Evaluation of percent flow captured by a small in-field runoff collector

Increased environmental concern about nutrient loadings in runoff and surfa ce water has heightened the need for evaluation of management practices at the field scale. Thus, there is a need for small in-field runoff collectors to assess nutrient migration at the field scale on various land management systems. A runoff sampler previously designed for the relatively flat terr ain of the Coastal Plain was modified to accommodate steeper slopes (5% to 12%), larger flow rates, and channelized flow common in the Southern Piedmo nt. We conducted a laboratory study with the modified sampler to evaluate t he effect of flow rate (1 to 5.5 L min(-1)) and slope (5% and 12%) on perce nt flow capture. Our results show that slope and flow rate had little to no effect on the percent flow capture of the modified runoff collector The 95 % confidence interval for percent flow capture in a single observation was 10.4 +/-2.5% for the 10x splitter and 2.0 +/-1.7% for the 100x splitter Bec ause of the potential errors for single observations, several runoff collec tors should be used if runoff volume needs to be quantified. The use of thi s small in-field runoff collector would be fairly unobtrusive, inexpensive in different management systems, and could help further our knowledge of mi gration of nutrients, pesticides, microorganisms, and sediments from fields into streams.