The Effect of Harbor Developments on Future High‐Tide Flooding in Miami, Florida

Abstract

Little is known about the effect of tidal changes on minor flooding in most lagoonal estuaries, often due to a paucity of historical records that predate landscape changes. In this contribution, we recover and apply archival tidal range data to show that the mean tidal range in Miami, Florida, has almost doubled since 1900, from 0.32 to 0.61 m today. A likely cause is the dredging of a ∼15 m deep, 150 m wide harbor entrance channel beginning in the early 20th century, which changed northern Biscayne Bay from a choked inlet system to one with a tidal range close to coastal conditions. To investigate the implications for high‐tide flooding, we develop and validate a tidal‐inference based methodology that leverages estimates of pre‐1900 tidal range to obtain historical tidal predictions and constituents. Next, water level predictions that represent historical and modern water level variations are projected forward in time using different sea level rise scenarios. Results show that the historical increase in tidal range hastened the occurrence of present‐day flooding, and that the total integrated number of days with high‐tide floods in the 2020–2100 period will be approximately O(103) more under present day tides compared to pre‐development conditions. These results suggest that tidal change may be a previously under‐appreciated factor in the increasing prevalence of high‐tide flooding in lagoonal estuaries, and our methods open the door to improving our understanding of other heavily‐altered systems.

Effect of Estuary Urbanization on Tidal Dynamics and High Tide Flooding in a Coastal Lagoon

“…Though our estimated values of P are not within the range for choking suggested by Hill (1994), a clear response to a perturbation of inlet depth is observed (a similar result was reported by De Leo et al. (2022) in Biscayne Bay, Miami, U.S.). Hence, modest changes to depth in shallow systems can have a noticeable effect in the tidal response, more so than in deeper systems.…”

“…It is likely that differences between the idealized setup by Stigebrandt (1980) and a real estuary, plus inherent uncertainties in how to estimate key parameters (e.g., surface area and inlet length), may lead to the discrepancies with analytical theory (see also De Leo et al. (2022)).…”

“…(2020)). Dynamical reasons for these changes include altered frictional effects, land reclamation, resonance, and alterations in tidal exchange at inlets (De Leo et al., 2022; Orton et al., 2020; Pareja‐Roman et al., 2020; Ralston et al., 2019). Tidal ranges and HTF frequency may be particularly sensitive to SLR and bathymetric changes in shallow estuaries where even modest interventions may significantly amplify the tidal response (Talke & Jay, 2020).…”

“…Factors that drive variations in HTFs may include sea‐level variability caused by the El Niño Southern Oscillation (Long et al., 2020), waves (Idier et al., 2019), the 18.6 and 8.85‐year cycles in tidal forcing (Baranes et al., 2020; Enríquez et al., 2022; Haigh et al., 2020; Ray & Foster, 2016), and changes in groundwater levels (Habel et al., 2020). At many locations, secular changes to tidal properties also lead to increased HTF frequencies, with an influence that sometimes approaches SLR effects (De Leo et al., 2022; Li et al., 2021; Ray & Foster, 2016; Talke & Jay, 2020). These observational studies motivate a question: how widespread and important are changes to tides to HTF probability, and why are tidal changes occurring?…”

“…Many lagoonal estuaries worldwide have undergone significant anthropogenic modifications, including harbor development, inlet deepening and widening, land reclamation, wetland loss, and shoreline hardening. Examples of altered lagoons include the Venice, Nador, and Marano‐Grado lagoons (Ferrarin et al., 2015; Umgiesser et al., 2014), the Ria de Aveiro in Portugal (Araújo et al., 2008), Florida's Intracoastal Waterway (Waterhouse et al., 2011), Biscayne Bay (De Leo et al., 2022), and Barnegat Bay (Kennish, 2001). These estuaries have undergone tidal changes, and many are subject to HTF (Rinaldo et al., 2008; USACE, 2021).…”