Assessing the long-term impact of vegetation cover on sediment load within buffer zones of the upper Qin River Basin, Guangxi, China

PDF HTML阅读 XML下载 导出引用 引用提醒 黄土高原流域水沙变化研究进展 DOI: 10.5846/stxb201909121903 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41822103，41471094）；中国科学院青年促进会项目（2016040） Changes in streamflow and sediment load in the catchments of the Loess Plateau, China: a review Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:人类活动和气候变化是影响流域水文过程的两大驱动因素，径流输沙是流域水文过程的总体反映，变化环境下径流输沙的变化规律与成因分析是水文学和全球变化研究的热点问题。黄土高原是我国水土流失最严重的地区。20世纪50年代以来，黄土高原地区开展了大规模的生态环境建设和水土流失综合治理，显著改变了流域土地利用和植被覆盖。下垫面条件改变与气候变化综合作用，使得流域水沙情势发生剧变。围绕黄土高原流域水沙变化的时空尺度特征与驱动机制，总结了径流输沙和水沙关系变化特征的研究结果，归纳了径流输沙变化的归因分析方法与人类活动和气候变化影响的贡献分割结果，探讨了气候变化、植被恢复、水土保持工程措施以及流域景观格局对水沙变化的影响机制。未来应加强流域水沙演变的时空尺度特征特别是水沙关系非线性特征的定量研究，阐明极端事件对水沙动态的影响与贡献；开展水沙变化影响机制的多要素综合解析，发展耦合地表覆被动态特征和气候变化的降雨-径流-输沙模型，揭示生态恢复与水沙演变过程互馈机制；开展未来气候变化、社会经济发展和生态建设工程情景下水沙动态的趋势预测，为黄土高原生态综合治理和水资源管理与黄河水沙调控提供策略建议。 Abstract:Human activities and climate change are two critical driving forces of catchment hydrological processes, for which, streamflow and sediment load are the two main indicators. Changing trends and attribution analysis of streamflow and sediment load under changing environments are now the focus of hydrological and global change studies. The Loess Plateau (LP) of China is well known for its severe soil erosion and the heavy sediment load of the Yellow River that flows through it. To control soil erosion in the LP, large ecological restoration construction projects and several soil and water conservation measures have been implemented since the 1950s, which have resulted in extensive land use and vegetation cover changes. These extensive changes in land surface conditions in combination with climate change have dramatically altered the hydrological regime, including streamflow, sediment load, and flow-sediment relationships in the LP. The spatio-temporal variability of streamflow and sediment load, and the dominant mechanisms behind these changes are important issues in the development of strategies for sustainable land and water management in the LP. We reviewed previous studies that documented changes in streamflow, sediment load, and flow-sediment relationships to improve our understanding of these processes. The methods used to separate the impacts of human activities and climate change on streamflow and sediment load and the results obtained in these studies are summarized here. The influence of climate change, vegetation restoration, soil and water conservation measures, as well as catchment landscape patterns on driving changes in streamflow and sediment load are also discussed. Finally, the following further studies are proposed:1) Studying the spatio-temporal patterns in streamflow and sediment load evolution and quantifying the non-linear characteristics of flow-sediment relationships, 2) Demonstrating the effects and contributions of extreme events on streamflow and sediment load dynamics, 3) Conducting comprehensive analyses on the influence of multiple factors on streamflow and sediment load, 4) Developing a coupled rainfall-streamflow-sediment yield model that includes the dynamic characteristics of surface cover and climate change, with the aim of revealing feedback mechanisms between ecological restoration and the evolution of streamflow and sediment load, and 5) Predicting streamflow and sediment load dynamics under future scenarios of climate change, with the added effects of socio-economic development and ecological construction engineering; which is likely to provide suggestions for ecological treatment and water resource management in the LP, and regulation of water and sediment in the Yellow River. 参考文献 相似文献 引证文献

Relationship between sediment load and climate extremes in the major Chinese rivers

HighlightsWinter cover crops and growing season filter strips were implemented without sacrificing significant land and achieved positive results. Cover crops reduced runoff depth, peak flow rate, sediment, TP, and TN load by 30%, 49%, 43%, 4%, and 7%, respectively.Filter strips reduced runoff depth, peak flow rate, sediment, TP, and TN load by 36%, 49%, 56%, 15%, and 21%, respectively.Abstract. Effective use of conservation practices in agricultural fields can reduce sediment and other pollutant loads entering waterways. In this study, we evaluated the effectiveness of using cover crops and filter strips on sediment and nutrient loss at the edge of paired, 7.83 ha (19.35 ac), commercial cotton fields in the Lower Mississippi River Basin (LMRB) in northeastern Arkansas. Cover crops included winter wheat, black oat, and ryegrass seeded in the winter fallow period, while filter strips included a grassy turn row at the field border and switchgrass transplanted around the drainage pipe at the edge of the treatment field. The field border of the control field was generally free from vegetation. A monitoring system measured discharge and collected composite water samples from rainfall and irrigation runoff events. Water samples were analyzed for phosphate (PO4-P), total phosphorus (TP), nitrate (NO3-N), ammonium (NH4-N), total nitrogen (TN), and suspended sediment concentrations. Data were collected from 2015 to 2020. Baseline data were collected when both fields had similar conservation practices (i.e., no cover crops in 2015 and no filter strips in 2015 and 2016). A comparison of 66 common runoff events between the control and cover crop treatment fields during the non-growing season indicated that the median peak flow and sediment loads were significantly reduced (p < 0.05), with an average reduction of 49% and 43%, respectively. Similarly, a comparison of 55 common runoff events between the control and filter strips treatment fields during the growing season found that the filter strips reduced significantly with average runoff by 36%, peak flow by 49%, and sediment loads by 56% (p < 0.05). Nutrient load reductions by the cover crop and filter strip treatments were not significantly different than by the control (p > 0.05). However, mean PO4-P, TP, NO3-N, NO2-N, NH4-N, and TN loads in the cover crop treatment field were lower than in the control field by 21%, 4%, 9%, 4%, 17%, and 7%, respectively. Similarly, mean PO4-P, TP, NO3-N, NH4-N, and TN loads in the filter strip treatment field were lower than in the control field by 23%, 15%, 11%, 42%, and 21%, respectively. The results demonstrated runoff depth, peak flow rate, nutrients, and sediment load reductions following the implementation of cover crops and filter strips at the commercial field scale. Keywords: Agricultural conservation practices, BMPs, Cotton, Cover crop, Edge-of-field monitoring, Filter strips, Switch grass.

Sediment load change in the Yangtze River (Changjiang): A review

<p>The hydrological series can no longer meet the stationarity hypothesis due to the influence of climate variability and human activities. The process of runoff and sediment load changed significantly under a changing environment. Analyzing the variations of runoff and sediment load and exploring the main influencing causes leading to their changes will be of great help to understand the dynamic process of water and sediment in river basin. Many studies have considered the effects of rainfall and reservoir on the downstream runoff or sediment: the impact of rainfall on runoff or sediment load is normally performed by comparing the statistical characteristics before and after an extreme weather event (e.g. heavy rain of the Yangtze river in 1998); the effect of reservoirs is usually determined by comparing the pre-dam and post-dam frequencies of runoff or sediment load. In this study, the major influencing factors of annual runoff and sediment load in Wujiang River basin were identified firstly based on the results of trend analysis and change-point diagnosis for runoff and sediment load. Then, Generalized Addictive Models in Location, Scale, and Shape (GAMLSS) is used to describe the rainfall and reservoir impacts on nonstationarity of runoff and sediment load, in which, distribution parameters (including the location, scale and shape parameter) are expressed as a function of the explanatory variables. The results show that: (1) runoff and sediment load of Wujiang River decrease with the intensification of climate change and human activities; (2) runoff is mainly affected by rainfall, the operation of cascade reservoirs has critical effect on the sediment load; (3) the correlation between runoff and sediment closely related to the nonstationarity of sediment load, namely, the sediment load change can directly lead to the alteration of dependence between runoff and sediment.</p>

The numerical model Hydro Trend is applied to simulate the variations of water discharge and sediment fluxes into Poyang Lake during 1956- 2010 from the five tributaries of Poyang Lake Basin, namely Gan, Fu, Xin, Rao and Xiu rivers. Furthermore, the influences of climate change, vegetation cover variation and reservoirs construction on the sediment load are analyzed, and the contribution of the above three factors to the sediment load entering the Poyang Lake is quantitatively evaluated. The results show that, during the period of 1956-2010,the average annual sediment discharge into Poyang Lake under the influence of climate,vegetation cover and reservoir construction reached 15.5 Mt, 20.8 Mt, 8.5 Mt, respectively;whereas, the sediment load entering the Poyang Lake under the combined- influence of the above three factors is 12.6 Mt a- 1. In addition, during the same period, the sediment load delivered to the Poyang Lake increased by 4.2 Mt a- 1due to water and soil erosion, and decreased by 8.2 Mt a- 1attributed to reservoir interception, which accounted for 32.4% and63.2% of the observed sediment load discharged into the Poyang Lake, respectively. From 1956 to 1989, the increased sediment load caused by water and soil erosion and the decreased sediment load induced by dam emplacement, in terms of both quantity of 5.1 Mt a- 1, is equivalent; However, during 1990- 2010, the sediment load resulting from water and soil loss decreased to 2.7 Mt a- 1, and that intercepted by reservoirs increased to 13.3 Mt a- 1, suggesting that the effect of reservoirs construction on the changes of sediment load entering the Poyang Lake is 5 times of that of water and soil erosion.

Channel evolution and hydrologic variations in the Colorado River basin: Factors influencing sediment and salt loads

With years of vegetation restoration and check dam construction on the Loess Plateau, the sediment load of the middle reaches of the Yellow River have decreased sharply; however, the effects of check dam on this decrease of sediment load with such extensive vegetation restoration remains unclear. In order to further clarify the effects of check dam on sediment load reduction under vegetation restoration, we calculated vegetation coverage and check dam index based on multi-source remote sensing data, and calculated sediment reduction rate caused by human activities by Mann-Kendall statistical test and double cumulative curve, then established regression equations incorporating the check dam index and the sediment reduction rate using data from different geomorphic regions with different vegetation coverages. The results showed that sediment load in the Hekou-Longmen region and its 17 tributaries decreased significantly every year, and the change in sediment load could be divided into 3 typical periods: the base period (P1), the period mainly impacted by check dam construction (P2) and the period with comprehensive impact of check dam construction and vegetation restoration (P3). Compared with sediment load of the tributaries during P1, the sediment load decreased by 60.96% during P2 and by 91.76% during P3. Compared with the contribution of human activities to the reduction in sediment load in P2, the contribution of human activities in P3 increased significantly, while that of precipitation decreased slightly. The sediment reduction effect of check dams is greater in basins with low vegetation coverage than in basins with high vegetation coverage. There are differences in sediment reduction effect of vegetation restorations in different geomorphic regions, and the effect of vegetation restoration alone have certain upper limits. Such as, the upper limit of sediment reduction rate of vegetation restoration for rivers flowing through the sandstorm region is 47.86%. Hence, only combined the construction of check dam with vegetation restoration can it achieve more significant sediment reduction benefit and control soil erosion more effectively.

Quantitative assessment of drivers of sediment load reduction in the Yangtze River basin, China

The abrupt reduction of the water discharge and sediment load in the Yellow River has attracted much attention during the past several decades. This paper investigates the temporal and spatial changes of annual sediment load and water discharge in the Weihe River basin, the largest tributary of the Yellow River, which contributes 40 % of the sediment and 26 % of the water to the Yellow River. The results suggest that sediment load and water discharge in the Weihe River basin from both mainstream and tributaries show significant decreasing trends (significance level of 0.05). The trends show the following three distinct stages: the fluctuating stage (1956–1969), the slowly decreasing stage (1970–1979) and the accelerated decreasing stage (1980–2010). Additionally, the water discharge decreases more quickly than sediment. Spatially, the greatest reduction in water discharge and sediment load occurs upstream of the river. Additionally, the decrease in water discharge and sediment load in the main stream is greater than in the tributary. The focal years of water discharge and sediment changes are the same for each station except for the Zhuangtou Station, which were approximately 1970 and during the 1990s. Human activities contribute much more to changes in the hydrological series, and the percentage of human activity impacts on the water discharge are much larger than the sediment load for most of the periods. The relationship between the average monthly water discharge and the sediment load shows a clockwise loop curve. The change points for the annual water discharge and the sediment load relationship occurred mainly in 1983 for most stations. The reduction in the water discharge and sediment load is caused mainly by human activities, especially soil and water conservation projects (such as afforestation, terraces, reservoirs and dams). In summary, the results in this study provide further evidence of the need for river basin management.

Scale-specific controls of monthly suspended sediment load in a typical inland river

Investigation of the variations in runoff, sediment load, and their dynamic relation is conducive to understanding hydrological regime changes and supporting channel regulation and fluvial management. This study is undertaken in the Xihanshui catchment, which is known for its high sediment‐laden in the Jialing River of the Yangtze River basin, southern China, to evaluate the change characteristics of runoff, sediment load, and their relationship at multi‐temporal scales from 1966 to 2016. The results showed that runoff changed significantly for more months, whereas the significant changes in monthly sediment load occurred from April to September. The contributions of runoff in summer and autumn and sediment load in summer to their annual value changes were greater. Annual runoff and sediment load in the Xihanshui catchment both exhibited significant decreasing trends (p < 0.05) with a significant mutation in 1993 (p < 0.05). The average annual runoff in the change period (1994–2016) decreased by 49.58% and annual sediment load displayed a substantial decline with a reduction of 77.77% in comparison with the reference period (1966–1993) due to climate change and intensive human activity. The power functions were satisfactory to describe annual and extreme monthly runoff–sediment relationships, whereas the monthly runoff–sediment relationship and extreme monthly sediment‐runoff relationship were changeable. Spatially, annual runoff–sediment relationship alteration could be partly attributed to sediment load changes in the upstream area and runoff variations in the downstream region. Three quantitative methods revealed that the main driver for significant reductions of annual runoff and sediment load is the human activity dominated by soil and water conservation measures, while climate change only contributed 22.73%–38.99% (mean 32.07%) to the total runoff reduction and 3.39%–35.56% (mean 17.32%) to the total decrease in sediment load.

Hydrological responses to the combined influence of diverse human activities in the Pearl River delta, China

An integrated multi-model approach to predict future land cover in the Da River Basin in Vietnam was developed to analyze future impacts of land cover change on streamflow and sediment load. The framework applied a land cover change model and an ecological model to forecast future land cover and leaf area index (LAI) based on the historical land cover change, and these data were then used in a calibrated distributed hydrological model and a new sediment rating curve model to assess hydrological changes and sediment load in the river basin. Results showed that deforestation would likely continue, and that forest area would decrease by up to 21.3% by 2050, while croplands and shrublands would replace forests and increase by over 11.7% and 10%, respectively. Streamflow and sediment load would generally increase due to deforestation in the Da River Basin in the 2050s, in both the wet and dry seasons, but especially in the wet season. In this case, the predicted annual sediment load was expected to increase by about 9.7% at the Lai Chau station. As deforestation increased, sediment load and reservoir siltation could likely shorten the lifespan of the recently constructed Son La Reservoir. The applied integrated modeling approach provides a comprehensive evaluation of land/forest cover change effects on the river discharge and sediment load, which is essential in understanding human impacts on the river environment and in designing watershed management policies.

Soil erosion and landslide triggered by heavy rainfall are serious problems that have threatened water resources in Taiwan watersheds. This study investigated the relationship among streamflow, sediment load, sediment concentration and typhoon characteristics (path and rainfall amount) during 2000–2017 for nine gauging stations in five basins (Tamshui River basin, Zhuoshui River basin, Zengwen River basin, Gaoping River basin, and Hualien River basin) representing the diverse geomorphologic conditions in Taiwan. The results showed that streamflow and sediment load were positively correlated, and the correlation was improved when the sediment load data were grouped by sediment concentration. Among these basins, the Zhuoshui River basin has the highest unit-discharge sediment load and unit-area sediment load. The soil in the upstream was more erodible than the downstream soil during the normal discharge conditions, indicating its unique geological characteristics and how typhoons magnified sediment export. The spatiotemporal variation in sediment loads from different watersheds was further categorized by typhoons of different paths. Although typhoon path types matter, the Zhuoshui and Hualien River basin were usually impacted by typhoons of any path type. The results indicated that sediment concentration, the watershed soil characteristics, and typhoons paths were the key factors for sediment loads. This study can be useful for developing strategies of soil and water conservation implementation for sustainable watershed management.