支持灌溉农业，其中 13% 的地区不适合旱地作物生产，主要是因为土壤质量差。为了量化土地利用适宜性的农场规模和区域规模经济重要性，我们选择了含水层中的六个案例研究县，并模拟了农场和社区规模的经济成果（分别为总收入和增加值），考虑和不考虑土地使用适用性。我们发现，不考虑土地利用适宜性会导致对转型土地的经济效益高估 12-45%，各县之间的差异主要受土壤容量分布、旱地作物组合和当地经济因素的影响。值得注意的是，这意味着土地转型的经济影响与面积损失不成正比，而是由这三个因素的潜在可变性介导。我们的分析强调了在规划未来土地利用轨迹时考虑当地生物物理限制的重要性。社区和区域土地利用规划需要考虑灌溉农田可能转变为非灌溉牧场生产而非旱地作物生产的可能性，这可能会产生重大的生物物理和经济影响。这意味着土地转型的经济影响与损失的面积不成正比，而是由这三个因素的潜在可变性介导。我们的分析强调了在规划未来土地利用轨迹时考虑当地生物物理限制的重要性。社区和区域土地利用规划需要考虑灌溉农田可能转变为非灌溉牧场生产而非旱地作物生产的可能性，这可能会产生重大的生物物理和经济影响。这意味着土地转型的经济影响与损失的面积不成正比，而是受这三个因素的潜在可变性影响。我们的分析强调了在规划未来土地利用轨迹时考虑当地生物物理限制的重要性。社区和区域土地利用规划需要考虑灌溉农田可能转变为非灌溉牧场生产而非旱地作物生产的可能性，这可能会产生重大的生物物理和经济影响。