Balancing Complexity, Parsimony, and Applicability in Hydrologic Modeling: A Comparative Evaluation of Four Infiltration Models across Parameterization Scenarios

Infiltration models are vital for predicting the onset and magnitude of flash floods. A multitude of infiltration models have been developed over the past century. In practice, model selection for a given study constitutes a compromise between complexity, parsimony, and feasibility. This study presents a comparative evaluation of four infiltration models of varying complexity available in the widely used HEC-HMS software: the curve number (CN), initial-constant (IC), Green-Ampt (GA), and the recently integrated linear-constant (LC) model. Using precipitation and runoff data from the Walnut Gulch Experimental watershed in Arizona, each model was analyzed across three different scenarios including, using published guidance, constrained calibration, and unconstrained calibration. Findings reveal that GA, the most complex model, excelled over the rest under published guidance and constrained calibration scenarios but was susceptible to equifinality issues under unconstrained calibration. Conversely, the simpler IC model performed well under unconstrained calibration. The results indicate the simple, two-parameter LC model offers a balance between complexity, parsimony, and feasibility in hydrologic modeling, particularly for arid and semiarid regions. This study provides valuable insight to hydrologists and researchers in selecting an appropriate infiltration model based on data availability and regional hydrologic conditions.