Complex feedbacks that shape the static structure and dynamic evolution of natural and human-altered landscapes arise from interactions within and between natural processes and human activities. This session aims to bring together hydrologists, geomorphologists, ecologists, soil physicists, and other Earth scientists who employ parsimonious mathematical frameworks—including dimensional analysis, deterministic differential equations, stochastic models, information theory, and optimization—to distill the observed complexity of terrestrial systems across diverse spatiotemporal scales and advance process-based understanding. We encourage studies ranging from theoretical insights to practical applications that show how elegant mathematical simplifications can elucidate rich system behaviors—such as scaling, nonlinearity, randomness, self-organization, and emergence, among others. Contributions are welcome on themes including, but not limited to, self-similarity and scaling in fluvial and aeolian landscape patterns and ecological systems, optimality in resource allocation—from plant-water interactions to socioeconomic carbon mitigation—and nonlinear land-atmosphere interactions.