Riparian Ecosystem Management Model (REMM): II. Testing of the water quality and nutrient cycling component for a Coastal Plain riparian system

The Riparian Ecosystem Management Model (REMM) was used to simulate nitroge n (N), phosphorus (P), and carbon (C) cycling and transport in a Coastal Pl ain riparian buffer system near Tifton, Georgia. The riparian buffer consis ted of zone 3 (grass next to a row crop field); zone 2 (mature pine forest downslope from zone 3); and zone 1 (hardwood forest downslope from zone 2, adjacent to a stream). Uncalibrated simulation results for a Jive-year peri od were compared to measured values for the same time period at the researc h site. In general, simulated water table nutrient concentrations were with in one standard deviation of observed values on an annual basis. Surface ru noff loads exiting zone 3 for most N and P forms were simulated within one standard deviation of the observed In contrast zone 2, surface runoff loads for inorganic N species were apt order of magnitude lower than observed. A lthough some of the surface runoff differences (observed vs. simulated) wer e large in relative terms, the overall trends within the riparian buffer we re generally well-represented and differences were not large in absolute te rms. Simulated values for one of the most important processes responsible f or effectiveness of riparian zones - denitrification, were within the range of those observed. Much of the temporal dynamics of the observed data were also captured in the REMM simulations. Certain constraints of the model us e are discussed, but REMM appears to be useful for representing many of the specific processes and general trends in riparian ecosystem buffers.