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ARS Home » Southeast Area » Jonesboro, Arkansas » Delta Water Management Research » Research » Publications at this Location » Publication #337741
Title: Continuous instream monitoring of nutrients and sediment in the agricultural watersheds

Author
item ARYAL, NIROJ - Orise Fellow
item Reba, Michele

Submitted to: Journal of Visualized Experiments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2017
Publication Date: 9/26/2017
Publication URL: http://handle.nal.usda.gov/10113/5832869
Citation: Aryal, N., Reba, M.L. 2017. Continuous instream monitoring of nutrients and sediment in the agricultural watersheds. Journal of Visualized Experiments. (127), e56036. https://doi.org/10.3791/56036.
DOI: https://doi.org/10.3791/56036

Interpretive Summary: 'Grab sampling' is the most common method used for monitoring nutrients and sediment in water resources. However, it is time-intensive, expensive and often impractical to monitor water resources using grab sampling on a finer temporal resolution such as an hour. The fine-temporal data on water resources monitoring is required by policy makers, resource managers, and researchers to study complex processes and understand drivers of the pollutant loads, and make informed water resource management decisions. This protocol demonstrates use of sensors, sondes, and samplers to monitor discharge, nutrients and sediment in agricultural watersheds using continuous (15-min) in-situ data from sondes and sensors, and weekly analysis of water samples in the laboratory. The manuscript shows that quality data can be achieved by reducing challenging conditions of an agricultural stream such as fouling of sensors and build-up of sediment and debris on the sensor surfaces using appropriate and timely calibration, maintenance and operation of the sondes and sensors.

Technical Abstract: Pollutants concentrations and loads in the watersheds vary considerably with time and space. Accurate and timely information on the magnitude of pollutants in water resources is a pre-requisite for understanding the drivers of the pollutant loads and making informed water resource management decisions. More commonly used ‘grab sampling’ method provides concentrations of pollutants at the time of sampling (snapshot concentration) and may over or under predict the pollutant concentrations and loads. Continuous monitoring of nutrients and sediment has received more attention recently due to advances in computing, sensing technology and storage devices. This protocol demonstrates the use of sensors, sondes, and instrumentation to continuously monitor in-situ nitrate, ammonium, turbidity, pH, conductivity, temperature, and DO(dissolved oxygen) and calculate loads from two streams (ditches) in two agricultural watersheds. With proper calibration, maintenance and operation of sensors and sondes, good water quality data can be obtained by overcoming challenging conditions such as fouling and debris buildup. The method can also be used in various sized watersheds characterized by agricultural, forested and/or urban land use.