Scripps Institution of Oceanography and ‡School of Global Policy and Strategy, University of California , San Diego, California 92093, United States.
Environ Sci Technol. 2017 Mar 7;51(5):2593-2601. doi: 10.1021/acs.est.6b05426. Epub 2017 Feb 24.
Accurate information on agricultural water needs and withdrawals at appropriate spatial and temporal scales remains a key limitation to joint water and land management decision-making. We use InVEST ecosystem service mapping to estimate water yield and water consumption as functions of land use in Fresno County, a key farming region in California's Central Valley. Our calculations show that in recent years (2010-2015), the total annual water yield for the county has varied dramatically from ∼0.97 to 5.37 km (all ±17%; 1 MAF ≈ 1.233 km), while total annual water consumption has changed over a smaller range, from ∼3.37 to ∼3.98 km (±20%). Almost all of the county's water consumption (∼96% of total use) takes place in Fresno's croplands, with discrepancy between local annual surface water yields and crop needs met by surface water allocations from outside the county and, to a much greater extent, private groundwater irrigation. Our estimates thus bound the amount of groundwater needed to supplement consumption each year (∼1.76 km on average). These results, combined with trends away from field crops and toward orchards and vineyards, suggest that Fresno's land and water management have become increasingly disconnected in recent years, with the harvested area being less available as an adaptive margin to hydrological stress.
准确的农业用水需求和提取信息，在适当的时空尺度上，仍然是联合水和土地管理决策的关键限制因素。我们使用 InVEST 生态系统服务制图来估计水产量和用水量作为加利福尼亚州中央山谷关键农业区弗雷斯诺县土地利用的函数。我们的计算表明，近年来（2010-2015 年），该县的总年度水产量变化很大，从约 0.97 到 5.37 公里（所有 ±17%；1 MAF ≈ 1.233 公里），而总年度用水量变化范围较小，从约 3.37 到约 3.98 公里（±20%）。该县几乎所有的用水量（约占总用水量的 96%）都发生在弗雷斯诺的农田中，当地的年地表水产量与作物需求之间的差异通过从县外分配地表水和在更大程度上通过私人地下水灌溉来弥补。因此，我们的估计限制了每年补充消费所需的地下水量（平均约 1.76 公里）。这些结果，再加上从大田作物向果园和葡萄园的转变趋势，表明近年来弗雷斯诺的土地和水资源管理变得越来越脱节，收获面积作为对水文压力的适应边际越来越少。
