A Framework for Testing Distributed Hydrologic Models at the Hillslope Scale

空间分布的水文模型在非点源污染物运移、侵蚀泥沙运移或景观变化的水文响应等方面具有很大的应用潜力。这些模型的预测能力取决于对流经流域的许多路径的水流的精确模拟。有许多复杂的计算机模型可以模拟这些流动路径，但由于缺乏数据、自然系统的复杂性和模型的复杂性，分布式模型和现实之间的联系仍然很弱，而且很难理解。为了测试、改进和/或开发有效和实用的分布式建模工具，我们需要在现场测量和过程模拟之间建立更强的联系，以更多地了解分布式建模的优点和局限性。然而，在建立这些联系时，由于缺乏信息和系统复杂性，我们面临着固有的限制。我们的研究旨在设计一个分布式模型测试平台，在此基础上，我们尽可能地捕获系统的复杂性并减少不确定性。为此，我们将最详细的可用现场测量集与最先进的数值模型相结合，以创建测量驱动的假设现实。水文反应。这个试验台的基础是10公顷（25英亩）的Tarrawarra流域（澳大利亚），它有一个简单但具有代表性的结构，0.5-1.5米深的土壤覆盖在基岩上，平缓起伏的收敛和分散的地形，以及相对均匀的草地覆盖。根据转包合同，斯坦福大学的基思·洛格博士将为塔拉瓦拉创造假想的现实。详细的综合水文模型（InHM），该模型完全能够在空间和时间上以高分辨率表示水在地下和地下运动的物理机制。当仔细校准与塔拉瓦拉观测相匹配时，InHM模拟是目前可能的最接近塔拉瓦拉水流路径的精确模拟。这些模拟将为测试地表和地下流动的简化表示提供有用和全面的基准。校准后的InHM模拟成为假设的现实。，我们将其视为一个全面的无差错数据库，用于评估可用于水文决策的更简单的分布式模型类型。尽管根据一系列实际情况评估更简单的模型是可取的，但即使是Tarrawarra数据集在空间和时间上也不够全面，无法进行严格的分布式模型测试。我们的。假设的现实。该方法的优点是最小化了测量收集和模型评估的约束。我们将测试两个分布式水文模型。假设的现实。遵循组合方案，其中我们改变模拟时间段，空间和时间尺度，输入信息和观测数据。该框架内的测试将用于告知模型结构、现场测量类型和位置、模型元素比例和模型参数值的选择。在这个阶段，我们还有很长的路要走，试图确定测量和模拟分布式水通道的适当技术。这项研究是沿着这条道路迈出的第一步；特定的目标是开发一个框架和工具库，用于检查复杂的、多维的、异构的系统。虽然规模小，结构简单，性质合成的塔拉瓦拉。假设的现实。在将特定模型测试结果转移到其他地区时产生了挑战，我们希望测试方法将成为解决空间显式水文模拟这一挑战的有用的第一步。假设的现实、框架数据库和分布式模型测试结果都将通过网站提供，为其他人提供测试不同的分布式模型或使用框架来解决感兴趣的科学问题的机会。这项工作将为博士和本科生提供教育机会，我们将开发部分连续水文数据序列的电影表示，用于高中和大学课程。

0537410BurgesSpatially distributed hydrologic models are tools with great potential in applications such as non-point source pollutant transport, erosion and sediment transport, or hydrologic responses to landscape change. The predictive skill in these models hinges on accurate simulation of flows along the many pathways through a watershed. Numerous sophisticated computer models exist for simulating these flow pathways, yet due to lack of data, natural system complexity, and model complexity, links between distributed models and reality remain weak and poorly understood. To test, improve, and/or develop effective and practical distributed modeling tools, we need to forge stronger links between field measurements and process simulations to learn more about the strengths and limitations of distributed modeling. In forging these links, however, we face inherent limitations stemming from lack of information and system complexity. Our research aims to design a distributed model test bed whereby, as much as possible, we capture the system complexity and reduce the uncertainties. We do this by combining one of the most detailed available field measurement sets with a state-of-the-art numerical model to create a measurement-driven hypothetical reality. of hydrologic response. The basis for this test bed is the 10 ha (25 acre) Tarrawarra catchment (Australia), which has a simple but representative structure, with 0.5-1.5 m deep soils overlaying bedrock, gently undulating convergent and divergent topography, and a relatively uniform grass cover. Under a subcontract, Dr. Keith Loague, Stanford University, will generate Tarrawarra hypothetical realities. with the detailed Integrated Hydrology Model (InHM), which is fully capable of representing the physical mechanisms of water movement through the subsurface and subsurface with high resolution in space and time. When carefully calibrated to match Tarrawarra observations, InHM simulations come as close as is currently possible to simulating Tarrawarra water flow pathways accurately. These simulations will provide a useful and comprehensive benchmark against which to test simplified representations of surface and subsurface flow. Calibrated InHM simulations become the .hypothetical realities., which we treat as a comprehensive error-free database for evaluation of the types of simpler distributed models that could be used for hydrologic decision making. Although it would be preferable to evaluate simpler models against a range of actual realities, even the Tarrawarra data set is not sufficiently comprehensive in space and time to conduct rigorous distributed model testing. Our .hypothetical reality. approach has the advantage of minimizing constraints on measurement collection and model evaluation. We will test two distributed hydrologic models against the .hypothetical realities. following a combinatorial scheme in which we vary the simulation time periods, spatial and temporal scales, input information, and observation data. Tests within this framework will be used to inform selection of model structure, field measurement types and locations, model element scale, and model parameter values. At this stage, we have a long path ahead of us in the attempt to identify appropriate techniques for measuring and simulating distributed water pathways. This research represents an initial step along that path; the particular goal is to develop a framework and a tool-base for examining complex, multidimensional, heterogeneous systems. Although the small scale, simple structure, and synthetic nature of the Tarrawarra .hypothetical reality. creates challenges in transferring the particular model test results to other areas, we hope that the testing approach will be a useful first step in addressing this challenge of spatially explicit hydrologic simulation. The hypothetical realities, framework database, and distributed model testing results will all be made available through a website, offering the opportunity for others to test different distributed models or to use the framework to address a science question of interest. The work will provide educational opportunities for doctoral and undergraduate students, and we will develop movie representations of parts of the continuous hydrological data sequences for use in high school and university courses.