How many check dams do we need to build on the Loess Plateau?
How many check dams do we need to build on the Loess Plateau?
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DOI：
10.1021/es302835r
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发表时间：
2012-07
影响因子：
11.4
通讯作者：
Zhao Jin;B. Cui;Yi Song;W. Shi;Kaibo Wang;Yi Wang;Jing Liang
中科院分区：
文献类型：
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作者：
Zhao Jin;B. Cui;Yi Song;W. Shi;Kaibo Wang;Yi Wang;Jing Liang
在我国黄土高原上修建淤地坝已有400多年的历史。在过去的几百年里，人们越来越认识到淤地坝在截留泥沙、改善沟坡稳定性和增加耕地方面的优势。在《环境科学与技术》一书中，Wang等人总结了淤地坝在环境服务和粮食安全方面的优势。报告显示，在过去的50年里，黄土高原上已经建造了大约11万座淤地坝，这些坝已经捕获了大约210亿m的沉积物。此外，填满的淤地坝可以开垦为农田，到2002年，已经建立了大约320 000公顷的坝田。淤地坝在土壤保持和耕地扩张方面的重要作用激发了决策者的热情。早在2003年，中国水利部就提出，中国（CMWR）启动了黄土高原淤地坝计划，计划在2003 - 2020年期间建设16.3万座淤地坝，需要投资830.6亿元人民币。决策者认为，黄土高原有能力建设多达33.4万座淤地坝，因此需要更大的投资。黄土高原的淤地坝建设正在经历一个跨越式的发展。中国水利部制定了从2010年到2015年投资200多亿元人民币建设47,000座淤地坝的目标。越来越多的环境科学家关注这样的大型工程对黄河水循环和泥沙平衡的负面影响。CMWR预计，到2020年，检查大坝建设将导致黄河水量减少4.3 - 55亿m。然而，这一减少的数量是非常不确定的。由于气候变暖的趋势和广泛的人类活动，实际数量可能超过预测数量。近年来，黄河的输沙量和径流量急剧减少. Huang等人报告称，2000年至2005年，黄河入海泥沙量急剧下降至1.5亿吨/年，仅为广泛引用的估计值10.8亿吨/年的14%。《黄河泥沙公报》公布的数据显示，2000年至2010年，花园口水文站的输沙量大幅下降，为每年1.07亿吨。这一数值仅占1950年至2000年期间每年10.54亿吨泥沙量的10%。1950 ~ 2000年黄河年径流量平均为400.5亿m，而近10年来减少到226.5亿m。许多科学家认为，人类活动是造成黄河输沙量和径流量减少的主要因素。但是，我们还没有确定一个合适的泥沙和流量，以保持黄河健康，从而确定适当的数量，淤地坝应该建立在黄土高原。黄土高原总面积64.87万公里，其中高平原20万公里，丘陵14万公里，石山10.72万公里，汾渭断陷谷6.36万公里，沙漠7.92万公里，河套冲积平原5.87万公里（图1）。不同的地理区域在水土保持和生态系统服务中发挥着不同的作用。黄土高原丘陵区是黄土高原水土流失最严重的地区，是淤地坝工程建设的重点地区。石山地区适合种植，因此应被视为造林和水源保护的关键地区。建议淤地坝工程的规划应符合地形地貌和地理功能分区。目前，在淤地坝的规划和工程建设中出现了许多重大问题。首先，缺乏对淤地坝的适当密度和分布的批判性讨论。晋陕蒙接壤区是丘陵高原的中心侵蚀区，是淤地坝建设的重点地区。但是，在高平原高原和落基山脉仍计划建设大量淤地坝。第二，有效的水土保持措施和气候变化显著减少了黄土高原的土壤侵蚀，
F more than 400 years, check dams have been constructed on the Loess Plateau of China. Over the past several hundred years, people have increasingly realized the advantages of check dams for capturing sediments, improving gully slope stabilities, and increasing croplands. In Environmental Science and Technology, Wang et al. summarized the advantages of check dams for environmental services and food security. The report demonstrated that about 110,000 check dams have been built on the Loess Plateau over the past 50 years and approximately 21 billion m of sediments have been captured by these dams. Moreover, the filled check dams can be reclaimed as croplands, and by 2002, approximately 320,000 hectares of dam croplands had been created. The significant role of check dams in soil conservation and cropland expansion inspires the passions of policy makers. As early as 2003, the Ministry of Water Resources of P.R. China (CMWR) initiated a program for check dams in the Loess Plateau, and 163,000 check dams are planned and an investment of 83.06 billion RMB of funding is required for the period 2003−2020. Policy makers consider that the Loess Plateau has the capacity to allow the construction of as many as 334,000 check dams and will therefore require an even greater amount of investment. The Loess Plateau is currently undergoing a great leap forward in check dam construction. The CMWR has set a target of 47,000 check dams, built at an investment of more than 20 billion RMB, from 2010 to 2015. Increasing numbers of environmental scientists are concerned about the negative effects of such large-scale engineering on the balance of the water cycle and sediment load in the Yellow River. The CMWR projects that, by 2020, check dam construction will lead to a 4.3−5.5 billion m decrease in water yield to the Yellow River. However, the amount of this decrease is highly uncertain. The actual amount may exceed the projected amount due to trends in climate warming and extensive human activities. The sediment load and streamflow in the Yellow River have dramatically decreased in recent years. Huang et al. reported that the sediment load delivered from the Yellow River to the sea decreased sharply to 0.15 billion tons per year between 2000 and 2005, representing only 14% of the widely cited estimate of 1.08 billion tons per year. The data released by the Yellow River Sediment Bulletin show that the sediment load gauged by the Huayuankou hydrologic station decreased substantially to 0.107 billion tons per year between 2000 and 2010. This value represents only 10% of the sediment load of 1.054 billion tons per year occurring between 1950 and 2000. Moreover, the annual streamflow in the Yellow River averaged 40.05 billion m between 1950 and 2000, whereas it decreased to 22.65 billion m during the past decade. Many scientists conclude that human intervention is the primary factor that caused the decrease in the sediment load and streamflow in the Yellow River. However, we still have not determined a suitable sediment load and streamflow that would keep the Yellow River healthy, and therefore determine the appropriate number of check dams that should be built on the Loess Plateau. The Loess Plateau covers an area of 648,700 km, including 200,000 km of highplain plateau, 140,000 km of hilly plateau, 107,200 km of rocky mountains, 63,600 km of Fen River− Wei River fault depression valley, 79,2000 km of deserts, and 58,700 km of Hetao alluvial plains (Figure 1). The different geographical regions play different roles in soil and water conservation and ecosystem services. The hilly plateau regions suffer the most severe soil erosion in the Loess Plateau and should therefore be considered critical areas for check dam engineering. The rocky mountain regions are appropriate for planting and should therefore be considered critical areas for afforestation and water conservation. We suggest that the planning of check dam engineering should comply with the landforms and geographical function zones. Currently, many significant problems occur in the planning and engineering of check dams. First, there is a lack of critical discussion on the appropriate density and distribution of check dams. The contiguous area of Shanxi-Shaanxi-Inner Mongolia is the central erosion area of the hilly plateau and is therefore the most critical target area for check dam construction. However, a large number of check dams are still planned for construction in the highplain plateau and rocky mountains. Second, effective soil and water conservation measures and climate change significantly decreased soil erosion in the Loess Plateau and