In order to further investigate the water movement and nutrient transport from agricultural fields, we developed equipment and algorithms to zoom in the hydrograph and chemograph both spatially and temporally. We installed self-designed high frequency sampling equipment to measure water quality from subsurface tile drainage outlet and from shallow groundwater.
At the drainage tile outlet, we installed V-notch weir and pressure transducers to measure drainage flow, and an optical spetrophometer to continuously monitor nitrate concentration.
In shallow groundwater, we digged 10 water quality wells at different locations in shallow groundwater. The multi-point sampler collected fresh water samples from wells every 6 minutes. In other words, we took water quality measurements in each well every hour. The following picture shows the running device deployed in early spring, 2018.
Further analysis of high frequency measurements is still undergoing to achieve the following objectives:
What is the temporal dynamics of drainage discharge and nitrate concentration inferred from high frequency measurements?
Can we interprete the relationship between nutrient concentration and discharge in tile drainage using high frequency measurements?
How to describe and predict the transport and fate of nitrate in and from agricultural fields?
(Updated on May 8th, 2018)