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AGNPS, Buffer Strips, Sediment, GIS


In this study, the Agricultural Nonpoint Source Pollution Model (AGNPS) was used to determine locations of vegetative buffer strip effectiveness on reducing sediment load within the East Bad Creek (EBC) watershed, a 690 ha agricultural watershed located mid Michigan. Modeling scenarios consisted of simulating the hydrology and sediment transport throughout the EBC watershed on a baseline scenario (no buffer) and with a 30-meter vegetative buffer strip placed around each stream segment (buffer strip scenario). The model’s results showed a 17% decrease in sediment load at the watershed’s outlet for a 10yr-24hr storm. As a result, the placement of buffer strips within the watershed was prioritized on three different scales. The reduction of sediment due to buffer strips was analyzed on a stream segment level, a field boundary level, and on a cell-by cell basis. The stream segment buffers and field buffers were ranked on their overall ability to reduce sediment load into the stream. The reduction in sediment yield from the stream segments and the fields varied from 3.49 to 58.54 tons and 0 to 19.31 tons respectively. The cell results were evaluated by highlighting 0.5 tons – 3.63 tons of sediment throughout the watershed, deeming those buffered cells efficient. The cell-by-cell evaluations highlighted specific critical areas of buffer efficiency on a 30-meter resolution where the stream segment and field evaluations identified specific stream segments and fields to target for buffer placement. The AGNPS model along with the Arcview Non-Point Source Model (AVNPSM) GIS interface demonstrates that agricultural watersheds can be quickly and efficiently evaluated to target locations of buffer placement. Therefore, helping watershed managers implement vegetative buffer strips in site-specific areas within the watershed to employ efficient implementation of conservation management programs.