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ARS Home » Southeast Area » Oxford, Mississippi » National Sedimentation Laboratory » Watershed Physical Processes Research » Research » Publications at this Location » Publication #299567
Title: GIS technology for spatiotemporal measurements of gully channel width evolution

Author
item MOMM, HENRIQUE - Middle Tennessee State University
item Wells, Robert - Rob
item Bingner, Ronald - Ron

Submitted to: Natural Hazards
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/6/2015
Publication Date: 1/21/2015
Publication URL: https://handle.nal.usda.gov/10113/5695360
Citation: Momm, H.G., Wells, R.R., Bingner, R.L. 2015. GIS technology for spatiotemporal measurements of gully channel width evolution. Natural Hazards. DOI 10.1007/s11069-015-1615-z.

Interpretive Summary: This manuscript describes a technology, developed at the NSL, to extract channel width information from photographs. A computer synchronizes and controls the cameras during experiments performed on eroding channels, similar to rills and ephemeral gullies. The images are processed to obtain discontinuities (channel edge) within the landscape. The cost of the equipment is low, the software used to construct the technology is open source, the results are highly accurate and offer processes understanding, and the method is fully adaptable to both field and laboratory research.

Technical Abstract: Field observations of gully evolution in active croplands have often revealed the presence of a less erodible soil layer that is typically associated with tillage practices (i.e. plowpan). This more erosion-resistant layer limits channel incision forcing the gully channel to expand laterally through basal scour of the bank toe and gravitational mass-movement of the gully channel sidewalls. Understanding the role and quantification of widening processes is vital to efforts to quantify soil loss from gullies. One major research challenge is designing laboratory experiments that replicate field conditions while accounting for and accurately measuring spatial and temporal gully channel characteristics. Technology was developed to capture 1-cm spaced cross-sections along a soil flume at user-defined time intervals. Off-the-shelf high-resolution cameras were positioned above the soil bed looking as close to nadir field-of-view as possible. Using open source technology, computer control of the cameras was used to trigger each camera at 10-second intervals and download individual images from the cameras. Batch processing scripts were used to geo-reference individual frames based on known coordinates and to re-sample each frame into a standard raster grid cell size of 0.25 cm. Custom developed image processing software was utilized to identify image discontinuities representing channel edges. After an additional filtering step, the set of discontinuities were converted into GIS polygons and these polygons were then used to produce a set of cross-sections for each time interval (hundreds of cross-sections for each time interval). The technology offers an inexpensive alternative for collecting data from laboratory experiments and serves as a template for multi-purpose investigations where soil bed discontinuities need to be accurately measured at high temporal resolution.