退耕还林工程对黄土高原典型流域水土保持功能影响实证研究
发布时间：2019-01-09 18:30
【摘要】：退耕还林工程不仅可以提升流域的水土保持功能,还可以恢复流域水源涵养功能,具有极为显著的生态效益。从1999年开始,我国实施了大面积地退耕还林还草这一重大生态工程,其中,黄土高原是该工程重点实施区。为定量评估退耕还林工程对流域水土保持功能和水源涵养功能的作用,重点对黄土高原延河、北洛河、无定河、窟野河和泾河五个典型流域植被变化与流域水沙过程变化响应关系进行了分析。主要研究结果如下：(1)用归一化植被指数(NDVI)表征植被变化,研究黄土高原典型流域植被覆盖时空变化。工程实施后的2000-2010年,延河、北洛河、无定河三个流域NDVI均随时间呈上升趋势,北洛河增幅最大,各流域NDVI最大值出现时间均在2007-2009年；(2)五个流域降水量变化趋势不显著,其中窟野河、泾河和延河呈上升趋势,无定河和北洛河呈下降趋势,北洛河降水波动最大；除无定河外,其他四个流域径流量呈下降趋势,其中窟野河下降趋势显著,泾河、北洛河年际波动较大；五个流域输沙量均呈下降趋势,其中窟野河、北洛河下降趋势显著,各流域输沙年际波动较大；黄土高原典型流域径流总量占黄河总径流量的比例从13.1%减少到8.2%,呈不显著下降趋势。延河1980-2010年降水量、径流量和输沙量均成下降趋势,其中径流输沙下降趋势显著,利用Mann-Kendall法确定2003年为水文序列分界点,将30年划分为前期(1980-2002年)和退耕还林影响期(2003-2010年)；(3)通过分析工程实施以来径流系数年际变化、同一流域不同时间段降水-径流关系、不同NDVI的流域降水-径流关系,定性分析退耕还林工程对流域降水-径流关系的影响。研究结果表明,五个流域径流系数均成下降趋势；延河前期降水-径流关系相关性较好,退耕还林影响期降水-径流关系相关性性不显著,同等年降水量情况下,退耕还林影响期年径流量下降0.87×108m3,退耕还林工程削弱降水-径流关系,减少流域产流；随着NDVI增加,无定河、延河和北的洛河降水-径流相关性依次减小,在相似降水条件下,无定河、北洛河和延河径流量依次减少,说明植被覆盖增加削弱降水-径流关系,减少流域产流；(4)为量化退耕还林工程对流域产流产沙的影响,以2000年为始,拟合流域NDVI与流域相应年份径流系数、输沙量的关系。结果表明NDVI与径流系数、输沙量呈负相关,通过显著性检验(α=0.05)。本研究为流域水土保持措施实施和干旱地区水资源可持续利用提供科学依据,完善研究人类活动对流域径流产沙作用的理论和方法,有利于政策后续评价。
[Abstract]:The project of returning cropland to forest can not only improve the function of soil and water conservation, but also restore the function of water conservation. Since 1999, China has carried out a major ecological project of returning farmland to forest and grassland in a large area, among which, the Loess Plateau is the key implementation area of the project. In order to evaluate quantitatively the effects of conversion of cropland to forest on soil and water conservation function of watershed, the emphasis is placed on Yanhe, Beiluo River and Wuding River in the Loess Plateau. The relationship between vegetation change and water and sediment process in five typical watersheds of Grotto River and Jinghe River was analyzed. The main results are as follows: (1) the change of vegetation was characterized by normalized vegetation index (NDVI), and the temporal and spatial changes of vegetation cover in typical watershed of Loess Plateau were studied. From 2000 to 2010 after the implementation of the project, the NDVI of Yanhe, Beiluo and Wuding rivers all showed an upward trend with time, the increase of NDVI in North Luohe River was the largest, and the maximum value of NDVI in each watershed appeared in 2007-2009. (2) the change trend of precipitation in the five basins is not significant, among which the Grotto River, Jing River and Yanhe River show an upward trend, Wuding River and North Luohe River show a downward trend, and the North Luohe River has the largest fluctuation of precipitation; Except the Wuding River, the runoff of the other four watersheds showed a downward trend, in which the Grottoes River decreased significantly, the Jinghe River and the North Luohe River fluctuated greatly. The sediment transport in the five watersheds showed a decreasing trend, among which the Grottoes River and the North Luohe River showed a significant downward trend, and the interannual fluctuation of sediment transport in each watershed was quite large. The proportion of total runoff to the total runoff of the Yellow River decreased from 13.1% to 8.2% in the Loess Plateau, showing no significant decline trend. The precipitation, runoff and sediment discharge of Yanhe River from 1980 to 2010 showed a decreasing trend, among which runoff and sediment transport showed a significant downward trend. The Mann-Kendall method was used to determine that 2003 was the boundary point of hydrological series. Divide 30 years into early period (1980-2002) and period of returning cropland to forest (2003-2010); (3) by analyzing the interannual variation of runoff coefficient since the implementation of the project, the relationship between precipitation and runoff in different time periods in the same watershed, and the relationship between precipitation and runoff in different NDVI watershed, the effect of returning cropland to forest project on the relationship between precipitation and runoff is analyzed qualitatively. The results show that the runoff coefficients of the five watersheds are in a downward trend. The relationship between precipitation and runoff was good in the early stage of Yanhe River, and the correlation between precipitation and runoff was not significant in the period of returning cropland to forest. Under the same annual precipitation, the annual runoff decreased by 0.87 脳 108m3 during the period of returning cropland to forest. The project of returning cropland to forest weakens the relationship between precipitation and runoff and reduces runoff production in the watershed. With the increase of NDVI, the correlation between precipitation and runoff in Wuding River, Yanhe River and Luohe River in the north decreased in turn. Under similar precipitation conditions, the runoff of Wuding River, Beiluo River and Yanhe River decreased in turn, indicating that the increase of vegetation cover weakens the relationship between precipitation and runoff. Reducing runoff production; (4) in order to quantify the effect of returning cropland to forestry project on runoff and sediment yield in watershed, the relationship between NDVI and runoff coefficient and sediment transport in corresponding year of watershed was fitted from 2000 to 2000. The results showed that NDVI was negatively correlated with runoff coefficient and sediment transport, and was significantly tested (伪 = 0. 05). This study provides a scientific basis for the implementation of soil and water conservation measures and the sustainable utilization of water resources in arid areas, and improves the theory and method of studying the effect of human activities on runoff and sediment in river basins, which is beneficial to the policy follow-up evaluation.
【学位授予单位】：中央民族大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S157
本文编号：2405946
[Abstract]:The project of returning cropland to forest can not only improve the function of soil and water conservation, but also restore the function of water conservation. Since 1999, China has carried out a major ecological project of returning farmland to forest and grassland in a large area, among which, the Loess Plateau is the key implementation area of the project. In order to evaluate quantitatively the effects of conversion of cropland to forest on soil and water conservation function of watershed, the emphasis is placed on Yanhe, Beiluo River and Wuding River in the Loess Plateau. The relationship between vegetation change and water and sediment process in five typical watersheds of Grotto River and Jinghe River was analyzed. The main results are as follows: (1) the change of vegetation was characterized by normalized vegetation index (NDVI), and the temporal and spatial changes of vegetation cover in typical watershed of Loess Plateau were studied. From 2000 to 2010 after the implementation of the project, the NDVI of Yanhe, Beiluo and Wuding rivers all showed an upward trend with time, the increase of NDVI in North Luohe River was the largest, and the maximum value of NDVI in each watershed appeared in 2007-2009. (2) the change trend of precipitation in the five basins is not significant, among which the Grotto River, Jing River and Yanhe River show an upward trend, Wuding River and North Luohe River show a downward trend, and the North Luohe River has the largest fluctuation of precipitation; Except the Wuding River, the runoff of the other four watersheds showed a downward trend, in which the Grottoes River decreased significantly, the Jinghe River and the North Luohe River fluctuated greatly. The sediment transport in the five watersheds showed a decreasing trend, among which the Grottoes River and the North Luohe River showed a significant downward trend, and the interannual fluctuation of sediment transport in each watershed was quite large. The proportion of total runoff to the total runoff of the Yellow River decreased from 13.1% to 8.2% in the Loess Plateau, showing no significant decline trend. The precipitation, runoff and sediment discharge of Yanhe River from 1980 to 2010 showed a decreasing trend, among which runoff and sediment transport showed a significant downward trend. The Mann-Kendall method was used to determine that 2003 was the boundary point of hydrological series. Divide 30 years into early period (1980-2002) and period of returning cropland to forest (2003-2010); (3) by analyzing the interannual variation of runoff coefficient since the implementation of the project, the relationship between precipitation and runoff in different time periods in the same watershed, and the relationship between precipitation and runoff in different NDVI watershed, the effect of returning cropland to forest project on the relationship between precipitation and runoff is analyzed qualitatively. The results show that the runoff coefficients of the five watersheds are in a downward trend. The relationship between precipitation and runoff was good in the early stage of Yanhe River, and the correlation between precipitation and runoff was not significant in the period of returning cropland to forest. Under the same annual precipitation, the annual runoff decreased by 0.87 脳 108m3 during the period of returning cropland to forest. The project of returning cropland to forest weakens the relationship between precipitation and runoff and reduces runoff production in the watershed. With the increase of NDVI, the correlation between precipitation and runoff in Wuding River, Yanhe River and Luohe River in the north decreased in turn. Under similar precipitation conditions, the runoff of Wuding River, Beiluo River and Yanhe River decreased in turn, indicating that the increase of vegetation cover weakens the relationship between precipitation and runoff. Reducing runoff production; (4) in order to quantify the effect of returning cropland to forestry project on runoff and sediment yield in watershed, the relationship between NDVI and runoff coefficient and sediment transport in corresponding year of watershed was fitted from 2000 to 2000. The results showed that NDVI was negatively correlated with runoff coefficient and sediment transport, and was significantly tested (伪 = 0. 05). This study provides a scientific basis for the implementation of soil and water conservation measures and the sustainable utilization of water resources in arid areas, and improves the theory and method of studying the effect of human activities on runoff and sediment in river basins, which is beneficial to the policy follow-up evaluation.
【学位授予单位】：中央民族大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S157
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，本文编号：2405946
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