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

拟议的研究将侧重于开发和应用模拟模型在地下/陆地表面/大气界面。其目标是从物理（过程表示和参数化）和数值（鲁棒性，准确性和效率）的角度推进综合水文和生态水文建模的最新技术。这项工作将基于少数几个公认的、完全分布式的、基于物理的耦合水文模型之一，这些模型使用先进的计算算法来解决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个别博士和博士后研究项目的基础，将包括：不同复杂性的物质转移和运输现象;将其他生态水文过程纳入现有模式;适当解决不同子系统之间的交换或耦合条件;将用于数据同化的模式现有集合框架扩展到参数估计和敏感性分析;以及该模型在多尺度和嵌套尺度上的应用，从野外地块到河流流域。将讨论与异质性、网格分辨率效应、竞争子模型或参数化方案、强非线性和边界条件有关的综合、基于过程的水文建模方面的挑战。模型性能将被评估为不同的状态变量，两个综合措施，如流量和溶质浓度在排放口，总系统水存储和溶质质量，和总地下水补给，和分布式响应，如土壤水分，质量浓度，和交换通量在不同的点沿着传感器网络。该项目将依赖于从实验山坡和流域规模的研究地点获得的详细的多变量观测数据。该研究将在国际一级进行高度合作，并将包括参与多学科实地实验和模型相互比较和基准研究。在研究界有很高的需求，可靠的，可扩展的，开源的代码，可以解决综合生态水文过程的基础上一致和严格的物理（和化学/生物），数学和数值原理。拟议的研究将改进模拟模型，以帮助我们加深对复杂自然现象的理解，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的影响。

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.