Other Titles
Wave Monitoring in Shallow Water Tidal Environments
Wave Measurements in Extremely Shallow Waters
Wave Measurements Along Tide Flats
Wave Attenuation on Tide Flats
Wind Wave and Wake Wave Measurements Along Mudflats 

ABSTRACT

Keywords: wave measurements, shallow waters, wave dissipation, oyster reefs, wake waves, sonic sensors.

1. Introduction

[DK - I'm jotting down thoughts, will clean up after]
Waves have the power to move sediment and alter landscape. The larger the wave, the more power and erosive potential it has. Therefore much of the historic scientific focus on waves has been on large waves approaching the coast from deep water. However, small shallow water waves also have the power to erode shorelines, and rising sea levels are putting many traditionally stable shorelines at increased risk of shoreward retreat. Shoreline protection projects are being planned, designed, and implemented all over the world. These projects take many shapes and sizes, ranging from hardened "gray" infrastructure projects, such as concrete seawalls or jetties, to softer "green" infrastructure projects, such as oyster reef restoration or mangrove forest restoration. In order to plan and design these projects effectively, understanding wave climate at the project location can be critical to project success. Additionally, with an increased focus around the world on green infrastructure "living shorelines" projects in all shapes and sizes, it is important to develop an accurate understanding of project efficacy, which is often assumed with little to no monitoring data to back it up. This is especially true when it comes to wave data, as one of the more important elements of shoreline protection is absorption or attenuation of wave energy as it comes in contact with the shoreline, and measurement of that effect can be difficult and expensive. 
Shallow-water wave measurement presents a number of challenges -- particularly in a tidal environment where rapid variations in depth can make measurement of small waves a moving target. Traditional wave measurement techniques were primarily developed for deep water and large waves, and in many cases are not ideal for small shallow-water waves in a tidal system.  This is further explained below [or, maybe a table? thinking on it]
Why do we want to measure shallow water waves, specifically?
-          Has implications related to shoreline erosion and infrastructure planning
-          Has implications related to living shorelines ‘fad’
o   Efficacy is often assumed, with very little research to prove it
However, measuring waves is expensive and costly
-          And most wave measurement technology is developed for deeper water, different kinds of waves
Challenges of Shallow-Water Wave Measurement
-          Difficulty using typical methods
o   ADCP has blanking distance, and it’s a very big instrument (burying has its own complications)
o   Pressure sensor does not work well in tidal scenarios due to depth decay
§  Even in array, complications
§  Changes in water density in an estuary due to fresh water lens during wet-weather freshening
-          Loose substrate on seabed can interfere with instrumentation when installed at bottom
-          Rapid variations in water depth create difficult measurement
-           
Challenges of Wind-Wave Measurement
-          Noise, need very high frequency
-          They do not work within confines of wave theory
o   Wind-forced waves are not the same, spectrum necessary
-          Buoys do not work well with small waves, not enough buoyancy with a small wave
USGS China Camp Study
-          Spent big to measure, failed
Solutions
Sonic Waves
-          Benefits
o   Cost efficient (ish), very high fidelity data
o   No biofouling and limited salt water corrosion
-          Limitations
o   Computer and wifi range
o   Battery length
o   Data can be noisy (but at 32Hz that’s ok)