Is the Relationship Between Peak Runoff Discharge and Land-Use Pattern Convex? A Numerical Experiment with the IHLUO Model

This study presents a modeling methodology to understand the impacts of spatial land use patterns on watershed hydrology and the characteristics of their interrelationship. An integrated hydrological and land-use optimization (IHLUO) model was used to delineate optimal land patterns that minimize peak runoff under various land use configurations. The solutions (i.e., peak runoff) obtained from the IHLUO model were analyzed using a Weibull distribution, in order to estimate the global optimum value and its confidence intervals and to assess their convergence toward the global optimum. The result supports the case for the global optimality, suggesting convexity of the hydrological function with optimized land-use variables. The convexity of the function is further argued, examining the physics of hydrological processes (the SCS-CN number) that are used in the hydrological simulation.