RIPARIAN ECOSYSTEM MANAGEMENT MODEL (REMM): I. TESTING OF THE HYDROLOGIC COMPONENT FOR A COASTAL PLAIN RIPARIAN SYSTEM

Abstract

The Riparian Ecosystem Management Model (REMM) was used to simulate shallow groundwater movement,water table depths, surface runoff, and annual hydrologic budgets for a Coastal Plain riparian buffer system near Tifton,Georgia, USA. The riparian buffer consisted of zone 3 (grass downslope from a row-crop field); zone 2 (mature pineforest downslope from zone 3); and zone 1 (mature hardwood forest downslope from zone 2, adjacent to stream).Measured surface runoff and shallow groundwater movement from the adjacent agricultural field were used as thehydrologic input to REMM. Uncalibrated simulation results for a five-year period were compared to measured values forthe same time period. The overall error in zone 2 and zone 1 mean water table depths was about 0.07 m, althoughabsolute errors were higher. The water table dynamics simulated by REMM were similar to observed although lags wereobserved in the response of the simulated water table to large rainfall events. Mixed results were obtained from observedversus simulated surface runoff comparisons, primarily due to large variability in observed runoff depths along theriparian transect. Simulated surface runoff depths for zone 3 were within one standard deviation for four out of the fiveyears. For zone 2, surface runoff depths could only be simulated within one standard deviation for two out of the fiveyears. Simulated seasonal total depths of surface runoff did not always agree with observed values but usually followedboth similar temporal and spatial patterns. Annual hydrologic budgets produced total streamflow comparable to thoseestimated for the riparian buffer site. These results provide an adequate basis for subsequent testing of other REMMmodel components including water quality and nutrient cycling.