Collaborative Research: Biophysical alteration of wetland geomorphology in response to rising sea level

合作研究：湿地地貌因海平面上升而发生的生物物理变化

• 批准号: 1130808
• 负责人: Steven Pennings
• 金额: $ 15.88万
• 依托单位: University of Houston
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-15 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1130808&HistoricalAwards=false
• 关键词: Collaborative; Research; Biophysical; alteration; wetland

Collaborative Research: Biophysical alteration of wetland geomorphology inresponse to rising sea levelOur objective is to examine the evolution of networks of tidal creeks in salt marshes asthey respond to rising sea level. We have documented rapidly growing creeks, incising into themarsh at 1-2 m per year, in coastal marshes throughout the South Atlantic Bight and in similarenvironments worldwide. Understanding the mechanisms driving the evolution of these drainagenetworks is crucial for predicting marsh responses to sea level rise under different conditions.The study will examine the physics of tidal flows and sediment erosion, while also consideringthe significant impact of marsh plants and animals (e.g. crabs) on these processes. Using acombination of field measurements, mesocosm experiments, and numerical modeling, we will 1)evaluate the physical mechanisms underlying sediment erosion in creeks, including variation inflow speed and processes changing the strength of the marsh soils, 2) test the hypotheses thatcrabs facilitate growth of creeks by loosening sediment through burrowing and removingstabilizing vegetation; and that hydrological conditions at creek heads are preferred by crabs, and3) develop a numerical model of creek evolution to test the importance of different parameterssuch as vegetation type, faunal density, tidal range and sediment supply on the morphologicalevolution of creeks. The model will help us to integrate our observations and generalize ourfindings over a range of conditions.Salt marshes provide valuable ecosystem services to humanity, but these productive habitats arethreatened globally by accelerating sea-level rise. Understanding the impact of sea-level rise onthe physical structure of a marsh is crucial to predicting both the response of marsh ecosystemsand the larger-scale morphological response of the coastline. The impact of increasing waterlevels on marshes depends on complex feedbacks between physical and biological processes.Initial studies of this issue focused on interactions between water depth and marsh elevation,which affect sediment deposition and plant growth. Recently, increasing attention is beingdirected towards the manner in which creek networks evolve as they respond to the largervolume of water they must convey during each tidal cycle at higher sea levels. The evolution ofcreek networks is a critical component of marsh response to sea-level rise, because creekmorphology affects the amount of water and sediment delivered to the marsh surface, and thedrainage of the marsh, and thus, the length of time the marsh is waterlogged. In turn, the floodingand drainage of the marsh influences the health of plants and animals in this ecologically vitalenvironment. The ability of creek networks to respond to increasing sea levels depends, in part,on how easy it is to erode the marsh surface, which depends on both sediment type, and onstabilization or loosening associated with flora and fauna. Uncovering the linkages betweengeology and biology will have bearing on the fields of geology, ecology and climatology, as wellas those interested in coastal protection and salt marsh evolution. The project will develop a newmodeling tool to examine response of marshes to sea-level rise, which will be broadly applicableto many salt marshes in the U.S. and globally.

协作研究：湿地地貌学对海平面升高目标的生物物理改变是检查盐沼泽中潮汐小溪网络的演变，他们对海平面的上升做出了反应。我们已经记录了迅速生长的小溪，每年以1-2 m的速度将其切入Themarsh，在整个南大西洋野事和全球类似环境中的沿海沼泽中。了解推动这些排水材料发展的机制对于预测在不同条件下对海洋水平上升的反应至关重要。该研究将检查潮汐流和沉积物侵蚀的物理学，同时也考虑了沼泽植物和动物的重大影响（例如，蟹肉）在这些过程中。使用现场测量，中验实验和数值建模的结合，我们将1）评估小溪中沉积物侵蚀的物理机制，包括变化流入速度和改变马什土壤强度的过程，2）测试该假设促进crabs促进生长的生长通过挖掘和去除植被，通过松动沉积物来散发小溪；螃蟹和3）开发了小溪进化的数值模型，以测试不同参数的重要性，以植被类型，动物密度，潮汐范围和沉积物供应对溪流的形态进化，以测试不同参数的重要性。该模型将帮助我们整合观察结果并在各种条件下概括我们的发现。盐沼泽为人类提供了宝贵的生态系统服务，但是这些生产性栖息地通过加速海平面上升而在全球范围内进行。了解海平面上升对沼泽物理结构的影响对于预测沼泽生态系统的反应和海岸线的较大形态反应至关重要。水平增加对沼泽的影响取决于物理和生物过程之间的复杂反馈。对该问题的生物研究集中在水深和沼泽高度之间的相互作用，这影响了沉积物沉积和植物生长。最近，越来越多的关注正在指向溪流网络在响应更大的潮汐周期中必须传达的较大水量时的溪流发展方式。 Creek网络的进化是沼泽对海平面上升的反应的关键组成部分，因为溪流学会影响沼泽表面的水和沉积物的量，以及沼泽的特征，因此，沼泽的时间长度是水槽。反过来，沼泽的洪水和排水会影响这种生态性活力环境中动植物的健康。小溪网络对海平面响应的响应的能力部分取决于侵蚀沼泽表面的容易性，这既取决于沉积物类型，又取决于与动植物相关的史坦型或松散。揭示地质学与生物学之间的联系将与地质，生态和气候学领域以及对沿海保护和盐沼演化感兴趣的人有关。该项目将开发一种新模型工具来检查沼泽对海平面上升的反应，这将在美国和全球广泛地应用许多盐沼。