Skip to main content
ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Agroecosystems Management Research » Research » Publications at this Location » Publication #417638
Research Project: Sustainable Intensification in Agricultural Watersheds through Optimized Management and Technology

Location: Agroecosystems Management Research

Title: USDA LTAR common experiment measurement: overland flow

Author
item Cole, Kevin
item Buda, Anthony
item Rice, Pamela
item Baffaut, Claire

Submitted to: Protocols.io
Publication Type: Research Notes
Publication Acceptance Date: 9/20/2024
Publication Date: 9/20/2024
Citation: Cole, K.J., Buda, A.R., Rice, P.J. 2024. USDA LTAR common experiment measurement: overland flow. Protocols.io. https://doi.org/10.17504/protocols.io.kxygxyk2zl8j/v1.
DOI: https://doi.org/10.17504/protocols.io.kxygxyk2zl8j/v1

Interpretive Summary: This protocol is part of a set to be published at protocols.io for the LTAR Common Experiment. This protocol describes how to measure overland flow from small agricultural basins. The goal is to provide repeatable guidelines to achieve consistent data collection, data processing, and quality control for obtaining data at research sites.

Technical Abstract: Overland flow is water that flows over a land surface (sheet flow) or in rills and gullies (concentrated fl ow) in response to rainfall or melting snow. Measuring overland flow on croplands and rangelands is important because it represents a key water pathway that controls pollutant losses from agricultural fields. When overland fl ow is accurately measured along with other water inputs and outputs, scientists can develop budgets describing how water and associated pollutants traverse cropland and rangeland systems. Tracking these budgets over extended time frames (years, decades) helps quantify the beneficial effects of improved agricultural management. In many edge-of-field and small watershed studies, overland flow measurements typically involve control structures such as flumes or weirs. Several hydrology textbooks and agency manuals (USDA, USGS) provide detailed guidance on weir and flume development, installation, and operation. In general, weirs and flumes are located at the outlets of drainage areas where overland flow exits an agricultural field. The devices are sized based on the range of expected flows. In most instances, weirs and flumes have preset equations that calculate discharge (the volume of overland flow leaving a field over a given unit of time) based on measurements of water height, or stage. A wide variety of sensors are useful in measuring stage in weirs and flumes, including floats, bubblers, and pressure transducers. Stage data from these sensors are then recorded at frequent time steps (seconds to hours) to provide continuous estimates of overland flow.