Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH, USA.
Department of Environmental Science and Technology, School of Human Settlement and Civil Engineering, Xi'an Jiaotong University, Xi'an China.
Sci Total Environ. 2015 Apr 1;511:161-75. doi: 10.1016/j.scitotenv.2014.11.076. Epub 2014 Dec 26.
In response to increasing demand for food, Chinese agriculture has both expanded and intensified over the past several decades. Irrigation has played a key role in increasing crop production, and groundwater is now an important source of irrigation water. Groundwater abstraction in excess of recharge (which we use here to estimate groundwater mining) has resulted in declining groundwater levels and could eventually restrict groundwater availability. In this study we used a hydrological model, WBMplus, in conjunction with a process based crop growth model, DNDC, to evaluate Chinese agriculture's recent dependence upon mined groundwater, and to quantify mined groundwater-dependent crop production across a domain that includes variation in climate, crop choice, and management practices. This methodology allowed for the direct attribution of crop production to irrigation water from rivers and reservoirs, shallow (renewable) groundwater, and mined groundwater. Simulating 20 years of weather variability and circa year 2000 crop areas, we found that mined groundwater fulfilled 20%-49% of gross irrigation water demand, assuming all demand was met. Mined groundwater accounted for 15%-27% of national total crop production. There was high spatial variability across China in irrigation water demand and crop production derived from mined groundwater. We find that climate variability and mined groundwater demand do not operate independently; rather, years in which irrigation water demand is high due to the relatively hot and dry climate also experience limited surface water supplies and therefore have less surface water with which to meet that high irrigation water demand.
为了应对不断增长的粮食需求，过去几十年间，中国农业无论是规模还是强度都在不断扩大。灌溉在提高作物产量方面发挥了关键作用，而地下水现在是灌溉用水的重要来源。地下水开采量超过补给量（我们在这里用它来估计地下水开采量），导致地下水位下降，最终可能会限制地下水的供应。在这项研究中，我们使用了一个水文模型 WBMplus，结合一个基于过程的作物生长模型 DNDC，来评估中国农业对地下水开采的依赖程度，并在包括气候、作物选择和管理实践变化的区域内量化地下水开采依赖型作物的产量。该方法可以将作物产量直接归因于来自河流和水库、浅层（可再生）地下水和地下水开采的灌溉用水。模拟 20 年的天气变化和 21 世纪初的作物面积，我们发现，假设所有需求都得到满足，地下水开采满足了总灌溉用水需求的 20%-49%。地下水开采量占全国总作物产量的 15%-27%。在中国，灌溉用水需求和地下水开采的作物产量存在很高的空间变异性。我们发现，气候变率和地下水开采需求并非独立运作；相反，由于气候相对炎热干燥而导致灌溉用水需求较高的年份，地表水供应也有限，因此地表水不足以满足如此高的灌溉用水需求。
