CMG Collaborative Research: Envirodynamics on River Networks

CMG 合作研究：河网环境动力学

• 批准号: 0934426
• 负责人: Michael Ghil
• 金额: $ 15.13万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0934426&HistoricalAwards=false
• 关键词: CMG; Collaborative; Research; Envirodynamics; River

The topology of river networks has been extensively studied over the past decades using the suite of quantitative methods developed in the pioneering works of Horton, Strahler, Shreve, and Tokunaga. As a result, stream-ordering schemes and statistical self-similarity concepts have been explored to a considerable extent in hydrologic and geomorphologic sciences and have penetrated other areas of natural sciences. At the same time, questions related to how the static topology of a river network affects the dynamical processes operating on this network have been studied to a considerably lesser degree, while the impact of such processes is of the greatest interest from environmental, economic, and societal points of view. This project maintains a sustained research effort focused on environmental transport along river networks, in particular, and dynamic processes on hierarchical branching structures, in general. The main goal is to develop a theoretical and modeling framework that will facilitate predictive understanding of the relationships between the geometry of a network and dynamic processes that operate on it. The analytic methods to be developed and applied in the project arise from the theories of hierarchical aggregation and complex networks. The proposed transport modeling is based on the mathematical theory of Boolean delay equations (BDEs), a framework especially tailored for the mathematical modeling of systems that exhibit thresholds, multiple feedbacks and distinct time delays. The BDE modeling will provide a flexible basis for a preliminary assessment of land-use and climate change effects on resource attributes of a river system, including sediment grain size distribution, algae production and transport, nutrient loading, and fish population. It will also constitute a simple ?platform? for testing hypotheses and guiding further data collection efforts for improved prediction under uncertainty. The project will adapt concepts and tools from other disciplines, mainly dynamical and complex systems, to earth-surface research. The proposed study opens a new direction in earth-surface modeling, focused on environmental transport on river networks. The intellectual merit of this project resides in the novel mathematical, modeling, and data exploration approaches, put forward by an interdisciplinary team toward predictive understanding of environmental dynamics on river networks. The critical societal and economic importance of network dynamic problems? in the geosciences and other areas of the physical and life sciences?adds substantially to the proposal?s intellectual merit. The project will result in better predictive understanding of environmental fluxes including precipitation, sediment bedload, nutrients, pollutants, etc., and provide new insight into rivers? habitat structure and food webs. The project will impact other science areas that involve network dynamics and hierarchical aggregation, including gene interactions, social networks, spread of diseases, and Internet security. The new results will be achieved by further developing a novel theoretical concept of dynamic networks, integrating this concept into concrete applications, and developing corresponding numerical models. The project PIs are actively involved in promoting interactions between mathematicians, physicists and researchers in geosciences and will further strengthen such interactions within this project. The collaborative and cross-disciplinary approach of this project makes it an ideal training ground for graduate students, post-docs and young scientists.

在过去的几十年里，人们利用霍顿、斯特拉勒、什里夫和德永的开创性著作中开发的一套定量方法对河流网络的拓扑结构进行了广泛的研究。因此，流序方案和统计自相似性概念在水文和地貌科学中得到了相当大的探索，并渗透到自然科学的其他领域。与此同时，与河流网络的静态拓扑如何影响该网络上运行的动态过程有关的问题的研究程度要小得多，而从环境、经济和社会的角度来看，这些过程的影响是最令人感兴趣的。该项目持续开展研究工作，重点关注河流网络沿线的环境传输，特别是分层分支结构的动态过程。主要目标是开发一个理论和建模框架，以促进对网络几何形状与在其上运行的动态过程之间的关系的预测性理解。该项目中要开发和应用的分析方法源于层次聚合和复杂网络的理论。所提出的传输建模基于布尔延迟方程（BDE）的数学理论，这是一个专门为具有阈值、多个反馈和不同时间延迟的系统的数学建模而定制的框架。 BDE 模型将为初步评估土地利用和气候变化对河流系统资源属性（包括沉积物粒度分布、藻类生产和运输、养分负荷和鱼类种群）的影响提供灵活的基础。它还将构成一个简单的“平台”？用于测试假设并指导进一步的数据收集工作，以改进不确定性下的预测。该项目将把其他学科（主要是动力系统和复杂系统）的概念和工具应用到地球表面研究中。这项研究开辟了地表建模的新方向，重点关注河流网络上的环境传输。该项目的智力价值在于新颖的数学、建模和数据探索方法，由跨学科团队提出，旨在预测性了解河流网络的环境动态。网络动态问题的社会和经济重要性如何？在地球科学以及物理和生命科学的其他领域，大大增加了该提案的智力价值。该项目将更好地预测环境通量，包括降水、沉积物、营养物、污染物等，并提供对河流的新见解？栖息地结构和食物网。该项目将影响涉及网络动态和层次聚合的其他科学领域，包括基因相互作用、社交网络、疾病传播和互联网安全。新的成果将通过进一步发展动态网络的新理论概念，将该概念融入具体应用，并开发相应的数值模型来实现。该项目的 PI 积极参与促进数学家、物理学家和地球科学研究人员之间的互动，并将进一步加强该项目内的这种互动。该项目的协作和跨学科方法使其成为研究生、博士后和年轻科学家的理想培训基地。