|Hjelmfelt Jr, Allen|
Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Other
Publication Acceptance Date: 7/22/1999
Publication Date: N/A
Technical Abstract: The performance of Hydrological Simulation Program-FORTRAN (HSPF) version 11.0 in simulating sediment yield from a claypan agricultural watershed was evaluated. The calibration of model parameters required to describe sediment behavior constituted the major activity. The claypan watershed studied is Goodwater Creek, a 72 km**2 (28 sq mi) agricultural watershed in nCentral MO. Claypan soils are characterized by poor drainage resulting partially from the presence of an argillic claypan horizon that limits groundwater recharge and promotes surface runoff and interflow. The watershed is on a glacial till plain that has a level to gently rolling topography, with slopes averaging 3%. The low permeability of the claypan layer ensures that surface runoff is the dominant component of streamflow. The runoff water transports pesticides and nutrients from the watershed either in solution or adsorbed onto sediment particles. These agricultural chemicals delivered to the stream threaten the quality of the stream water Thus, a clear understanding of the sediment process is essential for a successful evaluation of stream water quality as impacted by pesticide and nutrient loading. Sediment problems in the watershed have not received any significant study. In this study the HSPF model was first calibrated for land surface sediment erosion on a 36 ha (89 ac) research field within the Goodwater Creek watershed. Calibration for instream sediment transport was done for the entire Goodwater Creek watershed. The calibration was based on 2 yrs (1993 and 1995) of observed sediment concentration data. The year 1994 was dry and not significant for sediment study. Our results show that, with a proper calibration of hydrology and sediment parameters, HSPF accurately simulated sediment yield from the Goodwater Creek watershed.