Unmanned Aircraft Systems (UASs) have made dramatic technical advances in the past decade. Their use domestically is currently tightly constrained by existing Federal Aviation Administration (FAA) regulations. Within the next few years, the FAA is expected to provide a regulatory framework that allows for a greatly expanded role for UASs in domestic airspace for a wide variety of applications. One of those will be remote sensing for land and natural resource monitoring. While there has recently been a large body of published research on UAS applications to environmental monitoring, in practice, very little has been operationalized by private or public entities to date. In July 2014, Argonne National Laboratory hosted a workshop dedicated to environmental monitoring UAS applications with attendance by representatives from 11 federal agencies as well as academics. The workshop reviewed the UAS state-of-the-art within the federal arena and barriers to broader UAS use. While a number of agencies, the including National Oceanic and Atmosphere Administration, the United States Geological Survey, National Aeronautics and Space Administration, and the Bureau of Land Management have conducted proof-of-concept UAS demonstrations, typically using surplus Department of Defense equipment, the promise of UAS systems at the moment remains untapped for a variety of reasons. The consensus was, however, that UAS systems will play an increasingly important role in cost-effectively supporting timely natural-resource and land-management monitoring needs.

Environmental Practice 17: 170–177 (2015)

Experimental crop fields often contain large numbers of small spatial plots that require separate analysis. It can be difficult to precisely locate these plots in high-resolution imagery of the fields gathered by Unmanned Aircraft Systems (UAS). This prevents UAS imagery from being applied in High-Throughput Precision Phenotyping and other areas of agricultural research. If the imagery is accurately geo-registered, then it may be possible to extract plots from the imagery based on their map coordinates. To test this approach, a UAS was used to acquire visual imagery of 5 ha of soybean fields containing 6.0 m 2 plots. Sixteen artificial targets were set up in the fields before flights to be used as Ground Control Points (GCPs) for geo-registration. Geo-registration accuracy was quantified based on the horizontal Root Mean Squared Error (RMSE) of targets used as checkpoints. Twenty test plots were extracted from the geo-registered imagery. Plot extraction accuracy was quantified based on the percentage of the desired plot area that was extracted. It was found that using four GCPs minimized the horizontal RMSE and enabled a plot extraction accuracy of at least 70%, with a mean plot extraction accuracy of 92%. Future work will focus on enhancing the plot extraction accuracy through additional image processing techniques so that it becomes sufficiently accurate for all practical purposes in agricultural research and potentially other areas of research.

Environmental Practice 17: 178–187 (2015)

Increasingly, Unmanned Aerial Systems (UASs) are changing the way that scientists and practitioners collect environmental data. Current UASs, however, are largely relegated to collecting data while flying remotely, far away in the air. This article examines two case studies where micro-UASs fly in immediate proximity to the environment, enabling them to collect physical samples and capture sensor data that cannot be obtained at a distance. The first case study presents an aerial water sampler that flies to remote locations and dips a pump into the water to collect samples for lab analysis. The second case study examines a UAS that flies within a meter of crops to accurately measure their height. Each requires different sensors and methods specifically tailored to operating and interacting near the environment. This article evaluates the performance of these systems and also presents preliminary validation that they collect datasets that are compatible with those gathered by existing approaches. Futhermore, it distills some common underlying design and operating principles shared by UASs aimed at working close to the environment. Finally, this article concludes that in spite of numerous pending challenges, UASs that directly interact with the environment will transform the way environmental data is collected.

Environmental Practice 17: 188–200 (2015)

Utilizing unmanned aircraft systems (UAS) can be an efficient and repeatable means of surveying wildlife, especially waterbirds. As with any technology in its infancy, case studies offer opportunities to explore drawbacks and limitations, both anticipated and unanticipated. We examined the relationship between flight altitude and camera focal length on bird identification. We then conducted a post-hoc analysis to examine the effect of flight altitude on bird flushing behavior. We flew UAS missions at three locations in California and Nevada to assess the use of UAS for censusing non-nesting waterbirds. A minimum pixel resolution of approximately 5 mm was needed be able to identify most waterbird species from imagery. Sensors needed to be carefully calibrated in order to obtain images of sufficient quality to identify waterbirds over open water. Our results suggest that gas-powered UAS may result in increased rates of flushing at low flight altitudes for some waterbirds. With careful design of surveys and processing workflow, UAS show promise for censusing and monitoring waterbirds.

Environmental Practice 17: 201–210 (2015)

This study systematically examined environmental effects during and after Dez Dam Reservoir flushing operations. The study focused on potential upstream sources of pollution, sediment concentrations, water-quality parameters, and uses of water downstream of the dam, particularly emphasizing the presence of fish and macroinvertebrates as well as their habitats. The study was conducted from June 16–18, 2003 in the Dez Dam Reservoir, which is located in the southern part of Iran. The Dez Dam Reservoir is facing a serious sedimentation problem, and its dead volume will be quite full in the coming 10 years. Therefore, performing flushing operations through the three irrigation gates of the dam has received much more attention in recent years. The results of this study helped determine the hydraulic conditions that could decrease the negative environmental effects of the Dez Dam Reservoir flushing operations on downstream aquatic conditions.

Environmental Practice 17: 211–232 (2015)