摘要
摘要:海河流域含京津冀及周边三省，是我国水资源短缺和用水矛盾最突出的地区。中国科学院遗传与发育生物学研究所农业资源研究中心团队围绕不断加剧的水资源短缺，研究了流域水资源演变的关键驱动机制：山区径流变化、农业需水和虚拟水外输，分析了流域水资源演变的主要原因，并对未来的可能调控提出了建议。研究首先选取海河流域的八大山区子流域，分析了20世纪60年代以来的径流变化，确认70年代开始山区来水逐渐减少，径流减少的关键时期是1978-1985年，推断农业用水增加是径流减少的核心驱动因素；其次，基于作物模型、作物系数法和遥感等手段，量化了海河平原农业用水的时空格局和区域水量平衡，通过对比农业耗水量、地下水水位变化和南水北调中线供水量，确立了山前平原区南水北调实施后为实现水量平衡需控制用水的进一步扩大、低平原区仍然亏缺的未来水资源态势；最后，通过粮食贸易的虚拟水分析，指出本地区外输虚拟水达90亿m³，是造成水资源短缺的重要原因，减缓虚拟水外输或输入一定虚拟水是缓解区域水资源压力的可选方案。
关键词:海河流域/
水资源短缺/
径流/
农业用水/
虚拟水/
粮食贸易
Abstract:Including Beijing, Tianjin, Hebei and three surrounding provinces, Haihe River Catchment is facing an increasing shortage of water resources. This paper summarized our research progress on the driving mechanisms of water resources change including reasons for runoff changes, spatial variations and temporal changes of agricultural water use, and outflow of virtual water through external food supply. Firstly, by using the sequential Mann-Kendall to determine the abrupt changes in eight sub-catchments of Haihe River Catchment and traditional Mann-Kendall test for the period 1960-1999 to identify the basic trend of precipitation and runoff, it was confirmed that runoff reduction started since 1970s, and generally became statistically significant from 1978 to 1985. Through correlation comparisons for precipitation and runoff for the periods prior to and after abrupt runoff changes, human activity, rather than climatic change, was identified as the main driving factor of runoff changes. By using SWAT model, it was concluded that human influence on agricultural water demand contributed to 76% of runoff decline at the beginning of the China's rural reform. Secondly, through crop modeling, crop water demand calculation by crop coefficient and ET, and remote sensing methods, spatial and temporal distribution of agricultural water demand in the Haihe Plain were quantified. Changes of agricultural water demand were evaluated. This in turn laid the basis for surface water reallocation following the completion of the South-to-North Water Transfer (SNWT) project. By comparing agricultural water consumption, groundwater level change, and water supply from the SNWT canal, it was estimated that there could be a relative balance of water demand and supply in the piedmont plain with the designed water supply from SNWT upon strong limitation on further water-consumption increase especially for newly developed landscapes such as lakes, rivers, wetland, water consuming woodland, and etc. In the coast plain, water shortage would remain for the long-term, meanwhile more water supply together with brackish water use was to be developed. While agriculture placed the greatest demand on water resources, reducing the cultivation of water-consuming crops might be the most effective way to reduce agricultural water use. However, taking food demand into consideration, sustaining the balance between regional water and food security was a growing challenge. To solve such problem, we studied NEXUS or interlinkage among land use, water consumption, food production (Land-Water-Food NEXUS) in Beijing-Tianjin-Hebei Region. Virtual water flow embedded in food transfer was evaluated. According to our estimation, nearly 9×10⁹ m³ virtual water and 2×10⁶ hectares cropland were currently used for producing 1.2×10⁷ tons maize for external food supply, which highly resulted in the locally developing water shortage. Controlling food production and virtual water outflow shall be a suitable and very necessary way to alleviate the pressure of water shortage facing the quick developing strategies of Beijing-Tianjin-Hebei Region and the newly lunched Xiong'an New District.
Key words:Haihe River Catchment/
Water shortage/
Runoff/
Agricultural water demand/
Virtual water flow/
Land-Water-Food Nexus



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