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Systematic environmental monitoring of the land, atmosphere, oceans and collecting concurrent datasets using unmanned aerial vehicles (UAVs) is one of the major approaches of data science (Tripolitsiotis et al., 2016). With the new advancements on flight control and integrated circuit (IC) technology of data acquisitions, UAVs have been widely used in various applications. One of the typical application scenarios is data collection for large geographic areas and connected remote sensor devices in the Internet of things (Qi Pan et al., 2018). UAVs have been integrated with wireless sensor networks (WSNs) to create data collection platforms with high flexibility. Cao et al. (2017) tested the cloud-assisted drone (UAV) data collection for multiple emerging events using the distributed wireless sensor networks (WSNs). Some examples of previous UAV applications are: a) sampling microorganisms in a freshwater lake (Benson et al., 2016), b) forest monitoring (Zhang et al., 2016), c) coastal survey (Turner et al., 2016), d) mining survey (Lee and Choi, 2016), and e) 3D digital model building and photogrammetry (Nex and Remondino, 2014; Achille et al., 2015).
In this research, we acquire data in the field to study water chestnut invasive species. Trapa natans, commonly called water chestnut or water caltrop, is an exotic annual aquatic plant with a floating rosette of leaves (Figure 1) which is native to Eurasian and African continents (Countryman, 1978; Naylor, 2003). Water chestnut is one of the most controversial plants (Hummel and Kiviat, 2004). In Asia, especially in China and India, people plant water chestnut as an agricultural species. In Europe and Russia, it is a species with conservation concerns (Hummel and Kiviat, 2004); while, the invasion of water chestnut is a serious environmental problem in North America. This plant grows easily and has already invaded freshwater rivers, pools, and lakes, including the Hudson River and the Great Lakes watersheds (Kiviat, 1993; Countryman, 1978; Hummel and Kiviat, 2004).
The spread of water chestnut has already caused many ecological and economic impacts. The leaves of water chestnut cover the water surface, block the waterway, and cut off the air that fish and other aquatic life rely on to live (NYIS, 2014; Hummel and Kiviat, 2004; Naylor, 2003). The management of controlling water chestnut has been done during last several years. Various mechanical and chemical methods have been applied to remove extensively spreading water chestnut. However, these methods of removal take a long time to ensure complete eradication and are expensive (NYIS, 2014). For example, from 1982 to 2011, state and federal government agencies spent $9,600,000 on water chestnut control in Lake Champlain (Hunt and Marangelo, 2012). Scientists also attempted to apply some biological controlling methods, for instance, introducing a leaf beetle (Galerucella birmanica) from Asia (Ding et al., 2006). However, whether the result of these biological methods is environmentally friendly is still under research and discussion.