Field-scale evaluation of a multislot passive sampler.

Monitoring the quality and quantity of agricultural runoff offers many challenges. Various instruments are available and range in terms of complexity, initial costs, operating costs, and accuracy. This paper describes a low-cost multislot passive sampler (the crown divisor sampler) used to measure runoff from a 0.41 ha (1 ac) field. Similar samplers have been used in laboratory and plot-scale studies, but their accuracy has not been studied in the field. For this study, the crown divisor sampler was placed in series with a calibrated 0.2 m (0.8 ft) HS flume. The accuracy of the sampler was assessed by comparing the runoff volume predicted by the sampler to the known volume measured by the flume for several storm events. A series of tests were also performed in which a simulated storm event was routed through the flume and crown divisor sampler. The flume was acceptably accurate for the simulated storm event tests and for some of the storm events. In addition to the quantitative results, many practical lessons have been learned and are documented in this paper. [ABSTRACT FROM AUTHOR]