全球河流输沙量时空分布及其影响因素分析
发布时间：2018-09-18 14:45
【摘要】：河流携带泥沙注入海洋是生物地球化学循环重要一环,是全球剥蚀系统关键组成部分,也是评估土地退化和全球土壤资源减少重要度量。研究全球河流输沙量的变化对研究陆地的表面过程、及陆地海洋系统物质循环(如,碳循环)具有重要的意义。全球尺度研究河流输沙量空间分布格局和时序变化及其二者的影响因素可以揭示河流输沙的一般规律,对认识人类活动对河流输沙量的影响也具有重要意义。近50年,在气候变化和人类活动日益增强的背景下,全球众多河流输沙量都发生显著变化。研究人员以区域河流为研究对象,解释了河流输沙量在时间尺度上的时序变化及其影响因素。但从全球尺度进行河流输沙量的研究却较少,全球河流输沙量空间分布格局及其影响因素在国外才初步展开。本文以全球657条入海河流为研究对象,利用数理统计和空间分析方法对全球河流输沙量的空间分布格局进行了研究;以各气候区8条代表性河流为研究对象,利用数理统计方法对其时序变化及其影响因素进行分析;在此基础上,基于过去各影响因素的时序变化,对未来全球河流输沙量进行定性预测。具体研究结果如下:(1)全球河流总输沙量估计值在1.5—2.0×10~(10) t左右。由于河流输沙本身的非平稳特性和空间差异性,这样的估值需要谨慎地接受。整体而言,亚洲河流年均输沙量最大,占全球总输沙量的一半以上,然后依次是大洋洲、南美洲、北美洲、非洲和欧洲。(2)对河流输沙量空间分布影响因素分析表明:降水量与输沙模数无明显相关性,径流量与输沙量呈显著线性相关;将流域按径流深度进行分区后,湿润区(径流深度750mm/a)径流量与输沙量的相关性达0.99。总体而言,河流输沙量随着流域面积的增大而增加,但相同流域面积的河流输沙量差别很大;按地形、地质条件对流域进行分区,定性的分析表明高山比低地河流年输沙量高出1~3个数量级;新生界地层占主导的流域的年输沙量要高于前中生界流域。(3)采用Mann-Kendall趋势检验法和线性回归对各气候区8条代表性流域降水、径流和输沙时序变化进行研究,分析结果表明:寒带和热带河流输沙量呈增加趋势,其它气候区河流输沙量呈显著减少趋势;除了热带2条河流输沙量时序变化不显著外,其余河流输沙量时序变化极显著。各流域的降水虽有变化,但均未达到显著水平p0.05;除黄河和密西西北河外,其余河流径流量时序变化均不显著;密西西北河径流量呈显著增加趋势,而其输沙量却呈极显著减少趋势。因此,河流输沙量受气候变化的影响不显著。相比较而言,人类活动对河流输沙量的变化影响更大,尤其是坝库建设。初步的估计表明全球大坝拦截的泥沙量可达4.4×10~(10) m3,这是全球入海泥沙量的2倍多。因此,在研究河流输沙量变化时要明确地把坝库作为一个影响因素进行分析。发展中国家因毁林开荒、采矿或城市化,流域土地利用有较大的变化,导致河流输沙量显著增加。(4)相比降水量趋势性变化,气候变化导致的极端降水事件对其河流输沙量的影响更大,研究人员仍需对极端降水事件预测及其环境效应进行深入研究。局部地区毁林开荒、采矿、城市化建设导致的土地利用变化会导致河流输沙量的增加,这些地区主要集中在发展中国家,尤其是非洲和南美洲的国家。但由于大规模坝库建设,未来全球河流总输沙量仍将继续减少。
[Abstract]:River sediment transport into the ocean is an important part of the biogeochemical cycle, a key component of the global denudation system, and an important measure of land degradation and global soil resource reduction. It is of great significance to study the spatial distribution pattern and temporal variation of river sediment transport and their influencing factors on a global scale, which can reveal the general law of river sediment transport and is of great significance to understand the impact of human activities on river sediment transport. Researchers take regional rivers as the research object to explain the temporal variation of river sediment transport and its influencing factors on time scale. However, there are few studies on river sediment transport on global scale, and the spatial distribution pattern of global river sediment transport and its influencing factors are preliminarily launched in foreign countries. The spatial distribution pattern of global river sediment transport was studied by using mathematical statistics and spatial analysis method, and the temporal variation and its influencing factors of eight representative rivers in each climate area were analyzed by using mathematical statistics method. The results are as follows: (1) The estimated value of global river sediment transport is about 1.5-2.0 *10~ (10) t. Due to the non-stationary characteristics and spatial differences of river sediment transport, such an estimate needs to be cautiously accepted. The largest sediment volume is Oceania, South America, North America, Africa and Europe. (2) There is no significant correlation between precipitation and sediment transport modulus, but there is a significant linear correlation between runoff and sediment transport. The correlation between runoff and sediment transport is 0.99 in the runoff depth of 750 mm/a. Generally speaking, the river sediment transport increases with the increase of the basin area, but the river sediment transport in the same basin area varies greatly. According to the topography and geological conditions, the basin is divided, and the qualitative analysis shows that the annual sediment transport in the mountains is 1-3 more than that in the lowlands. The annual sediment transport in the basins dominated by Cenozoic strata is higher than that in the Pre-Mesozoic basins. (3) Mann-Kendall trend test and linear regression are used to study the temporal variation of precipitation, runoff and sediment transport in eight representative basins in each climatic region. The results show that the sediment transport in cold zone and tropical river is increasing, while that in other climatic regions is increasing. The sediment discharge of the two rivers in the tropics showed a significant decreasing trend, and the sediment discharge of the other rivers changed significantly except for the two tropical rivers. Therefore, river sediment transport is not significantly affected by climate change. In comparison, human activities have a greater impact on river sediment transport, especially on dam and reservoir construction. Therefore, dam and reservoir should be considered as an influencing factor when studying the variation of river sediment transport. Great changes in land use have resulted in a significant increase in river sediment transport in developing countries due to deforestation, mining or urbanization. (4) Compared with the trend change of precipitation, climate change has led to a significant increase in river sediment transport. Extreme precipitation events have a greater impact on river sediment transport. Researchers still need to study the prediction of extreme precipitation events and their environmental effects. Countries in Africa and South America. However, due to large-scale dam and reservoir construction, the global total river sediment transport will continue to decrease in the future.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S157
本文编号：2248245
[Abstract]:River sediment transport into the ocean is an important part of the biogeochemical cycle, a key component of the global denudation system, and an important measure of land degradation and global soil resource reduction. It is of great significance to study the spatial distribution pattern and temporal variation of river sediment transport and their influencing factors on a global scale, which can reveal the general law of river sediment transport and is of great significance to understand the impact of human activities on river sediment transport. Researchers take regional rivers as the research object to explain the temporal variation of river sediment transport and its influencing factors on time scale. However, there are few studies on river sediment transport on global scale, and the spatial distribution pattern of global river sediment transport and its influencing factors are preliminarily launched in foreign countries. The spatial distribution pattern of global river sediment transport was studied by using mathematical statistics and spatial analysis method, and the temporal variation and its influencing factors of eight representative rivers in each climate area were analyzed by using mathematical statistics method. The results are as follows: (1) The estimated value of global river sediment transport is about 1.5-2.0 *10~ (10) t. Due to the non-stationary characteristics and spatial differences of river sediment transport, such an estimate needs to be cautiously accepted. The largest sediment volume is Oceania, South America, North America, Africa and Europe. (2) There is no significant correlation between precipitation and sediment transport modulus, but there is a significant linear correlation between runoff and sediment transport. The correlation between runoff and sediment transport is 0.99 in the runoff depth of 750 mm/a. Generally speaking, the river sediment transport increases with the increase of the basin area, but the river sediment transport in the same basin area varies greatly. According to the topography and geological conditions, the basin is divided, and the qualitative analysis shows that the annual sediment transport in the mountains is 1-3 more than that in the lowlands. The annual sediment transport in the basins dominated by Cenozoic strata is higher than that in the Pre-Mesozoic basins. (3) Mann-Kendall trend test and linear regression are used to study the temporal variation of precipitation, runoff and sediment transport in eight representative basins in each climatic region. The results show that the sediment transport in cold zone and tropical river is increasing, while that in other climatic regions is increasing. The sediment discharge of the two rivers in the tropics showed a significant decreasing trend, and the sediment discharge of the other rivers changed significantly except for the two tropical rivers. Therefore, river sediment transport is not significantly affected by climate change. In comparison, human activities have a greater impact on river sediment transport, especially on dam and reservoir construction. Therefore, dam and reservoir should be considered as an influencing factor when studying the variation of river sediment transport. Great changes in land use have resulted in a significant increase in river sediment transport in developing countries due to deforestation, mining or urbanization. (4) Compared with the trend change of precipitation, climate change has led to a significant increase in river sediment transport. Extreme precipitation events have a greater impact on river sediment transport. Researchers still need to study the prediction of extreme precipitation events and their environmental effects. Countries in Africa and South America. However, due to large-scale dam and reservoir construction, the global total river sediment transport will continue to decrease in the future.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S157
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