Rivers often witness non-uniform bed load sedim ent transport. For a long tim e, non-uniform bed load transport has been assum ed to be at capacity regime determined exclusively by local flow. Yet whether the capacity...Rivers often witness non-uniform bed load sedim ent transport. For a long tim e, non-uniform bed load transport has been assum ed to be at capacity regime determined exclusively by local flow. Yet whether the capacity assumption for non-uniform bed load transport is justified remains poorly understood. Here, the relative time scale of non-uniform bed load transport is evaluated and non-capacity and capacity models are compared for both aggradation and degradation cases with observed data. As characterized by its relative time scale, the adaptation of non-uniform bed load to capacity regime should be fulfilled quickly. However, changes in the flow and sedim ent inputs from upstream or tributaries hinder the adaptation. Also, the adaptation to capacity regime is size dependent, the finer the sediment size the slower the adaptation is, and vice versa. It is shown that the capacity model may entail considerable errors compared to the non-capacity model. For modelling of non-uniform bed load, non-capacity modelling is recommended, in which the temporal and spatial scales required for adaptation are explicitly appreciated.展开更多
Numerical modelling of coastal morphology is a complex and sometimes unrewarding exercise and often not yielding tangible results. Typically, the underlying drivers of morphology are not properly accounted for in nume...Numerical modelling of coastal morphology is a complex and sometimes unrewarding exercise and often not yielding tangible results. Typically, the underlying drivers of morphology are not properly accounted for in numerical models. Such inaccuracies combined with a paucity of validation data create a difficulty for coastal planners/engineers who are required to interpret such morphological models to develop coastal management strategies. This study develops an approach to long term morphological modelling of a barrier beach system that includes the findings of over 10 years of coastal monitoring on a dynamic coastal system. The novel approach to predicting the long term evolution of the area combines a mix of short term hydrodynamic monitoring and long term morphological modelling to predict future changes in a breached barrier system. A coupled wave, wind, hydrodynamic and sediment transport numerical model was used to predict the coastal evolution in the dynamic barrier beach system of Inner Dingle Bay, Co. Kerry, Ireland. The modelling approach utilizes the schematisation of inputs to reflect observed trends. The approach is subject to two stages of validation both quantitative and qualitative. The study highlights the importance of considering all the parameters responsible for driving coastal evolution and the necessity to have long term monitoring results for trend based validation.展开更多
基于Web of Science数据库搜索关键词“波浪—海滩—沙丘相互作用”,筛分出与主题紧密相关的文献近百篇并对其梳理与分析,将研究阶段与理论模式进行划分,厘清当前研究存在的问题与机遇。结果发现,波浪—海滩—沙丘相互作用研究自1980s...基于Web of Science数据库搜索关键词“波浪—海滩—沙丘相互作用”,筛分出与主题紧密相关的文献近百篇并对其梳理与分析,将研究阶段与理论模式进行划分,厘清当前研究存在的问题与机遇。结果发现,波浪—海滩—沙丘相互作用研究自1980s以来经历了理论提出、区域拓展、深入研究3个发展阶段。理论模式从单一的概念模式发展为不同尺度概念下的相互作用理论模式,研究方法从单一的野外测绘和海图测深资料发展到野外实地观测、室内风洞试验、3S技术与数值模拟相结合的综合研究方法;研究区域,从澳大利亚东南部海岸扩展到欧洲、北美洲、南美洲和亚洲等地海岸。同时,波浪—海滩—沙丘相互作用研究中也存在一些尚未解决的问题:针对不同区域的海岸沙丘动力地貌系统难以总结出一个具有普适应的理论模式;微观尺度内,已有的理论内容难以完全的揭示波浪、潮汐水动力与碎波带/海滩和风动力与海滩—沙丘地貌之间的复杂相互作用机理;中观尺度内,整个碎波带、海滩与沙丘系统对风暴的响应与反馈机理还需要进一步观测与深入研究,且建立事件尺度内的动力与地貌响应过程和中期地貌形态变化之间的联系还需要更长时期的实地观测与模型改进;宏观尺度内,海平面抬升引起海岸变化的预测模型需要多时空的实地观测数据支持与验证。未来可结合历史资料、实地观测数据、高分辨率遥感影像数据,综合分析各环境要素与碎波带、海滩、沙丘地形地貌之间的动力过程与形态响应关系,采用数值模拟技术揭示不同时空尺度的波浪—海滩—沙丘相互作用关系机理,进一步完善波浪—海滩—沙丘相互作用理论内容。展开更多
细沟水流的输沙能力是土壤侵蚀的重要参数之一,对于土壤侵蚀预报和土壤侵蚀过程模拟尤为重要。在不考虑土壤团粒结构条件下,根据集中稳定水流条件下侵蚀产沙随沟长增加而增加并将最终趋近于水流输沙能力的事实,提出了通过改变沟长来量...细沟水流的输沙能力是土壤侵蚀的重要参数之一,对于土壤侵蚀预报和土壤侵蚀过程模拟尤为重要。在不考虑土壤团粒结构条件下,根据集中稳定水流条件下侵蚀产沙随沟长增加而增加并将最终趋近于水流输沙能力的事实,提出了通过改变沟长来量测水流输沙能力的实验室水槽测量方法。相应地提出了根据试验数据计算水流输沙能力的函数表达式。用一种粉粘（黄土）土壤,进行了一系列（405次）室内水槽摹拟试验。采用五种坡度（5°,10°,15°,20°,25°）、三个流量（2,4,8 L min-1）的细沟侵蚀产沙数据,分析了输沙能力与沟坡、入流量的相互关系。展开更多
基金funded by the N atural Science Foundation of China (G rants No. 11172217, 51279144 and 11432015)Chinese Academy of Sciences (G rant No. KZZDEW -05-01-03)
文摘Rivers often witness non-uniform bed load sedim ent transport. For a long tim e, non-uniform bed load transport has been assum ed to be at capacity regime determined exclusively by local flow. Yet whether the capacity assumption for non-uniform bed load transport is justified remains poorly understood. Here, the relative time scale of non-uniform bed load transport is evaluated and non-capacity and capacity models are compared for both aggradation and degradation cases with observed data. As characterized by its relative time scale, the adaptation of non-uniform bed load to capacity regime should be fulfilled quickly. However, changes in the flow and sedim ent inputs from upstream or tributaries hinder the adaptation. Also, the adaptation to capacity regime is size dependent, the finer the sediment size the slower the adaptation is, and vice versa. It is shown that the capacity model may entail considerable errors compared to the non-capacity model. For modelling of non-uniform bed load, non-capacity modelling is recommended, in which the temporal and spatial scales required for adaptation are explicitly appreciated.
文摘Numerical modelling of coastal morphology is a complex and sometimes unrewarding exercise and often not yielding tangible results. Typically, the underlying drivers of morphology are not properly accounted for in numerical models. Such inaccuracies combined with a paucity of validation data create a difficulty for coastal planners/engineers who are required to interpret such morphological models to develop coastal management strategies. This study develops an approach to long term morphological modelling of a barrier beach system that includes the findings of over 10 years of coastal monitoring on a dynamic coastal system. The novel approach to predicting the long term evolution of the area combines a mix of short term hydrodynamic monitoring and long term morphological modelling to predict future changes in a breached barrier system. A coupled wave, wind, hydrodynamic and sediment transport numerical model was used to predict the coastal evolution in the dynamic barrier beach system of Inner Dingle Bay, Co. Kerry, Ireland. The modelling approach utilizes the schematisation of inputs to reflect observed trends. The approach is subject to two stages of validation both quantitative and qualitative. The study highlights the importance of considering all the parameters responsible for driving coastal evolution and the necessity to have long term monitoring results for trend based validation.
文摘基于Web of Science数据库搜索关键词“波浪—海滩—沙丘相互作用”,筛分出与主题紧密相关的文献近百篇并对其梳理与分析,将研究阶段与理论模式进行划分,厘清当前研究存在的问题与机遇。结果发现,波浪—海滩—沙丘相互作用研究自1980s以来经历了理论提出、区域拓展、深入研究3个发展阶段。理论模式从单一的概念模式发展为不同尺度概念下的相互作用理论模式,研究方法从单一的野外测绘和海图测深资料发展到野外实地观测、室内风洞试验、3S技术与数值模拟相结合的综合研究方法;研究区域,从澳大利亚东南部海岸扩展到欧洲、北美洲、南美洲和亚洲等地海岸。同时,波浪—海滩—沙丘相互作用研究中也存在一些尚未解决的问题:针对不同区域的海岸沙丘动力地貌系统难以总结出一个具有普适应的理论模式;微观尺度内,已有的理论内容难以完全的揭示波浪、潮汐水动力与碎波带/海滩和风动力与海滩—沙丘地貌之间的复杂相互作用机理;中观尺度内,整个碎波带、海滩与沙丘系统对风暴的响应与反馈机理还需要进一步观测与深入研究,且建立事件尺度内的动力与地貌响应过程和中期地貌形态变化之间的联系还需要更长时期的实地观测与模型改进;宏观尺度内,海平面抬升引起海岸变化的预测模型需要多时空的实地观测数据支持与验证。未来可结合历史资料、实地观测数据、高分辨率遥感影像数据,综合分析各环境要素与碎波带、海滩、沙丘地形地貌之间的动力过程与形态响应关系,采用数值模拟技术揭示不同时空尺度的波浪—海滩—沙丘相互作用关系机理,进一步完善波浪—海滩—沙丘相互作用理论内容。
文摘细沟水流的输沙能力是土壤侵蚀的重要参数之一,对于土壤侵蚀预报和土壤侵蚀过程模拟尤为重要。在不考虑土壤团粒结构条件下,根据集中稳定水流条件下侵蚀产沙随沟长增加而增加并将最终趋近于水流输沙能力的事实,提出了通过改变沟长来量测水流输沙能力的实验室水槽测量方法。相应地提出了根据试验数据计算水流输沙能力的函数表达式。用一种粉粘（黄土）土壤,进行了一系列（405次）室内水槽摹拟试验。采用五种坡度（5°,10°,15°,20°,25°）、三个流量（2,4,8 L min-1）的细沟侵蚀产沙数据,分析了输沙能力与沟坡、入流量的相互关系。
