Comparing the capability of distributed and lumped hydrologic models for analyzing the effects of land use change

Empirically based lumped hydrologic models have an extensive track record of use for various engineering applications. Physically based, multi-dimensional distributed models have also been in development and use for many years. Despite the availability of high resolution data, better computational resources and robust, numerical methods implemented in such models, their usage is still limited, especially in the realm of surface water runoff simulation. Lumped models are often extended to solve complex hydrologic problems that may be beyond their capabilities. Here we attempt to differentiate the ability of lumped and distributed models to analyze a common watershed development issue such as land use change. For this, we employ two common US Army Corps of Engineers (USACE) models, well established in the literature and application, using the Hydrologic Engineering Center – Hydrologic Modeling System (HEC-HMS) model in a fully lumped mode and the fully distributed model Gridded Surface Subsurface Hydrologic Analysis (GSSHA). A synthetic watershed is used to establish that a distributed model like GSSHA more intuitively simulates land use change scenarios by distinguishing the spatial location of the change and its effects on the watershed response. An actual watershed at Tifton, Georgia is used to validate the observations made from the synthetic watershed.