Antithetical premises of a static versus dynamic Andean landscape produce contradictory interpretations of the Chicama-Moche Intervalley Canal. On a static landscape, inoperable canal gradients must be explained by social parameters such as poor surveying or construction techniques. The paradigm of Plate Tectonics and evidence of ongoing crustal convergence support an alternative premise of continuous, gradual landscape alteration and ground slope change. This premise provides a physical explanation for why abandoned canals often exhibit uphill gradients and ancient monuments are frequently not level. However, this premise also requires that complex methods in the engineering analysis of slope-altered structures be made explicit. Assessment of landscape alteration utilizes basic principles of physical geology, but their application to a particular study area must take local conditions into consideration. Similarly, analysis of the hydraulic properties of an irrigation canal utilizes basic principles of fluid dynamics, but local conditions must be considered in deciding which formulas to use and how to apply them. Improper application of geological principles and hydraulic equations has led our critics to incorrect results.