延河流域近50年植被与水沙变化关系分析

发布时间：2018-07-05 06:02

本文选题：延河 + 植被　；参考：《中国科学院研究生院（教育部水土保持与生态环境研究中心）》2014年硕士论文

【摘要】：针对黄河中游2000年以来出现的水沙锐减现象，以及植被减水减沙效益的定量估算问题，本研究以黄土丘陵沟壑区延河流域为研究区，分析延河流域1960-2010年间的流域径流量输沙量的变化特征，及其与降雨关系的变迁。同时，获取流域1970-2010年间流域的遥感影像，提取流域下垫面信息，分析植被变化与径流泥沙的关系，以及流域景观格局与水土流失的相关性。并结合历史文献从数量上分离出人工植被与自然恢复植被，基于水保法得到人工植被与自然植被的减水减沙效益。同时，研究选取了修正后的Morgan-Duzant（MD）版Morgan-Morgan-Finney（MMF）模型（2008年提出），结合延河流域地形、植被数据及室内试验数据对模型参数进行率定，利用模型估算了流域的年径流量与年输沙量，对由遥感影像提取的植被因子与流域水沙进行相关性分析，并利用相邻时期的数据进行了情景模拟，估算植被与降雨因素对流域来水来沙的影响。具体结论如下：（1）1960-1970年间延河流域径流输沙为剧烈上升期，1970-1996年为波动上升期，之后来水来沙开始下降，年径流量年与输沙量的线性拟合方程为y=4469.4x-5028.3（x-径流量，y-输沙量），R2=0.8747。流域中游和下游站点水沙变化趋势一致，但变异程度不同。1982-1996年间甘谷驿站的年径流量变化程度超过了延安站，1982-1996年间延安站以上来水增加较剧烈，而1996年以后延安站以上来水减少较剧烈。（2）70年代末延河流域耕地面积达5128.83km2，至2010年减少为1232.11km2，流域景观本底已由耕地转化为林草植被。回归分析结果表明，流域水沙随林草植被总面积增加、耕地面积减少均呈抛物线下降的趋势。景观格局分析发现，年径流量与耕地的斑块数量、密度呈负相关关系，，而与其最大斑块指数和聚集度呈正相关关系，年输沙量与耕地聚集度存在正相关关系；城镇的斑块数量、密度与年径流量、年输沙量存在显著的正相关关系。（3）基于“水保法”估算人工植被与自然植被的水沙效益，结果表明2003-2005年与1980年代相比，人工林草植被减少径流0.228亿m3，减少泥沙543.478万t，而自然恢复植被减少径流0.121亿m3，减少泥沙152.970万t。结合双累积曲线法结果，就人类干扰对水沙的影响而言，其中人工植被对径流、泥沙变化的贡献分别为46.94%、30.64%，而自然恢复植被对减水、减沙的贡献分别占24.97%、8.62%，剩余为其他水利水保措施的作用。（4）MD版MMF模型对延河流域年径流量模拟效果较好，相对误差范围在-26.41%至17.25%。结合延河流域的淤地坝、梯田等数据对输沙量模拟结果进行修正，修正后模拟的相对误差范围提高到-28.82%至45.13%。利用模型对不同时期的情景模拟表明，相邻时期植被对输沙量的影响在12%-30%之间，与“水保法”计算结果基本一致。（5）植被覆盖度不能完全反映植被的水土保持作用，本研究对植被覆盖度、截留率、林下降雨侵蚀力和坡面沉积率等直接或间接植被因子与径流泥沙的相关性进行了分析。结果表明，径流量与植被覆盖度的相关性较弱，而与截留率、林下降雨侵蚀力和坡面沉积率等间接植被因子相关性较强，相关系数平均值分别为-0.335，-0.54，-0.449。植被以综合作用的方式减少地表产流。输沙量与植被覆盖度的相关性较高，平均相关系数为-0.418，而与其他植被因子的相关系数分别为-0.27，-0.288，-0.17。输沙量主要受植被覆盖度影响，表明延河流域植被对泥沙运移的拦阻作用主要体现在植被的类型与数量上。
[Abstract]:In view of the sharp decrease of water and sediment in the middle reaches of the middle reaches of the Yellow River since 2000 and the quantitative estimation of the benefit of vegetation reduction and sediment reduction, this study takes the Yanhe River Basin in the Loess Hilly and gully region as the study area to analyze the change characteristics of the runoff and sediment transport in the valley of the Yanhe River Basin in 1960-2010 years, and the changes in the relationship with the rainfall. At the same time, 1970 of the river basin are obtained. In the period of -2010, the remote sensing images of the basin extracted the information of the underlying surface of the basin, analyzed the relationship between the vegetation change and the runoff and sediment, and the correlation between the landscape pattern of the basin and the soil erosion, and separated the artificial vegetation and the natural restoration vegetation from the historical literature, and the water reduction and sediment reduction effect of artificial vegetation and natural vegetation based on the water conservation method. At the same time, the revised Morgan-Duzant (MD) version of Morgan-Morgan-Finney (MMF) model was selected (proposed in 2008). The model parameters were determined by combining the terrain of the Yanhe River Basin, the vegetation data and the laboratory data, and the annual runoff and the annual sediment volume were estimated by the model, and the vegetation factor and the watershed extracted from remote sensing images were estimated. The correlation analysis of water and sediment was carried out, and the effects of vegetation and rainfall on water and sediment in the basin were estimated by using the data of the adjacent period.
(1) the runoff and sediment transport in the Yanhe River Basin in 1960-1970 years is rising sharply, the 1970-1996 year is the fluctuation period, and then the runoff and sediment begin to decline. The linear fitting equation of annual runoff year and sediment transport is y=4469.4x-5028.3 (x- runoff, y- sediment), and the trend of water and sediment change in the middle and downstream sites of the R2=0.8747. basin is the same, but the variation degree is different. In the period of.1982-1996, the change degree of annual runoff in Gangu post station was more than that of the YanAn Railway Station, and the increase of water increased violently in the last 1982-1996 years.
(2) the area of arable land in the Yanhe River Basin reached 5128.83km2 at the end of 70s and decreased to 1232.11km2 in 2010. The landscape of the river basin was transformed from cultivated land to forest and grass vegetation. The regression analysis showed that the water and sediment in the basin increased with the total area of the forest and grass vegetation and the decrease of the cultivated land area. The landscape pattern analysis found that annual runoff and cultivated land were found. There is a negative correlation between the number of patches and the density of the patches, but there is a positive correlation with the maximum plaque index and aggregation degree. There is a positive correlation between the annual sediment transport and the accumulation degree of cultivated land, and there is a significant positive correlation between the number of urban patches, the density and annual runoff, and the annual sediment transport.
(3) the water and sediment benefits of artificial vegetation and natural vegetation were estimated based on the "water conservation law". The results showed that compared with the 2003-2005 years in 1980s, the plantation vegetation reduced the runoff by 22 million 800 thousand M3 and the sediment 5 million 434 thousand and 780 T, while the natural restoration vegetation reduced the runoff by 12 million 100 thousand M3, and reduced the sediment 1 million 529 thousand and 700 T. combined with the double cumulative curve method. In terms of the effect of water and sediment, the contribution of artificial vegetation to runoff and sediment change is 46.94%, 30.64% respectively, while the contribution of Natural Restoration Vegetation to water reduction and sediment reduction is 24.97% and 8.62% respectively, and the rest is the role of other water conservation measures.
(4) the MD MMF model has a better simulation effect on the annual runoff in the Yanhe River Basin. The relative error ranges from -26.41% to 17.25%. combined with the silt dam in Yanhe River Basin and the terrace data to modify the sediment transport simulation results, and the relative error range of the modified simulation is increased to -28.82% to 45.13%. The influence of vegetation on sediment transport in the adjacent period is between 12%-30%, which is basically the same as that calculated by the "water conservation law".
(5) the vegetation coverage does not fully reflect the soil and water conservation effect of vegetation. The correlation of vegetation coverage, interception rate, rainfall erosivity and slope deposition rate is analyzed in this study. The results show that the correlation between runoff and vegetation coverage is weak, with interception rate and forest decline. The correlation between rain erosion force and slope deposition rate is strong, and the mean values of correlation coefficient are -0.335, -0.54 and -0.449., respectively. The correlation between vegetation coverage and sediment transport is higher, and the correlation coefficient is -0.418, and the correlation coefficient with other vegetation factors is -0.27, -0.28, respectively, respectively. 8, the -0.17. sediment discharge is mainly affected by vegetation coverage, indicating that the arresting effect of vegetation on sediment transport in the Yanhe River Basin is mainly reflected in the type and quantity of vegetation.
【学位授予单位】：中国科学院研究生院（教育部水土保持与生态环境研究中心）
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P333;Q948

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