Structure‐from‐motion photogrammetry analysis of historical aerial photography: Determining beach volumetric change over decadal scales

Abstract

Historical aerial photographs are an invaluable tool in shoreline mapping and change detection in coastal landscapes. We evaluate the extent to which structure‐from‐motion (SfM) photogrammetric methods can be applied to quantify volumetric changes along sandy beaches, using archival imagery. We demonstrate the application of SfM‐derived digital surface models (DSMs) at East Beach and Lady Bay in southwest Victoria, Australia, using photographic datasets taken in 1969, 1977 and 1986, and compare them to LiDAR‐derived DSMs acquired at both sites in 2007. The SfM approaches resulted in two entire and two partial suitable DSMs out of six datasets. Good‐quality DSMs were spatially continuous with a good spread of ground control points (GCPs) near the beach at Lady Bay, whereas unsuitable DSMs were mostly restricted by poor distribution and number of GCPs in spatially segmented areas of East Beach, due to limited overlapping of images, possible poor quality of GCPs and also the propagation of errors in the derived point clouds. A volume of approximately 223 000 ± 72 000 m3 was deposited at Lady Bay between 1969 and 2007, despite minimal erosion observed near the breakwater. The partially suitable dataset of East Beach indicated that beach erosion of at least 39 m3 m−1 occurred immediately to the east of the seawall after 1977. We also discuss the drawbacks and strengths of SfM approaches as a benchmark of historical erosion assessments along sandy beaches. © 2020 John Wiley & Sons, Ltd.

Identifying oceanographic conditions conducive to coastal impacts on temperate open coastal beaches and the importance of empirical impact data

“…Over 2 km of East Beach is protected to some extent by these structures, but unprotected areas are reportedly receding at a rate of between 0.1-0.3 m yr -1 (Flocard et al 2013) and volumetric losses across the whole of East Beach have been estimated at 39 m 3 yr -1 between 1977 and 2007 (Carvalho et al 2020). The erosional behavior of this system has been highly in uenced by the management measures, particularly the construction of the Moyne River training walls which has reduced longshore sediment transport around Gri ths Island and into the system (Carvalho et al 2020).…”

“…It has since undergone a series of management measures including dredging of the Moyne River to maintain access after the installation of the training walls, installation of a basalt breakwater in 1910, a rock revetment in the 1950s which has been extended and altered over time and a series of timber groynes built in the 1970s (Flocard et al 2013). Over 2 km of East Beach is protected to some extent by these structures, but unprotected areas are reportedly receding at a rate of between 0.1-0.3 m yr -1 (Flocard et al 2013) and volumetric losses across the whole of East Beach have been estimated at 39 m 3 yr -1 between 1977 and 2007 (Carvalho et al 2020). The erosional behavior of this system has been highly in uenced by the management measures, particularly the construction of the Moyne River training walls which has reduced longshore sediment transport around Gri ths Island and into the system (Carvalho et al 2020).…”

Structure-from-Motion-Derived Digital Surface Models from Historical Aerial Photographs: A New 3D Application for Coastal Dune Monitoring

“…In coastal environments, the first papers to test this novel application were by [35,36], even though only [37] and [36] tried to quantify volumetric changes to assess coastal erosion issues. SfM techniques using more recent oblique aerial photographs were tested by [38] to measure the topographic changes of a coastal cliff.…”

“…SfM techniques using more recent oblique aerial photographs were tested by [38] to measure the topographic changes of a coastal cliff. As demonstrated by [36], SfM approaches applied to historical aerial photographs can be used to quantify volumetric changes along sandy coastlines if several key requirements are fulfilled during the image preparation and processing stages. Volume changes, particularly in coastal dune fields, need to be quantified at the best achievable spatiotemporal scale, considering the essential role that dunes play in the evolutionary process of a coastal site [39][40][41][42].…”

“…The self-calibrating bundle adjustment routines provided by commercial software and applied to historical aerial photographs can produce positional errors in planimetry of up to 10 m if the calibration parameters of the camera are unknown [45]. Unfortunately, calibration certificates are quite rare [36,45], as are documents relating to the planning and operation of the flights [45]. According to [35], the scale and special characteristics of each archival photogrammetric dataset are the most important factors affecting the choice of self-calibration model.…”