Water resource problems are complicated by rapid global change and complex physical, biogeochemical and anthropogenic interactions. Predictions must be made over a wide range of spatial and temporal scales, and sometimes beyond the previously observed range of variability, under new sets of conditions and potentially in the context of strong feedbacks. Understanding and predicting hydrologic responses and their feedbacks on climate and other subsystems are of both scientific value and socio-economic urgency.
In an effort to help address these emerging water resource problems, the Process-based Adaptive Watershed Simulator (PAWS) was initially developed as Dr. Shaopeng Shen’s Ph.D. dissertation topic at Computational Hydrology and Reactive Transport lab, Michigan State University, with help from labmate Jie Niu. PAWS is a comprehensive, open-source, computationally-efficient parallel hydrologic model designed for large-scale simulation. The model is now coupled to the Community Land Model (CLM), and therefore is able to simulate Carbon/Nitrogen cycling, ecosystem dynamics and their interactions with the water cycle. Due to its comprehensiveness, efficiency, and flexibility, this tool provides a useful platform for the integration of biogeochemistry, fluid mechanics, and human dimensions into a uniform modeling framework, to investigate their mutual interactions, to test hypothesis about causal relationships and to assess future changes.
PAWS was developed with three key features in mind:
1. Comprehensive, physically-based gover
ning equations: these equations (e.g., Richards Equation) are derived deductively from established physical laws and able to reproduce lab/field observations.
2. Computational efficiency: efficient algorithms and sub-cell mechanisms allow the study of large-scale, long-term impacts and make optimization and uncertainty analysis tractable.
3. Flexibility: versatile program structure facilitates fast integration of disciplines and novel processes and permits multi-scale modeling. Multiple mechanisms account for the effect of model resolution.
Theoretical Documentation and User Manual for PAWS are available here.
Model description modified from the Space4Water Portal PAWS website.