\chapter{Literature Review}
In this chapter, literature relevant to the present study will be reviewed.

\section{Separating incident and reflected components from wave buoy data}

The separation of incident and reflected waves is a crucial step in numerically
modeling a seastate. Using the raw data from a buoy as the input of a wave
model will lead to incorrect results in the domain as the flow velocity at the
boundary will not be correctly generated.

Several methods exist to extract reflected components in measured seastates,
and they can generally be categorised in two types of methods: array methods
and PUV methods \parencite{inch2016accurate}. Array methods rely on the use of
multiple measurement points of water level to extracted the incident and
reflected waves, while PUV methods use colocated pressure and velocity
measurements to separate incident and reflected components of the signal.

\subsection{Array methods}
\begin{itemize}
	\item \cite{mansard1980measurement}: Presentation of least-square method to separate
incident and reflected spectra. Requires simultaneous measurement at 3
positions, on a line parallel to the direction of wave propagation.
\parencite{gaillard1980}

	\item \cite{frigaard1995time}: Separate 2D wave field into waves propagating towards
and away from a structure, using 2 gauges. Method quite efficient, even with
small filters. SIRW Method, realtime.

	\item \cite{baldock1999separation}: Starting from \textcite{frigaard1995time},
arbitrary 2D bathymetry using linear shoaling. Small error for large reflection
coefficients, larger for low reflection.

	\item \cite{suh2001separation}: Technique to separate incident and reflected waves on
a known current.

	\item \cite{inch2016accurate}: creation of a lookup table to correct noise-induced
bias in array methods.

	\item \cite{andersen2017estimation}: estimation of incident and reflected components
for non-linear waves.

	\item \cite{roge2019estimation}: extension to irregular waves.
\end{itemize}

\subsection{PUV methods}

\begin{itemize}
	\item ?? \cite{guza1977resonant}: model of the surf zone as a standing wave combined
with a progressive wave. Accurate results of surface elevation and runup for
reflectivities over 0.3.

	\item ?? \cite{guza1984}: 

	\item \cite{tatavarti1989incoming}: Decompose colocated random field
		measurements of wave elevation and currenct velocity into incoming and
		outgoing components. Less sensitive to noise.

	\item \cite{kubota1990}: comparison between different wave theories:
		quasi-nonlinear long-wave theory gave the best results.

	\item \cite{walton1992}: application to beaches, possibility to have higher
	reflected energy than incident energy.

	\item \cite{hughes1993}: colocated horizontal and vertical velocities or
	horizontal velocity and surface elevation. Validation for full reflection of
	irregular non breaking waves.

	\item \cite{huntley1999use}: principal component analysis technique to avoid
	noise-induced bias.

	\item \cite{sheremet2002observations}:
\end{itemize}