Seeing the forest for the trees: Interpreting and quantifying emergent catchment hydrology behavior

描述山区集水区水文响应的主要控制因素的统一理论仍然令水文学家难以理解，尽管在定量建模和过程理解方面取得了有价值的进展，从陆面流到贯通流，再到变量源区动力学。这可能归因于自然系统近乎无限的复杂性，我们无法在空间和时间上充分衡量必要的变量，以及难以量化非线性流域过程和阈值调节的径流产生。我们承认到目前为止在集水过程理解和建模方面取得的进展，并参与了一些活动，重点是扩大我们的系统行为理解的限制，以及开发混合概念(数学)模型，并通过综合过程观察进行内部验证和测试。我们正在蒙大拿州中部小带山脉的TenderFoot Creek实验森林(TCEF)反复进行一系列经验和模型研究，跨越七个相邻的不同流域和五年多不同的气候强迫。1)景观结构(形状)在源头、山区集水区、水文响应和源水贡献中的作用是什么？后续：结构的相对重要性是否会在不同的强迫变量(气候变异性)之间发生变化？2)我们能否基于景观结构在流域响应中的作用的假设，开发新的流域行为量化(模型)？后续：现场观测如何帮助推断特定的模型结构和参数，并限制预测的不确定性？3)基于景观结构的流域模型的有效性是否在多个流域或在不同的气候强迫下有所不同？后续：我们如何比较新模型概念化与基于地形控制、可变源区概念或简单水平衡表示的传统模型的可转移性？为了应对这些挑战，我们正在努力为研究和教育建立工具和基础设施。我们侧重于对流域科学至关重要的主题，以通过新的过程概念化和模型结构来提高流域理解的可转移性和流域响应的可预测性。

A unifying theory describing primary controls on mountain catchment hydrologic response continues to elude hydrologists despite valuable advances in quantitative modeling and process understanding from overland flow, to throughflow, to variables source area dynamics. This may be attributed to the near infinite complexities of natural systems, our inability to measure necessary variables adequately in space and time, and difficulties in quantifying non-linear watershed processes and threshold mediated runoff generation. We acknowledge the advances to date in catchment process understanding and modeling and are engaged in activities focused on both expanding the limits of our system behavior understanding and developing hybrid conceptual (mathematical) models internally validated and tested with synthesized process observations. We are conducting a suite of empirical and modeling studies performed iteratively at the Tenderfoot Creek Experimental Forest (TCEF) in the Little Belt Mountains of central Montana, across seven adjacent diverse watersheds and more than five years of variable climatic forcings. We specifically address the following challenges in catchment hydrology:1) What is the role of landscape structure (shape) in headwater mountain catchment hydrologic response and source water contributions? Follow-on: Does the relative importance of structure change across variable forcing (climatic variability)?2) Can we develop new quantifications (models) of watershed behavior based on hypotheses about the role of landscape structure in watershed response? Follow-on: How do field observations help infer specific model structures and parameters, and constrain predictive uncertainty?3) Does the effectiveness of catchment models based on landscape structure vary across multiple watersheds or under different climatic forcing? Follow-on: How do we compare the transferability of new model conceptualizations to traditional models based on topographic controls, variable source area concepts, or simple water balance representations?To address these challenges we are working to build tools and infrastructure for research and education. We focus on themes critical to watershed science to improve transferability of watershed understanding and predictability of watershed response via new process conceptualizations and model structures.