Drones prove to be useful tools for flood data collection

Article: Addo, K. A., Jayson-Quashigah, P. N., Codjoe, S. N. A., & Martey, F. (2018). Drone as a tool for coastal flood monitoring in the Volta Delta, Ghana. Geoenvironmental Disasters, 5(1), 17.

Drones, the common name for unmanned aerial vehicles or UAVs, have exploded in popularity in recent years. From their initial use as military aircraft, they now are widely used for photography, surveillance, and for sheer fun.

They are relatively inexpensive, easy to maintain and operate, require very little infrastructure, and are highly portable. As camera technology has improved, highly capable cameras have now shrunk in weight and size to make them easily portable by drones.

These attributes make drones ideal tools for ecological surveillance, particularly in remote and resource-poor areas.

A recent paper by Kwasi Addo and colleagues from the University of Ghana and the Ghana Meteorological Agency demonstrated the usefulness of drones in monitoring flooding and coastal erosion in a vulnerable region of Ghana called Fuvemeh.

A DJI Phantom drone, similar to the one used by the researchers. Source: Wikipedia

Fuvemeh is located in the Volta River delta on the West African coast. This area is isolated, relatively poor, and has very little infrastructure, which all make data collection using traditional methods next to impossible.

Deltas are made up of sediments, such as sand or silt, which are transported by rivers and settle out of the water at the river’s mouth. The action of waves steadily erodes or wears away river deltas. Normally, the loss of the delta by erosion is replaced by new sediment brought by the river. The competition of these processes maintains a sediment balance.

However, human activity near Fuvemeh and globally has altered this balance. The construction of dams, berms, and other structures in the Volta River watershed has reduced the sediment that is carried to the coast. Global warming has led to higher sea levels (from the melting Greenland and Arctic ice-sheets) and increased rainfall. All three of these factors have combined to overall increase land erosion in Fuvemeh.

Figure 4 from Addo et al., 2018. This is a photo taken by the researchers’ drone during their study. The red line shows the shoreline in 2017 (that’s when the photo was taken), and the blue line shows the shoreline in 2005. The shoreline has moved inland from 2005 to 2017 due to land erosion (green lines), except for a small area in the far left, where accretion has created new land (yellow lines).
Figure 5 from Addo et al., 2018. This is an aerial photo taken in 2005. The blue line shows the shoreline as it was at that time. The red line shows the shoreline in 2017. The large area in between is land that has eroded away from 2005 to 2017.

The changes in shoreline extent between the figures above (Figure 4 and 5 from Addo et al., 2018) highlight just how useful drones can be for comparing current and previous shorelines. The researchers also demonstrated the usefulness of drones for observing destructive events like floods while they are occurring. Because drones can be controlled from a distance, unlike a manned aircraft which requires an on-board pilot and other crew, they can be flown into harm’s way without endangering its operators.

The ease of use of drones for real-time collection of disaster data, which can vastly improve response and management, greatly enhances their utility. It also results in striking photos like the following figures from the article.

Figure 8 from Addo et al., 2018 shows heavy waves during February of 2016 in Fuvemeh.
Figure 9 from Addo et al., 2018 shows floodwaters damaging homes (A) and canoes (B) in Fuvemeh.

Before accessible drones and the improvement in airborne cameras, such high-resolution, up-close, on-demand and real-time images were not possible to obtain.

These images can now be used to clearly demonstrate how human activities upriver on the Volta and globally (through climate change) are negatively affecting the Fuvemeh region.

The methods and drone technology used by the researchers can easily be replicated around the world in any area in which drone flights are physically possible. Drone technology, photo technology, and the incorporation of the two into usable platforms has advanced tremendously over the last few years. As photographic drones continue to increase in capabilities, their already-tremendous usefulness in ecological and disaster observation will only increase.

Note: The original article, including images and figures is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors are credited. No changes were made to the images.

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Munim Deen

Munim is an epidemiologist and cartographer. His primary interests are infectious disease outbreaks and their intersection with the environment, public policy, and society at large. A geographic information system (GIS) devotee, he incorporates mapping and spatial analysis into his work whenever possible. A former newspaper columnist, he holds a bachelor's degree in microbiology and a master's degree in epidemiology.

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