Submitted to: Journal of the American Water Resources Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/2002
Publication Date: 6/1/2002
Citation: LOWRANCE, R.R., WILLIAMS, R.G., INAMDAR, S., BOSCH, D.D., SHERIDAN, J.M. EVALUATION OF USDA CONSERVATION BUFFER SYSTEMS FOR THE COASTAL PLAIN USING THE RIPARIAN ECOSYSTEM MANAGEMENT MODEL (REMM). JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION. 37(6):1445-1455. 2002. Interpretive Summary: Riparian ecosystem buffers are a key part of the USDA Conservation Buffer Initiative and are being installed under Conservation Reserve and other federal and state programs. A riparian ecosystem buffer consists of either all trees in one or two zones or a combination of trees and grass in three zones. Based on USDA specifications, the minimum width for a riparian ecosystem buffer is 15 ft with a minimum of 35 ft to control a water quality problem. Although based on best professional judgement, these minimum sizes of buffers are not well tested. The Riparian Ecosystem Management Model (REMM) was used to evaluate the sediment and nutrient removal functions of riparian ecosystem buffers. REMM was used to simulate 14 different buffers ranging from a minimum 15 ft one zone hardwood tree buffer to a 170 ft three zone buffer of perennial grass, pine trees, and hardwood trees. Two loadings were used as input to the buffer. The load cases were low sediment/low nutrient - typical of a well managed agricultural field and low sediment/high nutrient - typical of liquid manure application to perennial or year-round forage crops. The simulations showed that the minimum width buffer (15 ft) was inadequate for control of nutrients under either load case. The minimum two zone buffer (35 ft) that is eligible for cost share assistance on a field with known water quality problems was adequate to achieve at least 50% reduction of N, P, and sediment in the load cases simulated.
Technical Abstract: Riparian buffers are increasingly important as a watershed management tool and are being cost-shared by several federal and state programs such as Conservation Reserve and others that are collectively part of the USDA Conservation Buffer Initiative. Buffers as narrow as 4.6m (15ft) are eligible for cost-share assistance under USDA programs. The Riparian Ecosystem Management Model (REMM) provides a tool to judge the adequacy of these buffers for water quality improvement and to set design criteria for nutrient and sediment load reduction. REMM was used for a well-tested Coastal Plain condition to simulate 14 different buffers ranging from 4.6 m to 51.8 m (15 to 170 ft) with three different types of vegetation (hardwood trees, pine trees and perennial grass) with two water and nutrient loads. The load cases were low sediment/low nutrient - typical of a well managed agricultural field and low sediment/high nutrient - typical of liquid manure application to perennial or year-round forage crops. The two load cases approached the same low level of output from the buffer as the buffer size increased thus the wider buffers had higher percentage load reductions for the High Load case. The simulations showed that the minimum width buffer (4.6m) was inadequate for control of nutrients under either load case. The minimum width buffer eligible for cost share assistance on a field with known water quality problems (10.7 m, 35 ft) provided at least 50% reduction of N, P, and sediment in the load cases simulated.