Changeset 3252 for production/onslow_2006/report/discussion.tex

Timestamp:

Jun 28, 2006, 6:39:06 PM (18 years ago)

Author:

sexton

Message:

 

File:

• production/onslow_2006/report/discussion.tex (modified) (1 diff)

production/onslow_2006/report/discussion.tex

@@ +1 @@
+%As part of the CRA, it was decided to provide results for the
+%extremes of the tidal regimes to understand the potential range of impacts 
+%from the event. The Highest Astronomical Tide (HAT) and Lowest
+%Astronomical Tide (LAT) are defined as 1.5m AHD and -1.5m AHD 
+%respectively for Onslow, \cite{antt:06}. These values are tidal
+%predictions based on continous tidal observations from Standard Ports
+%over a period of
+%at least one year, with the Australian Hydrographic Service
+%recommending this be extended to three years to capture
+%changes to the mean sea level. Onslow is listed as
+%a Standard Port. 
 
-As part of the CRA, it was decided to provide results for the
-extremes of the tidal regimes to understand the potential range of impacts 
-from the event. The Highest Astronomical Tide (HAT) and Lowest
-Astronomical Tide (LAT) are defined as 1.5m AHD and -1.5m AHD 
-respectively for Onslow, \cite{antt:06}. These values are tidal
-predictions based on continous tidal observations from Standard Ports
-over a period of
-at least one year, with the Australian Hydrographic Service
-recommending this be extended to three years to capture
-changes to the mean sea level. Onslow is listed as
-a Standard Port. 
+%As an aside, current work at GA is
+%extracting information from LANDSAT imagery to reconstruct the 
+%tidal variations for various WA locations. Future modelling of
+%these areas will incorporate this information.
 
-Figure \ref{fig:contours} shows the contour lines for
-HAT, MSL and LAT for Onslow.
-It is evident from this figure that the extent of the tidal
-inundation is exaggerated which is due to
-short comings with the digital elevation model (DEM). The DEM has been 
+Initial simulations for this study used the DIGO DTED Level 2 data
+(see Section \sec:data} due to the fact it is
+``bare earth'', whereas the DLI data is distorted by 
+vegetation and buildings.
+Figure \ref{fig:contours_dted} shows the contour lines for
+HAT, MSL and LAT for Onslow using the DTED data. 
+It is evident from Figure \ref{fig:contours_dted}
+that the extent of the tidal inundation is exaggerated which is due to
+short comings with the digital elevation model (DEM) created from 
+the DTED data. The DEM has been 
 derived from 20m contour lines. {\bf Need some words from hamish here.}
-
-As an aside, current work at GA is
-extracting information from LANDSAT imagery to reconstruct the 
-tidal variations for various WA locations. Future modelling of
-these areas will incorporate this information.
+As a result, we turned to the WA DLI onshore data to present
+the results in this report. Figure \ref{fig:contours_dli} shows
+the contour lines for HAT, MSL and LAT for Onslow using the WA DLI data.
+It is obvious that there are significant differences in each DEM with
+secondary information regarding total station surveys and the knowledge
+of the HAT contour line pointing to increased confidence in the WA DLI
+data over the DTED data for use in inundation modelling.
 
 \begin{figure}[hbt]
 
   \centerline{ \includegraphics[width=150mm, height=100mm]
-{../report_figures/contours.jpg}}
+{../report_figures/contours_dted.jpg}}
 
-  \caption{Onslow regions showing the 1.5m AHD, 0m AHD and -1.5m AHD contour lines.}
-  \label{fig:contours}
+  \caption{Onslow region showing the -1.5m AHD (LAT), 0m AHD (MSL)
+ and -1.5m AHD (LAT) contour lines.}
+  \label{fig:contours_dted}
 \end{figure}
+
+\begin{figure}[hbt]
+
+  \centerline{ \includegraphics[width=150mm, height=100mm]
+{../report_figures/contours_dli.jpg}}
+
+  \caption{Onslow region showing the -1.5m AHD (LAT), 0m AHD (MSL) 
+and -1.5m AHD (LAT) contour lines.}
+  \label{fig:contours_dli}
+\end{figure}
+
+The purpose of this section then is to
+show the differences to the impact ashore when each data set is used
+to demonstrate the importance of using the best possible data set. As
+before, we show the time history of the water's stage and velocity for the
+point locations in Table \ref{table:locations} for the DTED data. 
+These results are shown in Section \ref{sec:timeseriesdted}.
+