Collaborative Research: Sea-level Rise and Vegetation Controls on Deltaic Landform Evolution: A Coupled Experimental and Numerical Modeling Study

合作研究：海平面上升和植被对三角洲地貌演化的控制：实验与数值模拟的耦合研究

• 批准号: 1324335
• 负责人: Wonsuck Kim
• 金额: $ 26.37万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1324335&HistoricalAwards=false
• 关键词: Collaborative; Research; Sea; level; Rise

Deltas are home for 25% of the human population (Syvitski et al., 2005). Across the world, combinations of changes in sea-level-rise rates, land use changes in the watersheds the feed deltas, and human activities on deltas themselves are causing rapid changes to delta landscapes and loss of valuable habitats and ecosystem services. Science for predicting changes in delta landscapes, ecosystems, and coastlines is now urgently required to successfully evaluate and implement plans to improve sustainability for deltas globally. However, changes on deltas are controlled by an array of interactions between coastal rivers, plants and animals, hurricanes and storms, and a range of human manipulations. The proposed study will enhance our understanding of, and ability to predict how deltas will respond to changes in climate and land-use forcing, focusing on both physical and biological aspects of delta systems using laboratory flume and computational experiments.Physical delta experiments will be conducted in the University of Texas (UT) Sediment Transport and Earth-surface Processes (STEP) basin, which allows for independent and precise controls of the major geological factors: sediment supply and relative sea level rise (RSLR). These experiments will also be the first to investigate interactions between physical and biological processes in shaping deltas. Experiments will involve seeding the delta surface with small plants (Alfalfa) at different spatial densities. The ecosystem is simplified in the experiments but still naturally coevolving with a growing and self-organizing fluviodeltaic system. Computational modeling efforts, based on the results of the physical experiments, will produce a reduced complexity model that captures the main eco-morphodynamic feedbacks under rapid relative sea-level rise over engineering and geological time scales. The resulting computational models will provide a platform for experiments addressing the ecomorphodynamic evolution of a range of delta types, under disparate sets of forcing (e.g. river vs. wave dominated) and under various scenarios of land-use and climate changes. The scientific insights to be gained through the coupled laboratory experiments and computational modeling include: 1) the fluviodeltaic system's response to RSLR, in particular, changes in avulsion (flood) frequency and shoreline roughness, 2) the self-organization of the deltaic distributary channel network that coevolves with vegetation, 3) the effects of spatial variation in vegetation density on channel avulsion location and frequency, and 4) how the feedbacks from vegetation dynamics during rapid RSLR affect deltaic landforms and resulting stratigraphy. This work will produce the first quantitative eco-morphodynamic model based on controlled laboratory experiments, allowing exploration of future changes in fluviodeltaic landscapes, channel activity, and vulnerability for a range of delta types and RSLR rates.

三角洲是25%人口的家园（Syvitski et al., 2005）。在世界范围内，海平面上升速度的变化、流域和饲料三角洲的土地利用变化以及三角洲本身的人类活动正在导致三角洲景观的快速变化，以及宝贵栖息地和生态系统服务的丧失。现在迫切需要预测三角洲景观、生态系统和海岸线变化的科学，以成功评估和实施改善全球三角洲可持续性的计划。然而，三角洲的变化是由沿海河流、植物和动物、飓风和风暴以及一系列人类操纵之间的一系列相互作用控制的。这项拟议的研究将增强我们对三角洲如何响应气候变化和土地利用强迫的理解和能力，重点关注三角洲系统的物理和生物方面，使用实验室水槽和计算实验。物理三角洲实验将在德克萨斯大学（UT）沉积物运输和地表过程（STEP）盆地进行，该盆地允许独立和精确地控制主要地质因素：沉积物供应和相对海平面上升（RSLR）。这些实验也将首次研究形成三角洲的物理和生物过程之间的相互作用。实验将包括在三角洲表面播种不同空间密度的小型植物（苜蓿）。在实验中，生态系统被简化了，但仍然与一个不断增长和自组织的河流三角洲系统自然地共同进化。基于物理实验结果的计算建模工作将产生一个降低复杂性的模型，该模型可以捕获工程和地质时间尺度上海平面相对快速上升下的主要生态形态动力学反馈。由此产生的计算模型将为实验提供一个平台，以解决在不同强迫（例如河流与波浪主导）和各种土地利用和气候变化情景下一系列三角洲类型的生态形态动力学演变。通过耦合实验室实验和计算建模获得的科学见解包括：1)河流三角洲系统对RSLR的响应，特别是崩裂（洪水）频率和岸线粗糙度的变化；2)与植被共同进化的三角洲分流河道网络的自组织；3)植被密度的空间变化对河道崩裂位置和频率的影响；4)快速RSLR期间植被动态的反馈如何影响三角洲地貌和由此产生的地层。这项工作将产生第一个基于受控实验室实验的定量生态形态动力学模型，允许探索河流三角洲景观的未来变化，通道活动，以及一系列三角洲类型和RSLR率的脆弱性。