Impact of contributing area on the performance of Vegetative Filter Strips

Abstract

The sediment and dissolved pollutants carried by surface runoff enter into the stream network. The vegetative filter strip (VFS) within buffer zone of stream can effectively reduce the pollutants by trapping the sediment within vegetative strip. The main objective of this study was to use AGNPS_VFS (Agricultural Nonpoint Source Pollution_Vegetative Filter Strip) tool kit to determine the impact of contributing area of each flow path on VFS performance for Canagagigue Creek watershed, Ontario, Canada. The 10m, 20m, and 30m wide VFS were simulated for nine storm scenarios (5-yr, 10-yr and 25-yr return period, and storm duration of 6-hr, 12-hr and 24-hr).The simulated results showed that some flow paths carried either very small sediment load or no load. The linear regression trends for sediment load and sediment removal efficiency (SRE) revealed that SRE decreased as contributing area increased. The maximum SRE was 90%, 94%, and 95% for 5yr-6hr duration, and the minimum SRE were observed as 9%, 40%, and 55% for 25yr-24hr for 10m, 20m, and 30m VFS. The sediment loads enter the system increased as flow regime changed from 5-yr to 25-yr return period and 6 hr to 24 hr duration. The area of flow path in watershed reduced 68% for 5yr-6hr scenario and 37% for 25yr-24hr scenario. This indicates that amount of storm considerably affects the contributing area of flow path. The analysis would help in identifying the flow path where VFS would produce the efficient results.