A Machine Learning Framework to Explain Complex Geospatial Simulations: A Climate Change Case Study

Tanvir Ferdousi, Abhijin Adiga, Mandy L. Wilson, S. S. Ravi, Anil Vullikanti, Madhav V. Marathe, Samarth Swarup, Mingliang Liu, Kirti Rajagopalan, Jennifer Adam

Abstract: The explainability of large and complex simulation models is an open problem. We present a framework to analyze such models by processing multidimensional data through a pipeline of target variable computation, clustering, supervised classification, and feature importance analysis. As a use case, the well-known large-scale hydrology and crop systems simulator VIC-CropSyst is utilized to evaluate how climate change may affect water availability in Washington, United States. We study how snowmelt varies with climate variables (temperature, precipitation) to identify different response characteristics. Based on these characteristics, spatial units are clustered into six distinct classes. A random forest classifier is used with Shapley values to rank static soil and land parameters that help detect each class. The results also include an analysis of risk across different classes to identify areas vulnerable to climate change. This paper demonstrates the usefulness of the proposed framework in providing explainability for large and complex simulations.