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林业科学 ›› 2016, Vol. 52 ›› Issue (8): 10-20.doi: 10.11707/j.1001-7488.20160802

• 论文与研究报告 • 上一篇    下一篇

不同水土保持措施对黄土高原小流域年径流和产沙的影响——以平凉纸坊沟为例

王明玉, 王百田   

  1. 北京林业大学水土保持学院 北京 100083
  • 收稿日期:2016-03-17 修回日期:2016-05-30 出版日期:2016-08-25 发布日期:2016-09-19
  • 通讯作者: 王百田
  • 基金资助:
    困难立地植被恢复技术研究与示范(2015BAD07B002)。

Impacts of Soil and Water Conservation Measures on the Annual Runoff and Sediment Yield in Small Watershed of Loess Plateau of China——A Case Study of Zhifanggou in Pingliang City of Gansu

Wang Mingyu, Wang Baitian   

  1. School of Soil and Water Conservation, Beijing Forestry University Beijing 100083
  • Received:2016-03-17 Revised:2016-05-30 Online:2016-08-25 Published:2016-09-19

摘要: [目的]为兼顾黄土高原土壤侵蚀控制和供水安全,研究不同水土保持措施对黄土高原小流域径流和产沙影响,以寻找节水、高效的流域综合管理技术。[方法]利用甘肃平凉纸坊沟典型小流域1955-2003年的水上保持措施与径流和输沙等监测数据,建立年径流系数和产沙模数与土地利用的线性关系,定量评价不同水土保持措施对径流和产沙的影响。[结果]1955-2003年,年降水量呈不显著降低趋势,年径流深和产沙模数显著减少;小流域降水产流能力随植被破坏而提高,随植被恢复而大幅降低;修建梯田和淤地坝等工程措施可增加小流域的径流拦蓄能力,但会因工程老化而逐渐降低甚至消失;小流域单位径流深的侵蚀与携沙能力随林草面积增加而下降很大,但工程治理后未能明显降低;拟合小流域年径流深随年降水量和土地利用及年产沙模数随年径流深和土地利用的线性关系,发现林地和梯坝地可消减年径流,其中林地消减强度为梯坝地的1.48倍;径流主要来自草地与坡耕地和其他2个地类,其中草地径流率是坡耕地和其他的1.8倍;林地和草地可降低产沙模数,其中林地作用是草地的2.5倍;产沙来自梯坝地与坡耕地和其他2个地类,尤其梯坝地贡献为坡耕地和其他的2倍;将流域面积10%的坡耕地和其他地类转为林地、草地和梯坝地后,年径流变化量分别为-9.6,+4.2和-8.1 mm,产沙模数变化量分别为-6 367.0,-2 532.4和+300.5 t·km-2a-1。[结论]植被措施的治理效果寿命长于工程措施。林地减沙效果好,但耗水最多;草地减沙效果和用水效率虽低于林地,却能维持甚至促进小流域产流;梯坝地减少径流作用稍低于林地,其拦截泥沙能力会逐渐降低甚至丧失,且用水效率最低。综合来看,干旱缺水地区要满足节水、高效的水土保持治理要求,应以恢复草地为主,既能持久减沙,又能增加或维持产流,且生态用水减沙效率较高。

关键词: 黄土高原, 土壤侵蚀, 土地利用, 流域产流, 流域治理, 径流深, 产沙模数

Abstract: [Objective] The water and soil conservation measures should be water-saving and high-efficiency for controlling soil erosion but without threatening the security of water supply in the dry Loess Plateau of Northwestern China. The effects of different water and soil conservation measures on annual runoff and sediment yield should be separated and evaluated, for guiding the integrated management of watersheds.[Method] The typical small watershed of Zhifanggou, located at the Pingliang City of Gansu Province, was selected for this study. The long-term monitoring data of runoff and sediment yield within the period of 1955-2003 were used. The multiple linear relations among the annual runoff ratio, sediment yield module and the land use area ratios were fitted through regression analysis. These relations were used to separate and evaluate the effects of different conservation measures on annual runoff and sediment yield of the small watershed.[Result] The annual precipitation showed a non-significant decreasing trend within the period of 1955-2003, while the annual runoff and sediment yield module showed a significant decreasing trend. The runoff generation capacity of the small watershed was increased after vegetation destruction, but greatly decreased after vegetation restoration. The runoff interception capacity of the small watershed was increased after the implementation of engineering measures, such as the terrace and check dams, but this effect had been declined and even disappeared with the aging of these engineering measures, caused by the silt-up of check dams and the degradation of terrace fields. The ability of unit depth of annual runoff in soil erosion and sediment yield was reduced a lot with increase of forest and greassland, but not obviously decreased with the implementation of engineering measures. The multiple and linear relation between the annual runoff, annual precipitation and the area ratio of each land use category, and the relation among the sediment yield module and the annual runoff and the area ratio of each land use category were fitted. The coefficients in these relations indicated that the 2 land use categories of forestland, terrace and dam fields will decrease the annual runoff, and the decreasing intensity of forestland was 1.48 times of that of terrace and dam fields. The runoff was mainly generated from the 2 land use categories of grassland, slope farmland and others. The runoff ratio from grassland was 1.8 times of that from slope farmland and others. The forestland and grassland showed a function of reducing the sediment yield, in which the reducing intensity of forestland was 2.5 time of that of grassland; The sediment was mainly from the 2 land use categories of terrace and dam fields, slope farmland and others, in which the contribution to sediment yield from terrace and dam fields was doubled high as that from slope farmland and others. If the slope farmland and others is converted to forestland, grassland, terrace and dam field in an intensity of 10% of the total area of watershed, the annual runoff will be changed by -9.6,+4.2, -8.1 mm, and the sediment yield module will be changed by -6 367.0, -25 32.4,+300.5 t·km-2a-1, respectively.[Conclusion] The functional period of vegetation measures (afforestation, grassland restoration) for soil erosion control is expected to be longer than that of engineering measures (terrace and check dams). The forestland can well reduce the sediment yield module, but consumes much more water. The grassland has lower sediment yield reduction and water use efficiency compared with forestland, but it can maintain or even increase the water yielding ability of watershed. The terrace and dam fields have also an effect of reducing runoff, which is just slightly lower than that of forestland. However, their sediment interception ability will gradually lower or even disappear with the aging of engineering measures; moreover, their water use efficiency for reducing sediment is the lowest one. In summary, to meet the requirements of water-saving and high-efficiency in soil erosion control in the dryland regions, the dominant measures should be grassland restoration. In this way, we can get a long-lasting service of sediment reduction and erosion control, an unreduced or even enhanced water yield, and higher eco-water use efficiency in erosion control.

Key words: Loess Plateau, soil erosion, land use, water yield, watershed management, Runoff, Sediment yield module

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