Fact-checked by Grok 2 weeks ago

Tidal bore

A tidal bore is a large, rapid surge of water forming a breaking wave or undulating series of waves that travels upstream along a river or narrow estuary against the prevailing current, driven by the incoming tide. It typically develops during periods of high tidal range, such as spring tides, when the tidal wave steepens due to frictional effects, channel convergence, and interaction with opposing river flow, resulting in a hydraulic jump-like phenomenon.^[1]^[2]^[3] Tidal bores exhibit distinct hydrodynamic characteristics, including heights ranging from 0.1 to over 5 meters, propagation speeds of 1 to 10 meters per second, and the generation of intense turbulence and mixing that can transport sediments and nutrients far upstream. They often produce a loud, rumbling noise resembling thunder or a freight train, accompanied by foaming white water at the front. Formation requires macro-tidal conditions with tidal ranges exceeding 4-6 meters, shallow channel depths, and funnel-shaped estuaries that amplify the tidal distortion.^[1]^[4]^[5]^[6] These phenomena occur globally in at least 117 rivers across 25 countries on six continents, primarily in regions with extreme tidal amplitudes like the Bay of Fundy.^[7] Notable examples include the Qiantang River bore in China, which can reach 9 meters high and 40 km/h, the Pororoca in Brazil's Amazon River, and the tidal bore in France's Seine River, each attracting surfers and observers due to their power and predictability. Tidal bores influence local ecosystems, navigation, and erosion patterns, and their study aids in understanding coastal dynamics and flood risks.^[2]^[8]^[9]^[5]

Fundamentals

Definition and Description

A tidal bore is a large-amplitude wave, or series of waves, generated by the incoming tide that propagates upstream into a river or bay, traveling against the prevailing river current.^[10]^[11] This phenomenon arises in estuarine environments where the rising tide creates a sudden and forceful surge of water, often in funnel-shaped channels that amplify the tidal energy.^[8] Unlike regular tidal movements, the bore forms a distinct hydraulic jump at its leading edge, resulting from the rapid transition of the tidal flow.^[11] Observationally, a tidal bore manifests as a dramatic and abrupt elevation of the water surface, typically appearing as a turbulent, breaking front that resembles a wall of churning water advancing upstream.^[12] Eyewitness accounts frequently describe the visual spectacle of foam-covered waves crashing forward, accompanied by intense turbulence that suspends sediments and creates a frothy surface.^[1] Auditorily, it produces a characteristic roaring or rumbling noise, akin to thunder or a distant train, which can be audible from several kilometers away due to the agitation of the water mass.^[13] Bore heights usually range from 0.5 to 2 meters, though exceptional instances can exceed 9 meters, highlighting their variable scale depending on local conditions.^[10]^[13] Tidal bores are distinctly tidal in origin, driven by gravitational forces from the sun and moon, setting them apart from tsunamis, which stem from sudden seismic or landslide displacements of the ocean floor.^[14] They also differ from storm surges, which result from meteorological effects like strong winds and low atmospheric pressure during cyclones, rather than periodic tidal cycles.^[15] This tidal basis underscores the bore's predictable recurrence with high tides, often under macro-tidal regimes with ranges exceeding 6 meters.^[11]

Etymology

The term "tidal bore" combines "tidal," referring to the influence of ocean tides, with "bore," which derives from Middle English *bore or bare, borrowed from Old Norse *bára meaning "billow" or "wave."^[16] This usage of "bore" to describe a sudden tidal surge first appeared in English around 1601, predating the compound "tidal bore," whose earliest recorded instance dates to 1836 in scientific and periodical literature.^[17]^[18] An archaic English term for certain tidal bores, particularly those on the Rivers Trent and Ouse, is "eagre" (also spelled "eagre" or "higre"), first attested in the mid-17th century and possibly derived from Old English ēagor meaning "flood" or "tide," or related to Old Norse ægir denoting "sea."^[19] This regional variant reflects local dialects in eastern England and was used interchangeably with "bore" until the 19th century, when standardized scientific terminology favored "tidal bore."^[20] In other languages, historical terms for tidal bores often evoke the phenomenon's roaring sound or dynamic appearance. The French "mascaret," applied to bores like that on the Seine, originates from Occitan mascaret, meaning "steer with a mottled face," likening the wave's foaming front to a herd of stampeding cattle; it entered common usage by the 16th century in Gascon dialects.^[21] In Portuguese, particularly for the Amazon River bore, "pororoca" comes from the Tupi-Guarani indigenous language, translating to "great roar" or "big noise," capturing the thunderous advance of the wave. For the Qiantang River bore in China, the term is "Qiántáng cháo" (钱塘潮), where "cháo" means "tide" or "surge," a designation rooted in classical Chinese texts dating back over a millennium, emphasizing the tidal essence without additional onomatopoeic flair. The adoption of "tidal bore" in 19th-century scientific literature, as seen in hydrological studies and tidal observations, marked a shift toward precise, descriptive nomenclature, replacing varied local terms with a unified English equivalent for global documentation.^[22]

Formation and Physics

Causes and Mechanisms

Tidal bores primarily form on macrotidal coasts, defined as those with a tidal range exceeding 4 meters, where the incoming tide interacts with river systems in specific geometric and hydrodynamic conditions.^[23] Essential prerequisites include funnel-shaped estuaries that narrow progressively upstream, causing the tidal wave to compress, steepen, and distort nonlinearly as it advances against the river flow.^[1] Additionally, the opposing river current must be weaker than the tidal inflow, typically requiring low freshwater discharge rates, such as around 150 m³/s in systems like the Garonne River, to allow the tide to overpower and reverse the flow.^[1]^[3] The Earth's rotation influences bore formation through the Coriolis effect, which deflects tidal currents and amplifies tidal ranges in certain latitudes by altering wave propagation in shelf seas and estuaries.^[24] In the Northern Hemisphere, this effect strengthens surface flows on the right-hand side when facing seaward, contributing to asymmetric tidal amplification in convergent channels conducive to bores.^[25] Seasonal variations significantly affect bore intensity, with stronger manifestations during equinoxes in spring and autumn, when the alignment of the sun and moon generates spring tides that maximize gravitational pull and tidal range.^[26] Lower freshwater discharge during dry seasons further favors bore development by reducing river opposition to the tide, while storm surges can elevate water levels and enhance tidal forcing, leading to more pronounced bores.^[1] Tidal bores are broadly classified into undular bores, which manifest as non-breaking undular waves forming a propagating wave train, and breaking bores, characterized by turbulent breaking waves.^[27] Undular bores occur under conditions of moderate nonlinearity and sufficient water depth, where the surge propagates without overturning, often in estuaries with Froude numbers below approximately 1.3 at the front.^[1] Breaking bores, in contrast, develop in shallower, more convergent settings with higher tidal velocities, where supercritical flow (Froude number exceeding 1.3) causes the wave front to break and generate turbulence.^[1]^[27]

Hydrodynamic Characteristics

Tidal bores are analyzed as propagating hydraulic jumps in shallow water flows, where their speed is approximated using the shallow water wave celerity formula c = \sqrt{g h}, with c denoting the bore speed, g the gravitational acceleration (approximately 9.81 m/s²), and h the undisturbed water depth ahead of the bore.^[1] This equation arises from the linearized shallow water equations, providing a first-order estimate for long-period waves like tidal bores under non-breaking conditions.^[1] Energy dissipation in tidal bores occurs mainly through turbulent mixing and bed friction, analogous to stationary hydraulic jumps, leading to gradual weakening as the bore advances. The process is governed by the momentum conservation equation across the bore front. For hydrostatic conditions per unit width and \rho = 1, this is h_1 v_1^2 + \frac{1}{2} g h_1^2 = h_2 v_2^2 + \frac{1}{2} g h_2^2, where h_1, v_1 and h_2, v_2 are the depths and velocities before and after the bore.^[1] This equation captures the abrupt transition from supercritical to subcritical flow, with energy loss quantified as \Delta E = \frac{(h_2 - h_1)^3}{4 h_1 h_2} g.^[1] As tidal bores propagate upstream against river flow, they experience deceleration due to boundary friction, resulting in decreasing speed and evolving amplitude and wavelength. In narrowing channel constrictions, bore height amplifies via shoaling, similar to wave focusing in shallower depths. Typical bore speeds range from 5 to 15 km/h, varying with local depth and geometry; for instance, in the Petitcodiac River, speeds reach 15 km/h during peak conditions.^[28] Hydrodynamic profiling of tidal bores relies on in-situ instruments like pressure sensors, which detect rapid water level surges at the front, and Acoustic Doppler Current Profilers (ADCPs), which map vertical velocity profiles and turbulence intensity. Pressure sensors, often sampled at high frequencies (e.g., 10 Hz), quantify amplitude and timing, while ADCPs provide 3D current data to validate momentum balances and dissipation rates.^[29]^[30]^[31]

Global Occurrences

Asia

Asia hosts several notable tidal bores, particularly in densely populated river systems where coastal tides interact with river flows, creating dramatic upstream waves with significant cultural and environmental roles. The Qiantang River in Zhejiang Province, China, exemplifies this phenomenon with what is recognized as the world's largest tidal bore, often called the "Silver Dragon." Formed by the East China Sea tides surging into the funnel-shaped estuary near Hangzhou Bay, the bore is amplified by the river's morphology, including a large underwater sandbar.^[32] This bore can achieve heights of up to 9 meters during peak conditions, particularly on spring tides, and propagates upstream at speeds of 6 to 12 meters per second (21.6 to 43.2 km/h), covering approximately 30 kilometers from the river mouth before dissipating.^[33] Historical records of the Qiantang bore date back to the 8th century, when it was described in writings as "The Old Faithful" for its predictable timing, with mentions appearing as early as the 7th and 2nd centuries BCE.^[34] Today, it draws global attention through an annual viewing festival, especially on the 18th day of the 8th lunar month, where thousands gather along the banks in Haining City to witness the spectacle, highlighting its regional cultural significance.^[35] In the Ganges-Brahmaputra delta spanning India and Bangladesh, smaller but consistent tidal bores occur in distributary channels, influenced by the Bay of Bengal's tides amid high sediment loads and seasonal monsoons. A prominent example is the "Baan" bore in the Hooghly River, a western distributary of the Ganges near Kolkata, India, which forms during high spring tides and reaches heights of 2.4 to 6.1 meters, traveling upstream for tens of kilometers.^[36] These bores in the delta, typically under 2 meters in the Brahmaputra's lower reaches, contribute to sediment redistribution and flooding dynamics in one of the world's most populated coastal regions.^[1] The Mekong River delta in Vietnam and Cambodia also experiences seasonal tidal bores, most pronounced during the dry season's low river flows when Bay of Bengal tides push upstream, creating waves observable in areas like Ben Tre Province with heights influenced by the meso-tidal range of up to 3.8 meters.^[37] These events, peaking in March and September, underscore the delta's vulnerability to tidal incursions amid changing river discharges.^[38]

Europe

Europe hosts several notable tidal bores, particularly in the United Kingdom and France, where they play key roles in shaping local river ecosystems through sediment redistribution and nutrient cycling. The Severn Bore on the River Severn in southwest England is one of the most prominent and accessible examples, forming due to the Bristol Channel's exceptional tidal range of up to 15 meters during spring tides. This bore reaches heights of up to 2 meters and propagates upstream for approximately 50 kilometers from the estuary near Avonmouth to Maisemore Weir near Gloucester, creating a visible wave front that stirs up sediments, alters water clarity, and transports organic debris, thereby influencing benthic habitats and fish migration patterns in the intertidal zones.^[26]^[10] The timing of the Severn Bore is precisely predictable using tide tables relative to high water at Avonmouth, occurring around 250 times annually with the strongest events near equinoxes, allowing for public viewing from accessible riverbanks and contributing to ecological monitoring efforts.^[26] In France, the historical mascaret on the Seine River was a significant tidal bore, reaching heights of up to 3 meters and traveling from the estuary at Le Havre upstream toward Rouen, where it historically supported dynamic estuarine ecosystems by enhancing sediment suspension and oxygenation. However, engineering interventions, including the construction of the Tancarville Canal in 1963 and extensive dredging of the estuary, have greatly diminished the bore, reducing it to occasional weak manifestations under conditions of large tides and low river discharge, thereby altering the river's hydrodynamic balance and associated habitats.^[39]^[10] Smaller tidal bores occur on other European rivers, such as the Wye in the UK, which experiences minor surges influenced by the same Bristol Channel tides, propagating limited distances and contributing modestly to local sediment dynamics in the Wye Valley's intertidal areas. The Severn Estuary, encompassing the Severn and Wye bores, benefits from EU environmental protections as a Special Area of Conservation under the Natura 2000 network, safeguarding its hyper-tidal ecosystems from development pressures and ensuring the bores' role in maintaining biodiversity.^[10]^[40]

North America

North America hosts some of the most prominent tidal bores on the continent, primarily driven by the extreme tidal ranges in the Bay of Fundy along the Canada-United States border, where incoming tides funnel into narrow estuaries and rivers. These bores form in several rivers emptying into the bay, including the Petitcodiac and Shubenacadie in New Brunswick and Nova Scotia, Canada, where the region's semidiurnal tides exceed 13 meters on average and can reach up to 16 meters during spring tides, creating powerful upstream surges.^[10]^[41] The Bay of Fundy is recognized globally for these tides, which amplify due to the basin's funnel shape and shallowing bathymetry, producing bores that propagate several kilometers inland.^[42] In the Petitcodiac River, the tidal bore historically reached heights greater than 2 meters before the construction of a causeway in 1968, which restricted tidal flow and diminished the phenomenon to rarely exceeding 1 meter.^[43] Restoration efforts culminated in the partial removal of the causeway and its replacement with a bridge opened in 2021, allowing tidal waters to flow freely once more and reviving the bore's extent up to about 10 kilometers upstream from the river mouth.^[44] The Mi'kmaq people, indigenous to the region, have long incorporated the river into their lore, with the name "Petitcodiac" possibly deriving from the Mi'kmaq term "Petkootkweăk," meaning "river that bends like a bow," or a related Maliseet word "petakuyak" evoking the "sound of thunder" akin to the bore's roar.^[44] The Shubenacadie River, also in Nova Scotia, features a bore typically around 0.3 meters but capable of surging higher during strong tides, extending variably upstream and attracting attention for its ecological role in sediment transport.^[10] Further south in the bay's system, smaller bores occur in rivers like the Hebert, Maccan, and Salmon, with heights near 0.3 meters and speeds up to 4-5 meters per second, contributing to the dynamic estuarine environment.^[10] In the United States, the Cook Inlet and its extension, Turnagain Arm in Alaska, produce notable bores influenced by the inlet's extreme 9-10 meter tidal range and glacial silt, resulting in a turbid, muddy wavefront.^[10] These bores reach heights of up to 1.8-3 meters and travel at speeds of 4.5-6.7 meters per second, propagating from Fire Island toward the Twentymile River over distances that vary with tidal strength.^[6] The phenomenon occurs daily, with complex wavefronts observed in studies, and the silt-laden waters enhance sediment deposition in the arm's fiord-like morphology.^[10]^[45] To the south, in the Colorado River Delta along the Mexico-United States border, estuarine tidal bores form in the upper Gulf of California but are now rare and smaller due to upstream water diversions and reclamation projects.^[10] Historically, these bores attained heights of up to 2 meters during spring tides, extending from Montague Island to El Mayor, though alterations since the mid-20th century have reduced their frequency and intensity.^[10]

South America

In South America, tidal bores are prominent in major river systems, particularly within the vast and biodiverse Amazonian basins, where their remote locations and powerful erosive forces shape estuarine environments. The most notable example is the pororoca on the Amazon River in Brazil, a tidal bore generated by the incoming Atlantic tide that propagates upstream as a series of undular or breaking waves. Reaching heights of up to 4 meters, the pororoca can travel approximately 800 kilometers inland, primarily during spring tides around the equinoxes in March and September, when tidal ranges are maximized. This phenomenon exerts significant erosive impact, uprooting trees, scouring riverbanks, and redistributing sediments in the Amazon estuary, contributing to dynamic channel morphology in otherwise stable tropical river systems.^[46] Similar tidal bores occur in the Orinoco River delta in Venezuela, where incoming tides reverse flow in distributary channels, forming waves that are more pronounced during the dry season (October to March) when river discharge is lower and tidal influence dominates. These bores, with heights typically under 2 meters, propagate several kilometers upstream in narrower caños, influencing sediment transport and water quality in the expansive deltaic wetlands. The Orinoco bores share the Amazon's remote character, occurring in sparsely populated regions that limit direct observation but highlight the role of tidal dynamics in tropical fluvial systems.^[47] Historical records of the Amazon pororoca date back to early European explorations, with Portuguese accounts from the 17th century describing its destructive force during expeditions into the estuary. Modern monitoring employs satellite imagery to track tidal bore propagation and its effects on fish migration patterns, revealing how these surges facilitate upstream nutrient transport that supports seasonal movements of species like the dorado catfish in Amazon floodplains. Such bores occasionally disrupt local navigation and fishing, though detailed economic assessments are addressed elsewhere.^[48]^[49]

Oceania

In Oceania, tidal bores are less common than in continental Asia or Europe due to the region's archipelagic geography and generally moderate tidal ranges, but notable examples occur in isolated coastal and riverine systems of Australia and Papua New Guinea, where large macrotidal amplitudes interact with funnel-shaped estuaries. These phenomena are influenced by regional ocean dynamics, including the strong tides of the Indian Ocean along Australia's northwest coast and monsoon-driven river flows in the Gulf of Papua. The Fitzroy River in Western Australia, discharging into King Sound near Derby, experiences powerful tidal bores at its mouth driven by some of the largest tidal ranges in the Southern Hemisphere, exceeding 11 meters during spring tides. These bores can capsize small vessels and are locally legendary for attracting sharks that follow the advancing wave. The river's tide-dominated delta amplifies the surge, creating hazardous conditions for navigation in this remote Kimberley region.^[50] In Papua New Guinea, the Fly River delta in the Gulf of Papua hosts regular tidal bores that propagate up to 200 kilometers inland, uprooting vegetation such as palms and altering shoreline habitats in the lowermost reaches. These bores contribute to tidally induced water level fluctuations extending 250 kilometers from the mouth, with strong currents and wave action observed during surveys, exacerbating sediment transport in the 90-kilometer-wide delta. Monsoon conditions, bringing heavy seasonal rainfall to upstream areas while the lower delta receives less than 100 inches annually, modulate river discharge and influence bore intensity, making the system particularly dynamic during wet periods from October to December.^[51] Aboriginal Australian Dreamtime narratives in coastal regions often incorporate themes of dramatic tidal or wave events, reflecting ancient observations of sea incursions and floods that parallel modern understandings of tidal surges. Anthropologist Norman B. Tindale documented numerous "tidal wave stories" across Australia, including accounts of sudden water rises that reshaped landscapes, distributed on annotated maps from his 1930s fieldwork; these oral traditions, passed through generations, emphasize ancestral beings shaping rivers and coasts amid rising waters. Such stories hold cultural significance for Indigenous communities along bores-affected rivers like the Fitzroy, linking environmental phenomena to spiritual and ecological knowledge.^[52] Recent climate monitoring in Oceania highlights sea-level rise's potential to alter tidal bore dynamics, particularly in northwest Australia. Projections indicate that a 1-meter uniform sea-level rise could decrease the amplitude of the dominant M₂ tidal constituent in King Sound by up to 20%, potentially dampening bore heights while increasing flooding risks in low-lying deltas; observations from tide gauges show accelerating mean sea levels at 0.113 mm/year² since the 1990s, prompting enhanced monitoring by the Australian Baseline Sea Level Monitoring Project to assess impacts on estuarine systems like the Fitzroy. In Papua New Guinea, similar monitoring tracks monsoon-enhanced bores amid regional sea-level increases of 6-8 mm/year, informing adaptation for vulnerable island and coastal communities.^[53]^[54] Tidal bores in Oceania, such as those on the Fly River, attract limited tourism focused on eco-observation and cultural tours.

Africa

Tidal bores in Africa occur in several river systems, particularly in coastal regions with significant tidal influences, contributing to sediment dynamics in deltas and estuaries. A notable example is the bore in the Pungue River delta in Mozambique, where a prominent tidal bore forms and reaches heights of about 0.7 meters approximately 50 kilometers inland. This small delta, covering 413 square kilometers, experiences the bore due to the interaction of ocean tides with the river mouth, influencing local erosion and deposition patterns.^[10] Other documented bores exist in West African rivers, such as those in Guinea-Bissau and Senegal, though they are less studied and often occur in remote areas with limited observation. These phenomena align with global patterns in macro-tidal environments and support the presence of tidal bores on every continent as noted in comprehensive catalogs.^[10]

Lakes

Tidal bores in lake systems are extremely rare, as most lakes are isolated from oceanic tidal influences and lack the necessary estuarine geometries for bore formation.^[10] Instead, true tidal bores occur only in tidally connected lake-like features, such as fjords or enclosed bays, where the incoming tide propagates against outgoing flows in shallow, narrowing channels. These atypical formations arise from the compression and acceleration of tidal waters in confined basins, often without the pronounced salinity gradients typical of riverine bores.^[10] In North America, the most prominent example is Turnagain Arm in Alaska, a narrow, fjord-like extension of Cook Inlet that functions as a lake-like tidal basin. Here, a daily tidal bore forms with each incoming high tide, reaching heights of up to 1.5–3 meters (5–10 feet) and speeds of 10–24 km/h (6–15 mph), driven by the region's extreme tidal range exceeding 9 meters (30 feet). The bore's formation is enhanced by the arm's shallow depths (averaging 3–6 meters) and funnel-shaped morphology, which amplifies the tidal wave as it advances upstream over mudflats.^[55]^[6] This phenomenon is observable from viewpoints along the Seward Highway and attracts surfers, though its force can erode shorelines and disrupt navigation.^[55] Seiches in the Great Lakes, such as those on Lake Erie and Lake Superior, are frequently mistaken for tidal bores due to their sudden water level surges, but they are actually wind- or pressure-driven standing waves rather than tidally generated. These oscillations can cause rapid rises of 1–2 meters over minutes, mimicking bore-like effects, yet they stem from basin resonance without oceanic tidal input.^[56]^[57] Connected lake systems like Lake Pontchartrain in Louisiana exhibit micro-tidal influences and surges that can resemble small bores during high tides or storms, as explored in recent hydrodynamic modeling. A 2023 study quantified nonlinear interactions between tides, surges, and mean flows in the estuary, revealing amplified water level variations up to 0.5 meters in the lake's northern reaches due to inlet constrictions.^[58] Such dynamics highlight how weakly tidal lakes can produce bore-like surges in hybrid estuarine environments.^[58] Outside North America, minor seiche events in Lake Geneva, Switzerland, have occasionally been conflated with tidal phenomena, but these are purely internal basin oscillations unrelated to tides.^[59] Overall, lacustrine tidal bores remain exceptional, confined to specific North American coastal basins where tidal propagation mimics riverine conditions in enclosed settings.^[10]

Impacts and Studies

Environmental and Ecological Effects

Tidal bores play a pivotal role in sediment dynamics within macrotidal estuaries, driving significant resuspension and upstream transport of fine sediments and associated nutrients. During bore propagation, suspended sediment concentrations can surge to 35 g/L, generating instantaneous fluxes up to 40 kg/m²/s, as observed in the Sée River estuary in Mont-Saint-Michel Bay, France. This enhanced transport deposits nutrients such as nitrates (0.76–5.73 mg/L) and phosphates (0.02–0.1 mg/L) farther upstream, as seen in Indonesia's Kampar River, where the "Bono" bore weakens in energy and releases materials, preventing stagnation and fostering nutrient enrichment for primary producers.^[60]^[61] Such deposition supports estuarine productivity but can elevate risks of eutrophication when nutrient levels exceed thresholds, like ammonia surpassing 0.016 mg/L in the Kampar system.^[61] The intense turbulence of tidal bores also accelerates erosion, reshaping riverbanks and estuarine morphology. In the Kampar River, bore passages cause notable bank scouring near Muda Island and the Sekap River mouth, leading to sediment redistribution that forms small islands and alters shorelines. Net sediment transport during bores is 2.6 to 3.8 times higher than during non-bore tides, amplifying erosion in vulnerable areas and contributing to habitat instability. Additionally, this resuspension redistributes pollutants bound to sediments, including industrial and agricultural contaminants, propagating them upstream and downstream in estuaries like Kampar, where low dissolved oxygen (3.95–4.51 mg/L) signals medium pollution levels exacerbated by bore-induced mixing.^[62]^[63] On biodiversity, tidal bores facilitate upstream fish migration by generating a propagating water surge that counters river flow, enabling species transit in systems like the Qiantang and Severn Rivers. This aids anadromous fishes in accessing spawning grounds, while the mixing of saline and freshwater layers enhances foraging opportunities through stirred organic matter. However, the bores' disruptive forces cause habitat scouring in riparian and intertidal zones, deforming soft sediments and displacing fauna such as fish and invertebrates onto floodplains, as documented in tropical rivers where inundation extends 500 m inland. Such erosion undermines riparian vegetation stability, threatening species reliant on bank habitats and potentially reducing local biodiversity through habitat fragmentation.^[64] Climate change, particularly rising sea levels, is projected to amplify tidal bores by increasing tidal amplitudes and bore heights. In the Malacca Strait, modeling indicates a 6–16% rise in M₂ tidal constituent amplitude by 2100 under sea level rise scenarios, leading to bore height increases of approximately 100 cm and heightened turbulent velocities (1.1–1.5 m/s).^[65] This amplification could accelerate tidal cycles via phase shifts, potentially elevating bore frequency and intensity in macro-tidal estuaries, with broader implications for sediment and nutrient fluxes.^[65]

Human and Economic Impacts

Tidal bores present substantial navigation hazards, particularly for small vessels, as the abrupt wave front can overwhelm and capsize boats, resulting in loss of life. In regions like the Canadian Arctic, bores have frequently overturned small craft during their passage.^[66] Historically, such phenomena have contributed to maritime disasters; for example, a tidal bore on the Indus River is believed to have destroyed much of Alexander the Great's fleet in 326 BCE during his retreat from India.^[34] On the Severn River in England, the bore has long complicated upstream shipping to Gloucester by creating turbulent conditions and debris hazards, though modern canal routes have mitigated some risks.^[34] Infrastructure in bore-affected areas faces repeated threats from flooding and erosion, with ports, bridges, and riverbanks suffering significant damage during high-magnitude events. In the Bay of Fundy region of Canada, where powerful bores propagate up rivers like the Petitcodiac, tidal flooding has inundated coastal infrastructure, necessitating multimillion-dollar repairs. Hurricane Fiona in September 2022 exacerbated these issues in the Fundy area, causing over $660 million in insured damages across Eastern Canada through combined storm surge and tidal amplification, including erosion of dikes and roadways.^[67] Agriculturally, tidal bores facilitate saltwater intrusion by propelling saline water farther upstream, leading to soil salinization in adjacent fields and reduced crop productivity. In the macro-tidal Petitcodiac River estuary within the Bay of Fundy, the bore induces episodic salinity spikes in river water and adjacent groundwater, elevating chloride levels and stressing nearby farmlands despite diking efforts.^[68] Climate change intensifies these impacts via sea-level rise, which modeling predicts will boost tidal bore amplitudes in vulnerable estuaries like the Petitcodiac, potentially worsening post-2022 flood severity and intrusion. For example, a 16.35% increase in principal lunar semi-diurnal tide height has been projected for similar macro-tidal systems such as Indonesia's Kampar Estuary.^[69]

Scientific Research and Observations

Scientific research on tidal bores has evolved from early theoretical frameworks to advanced empirical and computational approaches, providing insights into their formation, propagation, and hydrodynamic effects. In the 19th century, Lord Rayleigh applied wave theory to describe long waves and bores, laying foundational principles for understanding their steady-state motion in two dimensions.^[70] His work, detailed in a 1914 publication, modeled bores as part of nonlinear wave propagation, influencing subsequent analyses of solitary and undular waves.^[70] Modern numerical modeling has advanced this foundation, employing software like HEC-RAS for simulating unsteady tidal flows in estuarine systems. HEC-RAS, developed by the U.S. Army Corps of Engineers, uses the shallow water equations to replicate bore propagation and interaction with river discharge, as demonstrated in simulations of coastal-river interfaces.^[71] Similarly, the SWAN model, a third-generation spectral wave tool, incorporates tidal currents to predict wave modulation in shallow waters, though its application to bores focuses on energy dissipation via bore-based breaking mechanisms. These tools enable high-resolution predictions of bore height and speed, validated against field data in funnel-shaped estuaries.^[72] Field observations have benefited from technological innovations since the 2010s, with drone-based systems providing real-time velocity tracking of bore propagation. Unmanned aerial vehicles equipped with computer vision algorithms have measured bore speeds in dynamic estuarine environments, offering non-intrusive data on surface elevations and flow patterns.^[73] Satellite imagery, such as from the SWOT mission, has captured longitudinal profiles of tidal waves, revealing bore structures in rivers like the Severn with unprecedented spatial resolution.^[74] As of 2025, AI-enhanced models integrated with multispectral satellite and drone data have achieved high accuracy in water quality forecasting during bore events, as demonstrated in the Qiantang River using Bayesian-optimized XGBoost for suspended sediment and turbidity predictions.^[75] Tidal bores serve as natural laboratories for turbulence research, where breaking fronts generate intense shear layers and mixing zones observable in field and lab settings. Studies highlight how bores induce lateral flows and turbulent kinetic energy dissipation in meandering channels, contributing to broader understandings of geophysical fluid dynamics.^[25] Recent deployments in the Qiantang River, including 90 buoys with GPS and distributed acoustic sensing along 30 km of fiber optics, have quantified multi-scale hydrodynamics during bore events in 2024.^[76]^[77] Experimental setups in laboratory flumes replicate tidal bores to isolate variables like Froude number and channel geometry. Rectangular flumes, often 10-20 m long, use rapid gate operations or downstream level changes to generate undular or breaking bores, measuring pressure, velocity, and turbulence with acoustic Doppler velocimeters.^[78] These controlled simulations validate numerical models and reveal front dynamics, such as impact pressures up to 2-3 times hydrostatic values in breaking regimes.^[79]

Cultural and Recreational Aspects

Historical Significance

The earliest documented observations of tidal bores date back over two millennia in ancient China, where annals from the 7th and 2nd centuries BCE describe the dramatic surges of the Qiantang River bore, known locally as a formidable natural force that inspired both awe and caution among early inhabitants.^[34] During the Han Dynasty (206 BCE–220 CE), records indicate that viewing the bore became a cultural tradition, with communities gathering along the riverbanks to witness its power, often associating it with mythical elements for protection. For instance, eight iron oxen statues, each weighing about 1.5 tons, were erected near Haining village during the Qing Dynasty in the 18th century to symbolically ward off the bore's destructive assaults, reflecting beliefs in its supernatural origins.^[80]^[81] These ancient accounts highlight the bore's role in shaping early Chinese perceptions of environmental hazards and celestial influences. In the colonial era, European explorers encountered tidal bores in the Americas, notably during 17th-century expeditions along the Amazon River, where the pororoca—a Tupi indigenous term meaning "great roar" or "destroyer"—posed significant navigational challenges.^[82]^[83] Indigenous lore in the region mythologized the pororoca as a monstrous entity or ominous spirit, heralded by a thunderous roar that foretold floods and destruction, influencing local communities to view it as a harbinger of natural upheaval or divine warning.^[82]^[83] In Europe, tidal bores like the mascaret on the Seine River have been noted in historical records since the Middle Ages, with French folklore depicting them as omens or divine warnings, leading to the construction of protective dikes and religious rituals along the estuary. In North America, indigenous groups in Alaska, such as the Dena'ina, have long observed the Turnagain Arm bore, incorporating it into oral traditions as a powerful spirit of the water that demands respect to avoid its dangers.^[84] The 20th century brought new interactions with tidal bores through recreational pursuits, exemplified by the first recorded instance of bore surfing on the UK's Severn Bore in 1955, when Lieutenant Colonel Jack Churchill rode the wave on a custom 16-foot surfboard, transforming the phenomenon from a historical hazard into a sporting milestone.^[85] This event, occurring on July 21, built on centuries of observation while marking a shift toward human mastery over the bore's force, though it echoed ancient indigenous views of such waves as powerful omens requiring respect and preparation.^[85]

Surfing and Tourism

Tidal bore surfing originated on the River Severn in England, where Lieutenant Colonel Jack Churchill became the first documented rider on July 21, 1955, using a custom 16-foot board to navigate a 5-foot wave for over a mile.^[85] This pioneering feat marked the birth of river surfing, transforming the bore from a natural hazard into a recreational pursuit. Over the decades, advancements in wetsuit technology have enabled surfers to endure the cold, debris-laden waters of bores worldwide, expanding the sport from its UK roots to global hotspots.^[85] Modern wetsuits provide thermal protection and abrasion resistance, essential for extended rides on unpredictable waves like the Severn Bore, which can last up to 1 hour and 16 minutes as demonstrated by Steve King's 2006 Guinness World Record of 7.6 miles (12.2 km).^[86] Key destinations for bore surfing include the Turnagain Arm in Alaska, where guided tours navigate 3-10 foot waves amid glacial scenery, and the Pororoca on Brazil's Amazon River, offering rides up to 12 feet high at 30 mph.^[83] These sites attract adventure seekers through operator-led expeditions that combine surfing with cultural immersion, emphasizing preparation for hazards like strong currents and submerged obstacles.^[83] Annual events further boost participation, such as Brazil's National Pororoca Surfing Championship in São Domingos do Capim, held during peak equinox tides in March and September, drawing competitors for record-breaking runs exceeding 30 minutes.^[87] The sport drives substantial economic benefits through tourism, with the global tidal bore surfing market valued at $340 million in 2024 and projected to reach $720 million by 2033 at a CAGR of 8.7%.^[88] In the Bay of Fundy, Canada, the tidal bore supports eco-tourism via activities like guided rafting, enhancing local economies through visitor spending on accommodations, equipment rentals, and related services tied to the region's extreme 16-meter tides.^[89] Safety protocols have evolved to mitigate risks, including mandatory helmets, buoyant boards, and guided supervision on tours to address debris and rapid currents, particularly after increased incident awareness in the 2010s prompted stricter operator guidelines.^[83] Post-COVID recovery has accelerated eco-tourism around tidal bores, with travelers favoring sustainable, low-impact experiences that promote conservation alongside adventure.^[88] Operators now incorporate eco-friendly practices, such as biodegradable surfboards and habitat protection initiatives, aligning with broader trends in responsible recreation.^[88]

References

[1]
Tidal bore dynamics - Coastal Wiki
May 31, 2025 · The formation of tidal bores is mainly governed by the progressive distortion of the tidal wave as it propagates up the estuary. This extreme ...
[2]
Catalog of worldwide tidal bore occurrences and characteristics
Formation of a bore is dependent on depth and velocity of the incoming tide and river outflow. Bores may occur in series (in several channels) or in succession ...
[3]
Consideration of the Mechanisms for Tidal Bore Formation in an ...
Jul 23, 2018 · According to Chanson (2011a), a tidal bore occurs when tidal range exceeds 4–6 m and the flood tide is confined within a narrow, funnel shaped ...
[4]
[PDF] Lecture 7: Tidal Bores - WHOI GFD
Tidal bores form in rivers due to the steepening of tides, caused by differences in velocity and height, and the distance upstream can be calculated.
[5]
Experimental research on the impact pressure of tidal bore fronts - NIH
May 10, 2024 · A tidal bore is formed when tidal flow travels upstream against the current of a river or narrow estuary. Famous tidal bores can be found in ...
[6]
[PDF] ALASKA BORE TALES - National Weather Service
They have been described as breaking waves as high as 26 feet, sounding like locomotive trains, foaming and frothing along at speeds between 6 and 24 mph.Missing: famous | Show results with:famous
[7]
Tidal Bore - National Geographic Education
Oct 19, 2023 · The tide behind the wave makes the river's water rise for hours after the bore passes. A tidal bore can be quite violent.Missing: speed characteristics
[8]
Tidal Waves, Tidal Bores and Tsunamis | Geophysical Institute
Aug 15, 1983 · Some of the other famous tidal bores in the world occur in Canada's Bay of Fundy, in the Seine River of France, and in the Amazon River. A tidal ...Missing: characteristics | Show results with:characteristics
[9]
[PDF] Catalog of Worldwide Tidal Bore Occurrences and Characteristics
Formation of a bore is dependent on depth and velocity of the incoming tide and river outflow. Bores may occur in series (in several channels) or in succession.
[10]
[PDF] tidal bores - The University of Queensland
A tidal bore is a positive surge of tidal origin that may occur in an estuary when the tidal flow turns to rising; the existence of a tidal bore is linked with ...
[11]
Weird Science: Tidal Bores: The Longest Waves Ever Ridden
In places where an incoming high tide enters a shallow and sloping estuary, river, or harbor, the higher water level can form a wave called a tidal bore (SF Fig ...
[12]
Silver Dragon - Marine Science Institute. The University of Texas at ...
May 17, 2020 · The silver dragon is the tallest of all tidal bores. It flows from Hangzhou Bay, on China's eastern coast. The bay is about 60 miles wide as it ...
[13]
What is the difference between a tsunami and a tidal wave?
Although both are sea waves, a tsunami and a tidal wave are two different and unrelated phenomena. A tidal wave is a shallow water wave caused by the ...
[14]
What is storm surge? - NOAA's National Ocean Service
Jun 16, 2024 · Storm surge is the rise in seawater level caused solely by a storm; while storm tide is the observed seawater level during a storm, ...Missing: bore distinction
[15]
bore - Wiktionary, the free dictionary
Etymology 2 From Middle English *bore, bare, a borrowing from Old Norse bára (“billow, wave”), from Proto-Germanic *bērō (“that which bears or carries”), from ...
[16]
bore - Humanterm UEM | Plataforma colaborativa
bore: A tidal flood with a high abrupt front. Example: A dangerous bore at the mouth of the Amazon. . First Known Use: 1601, in ...
[17]
tidal bore, n. meanings, etymology and more
The earliest known use of the noun tidal bore is in the 1830s. OED's earliest evidence for tidal bore is from 1836, in Monthly Magazine.
[18]
EAGRE Definition & Meaning | Dictionary.com
Origin of eagre. 1640–50; apparently representing earlier agar, ager, obscurely akin to hyger, higre; (compare Anglo-Latin (12th century) higra the tidal bore ...Missing: etymology | Show results with:etymology
[19]
Eagre - WorldWideWords.org
Jun 10, 2006 · Eagre is an older dialect name for the phenomenon on the rivers Ouse and Trent as well as the Severn. It's been written in many ways, among them ...
[20]
mascaret - Wiktionary, the free dictionary
Etymology. Borrowed from Occitan mascaret (“steer with a mottled face”). The appearance of the tidal bore was thought to resemble a herd of stampeding cattle.
[21]
[PDF] Tidal Bores, Aegir, Eagre, Mascaret, Pororoca - NET
Aug 9, 2011 · The French name is 'mascaret' that is said to derive from the Gascony word. 'masquaret' meaning a 'galloping ox' (Petit Robert 1996). In Japan, ...
[22]
Macrotidal - Oxford Reference
Applied to coastal areas where the tidal range is in excess of 4 m. Tidal currents dominate the processes active in macrotidal areas.
[23]
Coriolis and tidal motion in shelf seas - Coastal Wiki
Oct 14, 2024 · Tidal waves in wide basins are strongly influenced by earth's rotation (Coriolis acceleration). Tidal waves turn around so-called amphidromic ...
[24]
Structures of Lateral Flow and Turbulence in a Breaking Tidal Bore ...
The Coriolis acceleration has the same direction as the centrifugal acceleration during flood tides and offsets much of the centrifugal acceleration during ebb ...
[25]
Tidal river bores | National Tidal and Sea Level Facility
The Qiantang river at Hangzhou in China has the largest tidal river bore in the world, which can be over 4m high, 3km wide, and travelling with a speed in ...Missing: recorded credible sources
[26]
Tidal river dynamics: Implications for deltas - AGU Journals - Wiley
Feb 29, 2016 · Tidal bores can be undular or breaking. Undular tidal bores occur most often and are characterized by a train of advancing free-surface ...
[27]
[PDF] Momentum Considerations in Hydraulic Jumps and Bores
Apr 1, 2012 · In this study, the application of the momentum principle in its integral form is revisited for a hydraulic jump in an irregular chan- nel ...
[28]
Tidal Bore - Bay of Fundy
As the maelstrom of roaring, churning water races upstream at speeds close to 15 km per hour (10 mph) it generates rapids in its wake that are between 3 and 3.5 ...
[29]
Tidal bore dynamics in funnel‐shaped estuaries - AGU Journals
Jan 9, 2015 · The formation and dynamics of tidal bores in funnel-shaped estuaries is investigated from both a global tidal wave scaling analysis and new ...Missing: credible | Show results with:credible
[30]
Sediment transport induced by tidal bores. An estimation from ...
The SSC measurements coupled with ADCP velocity data are used to calculate the instantaneous sediment transport (qs) associated with the tidal bore passage (up ...
[31]
Monitoring Tidal Bores using Acoustic Tomography System
Apr 11, 2016 · Since a point/vertical measurement cannot represent a river's cross section, the ADCP data for velocity and water level (pressure) near the ...Methods · Results · Discussion
[32]
Hydrodynamics of the Qiantang Tidal Bore and Its Responses to ...
The tidal bore height is one of the indicators of the strength of the tidal bore. During tidal bore propagation, the bore front advances upstream with a defined ...<|control11|><|separator|>
[33]
Tidal bore impact pressures on a trestle pier in the Qiantang River ...
Oct 26, 2022 · Field observation results of the QRTB indicate that its maximum velocity is generally 6–8 m/s, with a measured peak velocity of 12 m/s. Damage ...Results · Tidal Bore Profiles · Tidal Bore-Induced PressuresMissing: source | Show results with:source
[34]
Tidal bores, Mascaret, Pororoca. Myths, Fables and Reality
(1) The word mascaret is the French translation of tidal bore. The front of the tidal bore was locally called 'la barre'. It is thought that the word 'mascaret' ...
[35]
Enthusiasts gather by Qiantang River to capture spectacular tidal ...
Sep 18, 2024 · The Qiantang River tidal bore, a natural wonder, has lured numerous enthusiasts to Haining City in east China's Zhejiang Province to capture the mesmerizing ...
[36]
Hugli (Hooghly) River (NE India) - Sea-Seek
Extreme tidal bores are most prevalent in March and September and reach heights of 2.4 to 6.1m. During the Northeast Monsoon, from November to February, ...
[37]
Vietnam Uncovered: 27 Fast Facts For The Curious Traveller
Rating 4.5 (15) Dec 11, 2023 · " During high tide, seawater is pushed up the Mekong River, creating a tidal bore that can be observed in locations like the town of Ben Tre.
[38]
Tidal wave propagation along The Mekong deltaic coast
May 1, 2019 · At the mouths of the Mekong River, the maximum and mean tidal ranges are 3.8 m and 2.5 m, respectively (Saito et al., 2015). The average tide ...Missing: bore height
[39]
Tidal bore of the Seine river : mascaret - School of Civil Engineering
Translations of the word tidal bore include : Tidal bore (English) = Mascaret (French) = Pororoca (Portuguese, Brazil) = Aegir (or eagre) (Celtic). Risle river ...
[40]
The Severn Estuary - RSPB
The Severn Estuary is one of Europe's largest, a vital wildlife habitat with a 14m tidal range, supporting many birds and fish, and is a key migration route.
[41]
Bay of Fundy – WHSRN
The upper Bay of Fundy is recognized for having the highest tides in the world, rising and falling 13 meters on average and more than 16 meters during spring ...<|separator|>
[42]
Where is the highest tide? - NOAA's National Ocean Service
Jun 16, 2024 · The highest tides in the world can be found in Canada at the Bay of Fundy, which separates New Brunswick from Nova Scotia.
[43]
THE DAMMING OF THE PETITCODIAC RIVER: SPECIES ... - BioOne
Mar 1, 2003 · By interfering with migrations, the causeway dam eliminated or greatly reduced the populations of most diadromous fishes, including a large ...
[44]
Ain't No Bore - Petitcodiac Watershed Alliance
Jun 15, 2023 · This series will highlight 25 ecologically, historically, or socially important sites within the watershed to inspire curiosity surrounding our local ...
[45]
deBoer, D.G., 2007 - Deposition and preservation of estuarine ...
Turnagain Arm is home to a tidal bore generated during spring tides that can reach heights of up to 2 m and travel at speeds of up to 5 m/s.
[46]
[PDF] ENVIRONMENTAL IMPACT OF TIDAL BORES IN TROPICAL RIVERS
Breaking bores are rare, often restricted to king tide conditions and localised in some estuarine sections. For example, the pororoca is primarily an undular ...
[47]
Movie:TidalBoreAK - CSDMS
Abstract: This movie features the tidal bore in the Turnagain Arm of Cook Inlet, near Anchorage, Alaska. This tidal bore can be up to 2 metres and travels at 20 ...<|separator|>
[48]
Orinoco River Delta, Venezuela, South America - WWD Continents
Most of the channels are strongly influenced by tidal action, particularly during the dry season. Tidal range in the delta proper is 1.77 m. The subaerial ...
[49]
[PDF] Flooding in Central Chile: Implications of Tides and Sea Level ...
Nov 22, 2018 · When the river flow rate stayed below 40 m3/s, the tidal wave was clear. When the flow rate fluctuated between. 40–65 m3/s, the tidal range ...<|separator|>
[50]
The Amazon's Treasure - Revista Pesquisa Fapesp
In an eighteenth-century book, a Portuguese Jesuit shows empathy for Indigenous peoples and, as a naturalist, describes rivers, plants, and animals.Missing: records | Show results with:records
[51]
Amazon Hydrology From Space: Scientific Advances and Future ...
Oct 12, 2021 · Further developments in satellite observations are nevertheless required to fully characterize Amazon surface water extent and elevation.Missing: bore | Show results with:bore
[52]
Australia's Largest Tides - Australian Extremes
Feb 15, 2023 · New research done by the Australian Navy has found the largest tidal variation for Australia to be at Raft Point, 70km east of Yampi Sound.
[53]
Sailing Trip from Brooklyn to Spencer on the Hawkesbury River
Jul 1, 2024 · Sometimes in narrow channels between the islands, you had to time it to transit at slack tide as the tidal bore could be as much as 5 knots.A short clip riding the tidal bore on the River Ribble in the UK.Satellite images of Hawkesbury River sludge on 10th and 15thMore results from www.facebook.com
[54]
[PDF] An Ichthyological Survey of the Fly River in Papua New Guinea with ...
Long stretches of the shore are littered with uprooted palms and other trees displaced by tidal bores that regularly affect the lowermost 200 km of the Fly.
[55]
'Tidal Wave stories' | SA Museum
Annotated map of Australia showing distribution and types of Aboriginal tidal wave stories. Contains references to Tindale's manuscript notes, ...Missing: bore | Show results with:bore
[56]
[PDF] The impact of sea-level rise on tidal characteristics around Australia
Feb 15, 2019 · Sea-level rise causes new amphidromic systems in the Gulf of Carpentaria, large changes in the Arafura Sea, and dissipation changes in north- ...Missing: bores | Show results with:bores
[57]
Australian Baseline Sea Level Monitoring Project - BoM
The project is designed to monitor sea level around the coastline of Australia. The ultimate goal is to identify long period sea level changes, with particular ...
[58]
Alaska Bore Tide: When, Where & How To See It | ALASKA.ORG
Alaska's most famous bore tide occurs in Turnagain Arm, just outside Anchorage. It builds up to 6 – 10 feet tall and can reach speeds of 10 to 15 miles per ...Missing: America | Show results with:America
[59]
Seiches on the Great Lakes often mistaken for tides - MSU Extension
Sep 1, 2015 · Many people often mistake a seiche for a tide on the Great Lakes. Tides are changes in water levels as a result of gravitational forces of the moon and the sun.
[60]
What is a seiche? - NOAA's National Ocean Service
Jun 16, 2024 · A seiche is a standing wave in which the largest vertical oscillations are at each end of a body of water with very small oscillations at the node, or center ...
[61]
Quantification of the nonlinear interaction among the tide, surge and ...
Sep 5, 2023 · Li et al. Circular plumes in Lake Pontchartrain estuary under wind straining: estuarine ... research (Hu et al., 2023). The time series of ...<|control11|><|separator|>
[62]
Strong bottom currents in large, deep Lake Geneva generated by ...
Sep 3, 2024 · three Poincaré waves in 309-meter deep Lake Geneva (Switzerland/France) generate bottom-boundary layer currents up to 4 cm s−1. Poincaré wave ...Missing: tidal bore
[63]
https://www.sciencedirect.com/science/article/pii/S2307410825000537
[64]
[PDF] Nutrient Condition of Kampar Big River Estuary - E-Journal UNDIP
It deposits nutrients in the upstream when energy transport of tidal bore becomes weaker. (Chanson, 2004). Seabed erosion occurs on every wave crest that ...
[65]
Environmental Effect of Tidal Bore Propagation in Kampar River
Sep 22, 2025 · Sediment motion under tidal bores has a difference with the traditional theory in the river. There is rarely literature that reveals sediment ...
[66]
Water quality in the macro-tidal Kampar estuary, Indonesia
The tidal bore passages can cause significant sediment transport and resuspension through oscillation mechanisms, affecting upstream and downstream areas ...
[67]
(PDF) Environmental, ecological and cultural impacts of tidal bores ...
Its occurrence is essential to many ecological processes and the survival of unique ecosystems. The tidal bore is also an integral part of the cultural heritage ...
[68]
Seen an interesting tidal bore recently? - Nunatsiaq News
... tides rather than neap tides. There are many aspects to my study, including safety, as bores have quite often capsized small boats with loss of life. So if ...
[69]
Repairs to N.B.'s flooded roads expected to cost millions | CBC News
May 8, 2008 · The province spent about $500,000 repairing roads after the last major flood in 2005. But this year's damage is expected to be much worse, ...
[70]
[PDF] The Costs of the Climate Emergency - Ecology Action Centre
The Insurance Bureau of Canada (IBC) reported an estimated $660 million CAD in insured damages to Eastern Canada from Fiona,.
[71]
Impacts of groundwater dynamics around a macro-tidal river on ...
Jun 1, 2024 · A macro-tidal estuary with a tidal bore experiences episodic periods of increased salinity. Tidal forcing impacts groundwater levels and salinity close to the ...
[72]
Effects of Sea-Level Rise on Tidal Bore Characteristics and ...
Aug 19, 2025 · Additionally, the tidal bore height is expected to increase by about 0.5 m, while turbulent velocity may rise by 5 to 15%, further ...
[73]
On the theory of long waves and bores - Journals
In the theory of long waves in two dimensions, which we may suppose to be reduced to a "steady" motion, it is assumed that the length is so great in ...
[74]
Shallow Water or Diffusion Wave Equations
As mentioned previously, HEC-RAS has the ability to perform two-dimensional unsteady flow routing with either the Shallow Water Equations (SWE) or the Diffusion ...
[75]
Numerical simulation of tidal bores and hydraulic jumps
The three test cases include a) the propagation of a highly nonlinear tidal wave which develops into a periodic bore; b) the propagation and reflection of a ...
[76]
Automatic tracking and intelligent observation of tidal bore ...
In this article, we construct a tidal observation system framework based on UAV and computer vision in order to obtain the tidal bore propagating velocity ...Missing: satellite | Show results with:satellite
[77]
[PDF] Water Quality Inversion for Tidal Surge on Qiantang River Based on ...
By leveraging drone remote sensing technology, this study addresses the limitations of traditional monitoring methods in expansive water bodies, ...
[78]
New discovery in Qiantang River: Matrix tides unveiled - Zhejiang
Sep 19, 2024 · The 2024 expedition began on Aug 21, with over 100 researchers conducting studies along the Qiantang River. They focused on tidal patterns and ...Missing: quantum sensor
[79]
Multi-scale Hydrodynamics Monitoring Using Distributed Acoustic ...
The system leverages a 30-kilometer segment of communication fiber installed in the Qiantang River estuary, an area renowned for its significant tidal bore ...
[80]
Experimental research on the impact pressure of tidal bore fronts
May 10, 2024 · In this study, we conducted experiments by simulating tidal bores in a glass rectangular flume. We obtained the the instantaneous pressure of ...
[81]
Flume Experiment Investigation on Propagation Characteristics of ...
Mar 2, 2023 · In this study, the flume experiments for both undular and breaking bores' propagation in curved channel are performed to measure the free-surface elevation and ...
[82]
Qiantang River Tidal Bore: Photography, Best Time & Pictures
Qiantang River Tidal Bore (钱塘江观潮) is one the largest tidal bores in the world which reaches the most spectacular on the eighteenth day of the eight month ...
[83]
[PDF] Mythology in the Tides - IJESI
Feb 4, 2025 · The tidal bore is discussed and related to mythological and useful means of protection.Missing: omens indigenous lore
[84]
A Brief History Of Amazon Exploration | SA Vacations
Mar 1, 2020 · The first European to travel up the entire Amazon was the Portuguese explorer Pedro Teixeira. ... 17th century and throughout the 18th century.Missing: pororoca | Show results with:pororoca
[85]
Surfing the Brown Wave in Brazil: The Amazon's Pororoca
May 9, 2023 · In the past, the Pororoca was mythologized by locals as a monster because its passage usually floods low-lying lands adjacent to the river ...Missing: historical | Show results with:historical
[86]
Ultimate Guide to Tidal Bore Surfing: How to Ride River Waves
Indigenous legends speak of a great roar that heralds its arrival, a sound that still sends chills down surfers' spines today. The Future of Tidal Bore Surfing.
[87]
Colonel 'Mad Jack' Churchill surfed the 'Severn Bore' in ...
In 1955 a true British character Colonel 'Mad Jack' Churchill surfed the 'Severn Bore' in Gloucestershire on a homemade 14 foot surfboard.
[88]
Severn Bore: the birthplace of river surfing - Surfer Today
The Severn bore has its dangers - rocks, debris, car tires, livestock, and logs can get in the way, especially closer to the river banks. It can also get so ...Missing: navigation historical
[89]
People surf on the wave of a tidal bore known as "Pororoca" during...
Mar 23, 2015 · People surf on the wave of a tidal bore known as "Pororoca" during the annual surfing Pororoca festival in Sao Domingos do Capim.
[90]
Tidal Bore Surfing Tourism Market Research Report 2033
As per our latest market intelligence, the Global Tidal Bore Surfing Tourism market size was valued at $340 million in 2024, and is forecasted to hit $720 ...
[91]
Bay of Fundy Tides: The Highest Tides in the World!
A tidal bore is a tidal phenomenon in which the leading edge of ... – Jan 14, 2013: max tidal difference was 8.4 meters and the max height was 8.7 meters.Missing: credible | Show results with:credible<|control11|><|separator|>