Standards Development

Scope

This document specifies the operating methods for measuring tidal bore height, including general provisions for tidal bore measurement, manual observation, automatic observation, data processing and error control.

This document is applicable to the activity of in-situ measurement of tidal bore height.

Purpose

Tidal bores are complex shallow-water flows influenced by tidal phenomena. They are unique, fragile, and potentially destructive natural occurrences in estuaries and bays, forming an essential part of aquatic ecosystems and exemplifying the harmonious coexistence of humans and nature. Tidal bores are associated with tides, waves, hydrodynamics, sediment transport, deposition, ecology, and coastal climate change. Conducting on-site observations of tidal bores is crucial for understanding this phenomenon, refining theories, and advancing technology.

Tidal bores occur on all continents except Antarctica, with well-known tidal bore rivers including the Amazon River in Brazil, the Severn River in the UK, Cook Inlet in Alaska, the Qiantang River in China, and the Kampar River in Sumatra. Globally, tidal bore observation and research have been extensive and longstanding. Tidal bore height is one of the most fundamental and significant characteristics, and accurately measuring it is essential for tidal bore research. Field observations provide real-time data on tidal bores, helping track their temporal variations, leading to a deeper understanding of this phenomenon, and promoting its role in scientific education, ecological safety, and socio-economic development. The necessity of establishing standardized observations can be summarized as follows:

1. Promoting Unified Technical Standards

Tidal bores are highly turbulent, strongly intermittent, multi-scale, high-velocity, and intense two-phase flow phenomena, characterized by severe surface fluctuations and significant air entrainment. Furthermore, outdoor environmental conditions, transportation, weather, and safety concerns complicate field observations. Accurate measurement of tidal bore height requires clear specifications for instruments, observation methods, and data processing. Unified technical parameters and data formats provide standardized support for global tidal bore research, enhancing data interoperability and technological recognition while improving data-sharing efficiency worldwide.

2. Ensuring Safety in Water-Related Engineering and Navigation

Due to their high velocities, destructive power, and complex hydrodynamic properties, tidal bores pose significant risks to estuarine infrastructure and navigation. Their immense energy and impact pressure can damage water-related engineering projects, disrupt vessel operations, and threaten human livelihoods. For instance, before the Seine River in France was managed, unmonitored tidal bores capsized cargo ships and destroyed docks, resulting in the loss of hundreds of vessels. Observing tidal bores aids in developing extreme design conditions for water-related engineering projects, implementing early warning systems for tidal bore risks, and enhancing disaster prevention and mitigation frameworks.

3. Promoting Ecological Balance and Sustainable Development

Tidal bores create dynamic and unique ecosystems, serving as vital habitats for various marine and freshwater species. Carnivorous and scavenging animals frequently appear after tidal bores, preying on fish, crabs, and birds left behind. For example, in the Amazon region, Queensland's Styx River in Australia, and Cook Inlet in Alaska, predatory species such as piranhas, crocodiles, and eagles exploit post-bore feeding opportunities. The state of tidal bores is closely linked to the overall health and resilience of estuarine and coastal ecosystems. Observing tidal bores facilitates ecological conservation efforts and supports the construction of sustainable societies. 

4. Expanding Socio-Economic Activities

Tidal bores often have visual appeal and diversity, providing opportunities for recreational and tourism activities such as surfing and kayaking. Popular locations include the Amazon River in Brazil, the Batang Lupar River in Malaysia, the Qiantang River in China, and the Severn River in the UK, where various water sports, surfing events, and festivals thrive during peak tidal bore periods. Observing tidal bores contributes to ensuring the safety of economic and social activities while offering dynamic protection for participants.