Performance of a passive small-plot runoff collector under laboratory and field conditions

Abstract

<p>Large variability in soil erosion and water runoff in the field necessitates numerous replications in order to evaluate differences between treatments. One method for addressing this challenge is to use a simple, low-profile runoff collector that is adaptable to large and small runoff events. A runoff collector was designed to obtain representative soil and runoff loss measurements from small field plots with the capacity to store sediment and runoff suitable for laboratory analysis from larger return storms, while maintaining the sensitivity to collect a representative sample from small events. The criteria for collector performance include: consistency of percent runoff collected under variable conditions; simplicity of installation, serviceability, ease of transport; and cost. A laboratory component evaluated collector consistency; the percent collected should be independent of changes in flow rate (0.09 to 0.15 L/sec) and slope (2%, 5%, and 8%). It was determined that cloth placed in strategic sections of the collector to reduce water surface tension effects on flow stabilized flow and reduced collection variability; it is therefore recommended that cloth be used with this collector design. The 95% confidence interval for percent of introduced water that was collected was 10.83% [plus or minus] 0.49%. Laboratory and field results indicate that these collectors are suitable for use under a range of runoff rates and variable field conditions indicated by non-significant (Pr>F 0.442) flow rate and slope (Pr>F 0.0577) effects. It was determined from field experiences that the collector was relatively simple to transport and install, serviceability was not an issue, and costs were comparable to other collector types.</p>