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ARS Home » Plains Area » Las Cruces, New Mexico » Range Management Research » Research » Publications at this Location » Publication #321867
Title: Spatially explicit rangeland erosion monitoring using high-resolution digital aerial imagery

Author
item GILLAN, JEFFREY - New Mexico State University
item Karl, Jason
item BARGER, NICHOLE - University Of Colorado
item ELAKSHER, AHMED - New Mexico State University
item DUNIWAY, MICHAEL - Us Geological Survey (USGS)

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary: Measuring and monitoring soil erosion at landscape scales is a very important and challenging aspect of sustainable rangeland management. Traditional field-measurement techniques such as sediment traps, erosion pins and bridges can be labor intensive and difficult to scale above the site scale. The increasing availablility of very high resolution imagery from manned and unmanned aircraft has opened up new possibilities to measure and monitoring soil surface changes by digitial photogrammetric techniques. We created and co-registered digital elevation models from overlapping 5cm resolution aerial images and took the differences between these DEMS at a one-year interval to evaluate soil movement and loss in a southern Utah juniper removal treatment. Differencing the DEMs revealed the spatial patterns in net soil losses and gains and identified the proportion of the landscape experiencing significant change as a result of the juniper removal treatments. On average, we were able to detect surface elevation change of 7cm and greater. DEM differencing and corresponding measurements from process-focused field-based methods provided complementary information and a more complete assessment of the causes and impacts of soil loss and movement than any single technique alone. Photogrammetric DEM differencing could supplement erosion prediction models in the form of model validation or a companion data set that quantitatively tracks surface change over time.

Technical Abstract: Nearly all of the ecosystem services supported by rangelands, including production of livestock forage, carbon sequestration, and provisioning of clean water, are negatively impacted by soil erosion. Accordingly, monitoring the severity, spatial extent, and rate of soil erosion is essential for long-term sustainable management. Traditional field-based methods of monitoring erosion (sediment traps, erosion pins and bridges) can be labor intensive and therefore generally characterize plot and hillslope scales. There is a growing effort to monitor natural resources at broad scales which is driving the need for new soil erosion monitoring tools. One remote-sensing technique that can be used to monitor soil movement is a time series of digital elevation models (DEMs) created using aerial photogrammetry methods. By geographically co-registering the DEMs and subtracting one surface from the other, an estimate of soil elevation change can be created. Such analysis enables spatially explicit quantification and visualization of net soil movement including erosion, deposition, and redistribution. We constructed DEMs (12 cm ground sampling distance) immediately before and 1 year after a vegetation removal treatment on a 31 ha Piñon-Juniper woodland in southeastern Utah. Differencing the DEMs revealed the spatial patterns in net soil losses and gains and identified the proportion of the landscape experiencing significant change. On average, we were able to detect surface elevation change of 7cm and greater. DEM differencing and the process focused field-based methods provided complementary information and a more complete assessment of the causes and impacts of soil loss and movement than any single technique alone. Photogrammetric DEM differencing could supplement erosion prediction models in the form of model validation or a companion data set that quantitatively tracks surface change over time.