Application of marine radar to monitoring seasonal and event-based changes in intertidal morphology

Abstract

This paper demonstrates the application of marine radar and a newly developed waterline mapping technique to the continued surveillance and monitoring of inter-and intra-annual intertidal morphological change, thus capturing new detail on coastal system behaviours. Marine radar data from 2006-2009 are used to create a sequence of waterline elevation surveys that show clear morphological evolution of two different sites in the Dee estuary, UK. An estimate of volumetric change was made at two locations: West Hoyle sandbank and the NW Wirral beach. Both sites exhibited a similar cyclic pattern of volumetric change, with lowest volumes in autumn and winter, respectively. The average beach elevations above Admiralty Chart Datum clearly reflect the observed change in sediment volume, with reduced elevations in winter and increased elevations in summer, suggesting a trend of high-energy storm waves in autumn and winter that remove sediment and simultaneously moderate the vertical dimension of bedforms in the intertidal area. Data at this temporal and spatial scale are not easily obtainable by other current

Dynamic equilibrium behaviour observed on two contrasting tidal flats from daily monitoring of bed-level changes

“…The main limitation of the SED-sensors is that they take point measurements. Future studies could combine marine radar technology with SED-sensors to explore tidal flat dynamic equilibrium behaviours over larger scales while maintaining high monitoring resolution (Bell et al, 2016;Bird et al, 2017), and thus lead to improvements in current understanding of DET and morphological modelling.…”

Automatic Shoreline Position and Intertidal Foreshore Slope Detection from X-Band Radar Images Using Modified Temporal Waterline Method with Corrected Wave Run-up

“…Furthermore, this method was adopted by Wang et al [58], and its performances to fill the gaps in a global soil moisture dataset was analyzed. Recently, Bell et al [28] and Bird et al [29] have employed this algorithm to fill the gaps in beach profile data. This The mTWM with corrected wave run-up is applied to all alongshore locations to determine the spatio-temporal variation in shoreline positions for the entire study area over the period between April 12, 2005 andDecember 31, 2008, as shown in Figure 22.…”

“…Time-series of individual radar pixel intensities are gathered from hourly time-averaged images across the selected timescale of two weeks, including a full spring-neap cycle (as an example, June [17][18][19][20][21][22][23][24][25][26][27][28][29][30]2005). Figure 6a displays the cross-shore time stack images within the range between y = 5 m and y = 103 m. The red line marked in Figure 6b indicates the variation of the instantaneous waterline position digitized manually by visual inspection, and Figure 6c is the concurrent tidal records.…”

“…The most significant advantage of shoreline monitoring with X-band radar is that it can provide real-time and uninterrupted observations even in bad weather conditions. Since the last two decades, land-based remote sensing monitoring systems such as X-band radar have become popular in coastal studies [6,[25][26][27][28][29].…”

“…The vertical elevation bias between the compared results was approximately ±0.5 m, indicating that a relatively stable macrotidal environment was utilized as the test case. Furthermore, Bird et al [29] employed the TWM to monitor inter-and intra-annual intertidal morphological changes and described the seasonal variations in the morphology of Hilbre Island at the mouth of Dee Estuary, UK. The heterogeneous study area examined by Bird et al [29] found sandy, sandbank, intertidal sand flats, and saltmarsh beaches, along with several rocky outcroppings.…”