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Study on Effect of Vegetation Restoration on Sediment Reduction in the Loess Hilly Region

Author: LianZhenLong
Tutor: LiuPuLing
School: Graduate School,Chinese Academy of Sciences
Course: Soil
Keywords: Loess Hilly Region The Yangou Basin Land use patterns Vegetation restoration Sediment reduction benefit
CLC: S157.1
Type: Master's thesis
Year: 2008
Downloads: 38
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Abstract

Rehabilitation of vegetation in China's western region of ecological restoration and governance measures to improve the ecological environment of the region, to some extent effective. The research for the study, a typical small watershed of loess hilly region Yan valley natural slope runoff plots rainfall runoff and sediment yield, watershed runoff and sediment Hau Station long-term observations, combined with field simulated rainfall test results, analysis of different land the way overland runoff and sediment yield characteristics, soil and water conservation measures calculated Yan valley, vegetation restoration measures sediment reduction benefit; basin sediment changes affect factor analysis of rainfall factors watershed sediment load the impact of changes made to the following conclusions: 1. slope different land use types and slope characteristics of runoff and sediment yield in the same rainfall intensity conditions under different land use patterns and sediment yield process accumulated sediment yield different, the overall performance: plowing residential> mowing cell> cell vegetation cover. Different land uses in cell 30min sediment yield and rainfall time relationship in line with W = at-b of linear equations, and W = aIb power function relationship between rainfall intensity. Runoff and sediment yield different slopes cell studies have shown that the steep district regardless of the strength of the runoff and sediment, or cumulative production and the amount of runoff and sediment are significantly higher than the the gentle slope district of greater than 25 ° slope farmland farmland necessity of this policy. Study different ways of returning farmland to forest and grassland, water and sediment reduction benefit is significant since the farmland of the different years of slope vegetation runoff and sediment yield characteristics of various types of land use patterns, each plot the size of the annual output of the amount of runoff and sediment relations: the sloping land residential gt; grass plot gt in more than 70%; shrub plot, grass plot runoff over the slope farmland district reduced by 50% to 60%, shrub reduced cell over the sloping land plot runoff; each plot sediment reduction in more than 90%, the amount of sediment reduction greater than reductions traffic. Grass and shrub vegetation have an obvious role in water and soil conservation; different Abandoned years of shrub cells accumulated runoff and sediment are less than the grass plot, water and soil under different conditions of rainfall and rainfall intensity, shrub land remain active more than grass. Slope plots with runoff coefficient size relationship: sloping land district gt; mow mowing to gt; grass gt; mowing shrub to gt; the scrublands gt; locust woodland, reduced with terrestrial vegetation coverage increase a negative correlation between. Compared with the sloping land, grass, shrub and locust woodland district less traffic were 51.1%, 71.4% and 90%, the amount of sediment reduction was 99.3%, 99.5% and 99.6%, respectively, Robinia pseudoacacia, less water sediment reduction effect is most obvious sediment reduction effect of various land use types is significantly larger than the current reduction. Compared the structural characteristics of the grass and shrub communities and sediment reduction mechanism grass and shrub residential mow the cut treated sediment yield larger differences, mowing grass estate sand increased significantly, while the shrub residential mowing sediment yield increase is not obvious, mainly related to vegetation structural characteristics of both. Grassland community after 10 years of Abandoned Cropland in the formation of multi-annual herb, and growth in the near-surface layer of litter less vulnerable to destruction; shrub communities in perennial mountain elm, locust, perennial shrub lespedeza, surface litter material more developed underground plant roots, soil and water conservation significant effect. Near the surface in the initial stage of vegetation succession of grassland vegetation, sediment reduction benefit significantly, but still relatively fragile ecological functions needed Fengyubaohu main vegetation communities. 4 illustrates Yan Watershed vegetation restoration sediment reduction benefit by the slope of plot runoff and sediment yield analysis of different land use, combined with observations of locating cell, the use of water conservation method to calculate the average annual sediment modulus governance Yan valley 737 t/km2? sediment reduction benefit is greater than 80%; calculated sediment yield and basin Hau Station close observations prove less sand-effective computing realistic Yangou Basin and further instructions Yan valley comprehensive management of sediment reduction benefit. 5 discusses the impact of precipitation changes Yan watershed sediment load changes to the use of similar observations of small watershed analysis carried out on the the Watershed Management Yangou change before and after the rainfall and sediment yield by a combination of time and space, the results show that Abandoned after rainfall changes caused watershed sediment load average annual reduction 61228t, accounting for about 25% of the watershed sediment load reduction, two major factors in the recent years, measured basin sediment reduction, precipitation changes affect about 25 %, accounted for about 75% of the comprehensive management role.

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