U.S. Geological Survey, Western Geographic Science Center, Moffett Field, CA, USA.
U.S. Geological Survey, Western Geographic Science Center, Moffett Field, CA, USA.
J Environ Manage. 2024 Oct;369:122256. doi: 10.1016/j.jenvman.2024.122256. Epub 2024 Aug 28.
Climate change in California is expected to alter future water availability, impacting water supplies needed to support future housing growth and agriculture demand. In groundwater-dependent regions like California's Central Coast, new land-use related water demand and decreasing recharge is already stressing depleted groundwater basins. We developed a spatially explicit state-and-transition simulation model that integrates climate, land-use change, water demand, and groundwater gain-loss to examine the impact of future climate and land use change on groundwater balance and water demand in five counties along the Central Coast from 2010 to 2060. The model incorporated downscaled groundwater recharge projections based on a Warm/Wet and a Hot/Dry climate future from a spatially explicit hydrological process-based model. Two urbanization projections from a parcel-based, regional urban growth model representing 1) recent historical and 2) state-mandated housing growth projections were used as alternative spatial targets for future urban growth. Agricultural projections were based on recent historical trends from remote sensing data. Annual projected changes in groundwater balance were calculated as the difference between land-use related water demand, based on historical estimates, and climate-driven recharge plus agriculture return flows. Results indicate that future changes in climate-driven groundwater recharge, coupled with cumulative increases in agricultural water demand, result in overall declines in future groundwater balance, with a Hot/Dry future resulting in cumulative groundwater decline in all but Santa Cruz County. Cumulative declines by 2060 are especially prominent in San Luis Obispo (-2.9 to -5.1 Bm) and Monterey counties (-6.5 to -8.7 Bm), despite limited changes in agricultural water demand over the model period. These two counties show declining groundwater reserves in a Warm/Wet future as well, while San Benito and Santa Barbara County barely reach equilibrium. These results suggest future groundwater supplies may not be able to keep pace with regional demand and declining climate-driven recharge, resulting in a potential reduction in water security in the region. However, our county-scale projections showed new housing and associated water demand does not conflict with California's groundwater sustainability goals. Rather, future climate coupled with increasing agricultural groundwater demand may reduce water security in some counties, potentially limiting available groundwater supplies for new housing.
加利福尼亚州的气候变化预计将改变未来的水资源供应情况，影响支持未来住房增长和农业需求所需的水资源供应。在加利福尼亚州中央海岸等依赖地下水的地区，新的与土地利用相关的用水需求和不断减少的补给已经给枯竭的地下水盆地带来了压力。我们开发了一种空间显式的状态和转换模拟模型，该模型将气候、土地利用变化、水需求和地下水得失相结合，以研究未来气候和土地利用变化对中央海岸五个县的地下水平衡和水需求的影响，研究时段为 2010 年至 2060 年。该模型结合了基于空间显式水文过程模型的地下水补给降尺度预测，这些预测是根据温暖/湿润和炎热/干燥两种气候未来情景得出的。一个基于包裹的、区域城市增长模型的两个城市化预测分别代表 1）最近的历史和 2）国家规定的住房增长预测，被用作未来城市增长的替代空间目标。农业预测基于遥感数据的近期历史趋势。地下水平衡的年度预测变化是根据基于历史估算的土地利用相关用水需求与气候驱动的补给加上农业回流水之间的差异计算得出的。结果表明，未来气候驱动的地下水补给变化，加上农业用水需求的累积增加，导致未来地下水平衡总体下降，在炎热/干燥的未来情景下，除圣克鲁斯县外，所有县的地下水都出现累积下降。到 2060 年，圣路易斯奥比斯波县（-29 至-51 亿立方米）和蒙特雷县（-65 至-87 亿立方米）的累积下降尤其显著，尽管在模型期间农业用水需求变化有限。在温暖/湿润的未来情景下，这两个县的地下水资源储备也在下降，而圣贝尼托县和圣巴巴拉县几乎达到平衡。这些结果表明，未来的地下水供应可能跟不上地区需求和不断下降的气候驱动补给，导致该地区的水安全面临潜在风险。然而，我们的县一级预测显示，新住房和相关用水需求与加利福尼亚州的地下水可持续性目标并不冲突。相反，未来的气候加上不断增加的农业地下水需求，可能会降低一些县的水安全，从而限制新住房的可用地下水供应。
