Hydrological Model Intercomparison: Subsurface Flow and Reactive Transport Simulation in the Oasis-Desert Interaction Zone

Oasis-desert interactions, i.e., the transport processes of mass and energy, are important for ecosystem sustainability in arid regions, especially under the influence of climate change and human activities in recent years. Hydrological models and in situ observations are essential tools and can be integrated to predict flow and transport processes across multiple scales. However, due to the complexities and uncertainties of the models, there is a critical need for model benchmarking and intercomparison. The main purpose of this study is to assess selected hydrological models for simulating flow and reactive transport processes in a typical oasis-desert zone under both natural and disturbed conditions. The study area is located in the middle reach of the Heihe River Basin (HRB) composed of irrigated farmlands in the oasis surrounded by desert. Subsurface flow and contaminant transport (e.g. pesticides, herbicides, and fertilizers) are simulated by three community hydrological models (i.e. PFLOTRAN, ParFlow and MODFLOW+MT3DMS). Model performance are evaluated (i.e. accuracy, computational efficiency, robustness) from simulated results in a series of scenarios. The study will provide insightful guidance of hydrological modeling and eventually help regulate local water resources and ecosystem sustainability.