Collaborative Research: Investigating Human and Climate Influences on Delta Evolution Using Fluvial Discharge and Coastal Evolution Models

合作研究：利用河流流量和海岸演化模型研究人类和气候对三角洲演化的影响

• 批准号: 0952116
• 负责人: Albert Kettner
• 金额: $ 8.08万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-01-15 至 2013-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0952116&HistoricalAwards=false
• 关键词: Collaborative; Research; Investigating; Human; Climate

Influenced by both terrestrial and marine processes, deltas are critical sedimentary landforms at the land-sea interface that provide records of past environmental changes. Deltas worldwide are currently being severely altered by human activities, in particular river damming, which has reduced the amount of sediment reaching the coast. Although large dams are relatively recent phenomena, human alteration of landscapes has been ongoing since the advent and expansion of agriculture. Combining field data collection, fluvial modeling, and coastal evolution modeling, this research will examine whether human activities have significantly influenced the formation of the modern Ebro Delta, on the Mediterranean coast of Spain. Specifically, it is hypothersized that the growth of the Ebro Delta can be attributed to massive deforestation for agricultural purposes initiated in Roman times. Field research will document the evolution of the Ebro Delta over approximately the last 3,000 years by collecting and analyzing sediment cores from along the delta plain. The climate-driven hydrological model HydroTrend will be used to compute riverine sediment discharge to the coast over this time period, incorporating changes to sediment delivery that could be attributable to climatic changes and those that could be caused by human alterations to the Ebro River watershed. A numerical model of shoreline evolution capable of incorporating long timescales will be applied to examine the causes of the delta's shape and to evaluate how changes to riverine discharge would affect the coast after being reworked by waves. Coupling of the fluvial and coastal numerical models serves an important goal as proof-of-concept of the Community Surface Dynamics Modeling System (CSDMS).Understanding the historic and future morphologic change of deltas has become increasingly important as sea levels rise and sediment loads feeding deltas continue to be sequestered behind dams in the hinterland. Deltas are often densely populated and provide many importantt natural resources to society, particularly along the rocky Spanish Mediterranean coast with scant land near sea level. In regions that have been affected by human civilization, deltas can serve as a record of climate and land-use changes across large watersheds. The Ebro Delta, Spain, with its distinctive plan-view shape, has experienced significant morphologic changes over the last two millennia; changes that may be attributable to human activities in the Ebro watershed. The results of this research will have wide applicability to unraveling the history of deltas worldwide (e.g., Nile, Po, Danube, Indus, Mississippi). If human activities are largely responsible for the shape of the world's deltas, this would provide an important context for understanding how humankind will manage these resources over the coming centuries, particularly as climate changes and humans continue to alter these landforms.

受陆地和海洋过程的影响，三角洲是海陆界面上的重要沉积地貌，提供了过去环境变化的记录。目前，世界各地的三角洲正在被人类活动严重改变，特别是河流筑坝，这减少了到达海岸的泥沙数量。虽然大型水坝是相对较新的现象，但自从农业的出现和扩张以来，人类对景观的改变一直在进行。结合野外数据收集、河流模拟和海岸演变模拟，这项研究将检验人类活动是否对西班牙地中海沿岸现代埃布罗三角洲的形成产生了重大影响。具体地说，假设埃布罗三角洲的增长可以归因于罗马时代开始的以农业为目的的大规模砍伐森林。实地研究将通过收集和分析沿三角洲平原的沉积岩芯来记录埃布罗三角洲在大约过去3000年的演变。气候驱动的水文模型水文趋势将被用来计算这段时间内流向沿海的河流泥沙流量，其中包括可归因于气候变化的泥沙输送变化以及人类对埃布罗河流域的改变可能造成的泥沙输送变化。一个能够包含长时间尺度的海岸线演变的数值模型将被用于研究三角洲形状的原因，并评估河流流量的变化在被海浪改造后将如何影响海岸。河流和海岸数值模式的耦合是社区表面动力学模拟系统(CSDMS)的一个重要目标。随着海平面的上升和三角洲的泥沙负荷继续被隔离在腹地的大坝后面，了解三角洲的历史和未来的形态变化变得越来越重要。三角洲往往人口稠密，为社会提供了许多重要的自然资源，特别是沿着靠近海平面的土地稀少的多岩石的西班牙地中海海岸。在受人类文明影响的地区，三角洲可以作为大流域气候和土地利用变化的记录。西班牙的埃布罗三角洲，以其独特的平面图形状，在过去的两千年里经历了显著的地貌变化；这些变化可能归因于埃布罗分水岭的人类活动。这一研究成果将对揭示世界范围内的三角洲(如尼罗河、波河、多瑙河、印度河、密西西比河)的历史具有广泛的适用性。如果人类活动对世界三角洲的形成负有主要责任，这将为理解人类在未来几个世纪将如何管理这些资源提供重要的背景，特别是在气候变化和人类继续改变这些地貌的情况下。