X‐Band Radar Mapping of Morphological Changes at a Dynamic Coastal Inlet

Abstract

Remote sensing of the complex interactions between bathymetry, tidal flow, and waves in coastal inlets provides high‐resolution data sets that can be exploited to characterize the morphological variability of shallow ebb tidal deltas (ETD). Here we used observations from a mobile X‐band radar platform to determine optimal conditions during which radar‐derived shoal signatures best represent positions of underlying shoals. Significant increases in the spatial errors of radar shoal signatures were observed when offshore wave energy intensified. Consequently, the lowest spatial errors occurred when the radar shoal signatures were primarily a function of the tidal flow (i.e., low sea state). We used these findings to quantify shoal migration patterns at the New River Inlet, North Carolina. We found that the southwestern portion of the ETD had the largest morphological variability with typical shoreward migration rates of 2–3 m/day driven by incident wave energy. The migration rates and patterns estimated from X‐band observations were consistent with numerical modeling results and a previous video‐based New River remote sensing study. Our results confirm that X‐band radar can be used to quickly map shallow ETDs (e.g., 5 min of observations), allowing for rapid morphological assessments from shore or boat‐based platforms. The methods would prove particularly useful for initial assessment as well as continual monitoring of dynamic tidal inlets where large morphological responses can be rapidly assessed and used for geomorphological studies, and as decision aids for maritime or engineering operations.

Comprehensive Study of the Sand Spit Evolution at Tidal Inlets in the Central Coast of Vietnam

“…Using the same linear regression method for the data in Figures 8c and 9c, the growth rates of the sand spit area for both inlets are shown from Equation (8) to Equation (13) Substituting separately Equations ( 8)-( 13) into Equation ( 1) with the values of berm height D B = 3 m, and the depth of closure D C = 10 m for both the Ly Hoa and An Du coastal areas according to Hung [41], the LST rates for each period are expressed from Equation (14) to Equation ( 19) as follows.…”

“…Sophisticated numerical models that predict the hydrodynamics and sediment transport of the nearshore environments are reaching a level of complexity and numerical efficiency, but they require extensive data sets, including accurate and up-to-date bathymetric information [8][9][10][11]. As an alternative, remote sensing techniques such as video-camera systems [12], Light Detection and Ranging (liDAR) [13], X-band radar [14,15], and satellite imageries [16,17] can provide synoptic coverage over large areas with a wide range of temporal and spatial resolutions. Among these studies, Honegger et al (2020) [15] successfully extended the cBathy depth estimate algorithm to obtain the high-resolution bathymetry of a complex tidal inlet environment based on the time series of X-band radar image, while Rogowski et al (2018) [14] directly used X-band observations to accurately map the morphological changes in shallow ebb tidal deltas at the New River Inlet, North Carolina.…”

“…As an alternative, remote sensing techniques such as video-camera systems [12], Light Detection and Ranging (liDAR) [13], X-band radar [14,15], and satellite imageries [16,17] can provide synoptic coverage over large areas with a wide range of temporal and spatial resolutions. Among these studies, Honegger et al (2020) [15] successfully extended the cBathy depth estimate algorithm to obtain the high-resolution bathymetry of a complex tidal inlet environment based on the time series of X-band radar image, while Rogowski et al (2018) [14] directly used X-band observations to accurately map the morphological changes in shallow ebb tidal deltas at the New River Inlet, North Carolina. Although most remote-sensing technologies are low-cost, only satellite images are free, available in the long-term, and cover most places on earth.…”

X-Band Radar System to Detect Bathymetric Changes at River Mouths during Storm Surges: A Case Study of the Arno River

“…X-band radar systems have been used in coastal monitoring to detect morphological changes at a river mouth [ 21 , 22 , 23 , 24 ]. Remote sensing techniques are becoming increasingly popular thanks to their many advantages over in situ methods [ 25 , 26 , 27 , 28 ].…”