Characterization of the Morphological Behavior of a Sand Spit Using UAVs

Abstract

Sand spits are common in wave-dominated environments; with enough sand supply, they can evolve to affect circulation and navigation in channels or inlets. The focus of this paper is on the navigation channel of the Sisal Port, located on the northwestern Yucatan Peninsula (YP) coast, where a sand spit grew and was monitored from its formation (June 2018) until navigation was practically blocked (November 2018). The YP coast is characterized as being microtidal, with significant wave heights ranging from 0.1 to 0.4 m (April to September), and in the presence of high energy events (cold fronts and storms), waves can reach heights of up to 2.5 m offshore at 10 m depth (October to February). Prior to the beginning of UAV surveys, we used photos (June–July 2018) from a stationary field camera and hydrodynamic data from models (WaveWatch III for waves and MARV software for tidal levels) to generate a qualitative description of the sand spit in the channel. Combining products from UAVs flights (DEMs) and hydrodynamic measurements (wave energy flux), we characterized the behavior and response of the sand spit, from its formation near the jetty head, through its consolidation in October 2018, to when a cold front with HS ∼2.5 m breached it in mid-November. The results show that spit formation takes place during calm conditions (e.g., periods dominated by sea breezes), and depending on the energy threshold of high energetic events, this new spit will consolidate or be breached. Migration of the spit is related to overwash events and changes in wave direction. The presented methodology provides a well-rounded tool for characterizing the morphological behavior of spits on a shallow coast, which can be useful for improving coastal management.

Coastal Erosion Caused by River Mouth Migration on a Cuspate Delta: An Example from Thanh Hoa, Vietnam

“…The along-shore and cross-shore coordinates of the cuspate tips on both sides of the mouth of the Ma River were observed and are used for discussing the morphological be havior of the river's mouth. The method of using the coordinates of special points such as the tips of sand spits or the center of gravity to discuss the evolution of a sand body has been applied widely in coastal engineering [27,30,32,34,44,45]. Figure 6 illustrates the schematic for measuring the coordinates of the cuspate tips, which are considered the most prominent protrusions into the open water.…”

Coastal Erosion Caused by River Mouth Migration on Cuspate Delta: An Example from Thanh Hoa, Vietnam

“…In this section, the along-shore and cross-shore coordinates of the cuspate tips on both sides of Ma River mouth will be measured and used for discussing the morphological behavior of the river mouth. The method of using the coordinates of special points such as sand spit's tips or the central of gravity to discuss the evolution of a sand body has been applied widely in coastal engineering [26,28,29,31,41,42]. Figure 5 illustrates the schematic for measuring the coordinates of the cuspate tips, which are considered as the most prominent protrusions into the open water.…”