|Wauchope, Robert - Don|
|Chandler, Laurence - Larry|
Submitted to: Water Resources Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/13/1999
Publication Date: N/A
Interpretive Summary: The more we learn about the ways pesticides behave in the environment, the more complicated evaluating their safety becomes. The task of assessing the risks of pesticides has become so huge that pesticide companies, and the public agencies regulating them, simply cannot do it well. The number and kinds and expense of experiments has become overwhelming. Computer simulation models have become a great hope as a way to simplify and systematically assess all the factors. Some promising models are already in use, particularly in estimating potential concentrations of pesticides in fields, soils, and surface and groundwater draining fields. But in general these models, though promising, require real field data to "validate" whether they work properly. While there is an enormous amount of pesticide environmental data, very little of it is detailed enough to test all the equations and the interactions used in the models. This paper ris one in a series detailing the results of a large and multidisciplinary field project which is an attempt to (partially) fill this need. Nine scientists participated; this is the most intensive and detailed pesticide/ fertilizer runoff experiment ever done. We used a recently developed large-plot rainfall simulator, grew a crop, and treated it with pesticides and fertilizers and attempted to measure everything-weather, soil properties, crop development, soil moisture and evapotranspiration, and pesticide/fertilizer losses in runoff and leachate water. In this paper we detail the water runoff results: the data is unique in its' detail and reproducibility, and reveals subtleties which will severely test the models.
Technical Abstract: A rainfall simulator was used to apply 5cm rainfall in two hours to two replicate 624m2 plots at six distinct times during each of the growing seasons of 1992 and 1993. Because the simulator generated reproducible and time-invariant rainfall intensities, the resulting 24 hydrographs reproducibly reveal the effects of wheel tracks, tillage, soil reconsolidation, surface sealing and corn canopy development. A time-series data set including weather, crop development, soils properties, evapotranspiration and antecedent moisture is available. These data should provide hydrologic modelers, particularly those interested in modeling runoff with a time resolution of less than one day, with a useful validation data set.