Improving process representation and numerics for integrated hydrological modeling at the subsurface/land surface/atmosphere interface

拟议的研究将集中在次表层/陆地表面/大气界面模拟模型的开发和应用上。其目标将是从物理(过程表示和参数化)和数值(稳健性、准确性和效率)两个角度推进水文学和生态水文学综合建模的最新进展。这项工作将基于少数公认的、完全分布式的、基于物理的、耦合的水文模型之一，这些模型使用先进的计算算法来求解地表和地下水流和溶质运移的质量守恒方程。这项工作的主要主题，也将是各个博士和博士后研究项目的基础，将包括：不同复杂程度的质量传递和传输现象；将更多的生态水文过程纳入现有模型；适当解决不同子系统之间的交换或耦合项；将模型现有的集合框架扩展到参数估计和敏感性分析；以及模型在多个尺度和嵌套尺度上的应用，从实地小区到流域。与异质性、网格分辨率效应、相互竞争的子模型或参数化方案、强非线性和边界条件相关的综合、基于过程的水文建模中的挑战将被解决。将评估不同状态变量的模型性能，既有综合测量，如排放出口的流量和溶质浓度，系统总储水量和溶质质量，以及总地下水补给，也有分布响应，如沿传感器网络的不同点处的土壤水分、质量浓度和交换通量。该项目将依赖于从试验性山坡和分水岭尺度研究现场获得详细的、多变量的观测数据。这项研究将在国际一级高度协作，并将包括参与多学科实地试验、模型相互比较和基准研究。研究界对可靠的、可扩展的、开放源代码的代码有很高的需求，这些代码可以基于一致和严格的物理(以及化学/生物)、数学和数值原理来解决综合的生态水文过程。拟议的研究将导致改进的模拟模型，以帮助我们加深对复杂自然现象、不同过程如何相互作用以及这些系统如何受到人为压力和其他因素影响的理解。

The proposed research will focus on the development and application of simulation models at the subsurface/land surface/atmosphere interface. The objective will be to advance the state of the art in integrated hydrological and ecohydrological modeling from both physical (process representation and parameterization) and numerical (robustness, accuracy, and efficiency) perspectives. The work will be based on one of only a handful of accepted, fully-distributed, physically-based, coupled hydrological models that use advanced computational algorithms to resolve the governing mass conservation equations for surface and subsurface water flow and solute transport. The main themes of the work, which will also be the bases for individual PhD and postdoctoral research projects, will include: mass transfer and transport phenomena of varying complexity; incorporation of additional ecohydrological processes into the existing model; proper resolution of exchange or coupling terms between different subsystems; extension of the model's existing ensemble framework, implemented for data assimilation, to parameter estimation and sensitivity analysis; and applications of the model across multiple and nested scales, from field plot to river basin. Challenges in integrated, process-based hydrological modeling related to heterogeneity, grid resolution effects, competing submodel or parameterization schemes, strong nonlinearities, and boundary conditions will be addressed. Model performance will be assessed for different state variables, both integrated measures such as flow rate and solute concentration at the discharge outlet, total system water storage and solute mass, and total groundwater recharge, and distributed responses such as soil moisture, mass concentration, and exchange fluxes at different points along a sensor network. The project will rely on the availability of detailed, multivariate observation data from experimental hillslope and watershed scale study sites. The research will be highly collaborative at an international level and will include participation in multidisciplinary field experiments and model intercomparison and benchmarking studies. There is high demand in the research community for reliable, extendable, open source codes that can resolve integrated ecohydrological processes based on consistent and rigorous physical (and chemical/biological), mathematical, and numerical principles. The proposed research will result in improved simulation models to help us deepen our understanding of complex natural phenomena, of how different processes interact, and of how these systems can be impacted by anthropogenic stresses and other factors.**