基于生态耗水中小流域水沙变化及其对土地利用的响应

发布时间：2018-04-25 13:24

本文选题：黄土高原 + 土壤侵蚀　；参考：《北京林业大学》2016年博士论文

【摘要】：为兼顾黄土高原土壤侵蚀控制和供水安全,需寻找节水、高效的侵蚀治理模式,需定量区分不同土地利用结构对小域径流和产沙的影响,尤其在小流域尺度,从而为指导流域综合治理提供科技支持。为此,利用甘肃平凉纸坊沟小流域1955-2003年的治理措施与年降水量、径流深、产沙模数等监测数据开展研究。将小流域治理进程划分出1955-1964、1965-1976、1977-1985、1986-2003年4个治理年段,其中前3个年段以修建淤地坝和梯田等工程措施为主,在第4年段开始注重林草恢复。区分了人类活动和降水变化对年径流变化的影响,分析了年降水-年径流、年径流-年产沙模数的关系及其变化,建立了年径流系数和年产沙模数随土地利用结构变化的多元线性关系,定量评价了不同土地利用结构对小流域年径流深和年产沙模数的影响和其水土保持减沙生态用水效率。研究表明：在1955-2003年间,年降水虽无明显变化,但年径流却显著减少,从20世纪50年代的59.1 mm降到21世纪初的12.2 mm,降幅达72.4%。以1955-1964年段为基准期,估算了不同时期人类活动和降水变化对年径流变化的贡献,表明除干旱年段的降水对年径流减少贡献明显外,其它年段的径流变化主要是由人类活动引起的,且其绝对贡献量呈逐渐增大趋势。在1955-2003年,随水土保持治理等人类活动加强,小流域年径流深显著减少,年产沙模数也明显减少。与基准年段(1955-1964年)相比,小流域治理使年径流量与年降水量的相关性逐渐降低,这可从降水产流能力和径流拦蓄能力两方面解释。降水产流能力在第2、3年段因植被破坏而提高,在第4年段因植被恢复而大幅降低；因工程治理而增加的径流拦蓄能力随淤地坝建设和梯田的建设与功能退化经历了“增加-降低-消失”的变化。为排除年径流量变化的干扰,按年段分析了产沙模数与年径流深的关系。在前3个年段,产沙模数与年径流深的相关性及单位径流深的产沙量变化不大,表明工程治理虽减少径流却未明显降低径流的产沙能力；但第4年段的林草面积增加使径流的产沙能力下降很大。拟合了小流域年径流深随年降水量和土地利用变化,以及年产沙模数随年径流深和土地利用变化的多元线性回归方程,表明林地和梯坝地消减年径流深,其中林地消减强度为梯坝地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它的1.8倍。林地和草地具降低产沙模数的作用,其中林地作用强度是草地2.5倍；产沙来自梯坝地与坡耕地和其它这2个地类,尤其梯坝地贡献高出坡耕地和其它达一倍。将流域面积10%的坡耕地和其他地类转为林地、草地、梯坝地后,年径流变化分别为-9.6、+4.2、-8.1 mm,产沙模数变化分别为-6367.0、-2532.4、+300.5t/km2/a。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,虽然其生态用水的减沙效率最高；草地减沙效果和用水效率虽低于林地,却能促进或维持小流域产流；梯坝地减少径流作用稍低于林地,其泥沙影响主要为拦截泥沙而不是降低侵蚀产沙,但其拦沙能力会随库容淤积及梯田损毁而逐渐降低甚至丧失,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,应尽可能多恢复草地覆盖,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。
[Abstract]:In order to take account of soil erosion control and water supply safety in the Loess Plateau, it is necessary to find water saving and efficient erosion control model. It is necessary to distinguish the effects of different land use structures on the runoff and sediment yield in small areas, especially in small watershed scale, so as to provide scientific support for the comprehensive management of the river basin. Therefore, 1955-20 small watershed in Pingliang, Gansu, is used. The 03 year management measures are studied with annual precipitation, runoff depth, sediment yield modulus and other monitoring data. The treatment process of small watershed is divided into 4 years of 1955-19641965-19761977-19851986-2003 years. Among them, the first 3 years are based on the construction of Silt Dams and terraced fields, and the restoration of forest and grass is emphasized in the fourth year period. The relationship between annual runoff, annual runoff and annual runoff yield modulus is analyzed, and the multiple linear relationship between annual runoff coefficient and annual runoff yield modulus with the change of land use structure is established, and the annual runoff depth and annual sediment modulus of different land use structures are quantitatively evaluated. The study shows that, although there is no obvious change in the annual precipitation, the annual runoff has decreased significantly in 1955-2003 years, from 59.1 mm in 1950s to 12.2 mm at the beginning of twenty-first Century, and the decline is 72.4%. to 1955-1964 years as the base period, and the annual human activities and precipitation changes in different periods are estimated. The contribution of runoff change shows that the contribution of precipitation to annual runoff is obvious except that in the year of drought, the change of runoff in other years is mainly caused by human activities, and its absolute contribution is gradually increasing. In the 1955-2003 year, the annual runoff of small watershed decreased significantly with the improvement of water and soil conservation and the annual runoff of small watershed. Compared with the base year period (1955-1964 years), the correlation between the annual runoff and the annual precipitation is gradually reduced, which can be explained by the two aspects of the capacity of precipitation and runoff and the capacity of the runoff. The precipitation runoff capacity is increased by the vegetation destruction in the last 2,3 period, and a significant reduction in the restoration of vegetation in the fourth year period; In order to eliminate the change of annual runoff, the relationship between sediment yield modulus and annual runoff depth is analyzed. The correlation between sediment yield and annual runoff depth and unit runoff depth in the first 3 years. The amount of sediment yield in the fourth year period was not obviously reduced in runoff yield, but the increase in the area of the forest and grass decreased the runoff yield greatly. It fitted the annual runoff and land use changes in the small watershed, and the annual runoff depth and land use change. The multiple linear regression equation shows that the forestland and the terracing land reduce the annual runoff depth, and the forest land reduction intensity is 1.48 times that of the terraced land, and the runoff mainly comes from the grassland and the slope farmland and the other 2 places, of which the grassland runoff is 1.8 times the slope farmland and the other. The woodland and grassland have the function of reducing the sediment yield, and the woodland strength is the grass. The sediment yield is 2.5 times, the sand production comes from the staircase and the slope land and the other 2 fields, especially the slope land of the staircase and the other times. The sloping arable land and other fields of 10% of the basin area are converted into woodland, grassland and staircase, and the annual runoff changes are -9.6, +4.2, -8.1 mm, respectively, -6367.0, -2532.4, +300.5t/km2/a, respectively. The effect of vegetation measures is longer than that of engineering measures. The effect of woodland reduction is good, but the water consumption is the most. Although the efficiency of its ecological water consumption is the highest, the effect of sand reduction and the efficiency of water use are lower than that of the woodland, but it can promote or maintain the flow of small catchment; the gradient of the dam land is a little lower than the woodland, and its sediment effect is mainly intercepted. Sediment rather than erosion and sediment yield, but its ability to block the sand will gradually decrease or even lose with the accumulation of reservoir capacity and the destruction of terraced fields, and the water efficiency is the lowest. And the efficiency of reducing sand in ecological water is high.

【学位授予单位】：北京林业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S157

【相似文献】