Doctoral Dissertation Research: The Development of a Framework for Quantifying Hydrologic Surface Connectivity of a Coastal River-Floodplain System

本博士论文研究项目将开发一个框架，用于分析河流与洪泛区之间的连接程度，考虑其水文条件，地貌模式和过程，以及洪泛区内的植被分布。河流及其洪泛区的生产性和多样性以及它们提供的生态系统服务在很大程度上受到河流-洪泛区连通性的影响，并取决于这种连通性。由于人类活动对地球仪的影响，河流-洪泛区连通性的损失已经得到了很好的记录，但由于缺乏量化洪泛区景观连通性的正式框架，量化这些损失变得复杂。该项目将开发一个框架，结合水文表面连通性的概念与图形/网络理论。这样一个框架将有助于推进对河流洪泛区过程的科学理解，因为它将始终如一地量化措施，并最终允许使用标准方法对这些系统进行分类和比较。此外，这种更标准的方法将在许多河流的环境流量政策的发展中找到有用的应用。 作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立的研究事业。图论已被广泛应用于水文学，地貌学和生态学领域，以表征景观系统内的连通性及其属性。这使得图论非常适合开发一个框架，用于表征河流洪泛区系统使用景观连通性的角度来看。本计画的两个目标是：（1）定量地确定四种方法在特定河流-洪泛区系统内水文面连通性的变化（形态分析，基于现场的直接测量，图像分析和数值模拟）通常用于分析水文表面连通性;以及（2）评估水文表面连通性指标系列之间的相似性和差异，并确定每种方法捕获河流景观系统第一个目标将通过应用图形理论措施量化景观连通性的水文表面连通性的估计确定使用现场数据，图像分析和建模技术。过去曾使用过这些方法，但并非一贯如此。 第二个目标将使用第一个目标的结果来解决，以便比较用于确定水文表面连通性的每种方法的连通性及其属性的估计值。连通性措施之间的相似性和差异将用于确定分析水文表面连通性的每种方法如何捕获河流洪泛区过程的各个方面。在得克萨斯州的使命河的案例研究将被用来开发这个框架，并确定其效用。

This doctoral dissertation research project will develop a framework for analyzing the degree of connection between a river and its floodplain considering its hydrologic conditions, geomorphic patterns and processes, and the distribution of vegetation within the floodplain. The productive and diverse nature of rivers and their floodplains and the ecosystem services they provide is greatly influenced by and dependent on river-floodplain connectivity. Losses in river-floodplain connectivity due to human impacts across the globe has been well documented, but quantifying these losses has been complicated by a lack of formal framework for quantifying landscape connectivity within floodplains. This project will develop a framework that combines the hydrologic surface connectivity concept with graph/network theory. Such a framework will help advance scientific understanding of river-floodplain processes as it will consistently quantify measures and ultimately permit these systems to be categorized and compared using a standard approach. Moreover, this more standard approach will find a useful application in the development of environmental flow policies for many rivers. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.Graph theory has been widely used within the fields of hydrology, geomorphology, and ecology to characterize connectivity and its attributes within landscape systems. This makes graph theory well-suited for the development of a framework for characterizing river-floodplain systems using a landscape connectivity perspective. The two objectives of this project are: (1) to quantitatively determine how hydrologic surface connectivity varies within a specific river-floodplain system for the four methods (morphometric analyses, field-based direct measurements, image analyses, and numerical modeling) commonly used to analyze hydrologic surface connectivity; and (2) to evaluate the similarities and differences amongst the family of hydrologic surface connectivity indicators and to determine the effectiveness with which each method captures attributes of the riverine landscape system. The first objective will be addressed by applying graph theoretical measures for quantifying landscape connectivity to estimates of hydrologic surface connectivity determined using field data, imagery analysis, and modelling techniques. These have been used in the past, but not consistently. The second objective will be addressed using results from the first objective in order to compare estimates of connectivity and its attributes for each approach used in determining hydrologic surface connectivity. The similarities and differences amongst the connectivity measures will be used to determine how well each method for analyzing hydrologic surface connectivity captures aspects of river-floodplain process. A case study of the Mission River in Texas will be used to develop this framework and determine its utility.