Edge-of-Field Monitoring Using Depth-Integrated Sample Arm (DISA)

During edge-of-field monitoring of an agricultural field runoff event, a depth-integrated sample arm (DISA) is used to take a water sample at the same time a traditional water sample is taken from an intake located at the bottom of the H-flume exit, where the water is assumed to be completely mixed. The DISA is normally used to collect a continuous vertical sample representing the entire water column, but in this case it collects a single fixed-location sample from a raised position off the bottom of the flume (80% of the water-column height) to verify that the traditional sample is completely mixed and without particle size or concentration bias.