Instrumentation for Full-year Plot-scale RunoffMonitoring

摘要

Replicated 0.34 ha cropping systems plots have been in place since 1991 at the USDA-ARS Goodwater Creek Experimental Watershed in central Missouri. Recently, instrumentation has been installed at 18 of those plots for continuous runoff water quality and quantity monitoring. That installation required several novel approaches to address infrastructure and instrumentation challenges. Plot berms, flumes, and flume approaches were designed to facilitate efficient farming operations with field-scale equipment. Commercial runoff samplers were employed in flow-proportional mode, but stage transducers available with the samplers did not have the required accuracy of 2 mm stage over the expected range in ambient temperatures. To meet this requirement, we designed a system based on a temperature-compensated differential pressure transducer mounted in a stilling well. A datalogger recorded stage data and controlled the sampler through a custom electronic interface. An electric heating system was installed toprotect the stilling well and transducer from freezing down to approximately -10 C. A laptop-based program was developed to manage calibration and data downloads for the 18 systems, and a wireless telemetry link was established. This paper documents thedesign of the plot infrastructure and instrumentation and describes the initial performance of the system as deployed in the field.