Analyzing the relationship between peak runoff discharge and land-use pattern – a spatial optimization approach

Abstract

This paper investigates the impacts of land-use patterns on watershed hydrology and characterizes the nature of this relationship. The approach combines a spatially ex- plicit, process-based hydrological simulation model, a land-use optimization model, the Integrated Hydrological and Land-Use Optimization (IHLUO) model, and an exten- sive GIS database. Numerical experiments are conducted to assess changes in the peak discharge rate under various spatial land-use arrangements, and to delineate the optimal land distribution that minimizes the peak discharge. The area of application is a catchment of the Old Woman Creek watershed in the southwestern coastal area of Lake Erie, OH. The global optimality of the delineated land pattern at a 30-m resolu- tion is evaluated using a combinatorial statistical method. A large number of solutions has been generated from clearly different initial solutions, and these solutions turn out to be very close to each other, strongly supporting the case for a convex relationship between peak discharge and land-use pattern. TheWeibull distribution is used to generate a point estimate of the global optimal value and its confidence interval. The peak discharge function is further examined in light of the underlying physics used in the simulation model.