Collaborative Research: Modeling and monitoring of landscape evolution along a climate gradient: Kohala Peninsula, Hawaii

合作研究：沿气候梯度模拟和监测景观演化：夏威夷科哈拉半岛

• 批准号: 1024982
• 负责人: Joel Johnson
• 金额: $ 20.17万
• 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: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2015-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1024982&HistoricalAwards=false
• 关键词: Collaborative; Research; Modeling; monitoring; landscape

Climate, and more specifically rainfall, is amongst the most important forces that shape a landscape, yet quantifying the impacts of rainfall on landscape development remains a challenge. It is easy to see the differences between the topography in arid versus humid landscapes, but it is has proven difficult to quantify how physical processes such as soil development, surface and subsurface water flow, and hillslope and fluvial erosion, differ between these two environments. The Kohala Peninsula, on the northern tip of the Big Island of Hawaii, offers an excellent field environment to address this question. Across the approximately 20 km wide peninsula, rainfall rates very from upwards of 4,000 mm/year to less than 200 mm/year. Deeply incised gulches dominate the topography of the wet side of the peninsula, while on the dry side, shallow gulches disappear and reappear across the landscape. The wet side of the peninsula has developed deep soils and the process of weathering is so intense that a fingernail can scrape a groove in many rocks. In contrast, on the dry side, surface soils are often shallow and rocky and exposed rock surfaces are much less weathered. This project will quantify the differences in hydrologic and erosion processes on the contrasting sides on the peninsula using both field monitoring and numerical modeling. Two watersheds, one on the dry side and one on the wet side, will be equipped with devices to measure rainfall rates, water flow depths on both the hillslopes and in the gulches, soil moisture content, and erosion rates. These devices will operate continually throughout the duration of the project. Field surveys will provide detailed observations of the geometry of the gulches and the variables that control incision rates, such as sediment grain size, rock hardness, and degree of fracturing. These data will be incorporated into a numerical landscape evolution model. The model will be used to systematically explore feedbacks between key climatic controls and surface process responses over the time scales at which landscapes evolve. Field data will be used to both constrain physical processes in the model and inspire the specific modeling scenarios.This project will address a fundamental scientific question of how rainfall patterns actually influence the processes of weathering and erosion. Rainfall gradients are present across almost every mountain range on Earth and the findings from this study will have broad significance beyond the Hawaiian Islands. Knowledge of the detailed interactions among climate, hydrology, and erosion can be applied to landscapes across the planet. Furthermore, by quantifying links between landscape development and rainfall, the effects of potential climate change on landscape evolution can be predicted more effectively. This project will develop a number of numerical models that will be freely available for use throughout the scientific community, so that the findings from this study can be easily applied in other settings and to a wide range of scientific questions.

气候，更具体地说是降雨，是塑造景观的最重要力量之一，但量化降雨对景观发展的影响仍然是一个挑战。 很容易看出干旱和潮湿景观之间的地形差异，但事实证明很难量化这两种环境之间的物理过程（例如土壤发育、地表和地下水流、山坡和河流侵蚀）之间的差异。 位于夏威夷大岛北端的柯哈拉半岛为解决这个问题提供了极好的现场环境。 在大约 20 公里宽的半岛上，降雨量从每年 4,000 毫米到每年不到 200 毫米不等。 半岛湿润一侧的地形主要是深切的峡谷，而在干燥的一侧，浅浅的峡谷消失并重新出现在地貌中。 半岛潮湿的一面已经形成了深厚的土壤，风化过程非常剧烈，指甲可以在许多岩石上刮出凹槽。 相比之下，在干燥的一面，表层土壤通常很浅，多岩石，暴露的岩石表面风化程度要低得多。 该项目将利用现场监测和数值模拟来量化半岛两侧水文和侵蚀过程的差异。 两个流域，一个在干燥一侧，一个在潮湿一侧，将配备测量降雨率、山坡和峡谷水流深度、土壤湿度和侵蚀率的装置。 这些设备将在整个项目期间持续运行。 现场调查将提供对峡谷几何形状和控制切割率的变量的详细观察，例如沉积物粒度、岩石硬度和破裂程度。 这些数据将被纳入数值景观演化模型中。 该模型将用于系统地探索景观演变的时间尺度上关键气候控制和地表过程响应之间的反馈。 现场数据将用于约束模型中的物理过程并激发特定的建模场景。该项目将解决降雨模式如何实际影响风化和侵蚀过程的基本科学问题。 地球上几乎每一个山脉都存在降雨梯度，这项研究的结果将在夏威夷群岛之外具有广泛的意义。 关于气候、水文和侵蚀之间详细相互作用的知识可以应用于全球各地的景观。 此外，通过量化景观发展与降雨之间的联系，可以更有效地预测潜在气候变化对景观演变的影响。 该项目将开发许多数值模型，供整个科学界免费使用，以便本研究的结果可以轻松应用于其他环境和广泛的科学问题。