|Hjelmfelt Jr, Allen|
Submitted to: Journal Hydrologic Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/1998
Publication Date: N/A
Interpretive Summary: Grass waterway and riparian buffer strips (vegetative filter strips) are indicated as a "best management practice" (BMP) for control of soil loss and agricultural chemicals. Little information is available to determine how much of the BMP is sufficient. A physically-based distributed model was applied to a field-size experimental watershed to investigate the design parameters. The model was calibrated using field observations with no vegetative filter strip, then modeled using waterways of varying lengths. The vegetative filter causes little increase in infiltration due to the claypan soil on which the field is located. As a result, there is little reduction in soil loss using a grass waterway extending halfway through the field. This investigation indicates the size of filter strip needed to achieve various levels of control. This information will be useful to producers and regulators making plans for control of soil loss and for meeting Total Maximum Daily Load (TMDL) limits.
Technical Abstract: The impact of vegetation filter strips (VFS) on runoff, sediment yield, and atrazine loss from a cultivated field was investigated using a physically- based, distributed watershed model. The field to which the model is applied has a gentle to flat sloping surface covered by a thin top soil layer underlain by a claypan and is located in Goodwater Creek watershed, a aUSDA research site in Central Missouri. The model, which works on a cell base, was developed to route runoff, sediment, and soluble chemical down slope from one cell to the next. Spatial variability of soil, depth of the top soil, and vegetation are allowed among cells; each cell, however, is represented as a homogeneous unit. Our investigation indicates that changing waterway cover from natural sparse vegetation to dense grass has great potential for retarding runoff and for reducing sediment loss but is not effective for controlling atrazine loss on claypan soil.